Monitoring Renal Perfusion Using Ultrasound

Abstract

The blood flow monitor includes an ultrasound transducer probe with a two-dimensional array of transducer elements. An adhesive patch is connected to the ultrasound transducer probe and configured to attach the ultrasound transducer probe to a patient. The blood flow monitor also includes a system memory that stores beamformer software code. A processor is in communication with the ultrasound transducer probe and the system memory. The processor is configured to execute the beamformer software code to steer a beam and scan the patient with the array of transducer elements to find a Doppler flow signal of a target blood flow in the patient.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 63 / 479,250, entitled "MONITORING KIDNEY PERFUSION USING ULTRASOUND," filed January 10, 2023, the disclosure of which is incorporated herein by reference in its entirety. [Background technology]

[0002] Acute kidney injury (AKI) occurs when the kidneys experience a sudden decrease in function. AKI can be a complication of major abdominal surgery and, if not detected and treated early, can increase a patient's risk of chronic kidney disease. Reduced perfusion to the kidneys during surgery is one cause of AKI. Detecting AKI in patients has traditionally been done by looking at two biomarkers. The first biomarker is analyzing the patient's urine output, and the second biomarker is measuring serum creatinine from the patient's blood sample. These biomarkers generally do not appear in patients until approximately 8 to 48 hours after kidney injury. Due to the slow onset of these biomarkers, physicians can only use them to detect whether AKI has occurred relatively long after kidney damage has occurred; they cannot be used to monitor kidney health in real time during surgery. The ability to monitor kidney health during surgery not only provides physicians with the ability to detect AKI early, but also, in some cases, to prevent AKI in patients. Summary of the Invention [Means for solving the problem]

[0003] The renal blood flow monitor includes an ultrasound transducer probe with a two-dimensional array of transducer elements. An adhesive patch is connected to the ultrasound transducer probe and configured to attach the ultrasound transducer probe to a patient and maintain contact between the patient and the ultrasound transducer probe without an operator. The renal blood flow monitor also includes a beamformer for driving the two-dimensional array of transducer elements. The beamformer is configured to cause the two-dimensional array of transducer elements to emit multiple ultrasound beams from the two-dimensional array of transducer elements and track a Doppler flow signal of the patient's renal blood flow relative to the array of transducer elements.

[0004] A method for monitoring a patient's renal blood flow is disclosed. The method includes positioning an ultrasound transducer probe over the patient's abdomen. The ultrasound transducer probe includes a two-dimensional array of transducer elements. The patient's abdomen is scanned by the two-dimensional array of transducer elements, and a beamformer drives the array of transducer elements to find and sense Doppler flow signals of the patient's renal blood flow. The ultrasound transducer probe is attached to the patient's abdomen by an adhesive patch connected to the ultrasound transducer probe. The ultrasound transducer probe is at a location over the patient's abdomen where the Doppler flow signals of the patient's renal blood flow are found. The beamformer and the array of transducer elements track-scan the Doppler flow signals of the patient's renal blood flow and continuously sense the Doppler flow signals of the patient's renal blood flow during surgery, medical procedures, or medical observations without an ultrasound operator.

[0005] The organ blood flow monitor includes an ultrasound transducer probe with a two-dimensional array of transducer elements. An adhesive patch is connected to the ultrasound transducer probe and configured to attach the ultrasound transducer probe to a patient. The organ flow monitor also includes a beamformer for driving the two-dimensional array of transducer elements. The beamformer is configured to cause the two-dimensional array of transducer elements to emit multiple ultrasound beams from the two-dimensional array of transducer elements and track a target organ blood flow signal relative to the array of transducer elements.

[0006] A method for monitoring organ blood flow in a target organ of a patient during surgery, medical treatment, or medical observation is disclosed. The method includes positioning an ultrasound transducer probe over the patient's abdomen. The ultrasound transducer probe includes a two-dimensional array of transducer elements. A beamformer drives the array of transducer elements to scan a target organ location in the patient and find a Doppler flow signal of the patient's organ blood flow. An adhesive patch connected to the ultrasound transducer probe attaches the ultrasound transducer probe to the patient at the target organ location where the Doppler flow signal of the patient's organ blood flow is found. The beamformer track-scans the Doppler flow signal of the patient's organ blood flow and continuously senses the Doppler flow signal of the patient's organ blood flow during surgery, medical treatment, or medical observation without repositioning the ultrasound transducer probe.

[0007] The renal blood flow monitor includes an ultrasound transducer probe and an adhesive patch connected to the ultrasound transducer probe for attaching the ultrasound transducer probe to the patient, and includes an organ recognition algorithm configured to distinguish the renal blood flow signal from a non-renal blood flow signal based on a waveform characteristic of the renal blood flow signal.

[0008] The renal blood flow monitor includes an ultrasound transducer probe with an array of transducer elements. An adhesive patch is connected to the ultrasound transducer probe and configured to connect the ultrasound transducer probe to a patient. The renal blood flow monitor also includes a system memory that stores beamformer software code. A processor is in communication with the system memory and the control module of the ultrasound transducer probe. The processor is configured to execute the beamformer software code to beam scan the patient with the array of transducer elements and determine a Doppler flow signal of the patient's renal blood flow.

[0009] The blood flow monitor includes an ultrasound transducer probe with a two-dimensional array of transducer elements. An adhesive patch is connected to the ultrasound transducer probe and configured to attach the ultrasound transducer probe to a patient. The blood flow monitor also includes a system memory that stores beamformer software code. A processor is in communication with the system memory and the ultrasound transducer probe control module. The processor is configured to execute the beamformer software code to steer a beam and scan the patient with the array of transducer elements to find a Doppler flow signal of a target blood flow in the patient.

[0010] This Summary is provided by way of example only, and not by way of limitation. Other aspects of the disclosure will be understood upon consideration of the entire disclosure, including the entire text, claims, and accompanying figures. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram illustrating an exemplary blood flow monitor with an ultrasound transducer probe attached to a patient's abdomen by an adhesive patch. [Figure 2] FIG. 2 is another schematic diagram illustrating the blood flow monitor of FIG. 1. [Figure 3] FIG. 1 is a schematic diagram of an ultrasound transducer probe attached to a patient's abdomen by an adhesive patch for monitoring the patient's kidneys. [Figure 4A] FIG. 1 is another schematic diagram of an ultrasound transducer probe attached to a patient's abdomen by an adhesive patch for monitoring the patient's kidneys. [Figure 4B] FIG. 1 is another schematic diagram of an ultrasound transducer probe attached to a patient's abdomen by an adhesive patch for monitoring the patient's kidneys. [Figure 5] 1 is a schematic diagram of an ultrasound transducer probe with an array of transducer elements. [Figure 6] FIG. 10 is a schematic diagram illustrating another exemplary blood flow monitor with two ultrasound transducer probes attached to a patient's abdomen for monitoring both of the patient's kidneys. [Figure 7] FIG. 1 is a schematic diagram illustrating two blood flow monitors and two ultrasound transducer probes attached to a patient's abdomen to monitor blood flow in the patient's kidneys and liver. [Figure 8]2 is a chart from an experiment showing a first plot of renal blood flow measured by the blood flow monitor of FIG. 1 compared to both a second plot of renal blood flow measured by an invasive transonic flow probe and a plot of mean arterial blood pressure (MAP). [Figure 9] FIG. 1 is a schematic diagram illustrating another exemplary blood flow monitor with an ultrasound transducer probe attached to a patient's abdomen by an adhesive patch. [Figure 10] FIG. 10 is another schematic diagram illustrating the blood flow monitor of FIG. 9. [Figure 11] FIG. 1 is a block diagram of a method for continuously monitoring blood flow in an organ of a patient. [Figure 12] FIG. 1 is a block diagram of another method for continuously monitoring blood flow in an organ of a patient. [Figure 13] FIG. 1 is a schematic diagram illustrating another exemplary blood flow monitor. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present disclosure is directed to a system and method for real-time monitoring of blood flow in a patient's abdominal organs (e.g., kidneys) during a surgical procedure, medical treatment, or medical observation of the patient. The system includes a blood flow monitor with an ultrasound transducer probe. The system also includes an adhesive patch capable of attaching the ultrasound transducer probe to the patient and maintaining the ultrasound transducer probe attached to the patient throughout the surgical procedure, medical treatment, or medical observation of the patient without assistance from an ultrasound operator. The blood flow monitor also includes a beamformer and ultrasound front-end (UFE) circuit in communication with the ultrasound transducer probe for driving an array of transducer elements of the ultrasound transducer probe.

[0013] In this disclosure, a Doppler flow signal is defined as comprising an ultrasound pulse-echo signal received from tissue that has been filtered to contain only those spectral components with a Doppler shift large enough to be reliably identified as being caused by flowing blood cells. An instantaneous spectrum is defined as the power spectrum of a windowed portion of the Doppler flow signal, with the window centered at a particular time point. In this disclosure, a Doppler spectrogram is defined as a time-frequency representation of a Doppler flow signal, in which instantaneous spectra are calculated for many time points to characterize how the instantaneous spectrum changes over time. Doppler spectrograms are often visualized as heatmap plots, with frequency along one axis and time along a second axis. The relative intensity of a Doppler spectrogram can be interpreted as an indication of the proportion of scatterers with a particular velocity (i.e., a particular Doppler shift) at a particular time point. Negative frequency components of the Doppler spectrogram arise from scatterers moving away from the ultrasound transducer probe, while positive frequency components arise from scatterers moving toward the ultrasound transducer probe. The integrated power spectrum is defined as containing the integral of the Doppler spectrogram along the frequency dimension. The integration of the Doppler spectrogram can be performed over the entire frequency range, over only positive frequencies, over only negative frequencies, or over some other subset of frequencies. In cases where the signal from a particular blood vessel is desired, the integrated power spectrum will be calculated over a range of frequencies appropriate to isolate the Doppler flow signal from that vessel from interfering signals from nearby vessels.In particular, because blood flow in the renal artery is directed toward the ultrasound transducer probe and blood flow in the renal vein is directed away from the ultrasound transducer probe, the integrated power spectrum calculated for the renal artery may include integral values ​​over only positive frequencies, while the integrated power spectrum calculated for the renal vein may be calculated over only negative frequencies.

[0014] Depending on the application, the system can be configured to measure flow in many different arteries or veins in various organs using the same techniques described in this disclosure for scanning, tracking, and measuring Doppler signals. When the method is not specific to a particular vessel, the vessel being tracked will be referred to as the target vessel.

[0015] The beamformer is configured to continuously track the Doppler flow signal of a patient's organ blood flow (e.g., kidney blood flow) by emitting a set of sequential beams from the array of transducer elements and tracking the Doppler flow signal of the organ blood flow for the array of transducer elements focused at different locations. By tracking the Doppler flow signal of the organ blood flow, the beamformer enables the ultrasound transducer probe to continuously sense the Doppler flow signal of the organ blood flow throughout the entire surgical procedure, medical procedure, or medical observation without moving or readjusting the position of the ultrasound transducer probe on the patient. Even if the organ shifts position within the patient's abdomen, the beamformer enables the ultrasound transducer probe to continue sensing the organ blood flow without moving or readjusting the position of the ultrasound transducer probe on the patient. The ultrasound transducer probe sends real-time, continuous readings of the organ blood flow to a blood flow monitor for organ health monitoring and perfusion throughout the duration of the surgical procedure, medical procedure, or medical observation. The blood flow monitoring system is described in detail below with reference to Figures 1-13.

[0016] FIG. 1 is a schematic diagram of a patient 10 and a monitoring system 11 that continuously monitors organ blood flow in the patient 10 during a surgical procedure, medical treatment, or medical observation. As shown in the example of FIG. 1, the monitoring system 11 may include a renal blood flow monitor 12, an ultrasound transducer probe 14, an adhesive patch 16, ultrasound front-end circuitry 17, a system processor 18, a system memory 20 with software code 22, a probe cable 24, an analog-to-digital (ADC) converter 26, and a display 28. The software code 22 may include a transducer probe control module 30 and an injury monitoring module 32. The display 28 may include a user interface 34, a plot 36, and an injury score indicator 38. FIG. 1 also illustrates the abdomen 40 of the patient 10, along with kidneys 42L and 42R, a liver 44, and a spleen 46. In the example of FIG. 1, the monitoring system 11 is monitoring renal blood flow in kidney 42L of the patient 10. In other examples, monitoring system 11 can be used to monitor hepatic blood flow in liver 44, to monitor peritoneal blood flow in spleen 46, pancreas (not shown), and stomach (not shown) of patient 10, to monitor mesenteric blood flow in the intestine, and / or to monitor portal vein blood flow from the stomach of patient 10. Thus, renal blood flow monitor 12 can be adapted as an organ blood flow monitor 12 for any abdominal organ of patient 10.

[0017] Renal blood flow monitor 12 can be an integrated hardware unit including, for example, system processor 18, system memory 20, display 28, ultrasound front-end circuitry 17, and ADC 26. In other examples, any one or more components and / or described functionality of the organ blood flow monitor can be distributed among multiple hardware units. For example, in some examples, display 28 can be a separate display device that is remote from and operably coupled to renal blood flow monitor 12. While generally shown and described in the example of FIG. 1 as an integrated hardware unit, it should be understood that renal blood flow monitor 12 can include any combination of devices and components electrically, communicatively, or otherwise operably connected to perform the functionality attributed to renal blood flow monitor 12 herein.

[0018] The ultrasound transducer probe 14 can be attached or secured to the patient 10 by an adhesive patch 16. In the example of FIG. 1 , the ultrasound transducer probe 14 is positioned on the abdomen 40 of the patient 10 over at least a portion of the kidney 42L. The adhesive patch 16 can include a sheet of structural material (e.g., fabric or flexible plastic) with a layer of bonding adhesive deposited on its surface. The adhesive patch 16 can be bonded or mechanically connected to the ultrasound transducer probe 14 or to a frame (not shown) connected to the base of the ultrasound transducer probe 14 and can extend outward from the ultrasound transducer probe 14 along the surface of the abdomen 40 of the patient 10. In another example, the adhesive patch 16 can be placed over the ultrasound transducer probe 14 to attach the ultrasound transducer probe 14 to the abdomen 40 of the patient 10. The adhesive patch 16 maintains the ultrasound transducer probe 14 attached to the patient 10 and fixed in place throughout the duration of the surgery, medical procedure, or medical observation of the patient 10. Because the adhesive patch 16 keeps the ultrasound transducer probe 14 stationary and in contact with the patient 10, an ultrasound operator or technician is not required to maintain the ultrasound transducer probe 14 in place during the surgery, medical procedure, or medical observation. A coupling layer (not shown) comprising couplant material can be positioned between the skin of the patient 10 and the ultrasound transducer probe 14. The coupling layer enables transmission of ultrasound energy between the skin of the patient 10 and the ultrasound transducer probe 14.

[0019] In the example of FIG. 1 , the ultrasound transducer probe 14 detects and senses a Doppler flow signal DF of the kidney 42L. The ultrasound transducer probe 14 can be operably connected to the renal blood flow monitor 12 by a cable 24. Via the cable 24, the ultrasound transducer probe 14 can receive electrical signals from an ultrasound front-end circuit 17 of the renal blood flow monitor 12 and relay ultrasound signals received from the patient 10 to the renal blood flow monitor 12 for extraction of the Doppler flow signal DF of the kidney 42L. In another example, the ultrasound front-end circuit 17 combined with the ultrasound transducer probe 14 can be battery-powered and include a receiver for wirelessly receiving commands from the renal blood flow monitor 12. The combined ultrasound front-end circuit 17 and ultrasound transducer probe 14 can also include a transmitter for wirelessly communicating the Doppler flow signal DF of the kidney 42L to the renal blood flow monitor 12 for analysis. In some examples, the combined ultrasound transducer probe 14 and ultrasound front-end circuitry 17 provide the Doppler flow signal DF to the renal blood flow monitor 12 as an analog signal 25, which is converted by the ADC 26 into digital hemodynamic data representative of renal blood flow in the kidney 42L. In other examples, the combined ultrasound transducer probe 14 and ultrasound front-end circuitry 17 can provide the sensed Doppler flow signal DF to the renal blood flow monitor 12 in digital form, in which case the renal blood flow monitor 12 can not include or utilize the ADC 26. In yet other examples, the ultrasound transducer probe 14 can provide the Doppler flow signal DF of renal blood flow in the kidney 42L to the blood flow monitor 12 as an analog signal 25, which is analyzed by the blood flow monitor 12 in its analog form.

[0020] The system memory 20 can be configured to store information within the renal blood flow monitor 12 during operation. The system memory 20 is described in some examples as a computer-readable storage medium. In some examples, the computer-readable storage medium can include a non-transitory medium. The term "non-transitory" can indicate that the storage medium is not embodied in a carrier wave or propagated signal. In certain examples, the non-transitory storage medium can store data that may change over time (e.g., in RAM or cache). The system memory 20 can include both volatile and non-volatile computer-readable memory. Examples of volatile memory can include random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), and other forms of volatile memory. Examples of non-volatile memory can include, for example, a magnetic hard disk, an optical disk, flash memory, or electrically programmable memory (EPROM) or electrically erasable and programmable (EEPROM) memory.

[0021] As shown in FIG. 1 , the system memory 20 of the renal blood flow monitor 12 can store software code 22 that forms a monitoring model for the renal blood flow monitor 12. The software code 22 can include a transducer probe control module 30 for controlling and commanding the ultrasound transducer probe 14. The transducer probe control module 30 includes a beamformer, as discussed in more detail below with reference to FIG. 2 , that maintains the ultrasound transducer probe 14 focused on the renal blood flow in the kidney 42L and continuously senses and communicates a Doppler flow signal DF of the renal blood flow to the renal blood flow monitor 12 throughout the surgical procedure, medical treatment, or medical observation of the patient 10. The software code 22 can also include an injury monitoring module 32 that includes acute kidney injury (AKI) monitoring software code and / or specific organ injury (SOI) monitoring software code. This code is monitoring software code that enables the injury monitoring module 32 to determine renal blood flow characteristics of the patient 10 in real time, monitor the renal blood flow characteristics over time, and determine an AKI risk score for the patient 10 from the characteristics and the renal blood flow Doppler flow signal DF of the kidney 42L. The AKI risk score represents the probability that the kidney 42L is experiencing or approaching AKI. When the monitoring system 11 is used to monitor organs other than the kidneys 42L and 42R of the patient 10, the injury monitoring module 32 can be adapted to determine a real-time organ injury risk score from the organ blood flow Doppler flow signal of the organ being monitored (e.g., the liver 44).

[0022] The system processor 18 is a hardware processor configured to execute software code 22 implementing the transducer probe control module 30 and the injury monitoring module 32, to continuously sense the Doppler flow signal DF, and to monitor the Doppler flow signal for AKI of the kidney 42L. Examples of the system processor 18 may include any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other equivalent discrete or integrated logic circuitry.

[0023] The display 28 provides a user interface 34, which includes control elements that enable user interaction with the renal blood flow monitor 12 and / or other components of the monitoring system 11. The display 28 is in communication with the system processor 18 and is configured to provide a real-time plot 36 of a Doppler flow signal DF of renal blood flow in the kidney 42L. In addition to showing the plot 36 of the Doppler flow signal DF, the display 28 may also provide an audible representation of the Doppler flow signal DF via a speaker. The display 28 also displays an injury score indicator 38, as shown in FIG. 1 , which is a representation of the patient's 10 real-time AKI risk score determined from the Doppler flow signal DF by the system processor 18 and the injury monitoring module 32. The display 28 may also include a sensory alarm that alerts medical personnel when the patient's 10 real-time AKI risk score is approaching or exceeding a predetermined threshold. Additionally, the sensory alarm may be implemented as one or more of a visual alarm, an audible alarm, a tactile alarm, or other type of sensory alarm. For example, the sensory alarm may be evoked as any combination of a flashing and / or colored graphic presented by the user interface 34 on the display 28, an audible alarm (e.g., a siren or repeating voice), and a tactile alarm configured to cause the renal blood flow monitor 12 to vibrate or otherwise deliver a perceptible physical stimulus to the healthcare professional.

[0024] Display 28 can be a liquid crystal display (LCD), a light-emitting diode (LED) display, an organic light-emitting diode (OLED) display, or other display device suitable for providing information to a user in graphical form. User interface 34 can include graphical and / or physical control elements that enable user input to interact with renal blood flow monitor 12 and / or other components of monitoring system 11. In some examples, user interface 34 can take the form of a graphical user interface (GUI), which presents graphical control elements presented, for example, on a touch-sensitive and / or presence-sensitive display screen of display 28. In such examples, user input can be received in the form of gestural input (e.g., touch gestures, scrolling gestures, zoom gestures, or other gestural inputs, etc.). In certain examples, user interface 34 can take the form of and / or include physical control elements (e.g., physical buttons, keys, knobs, or other physical control elements configured to receive user input for interacting with components of monitoring system 11, etc.). The user interface 34 may include a speaker that enables the renal blood flow monitor 12 to have the ability to generate audible alarms.

[0025] In operation of the monitoring system 11, before a surgical procedure, medical procedure, or medical observation begins, a medical worker places the ultrasound transducer probe 14 on the abdomen 40 of the patient 10. The medical worker uses the ultrasound transducer probe 14 to locate a Doppler flow signal DF of the renal blood flow in the kidney 42L. The ultrasound transducer probe 14 is capable of generating an audible representation of the Doppler flow signal DF to assist the medical worker in locating the Doppler flow signal DF of the renal blood flow in the kidney 42L. Once the medical worker locates the Doppler flow signal DF of the renal blood flow in the kidney 42L, the medical worker attaches and secures the ultrasound transducer probe 14 to the patient 10 with an adhesive patch 16. The adhesive patch 16 maintains the ultrasound transducer probe 14 in constant contact with the patient 10, preventing the ultrasound transducer probe 14 from shifting position on the patient 10 and losing the Doppler flow signal DF of the renal blood flow in the kidney 42L during surgery, medical procedures, or medical observations. The ultrasound transducer probe 14 relays the received ultrasound signal to the renal blood flow monitor 12 via a cable 24 or wirelessly. In the case of wireless transmission, the ultrasound transducer probe 14 includes an ultrasound front-end circuit 17. The system processor 18 of the renal blood flow monitor 12 receives the Doppler flow signal DF and processes it sequentially or simultaneously through a transducer probe control module 30 and an injury monitoring module 32.

[0026] The system processor 18 executes the AKI monitoring software code of the injury monitoring module 32 to establish a baseline value for renal blood flow in the kidney 42L of the patient 10 from the Doppler flow signal DF sensed by the ultrasound transducer probe 14. Deviation from the baseline value for renal blood flow can be used by the system processor 18 and the injury monitoring module 32 as a coefficient for calculating a real-time AKI risk score for the kidney 42L. The system processor 18 further executes the AKI monitoring software code of the injury monitoring module 32 to continuously monitor the Doppler flow signal DF of renal blood flow sensed by the ultrasound transducer probe 14 throughout the duration of the surgical procedure, medical procedure, or medical observation of the patient 10 and estimate an AKI risk score for the kidney 42L of the patient 10 from the Doppler flow signal DF. The system processor 18 outputs the Doppler flow signal DF and the real-time AKI risk score for the kidney 42L to the display 28. Display 28 produces a plot 36 showing a Doppler flow signal DF of renal blood flow in kidney 42L plotted over time. Display 28 also produces an injury score indicator 38 that represents the real-time AKI risk score of kidney 42L within injury score indicator 38.

[0027] As the surgical procedure, medical treatment, or medical observation of the patient 10 progresses, the system processor 18 continues to receive the Doppler flow signal DF from the ultrasound transducer probe 14 and output both the Doppler flow signal DF and the real-time AKI risk score for the kidney 42L to the display 28. If the real-time AKI risk score for the kidney 42L changes toward an undesirable threshold or at an undesirable rate, the system processor 18 and display 28 can alert a medical professional, who can potentially take action to increase renal perfusion and prevent or minimize AKI to the kidney 42L. For example, the medical professional can administer a drug or fluid that increases renal blood flow and perfusion to the kidney 42L or improves autoregulation of renal blood flow to the kidney 42L. At the end of the surgery, medical procedure, or medical observation, the system processor 18 and the injury monitoring module 32 can estimate a final AKI risk score for the kidney 42L and output the final AKI risk score to the display 28. If the final AKI risk score for the kidney 42L indicates that the kidney 42L is at high risk for AKI, the medical professional can take immediate action to treat the kidney 42L without having to wait for biomarkers to appear in the patient's 10 blood and urine samples. Biomarkers indicative of AKI can take hours or days to appear in the patient's 10 blood and urine samples. The monitoring system 11 allows the medical professional to quickly determine whether the patient 10 needs to be treated for AKI of the kidney 42L.

[0028] If the kidney 42L of the patient 10 moves within the abdomen 40 of the patient 10 during surgery, medical treatment, or medical observation, the transducer probe control module 30 will detect a change in the Doppler flow signal DF and respond by adjusting the location of the focal point of the set of beams for scanning the abdomen 40 of the patient 10 to relocate the Doppler flow signal DF and aim the ultrasound transducer probe 14 at the new location of the Doppler flow signal of the renal blood flow of the kidney 42L. As discussed below with reference to Figures 2-5, the renal blood flow monitor 12 can include a beamformer that can steer the beam signals produced by the array of transducer elements of the ultrasound transducer probe 14.

[0029] FIG. 2 is another schematic diagram of the renal blood flow monitor 12. As shown in FIG. 2, the renal blood flow monitor 12 can include a beamformer 48 with a predictive filter 49. The ultrasound transducer probe 14 can include an array 50 of transducer elements 52. Each transducer element 52 in the array 50 can include a piezoelectric material (e.g., lead zirconate titanate) capable of transmitting and detecting ultrasound pulses. The array 50 of transducer elements 52 in the ultrasound transducer probe 14 can form a two-dimensional phased array having a probe length PL and a probe width PW. As a phased array, each transducer element 52 in the array 50 can generate pulses independently of the other transducer elements 52 in the array 50. The monitoring system 11 can also include or be in communication with a respiratory monitor 51.

[0030] In the example of FIG. 2 , the beamformer 48 drives the array 50 of transducer elements 52 via the system processor 18 and the ultrasound front-end circuitry 17. The beamformer 48 functions as a transducer probe controller with flow signal tracking software code that controls when each transducer element 52 in the array 50 emits an ultrasound pulse. The beamformer 48 determines the timing and pattern in which each transducer element 52 emits a pulse, enabling the array 50 to form one or more ultrasound beams and to sweep or steer the one or more ultrasound beams without physically moving the position of the ultrasound transducer probe 14 on the patient 10. The beamformer 48 may be a software sub-module of the transducer probe control module 30, which is executed by the system processor 18 and is capable of controlling the activation of the transducer elements 52 in the array 50. The prediction filter 49 can be a software sub-module of the beamformer 48 and / or transducer probe control module 30, which can be executed by the system processor 18 to predict the expected trajectory of the target vessel based on measured inputs from the beamformer 48 and / or from inputs from other external sensors (e.g., a respiratory monitor 51, etc.). In other examples, the beamformer 48 can be a hardware component separate from the system processor 18 and system memory 20, and can comprise memory and software separate from the software code 22 that cooperates with the system processor 18 to control the activation of the transducer elements 52 of the array 50. In the example of FIG. 2, the beamformer 48 is contained within the renal blood flow monitor 12 as part of the transducer probe control module 30 of the software code 22 executed by the system processor 18.In another example, the beamformer 48 can be housed completely or partially within the casing of the ultrasound transducer probe 14 as a separate hardware and software unit that cooperates with the system processor 18. Housing the beamformer 48 in the same unit as the renal blood flow monitor 12 (whether as part of the software code 22 or as an add-on hardware component) can reduce the overall size and thickness of the ultrasound transducer probe 14. The ultrasound transducer probe 14 can have a relatively thin and flat profile, with a thickness that is less than the width or diameter of the ultrasound transducer probe 14. Attaching the ultrasound transducer probe 14 to the patient 10 with an adhesive patch 30 is easier and safer when the ultrasound transducer probe 14 has a thin and flat profile.

[0031] FIG. 3 is another schematic diagram of an ultrasound transducer probe 14 attached to the abdomen 40 of a patient 10 by an adhesive patch 16 over a kidney 42L. The Doppler flow signal DF of the kidney 42L can be measured either from the renal artery RA as blood enters the kidney 42L from the aorta of the patient 10 via the renal artery, or from the renal vein RV as blood exits the kidney 42L via the renal vein RV into the vena cava of the patient 10. The ultrasound transducer probe 14 generates an emitted signal OW that travels into the abdomen 40 of the patient 10. Due to the physical properties of Doppler, the Doppler signal BW of the blood flow in the renal artery RA is "blue-shifted" as the blood flow in the renal artery RA is moving toward the ultrasound transducer probe 14. The Doppler signal RW of the blood flow in the renal vein RV is "red-shifted" as the blood flow in the renal vein RV is moving away from the ultrasound transducer. Because the Doppler signal BW is blue-shifted and the Doppler signal RW is red-shifted, the renal blood flow monitor 12 can easily distinguish renal artery blood flow from renal vein blood flow. In a human subject, the renal artery RA and renal vein RV are close and aligned in parallel, allowing the beamformer 48 to position the beam to simultaneously capture both the arterial and venous flow of the kidney 42L.

[0032] 4A-5 will be discussed simultaneously. FIG. 4A is another schematic diagram of an ultrasound transducer probe 14 attached to the abdomen 40 of a patient 10 by an adhesive patch 16 over a kidney 42L. FIG. 4B is another schematic diagram of an ultrasound transducer probe 14 attached to the abdomen 40 of a patient 10 by an adhesive patch 16 over a kidney 42L. FIG. 5 is another schematic diagram of an ultrasound transducer probe 14. In the example of FIGS. 4A and 4B, the ultrasound transducer probe 14 is attached to the surface of the abdomen 40 by an adhesive patch 16 over the kidney 42L and over at least some of the ribs 54a, 54b, and 54c of the patient 10.

[0033] The ultrasound transducer probe 14 may include a probe length PL, probe width PW (shown in FIG. 2), or diameter large enough to enable the array 50 of transducer elements 52 of the ultrasound transducer probe 14 to cover one or more acoustic windows in the patient 10. An acoustic window of the patient 10 is defined as an area of ​​the patient 10 where ultrasound transmission is substantially unattenuated compared to its immediate surroundings. For example, the array 50 of transducer elements 52 of the ultrasound transducer probe 14 may be sized in length or width to extend across at least two intercostal spaces of the patient 10. For example, in FIG. 4A , the array 50 of transducer elements 52 of the ultrasound transducer probe 14 is positioned over a first acoustic window W1 (formed by the intercostal space between ribs 54a and 54b) and a second acoustic window W2 (formed by the intercostal space between ribs 54b and 54c). In the example of FIG. 4A , the beamformer 48 (shown in FIG. 2 ) selectively activates transducer elements 52 in the array 50 to steer signal beams 56 a, 56 b, and 56 c (not visible) into the abdomen 40 through the first acoustic window W1 and / or the second acoustic window W2, avoiding the ribs 54 a, 54 b, and 54 c. In the example of FIG. 4B , the ultrasound transducer probe 14 is positioned slightly higher on the abdomen 40 of the patient 10 compared to the example of FIG. 4A . However, the probe length PL or probe width PW of the ultrasound transducer probe 14 is long enough that the ultrasound transducer probe 14 still has access to the first acoustic window W1 and can still scan and steer signal beams 56 a, 56 b, and 56 c (not visible) into the abdomen 40 through the first acoustic window W1. Regardless of where the ultrasound transducer probe 14 is placed on the ribs 54a, 54b, and 54c, the ribs 54a, 54b, and 54c do not obstruct a direct view of the kidney 42L from the array 50 of the ultrasound transducer probe 14.

[0034] When the ultrasound transducer probe 14 is initially placed on the patient 10, the beamformer 48 controls the transducer elements 52 in the array 50 to beam scan the abdomen 40 and identify the location of the target blood vessel. To find the target blood vessel, the beamformer 48 divides the entire field of view of the array 50 into multiple subvolumes and searches each subvolume using a set of predefined beams (e.g., beams 56a, 56b, and 56c). To reduce search time, the search can be performed in two steps. In the first step, the subvolume can be made larger in the depth dimension of the abdomen 40, while a two-dimensional scan is performed only in the other two dimensions. Once the signal locations in the other two dimensions have been determined by the two-dimensional scan, the next step is to reduce the size of the subvolume in the depth dimension and perform a search along the depth dimension at the locations previously determined in the other two dimensions.

[0035] The beamformer 48 also controls the transducer elements 52 in the array 50 to track scan the abdomen 40 and track the target vessel over time. The beamformer 48 beam scans and / or track scans the Doppler flow signal DF of the renal blood flow in the kidney 42L of the patient 10 by sequentially emitting signal beams 56a, 56b, and 56c from the array 50 of transducer elements 52 and by focusing each of the beams 56a, 56b, and 56c at a different location. At least three beams are required for tracking in both the azimuth and elevation dimensions (sometimes referred to as the altitude dimension). Using more beams results in a lower Nyquist frequency for the Doppler shift and, therefore, a more accurate target vessel location estimate, at the expense of the possibility of aliasing in the instantaneous spectrogram. Therefore, the beamformer 48 is not limited to three beams and can include more than three beams. The beam locations of beams 56a, 56b, and 56c are selected to have a sufficient degree of overlap of beams 56a, 56b, and 56c so that when the target vessel is located at the center of the three beams, the signal-to-noise ratio of the Doppler flow signal in each of the beams is acceptably large (e.g., >20 dB). For example, the beam locations can be selected so that the centers of beams 56a, 56b, and 56c are at points where the pressure for each of beams 56a, 56b, and 56c is 3 dB below its peak value.

[0036] By comparing the integrated spectral power measured along multiple signal beams (e.g., beams 56a, 56b, and 56c), the beamformer 48 and / or renal blood flow monitor 12 can estimate the bearing (i.e., azimuth and elevation angles) of the target vessel relative to the array 50 of transducer elements 52. As the target vessel (e.g., the renal artery RA and / or the renal vein RV) moves within the abdomen 40, the target vessel will move closer to the focal points of some of the signal beams 56a, 56b, and 56c (which will increase the integrated spectral power measured along those beams) and will move farther away from the focal points of some of the other signal beams 56a, 56b, and 56c (which will decrease the integrated spectral power measured along those beams). As the target vessel moves, the beamformer 48 can redirect the signal beams 56 a, 56 b, and 56 c (and possibly more signal beams) toward those beams with higher measured integrated power spectra and away from those beams with lower integrated power spectra, thereby tracking the target vessel, whose scatterers generate a Doppler flow signal DF. In one embodiment incorporating this tracking methodology, the beamformer 48 computes an estimated location for the target vessel as a vector sum of unit vectors along the signal beam directions weighted by the integrated spectral power measured along each of the signal beams 56 a, 56 b, and 56 c. The weighting by integrated spectral power ensures that when the beamformer 48 redirects the signal beams 56 a, 56 b, and 56 c to the estimated target vessel location, the centroid of the beams 56 a, 56 b, and 56 c will move toward those beams with the greatest integrated spectral power and therefore located closest to the target vessel.

[0037] In another embodiment, the beamformer 48 and / or the renal blood flow monitor 12 can include a physical model that predicts the integrated spectral power for a given displacement between the signal beam and the target vessel to improve estimation of the target vessel location. The model can calculate the integrated power spectrum, for example, as the overlap integral between an assumed beam shape (e.g., a Gaussian beam, a beam described by a sombrero function, or a beam described by a cardinal sine function, depending on the transducer shape and apodization) and an assumed geometric shape for the target vessel (e.g., a cylindrical vessel with a uniform density of moving scatterers across its cross section). In some embodiments, the model can incorporate information about the change in beam shape with distance from the transducer elements 52, as obtained from experimental measurements or acoustic simulations. In some embodiments, the model can use an asymmetric beam shape, such as an elliptical Gaussian beam with narrower and wider dimensions, such as would be produced by an asymmetric array of transducer elements. To estimate the target vessel location from the integrated power spectrum observed along multiple signal beams, the model is inverted using standard function inversion methodologies (e.g., least-squares fitting, interpolation, series expansion, look-up tables, root-finding methods, etc.) Once the inverse function is approximated, it can be used to obtain an estimate of the vascular target from the integrated spectral power measured along the signal beams.

[0038] In some embodiments, the beamformer 48 and / or renal blood flow monitor 12 can use the target vessel location estimates as input to a prediction filter 49, shown in FIG. 2, which contains a model of the expected trajectory of the target vessel. For example, in cases where the primary source of target vessel motion is from respiration, the prediction filter 49 can contain a periodic trajectory model that describes the motion as periodic at the respiration frequency. In some embodiments, the periodic trajectory model can be implemented as a partial Fourier sum in each direction with the respiration frequency as its fundamental frequency. In such embodiments, the model parameters can include some or all of the amplitude and phase of each Fourier component in each direction (or, equivalently, the amplitude of the in-phase and quadrature components), as well as the location of the origin around which the periodic motion occurs. In some embodiments, the prediction filter 49 allows the model parameters to be updated in response to the target vessel location estimates obtained from the integrated power spectrum along multiple signal beams, so that drift in the model parameters over time or the inability of the model to completely describe the trajectory can be addressed.

[0039] In some embodiments, the predictive filter 49 can incorporate an uncertainty estimate into the estimate of the target vessel location obtained from the integrated power spectrum measurements. This uncertainty estimate can be used to adjust the degree to which the model parameters are affected by new measurements during parameter updates. In some embodiments, this uncertainty estimate can be used to cause the monitoring system 11 to ignore measurements that are invalid, for example, due to transient events that corrupt the measurements over a period of time. In some embodiments, this uncertainty estimate can be used to reduce the degree to which the measurements affect the model parameters when the signal-to-noise ratio of the integrated power spectrum is low, and can be used to increase the degree to which the measurements affect the model parameters when the signal-to-noise ratio of the integrated power spectrum is high. In some embodiments, the uncertainty estimate can be adjusted in response to changes in the instantaneous spectral moments (e.g., mean velocity, spectral bandwidth) of the Doppler flow signal or changes in the maximum velocity envelope of the Doppler spectrogram. In some embodiments, the uncertainty estimate can be adjusted based on the total integrated power spectrum (including both negative and positive frequencies) or based on the integrated power spectrum over a range of Doppler shifts different from the range used to estimate the target vessel location. For example, the integrated power spectrum over negative frequencies can be used to estimate the uncertainty in a location estimate arrived at using the integrated power spectrum over positive frequencies.

[0040] The integrated spectral power is an inherently noisy signal because the Doppler spectrogram contains speckle resulting from constructive and destructive interference among numerous scatterers randomly distributed throughout the insonified abdominal volume 40, as well as statistical noise due to variations in the number and orientation of scatterers in the beam over time. Additionally, the integrated power spectrum is modulated by the cardiac cycle because a larger proportion of scatterers will have a Doppler shift large enough to pass the filter that defines the Doppler flow signal during systole than during diastole. If unmitigated, the variability of the integrated power spectrum due to speckle and the cardiac cycle will lead to noisy estimates of the target vessel location, resulting in inaccurate tracking. In some embodiments, noise on the integrated power spectrum is reduced by applying a filter to the integrated power spectrum signal before using it to estimate the target vessel location. Increasing the filter kernel duration makes the filter more effective at removing noise, but when the filter kernel duration becomes comparable to the time scale of the target vessel's target vasomotion, the filter begins to degrade tracking accuracy. Because the fastest source of target vasomotion is respiration, a filter kernel size shorter than the respiratory cycle duration advantageously reduces modulation from the cardiac cycle and speckle while maintaining target vessel location estimation accuracy. Statistical noise and speckle noise create long-tailed intensity distributions with a high probability of producing very large values. Consequently, due to these occasional very large intensities, linear filters are ineffective at smoothing the integrated power spectrum. Median filters are advantageously less susceptible to outliers and provide a smoother output than is possible with linear filters. Consequently, in some embodiments, a median filter is used to filter the integrated power spectrum.In some embodiments, the median filter kernel size is selected to be greater than the cardiac cycle duration but less than the respiratory cycle duration.

[0041] In some embodiments, information obtained from other sensors separate from the ultrasound transducer probe 14, or a priori information, can also be provided to the prediction filter 49, which estimates the target vessel location. The prediction filter 49 can be configured to incorporate this additional information when adjusting its model parameters and when adjusting the estimate of the target vessel location obtained from the integrated power spectrum. For example, the prediction filter 49 can receive input from a respiratory monitor 51 connected to the patient 10 and use measurements from the respiratory monitor 51 to update model parameters that capture the respiratory frequency of the patient 10. In some embodiments, the prediction filter 49 can incorporate both measurements made by an external sensor (e.g., the respiratory monitor 51) and the estimate of the target vessel location obtained from the integrated power spectrum to adjust its model parameters. In some embodiments, the prediction filter 49 can use information obtained from integrated power spectrum measurements taken at an earlier time point. For example, in some embodiments, tracking of the target vessel can be stopped and the directions of signal beams 56a, 56b, and 56c can be fixed to observe the periodicity of the integrated power spectrum as the target vessel moves due to respiration. This observation can be used to estimate the respiration frequency, which can be incorporated into the predictive model 49 when tracking resumes.

[0042] In some embodiments, the predictive filter 49 is implemented as a linear Kalman filter. In some embodiments, the predictive filter 49 is implemented as an unscented Kalman filter. In some embodiments, the predictive filter 49 is implemented as an extended Kalman filter.

[0043] In some embodiments, the prediction filter 49 can be configured to generate an estimate of the integrated power spectrum signal along each of the multiple signal beams (e.g., signal beams 56a, 56b, and 56c) based on the target vessel location, beam shape, and an internal parametric model of the target vessel shape and orientation. The prediction filter 49's estimate of the integrated power spectrum for each of the multiple signal beams can be compared to measurements of the integrated power spectrum along each signal beam, and the difference between the prediction and measurement can be used to update model parameters, including those describing the target vessel location. In calculating the integrated power spectrum along the multiple signal beams, the prediction filter 49 can utilize a physical model of the integrated power spectrum that calculates the overlap integral between the target vessel and the ultrasound beam profile. In some embodiments, the physical model can include a description of how the beam profile changes with depth. In some embodiments, the physical model can include an asymmetric beam profile, such as would be produced by an asymmetric transducer array.

[0044] In some embodiments, the difference in integrated power spectra between the different signal beams 56 a, 56 b, and 56 c is used by the beamformer 48 and / or renal blood flow monitor 12 to estimate the orientation (azimuth and elevation) of the target vessel, while the range (distance from the transducer) of the target vessel is estimated by the beamformer 48 and / or renal blood flow monitor 12 by calculating the integrated power spectrum at multiple range samples, assigning each range sample a likelihood of containing the target vessel, and calculating an estimate of the center of the target vessel from the multiple range samples. In some embodiments, the likelihood that a range sample contains the target vessel is proportional to the integrated power spectrum at that range, such that an estimate of the target vessel range location can be estimated by the beamformer 48 and / or renal blood flow monitor 12, for example, by selecting the range sample with the largest integrated power spectrum or by calculating the location of a centroid over the range samples. In other embodiments, the beamformer 48 and / or renal blood flow monitor 12 may use a likelihood function that takes into account the integrated power spectrum, spectral moments, Doppler spectrogram shape, and / or integrated power in spectral ranges other than the range over which the integrated power spectrum is calculated. In many cases, a target vessel may extend over multiple range samples, in which case the accuracy of the integrated power spectrum may be improved by averaging over multiple range samples that are likely to contain the target vessel.

[0045] In some embodiments, the estimate of the target vessel range incorporates the integrated power spectrum calculated for each of multiple signal beams (e.g., 56a, 56b, 56c). In some embodiments, the beamformer 48 and / or renal blood flow monitor 12 can arrive at this estimate by first averaging the integrated power spectrum across multiple beams at each range sample, and then calculating on this averaged signal the likelihood that each range sample contains the target.

[0046] Separating the target vessel's orientation estimate from its range estimate in this manner is advantageous because it allows the beamformer 48 and / or renal blood flow monitor 12 to calculate range estimates more frequently than orientation estimates over time. While the beamformer 48 and / or renal blood flow monitor 12 can obtain a range estimate for each ultrasound transmission event, an orientation estimate requires the beamformer 48 to move the ultrasound beam to multiple locations and for measurements made at the different locations to be compared by the beamformer 48 and / or renal blood flow monitor 12. Having a reliable estimate of the range associated with each transmission event ensures that when the beamformer 48 and / or renal blood flow monitor 12 uses the integrated power spectrum to estimate orientation across multiple signal beams, the integrated power spectrum from the range or ranges closest to the target vessel is used by the beamformer 48 and / or renal blood flow monitor 12 in the orientation calculation. Separating the range from heading estimate also simplifies the predictive model used to estimate heading, thereby making the predictive model more robust and reliable.

[0047] Similarly, as the beamformer 48 and ultrasound transducer probe 14 scan across the field of view to locate a target vessel, the separation of the range estimate from the orientation estimate advantageously reduces the number of dimensions in which the beamformer 48 and ultrasound transducer probe 14 must scan the beam from three to two. The estimation methods described in the preceding paragraphs apply equally to scanning as to tracking.

[0048] To enable the ultrasound transducer probe 14 to measure the Doppler flow signal DF of renal blood flow in the kidney 42L, the ultrasound transducer probe 14 can have a low center frequency between 0.5 MHz and 4.0 MHz. A center frequency between 0.5 MHz and 4.0 MHz allows the ultrasound transducer probe 14 to penetrate more than 15 cm into the patient 10, which is deep enough to measure renal blood flow. This depth also allows the ultrasound transducer probe 14 to measure hepatic blood flow, peritoneal blood flow, portal vein blood flow, and mesenteric blood flow.

[0049] As best shown in the example of FIG. 5 , each transducer element 52 in the array 50 includes an element width EW and an element length EL, both of which are greater than one wavelength in soft tissue of the ultrasound waves emitted by the array 50 of transducer elements 52. The array 50 of transducer elements 52 also includes a pitch EP that defines an inter-element spacing between the centers of adjacent transducer elements 52. In the example of FIG. 5 , the pitch EP is greater than one wavelength in soft tissue of the ultrasound waves emitted by the array 50 of transducer elements 52. The element width EW, element length EL, and pitch EP are all greater than one wavelength in soft tissue of the ultrasound waves emitted by the array 50 of transducer elements 52, reducing the element count for a selected aperture of the ultrasound transducer probe 14. In conventional phased array imaging transducers, the use of a pitch greater than one wavelength would result in significant image degradation due to grating lobes. However, for the ultrasound transducer probe 14, grating lobes do not degrade the Doppler spectrogram because large blood vessels are sparsely distributed in the body, making it highly unlikely that an interfering Doppler signal source would be located at a grating lobe location when the main lobe is focused on the target vessel. The monitoring system 11 does not use the ultrasound transducer probe 14 for high-resolution imaging of the kidney 42L, and therefore the ultrasound transducer probe 14 does not need to have as high a transducer element count as ultrasound transducer probes used for ultrasound imaging.

[0050] Multiple continuous organ blood flow sensors can be placed on a single patient. This can be advantageous for monitoring multiple organs at once, particularly both kidneys. Figure 6 shows two ultrasound transducer probes 14A and 14B connected to a patient 10, with a single renal blood flow monitor 12 connected to both ultrasound transducer probes 14A and 14B. Ultrasound transducer probe 14A is positioned over the left kidney 42L to detect and track renal blood flow in the left kidney 42L. Ultrasound transducer probe 14B is positioned over the right kidney 42R to detect and track renal blood flow in the right kidney 42R. The renal blood flow monitor 12 in Figure 6 receives Doppler flow signals from both ultrasound transducer probes 14A and 14B and can output a first plot 36A of the Doppler flow signal for the left kidney 42L and a second plot 36B of the Doppler flow signal for the right kidney 42R to the display 28. 6 is also capable of outputting a first injury score indicator 38A and a second injury score indicator 38B to the display 28. The first injury score indicator 38A is a representation of the real-time AKI risk score of the left kidney 42L, and the second injury score indicator 38B is a representation of the real-time AKI risk score of the right kidney 42R.

[0051] FIG. 7 is a schematic diagram of a patient 10 equipped with two monitoring systems 11K and 11L. The monitoring system 11K includes a renal blood flow monitor 12K and an ultrasound transducer probe 14K positioned on the left side of the patient's 10 abdomen 40 to monitor renal blood flow in the left kidney 42L. The monitoring system 11K functions in a manner similar to the monitoring system 11 described above with reference to FIGS. 1-6. The renal blood flow monitor 12K outputs a plot 36K of a Doppler flow signal of renal blood flow in the left kidney 42L to a display 28. The renal blood flow monitor 12K in FIG. 7 can also output an injury score indicator 38K to the display 28. The injury score indicator 38K is a representation of the real-time AKI risk score of the left kidney 42L.

[0052] The monitoring system 11L includes a hepatic blood flow monitor 12L and an ultrasound transducer probe 14L positioned over the right side of the patient's 10 abdomen 40 to monitor blood flow in the hepatic or portal vein of the liver 44. The monitoring system 11L functions in a manner similar to the monitoring system 11 described above with reference to Figures 1-6. The hepatic blood flow monitor 12L outputs a Doppler flow signal plot 36L of blood flow in the liver 44 to a display 28. The hepatic blood flow monitor 12L in Figure 7 can also output an injury score indicator 38L to the display 28. The injury score indicator 38L is a representation of the liver's 44's real-time organ injury risk score.

[0053] FIG. 8 is a chart from an experiment demonstrating the monitoring system 11. The chart shows three plots. The first plot, P1, is a plot of the test subject's (pig's) mean arterial pressure (MAP) measured over time by a hemodynamic sensor. The second plot, P2, is a plot of the test subject's renal blood flow over time, measured by an invasive flow probe surgically implanted around the test subject's renal artery to provide a baseline measurement of renal blood flow. The third plot, P3, is a plot of the test subject's renal blood flow index over time, as measured by the ultrasound transducer probe 14 of the monitoring system 11. The experiment lasted at least 40 minutes. A balloon catheter was inserted into the test subject's inferior vena cava. During the experiment, the balloon catheter was inflated and deflated several times, causing a decrease and an increase in the test subject's MAP, as represented by the vertical dashed lines in the chart. When the balloon catheter was inflated, the test subject's MAP decreased, which also caused the test subject's renal blood flow to decrease. When the balloon catheter was deflated, the test subject's MAP increased, which also caused the test subject's renal blood flow to increase. As shown in plots P2 and P3, the noninvasive ultrasound transducer probe 14 of the monitoring system 11 in this experiment was able to identify changes in the test subject's renal blood flow in a manner similar to an invasive transonic flow probe surgically implanted around the test subject's renal artery.

[0054] 9 and 10 will be discussed simultaneously. FIGS. 9 and 10 are schematic diagrams of the monitoring system 11 of FIGS. 1 and 2 with the addition of an organ recognition algorithm 58. In the example of FIGS. 9 and 10, the organ recognition algorithm 58 is a software module stored in the system memory 20 as part of the software code 22. The organ recognition algorithm 58 can be based on either machine learning or standard signal processing. When executed by the system processor 18, the organ recognition algorithm 58 is capable of recognizing and distinguishing the target organ blood flow signal of the patient 10 from non-target blood flow signals based on the waveform characteristics of the target organ blood flow signal. In the example of FIGS. 9 and 10, the target organ blood flow signal is a renal blood flow Doppler flow signal DF of the kidney 42L, and the organ recognition algorithm 58 recognizes the renal blood flow Doppler flow signal DF from other non-renal blood flow signals based on the waveform characteristics of the Doppler flow signal DF. The organ recognition algorithm 58 can assist the renal blood flow monitor 12 in monitoring the renal blood flow of the kidney 42L by verifying that the system processor 18 and transducer probe control module 30 are continuously electronically targeting the ultrasound transducer probe 14 to the renal blood flow Doppler flow signal DF and not erroneously targeting some other organ blood flow. This feature can be very useful when the monitoring system 11 monitors the patient 10 over time, because the kidney 42L and other organs can shift and move within the abdomen 40, causing the Doppler flow signal DF to drift relative to the ultrasound transducer probe 14 or causing other organ blood flow signals to appear within the sensing window of the ultrasound transducer probe 14.

[0055] As shown in FIG. 10 , the organ recognition algorithm 58 may include a waveform analyzer 62 and a waveform lookup table 64. The waveform lookup table 64 is a table of renal blood flow waveform characteristics and non-renal blood flow waveform characteristics. For example, the waveform lookup table 64 may include a subtable of waveform characteristics belonging to the Doppler flow signal DF of the renal blood flow of the kidney 42L. The waveform lookup table 64 may include another subtable of waveform characteristics belonging to the Doppler signal of the hepatic blood flow of the liver 44. The waveform lookup table 64 may include another subtable of waveform characteristics belonging to the Doppler signal of the portal vein blood flow of the stomach (not shown). The waveform lookup table 64 may be pre-populated with waveforms obtained from prior measurements from a population. The waveform lookup table 64 may also include information from the patient 10 gathered by scanning each of the patient's 10 organs in the region of the abdomen 40 to be monitored by the monitoring system 11 prior to an operation, medical procedure, or medical observation. For example, before the monitoring system 11 is attached to the patient 10 to monitor renal blood flow in the kidney 42L, the technician can use the ultrasound transducer probe 14 and the renal blood flow monitor 12 to scan the area of ​​the abdomen 40 around the kidney 42L, collect waveform characteristics of each significant blood flow signal in that area using the waveform analyzer 62, and input a waveform lookup table 64 specific to the patient 10. Once the waveform lookup table 64 is input, the technician can again locate the Doppler flow signal DF of the renal blood flow in the kidney 42L with the ultrasound transducer probe 14 and attach the ultrasound transducer probe 14 to the patient 10 with the adhesive patch 16.

[0056] The waveform analyzer 62, when executed by the system processor 18, performs a waveform analysis of the Doppler flow signal DF of renal blood flow sensed by the ultrasound transducer probe 14 to extract waveform characteristics of the Doppler flow signal DF. The system processor 18 can then execute the waveform analyzer 62 and compare the waveform characteristics of the Doppler flow signal DF with a waveform lookup table 64 to verify that the Doppler flow signal DF is indeed a signal of renal blood flow in the kidney 42L. After comparing the waveform characteristics of the Doppler flow signal DF with the waveform lookup table 64, the system processor 18 and the waveform analyzer 62 output a decision score 60 (or a representation of the decision score 60) to the display 28. The decision score 60 indicates whether the Doppler flow signal DF is from renal blood flow or non-renal blood flow. For example, as shown in FIG. 9, the decision score 60 can display "renal" when the Doppler flow signal DF is from renal blood flow. If the monitoring system 11 is being used to monitor hepatic flow in the liver 44, the decision score 60 may display "liver" when the monitoring system 11 finds a Doppler flow signal for hepatic flow. In other examples, the decision score 60 may use a numerical indicator or an acronym. In yet another example, the decision score 60 may include a quality grade or index of the signal of interest assessed from the waveform characteristics of the Doppler flow signal DF. The decision score 60 and quality grade or index are continuously provided to the Kalman filter, which can then more accurately estimate the reliability of the measurement in real time and properly estimate future locations based on a weighted balance between the predictive model and the current measurement.

[0057] The quality grade or index of the decision score 60 distinguishes acceptable Doppler flow signals (DF) of blood flow from noise, artifacts, or other physiologically irrelevant blood flow signals. A waveform analyzer 62 establishes the quality grade or index embodied by the decision score by comparing the Doppler flow signal DF to a waveform lookup table 64. In certain embodiments, the system processor 18 is capable of executing the waveform analyzer 62 and calculating signal features such as the signal-to-noise ratio (SNR), integrated power spectrum, spectral envelope, pulsatility, and spectral bandwidth.

[0058] The signal features calculated and collected by the waveform analyzer 62 then undergo statistical processing to ensure classification of the output from the beamformer 48. Such classification may include identifying signals as “kidney,” “liver,” artery, vein, noise, or artifact, among others. In some embodiments, this multi-class classification is generated by application of a machine learning-based classifier. The machine learning-based classifier is trained on a labeled training dataset of Doppler flow signals that uses the waveform analyzer 62 output (e.g., SNR, integrated power spectrum, spectral envelope, pulsatility, and spectral bandwidth) as input features. The waveform analyzer 62 can classify Doppler flow signals using various classifier models, including random forest classifiers and support vector machine (SVM) classifiers. One embodiment of this classification system was trained on a dataset of 5,756 samples, each containing a 0.25-second segment of Doppler signals taken from one of four healthy subjects. The dataset was 17 minutes in total length, and some of the samples in the dataset overlapped with each other. Each sample was labeled as either "renal artery flow," "non-blood artifact," or "noise." Following training, the model was able to correctly classify renal artery flow with 93% accuracy in a training set of 2,467 samples.

[0059] In some embodiments, the waveform analyzer 62 uses a machine learning-based classifier that not only provides a predicted class label, but also a confidence estimate in terms of the probability of correct classification of the classification. For example, in an embodiment of the waveform analyzer 62 that uses a random forest classifier model, the percentage of trees that voted for a particular classification can be interpreted as a confidence score ranging from 0 to 1. In an embodiment of the waveform analyzer 62 that uses an SVM classifier, each SVM score gives the distance of the sample to a decision hyperplane in feature space. The waveform analyzer 62 can use a logistic regression model to convert these SVM scores into probabilities for various binary classifications. The waveform analyzer 62 can use any other machine learning or classification algorithm that can produce a probability of correct classification.

[0060] In some embodiments, the classification of the Doppler flow signal DF and the probability of correct classification of the Doppler flow signal DF are used to establish a measurement uncertainty that is passed into a Kalman filter used by the beamformer 48 and / or renal blood flow monitor 12 to track the target vessel location. In some embodiments, the classifier is configured as a binary classifier that classifies the Doppler flow signal as "blood flow from the target vessel" and "not blood flow from the target vessel," along with an estimate of the probability that the classification is correct. The function maps the probability range [0,1] that the Doppler flow signal is blood flow from the target vessel to an uncertainty range [∞,0], where an uncertainty of ∞ indicates complete certainty that the Doppler flow signal is not blood flow from the target vessel, and 0 indicates complete certainty that the Doppler flow signal is blood flow from the target vessel. In various embodiments, the function that maps the probability of correct classification to measurement uncertainty can be a rational polynomial function, a logit function, a logarithmic function, or an exponential function, or another function that maps from [0,1] to [∞,0].

[0061] In some embodiments, the classification and probability of correct classification can be applied to the problem of locating a target vessel (such as a kidney vessel or liver vessel) by assigning a probability to each scan of the abdomen 40 by the array 50. The target vessel is then identified as being located at the location in the scan that is classified as containing flow from the target vessel with the highest probability of correct classification.

[0062] Although organ recognition algorithm 58 has been described as distinguishing renal blood flow Doppler flow signal DF from non-renal blood flow signals of patient 10, organ recognition algorithm 58 can also be used to identify other organ blood flow signals. For example, if monitoring system 11 is being used on patient 10 to monitor hepatic blood flow of liver 44, organ recognition algorithm 58 can be executed by system processor 18 to distinguish and verify the hepatic blood flow Doppler flow signal of liver 44 from renal blood flow or other organ blood flow signals of patient 10.

[0063] FIG. 11 is a block diagram of one method 65 for operating the monitoring system 11 shown in FIGS. 9 and 10 to continuously monitor renal blood flow and perfusion of the kidney 42L of a patient 10. A first step 66 of the method 65 involves positioning the ultrasound transducer probe 14 on the patient 10. Next, in a second step 68, the system processor 18 executes the transducer probe control module 30 with the beamformer 48 to beam scan the patient 10 with the ultrasound transducer probe 14 to find a Doppler flow signal DF of the renal blood flow of the kidney 42L. If a Doppler flow signal DF is not found, the renal blood flow monitor 12 can alert and instruct medical personnel to reposition the ultrasound transducer probe 14 on the patient 10 and repeat the second step 68. In a third step 70, the system processor 18 can optionally execute the organ recognition algorithm 58 to verify that the Doppler flow signal DF is indeed a signal of renal blood flow in the kidney 42L. Once the Doppler flow signal DF is found and verified, a fourth step 72 of the method 65 can be performed by attaching and securing the ultrasound transducer probe 14 to the patient 10 with the adhesive patch 16. The adhesive patch 16 maintains the ultrasound transducer probe 14 in the appropriate location on the patient 10, maintaining contact between the abdomen 40 and the ultrasound transducer probe 14, so that the monitoring system 11 can continue to sense and analyze the Doppler flow signal DF over an extended period of time (e.g., during a surgical procedure or a stay in an intensive care unit (ICU) or emergency room). In a fifth step 74 of the method 65, the system processor 18 continuously outputs a plot of the Doppler flow signal DF of renal blood flow to the display 28.As part of a fifth step 74, the system processor 18 executes the injury monitoring module 32 to estimate the patient's 10 real-time AKI risk score from the Doppler flow signal DF and outputs a representation of the real-time AKI risk score to the display 28 as an injury score indicator 38. While the renal blood flow monitor 12 continues to read the renal blood flow Doppler flow signal DF, the system processor 18 executes a sixth step 76 by executing the transducer probe control module 30 to track the Doppler flow signal DF as described above with reference to FIGS. 2-5. If the renal blood flow Doppler flow signal DF begins to shift and drift relative to the ultrasound transducer probe 14, the system processor 18 can execute a seventh step 78 by executing the transducer probe control module 30 to adjust the beam scanning position or angle of the ultrasound transducer probe 14 to track the Doppler flow signal DF.

[0064] As the patient 10's surgical or medical procedure progresses, or as the patient 10's stay in the ICU or emergency room progresses, the system processor 18 continues to receive the Doppler flow signal DF from the ultrasound transducer probe 14 and output both the Doppler flow signal DF and the kidney 42L's real-time AKI risk score to the display 28. If the kidney 42L's real-time AKI risk score changes toward an undesirable threshold or changes at an undesirable rate, the system processor 18 and display 28 can alert a medical professional, who can potentially take action to increase renal perfusion and prevent or minimize AKI to the kidney 42L. For example, the medical professional can administer a drug or fluid that increases renal blood flow and perfusion to the kidney 42L or improves autoregulation of renal blood flow to the kidney 42L. The monitoring system 11 allows medical personnel to take immediate action to treat the kidney 42L without having to wait for biomarkers to appear in blood and urine samples from the patient 10. Biomarkers indicative of AKI can take hours or days to appear in blood and urine samples from the patient 10. The monitoring system 11 allows medical personnel to quickly determine whether the patient 10 needs to be treated for AKI of the kidney 42L.

[0065] 12 is a block diagram of another method 80 for operating the monitoring system 11 shown in FIGS. 9 and 10 to continuously monitor organ blood flow in a target organ of the patient 10 and to help maintain proper perfusion of the target organ. The target organ of the patient 10 can be the kidney 42L or kidney 42R, or any other organ of the patient 10 (e.g., the liver 44, spleen 46, pancreas, stomach, intestines, heart, brain, etc.). A first step 82 of the method 80 involves positioning the ultrasound transducer probe 14 on the patient 10. Then, in a second step 84, a technician manually scans the patient 10 with the ultrasound transducer probe 14 of the monitoring system 11 (or another ultrasound probe) to find the organ blood flow signal of the target organ. During a second step 84, the technician can also input the waveform lookup table 64 of the organ recognition algorithm 58 by scanning the organ blood flow signals of the target organ and the surrounding organs and feeding those signals through the system processor 18 and waveform analyzer 62.

[0066] Once the organ blood flow signal of the target organ is found, the technician performs a third step 86 by attaching and securing the ultrasound transducer probe 14 to the patient 10 with an adhesive patch 16 at the location where the organ blood flow signal was found in the second step 84. The adhesive patch 16 maintains the ultrasound transducer probe 14 in the appropriate location on the patient 10, maintaining contact between the abdomen 40 and the ultrasound transducer probe 14 so that the monitoring system 11 can continue to sense and analyze the organ blood flow signal over an extended period of time (e.g., during surgery or a stay in an ICU or emergency department). With the ultrasound transducer probe 14 secured to the patient 10 by the adhesive patch 16, the system processor 18 can proceed to a fourth step 88 by executing the transducer probe control module 30 with the beamformer 48 and commanding the ultrasound transducer probe 14 to beam scan the patient 10 to again find the organ blood flow signal of the target organ. The system processor 18 may also perform a fifth step 90 to verify that the ultrasound transducer probe 14 is actually sensing and reading organ blood flow in the target organ and is not targeted at undesired flow signals.

[0067] Once the target organ's organ blood flow signal has been found and verified, system processor 18 performs a sixth step 92 of method 80 by continuously outputting a plot of the target organ's organ blood flow signal to display 28. As part of sixth step 92, system processor 18 may also execute injury monitoring module 32 to estimate a real-time organ injury risk score for patient 10 from the organ blood flow signal and output a representation of the real-time organ injury risk score to display 28 as injury score indicator 38. While blood flow monitor 12 continues to read and analyze the target organ's organ blood flow signal, system processor 18 performs a seventh step 94 by executing transducer probe control module 30 to track scan the target organ's organ blood flow signal as described above with reference to Figures 2-5. If the organ blood flow signal of the target organ begins to shift and drift relative to the ultrasound transducer probe 14, the system processor 18 can perform an eighth step 96 by executing the transducer probe control module 30 to adjust the beam scan position or angle of the ultrasound transducer probe 14 to track the organ blood flow signal of the target organ.

[0068] As the patient's 10 surgical or medical procedure progresses, or as the patient's 10 stay in the ICU or emergency room progresses, the system processor 18 continues to receive the target organ's organ blood flow signal from the ultrasound transducer probe 14 and output both a plot of the organ blood flow signal and the target organ's real-time organ injury risk score to the display 28. If the target organ's real-time organ injury risk score changes toward an undesirable threshold or at an undesirable rate, the system processor 18 and display 28 can alert medical personnel, who can potentially take action to increase (or decrease) perfusion to the target organ and prevent or minimize injury to the target organ. For example, the medical personnel can administer a drug or fluid that increases blood flow to the target organ or improves the target organ's autoregulation. The monitoring system 11 enables medical personnel to take immediate action to treat the target organ without having to wait for biomarkers to appear in the patient's 10 blood and urine samples.

[0069] 13 is a schematic diagram of the monitoring system 11 from FIGS. 1 and 2 with the injury monitoring module 32 of the software code 22 further including two software sub-modules: a renal blood flow monitoring software code 98 and a renal blood flow index monitoring software code 100. When the system processor 18 executes the injury monitoring module 32, the injury monitoring module 32 is able to use either or both of the renal blood flow monitoring software code 98 and the renal blood flow index monitoring software code 100 as characteristics of renal blood flow to determine in real time an AKI risk score for the patient 10 from the Doppler flow signal DF of the renal blood flow in the kidney 42L.

[0070] The renal blood flow monitoring software code 98, when executed by the system processor 18, includes software code that initially estimates a baseline flow value for renal blood flow in the kidney 42L of the patient 10 from the Doppler flow signal DF. The system processor 18 can also execute the renal blood flow monitoring software code 98 to generate real-time renal flow values ​​for renal blood flow and continuously output the real-time renal flow values ​​to the display 28. The system processor 18 can also execute the renal blood flow monitoring software code 98 to track the cumulative sum of time that the real-time renal flow values ​​are below the baseline flow values. The system processor 18 can also execute the renal blood flow monitoring software code 98 to track how low or deep the real-time renal blood flow is below the baseline flow values ​​over time throughout the patient 10's surgery, medical procedure, or medical observation. The injury monitoring module 32 can use the cumulative sum of time that the real-time renal flow values ​​are below the baseline flow values ​​and the low real-time renal blood flow values ​​as variables in estimating the patient 10's AKI risk score.

[0071] The renal blood flow index monitoring software code 100 includes software code that, when executed by the system processor 18, initially estimates a real-time renal blood flow index from the Doppler flow signal DF of the renal blood flow in the kidney 42L and continuously outputs the real-time renal blood flow index to the display 28. The real-time renal blood flow index can be estimated without normalization from various Doppler flow characteristics (e.g., intensity-weighted sum or mean flow velocity over time, or peak flow velocity, etc.).

[0072] A normalized blood flow index is useful. The renal blood flow index monitoring software code 100 can use the renal resistive index (RRI) to calculate a normalized real-time renal blood flow index from the renal artery flow. The system processor 18 and renal blood flow index monitoring software code 100 can use Equation 1 to determine the RRI from the Doppler flow signal DF of the renal blood flow in the kidney 42L.

[0073]

number

[0074] The renal blood flow index monitoring software code 100 can also use the venous impedance index (VII) to calculate a normalized real-time renal blood flow index from the renal blood flow Doppler flow signal DF in the renal vein of the kidney 42L. The system processor 18 and the renal blood flow index monitoring software code 100 can determine the VII from the renal blood flow Doppler flow signal DF in the kidney 42L using Equation 2.

[0075]

number

[0076] After calculating the real-time renal blood flow index for renal blood flow in the kidney 42L, the system processor 18 can also execute the renal blood flow index monitoring software code 100 to generate a baseline index value for the renal blood flow. A value between 0.50 and 0.70 for the RRI is considered normal. The system processor 18 and the renal blood flow index monitoring software code 100 can determine the baseline index value by monitoring the real-time renal blood flow index while the patient 10 is in a normal, healthy condition or by selecting a baseline value established by previous clinical studies (e.g., selecting a baseline RRI between 0.50 and 0.70). An RRI value above 0.70 may indicate organ damage to the kidney 42L.

[0077] The system processor 18 can execute the renal blood flow index monitoring software code 100 to track the cumulative sum of time that the real-time renal blood flow index is above the baseline index value. The system processor 18 can also execute the renal blood flow index monitoring software code 100 to track how high the real-time renal blood flow index exceeds the baseline index value over time. The injury monitoring module 32 can use the cumulative sum of time that the real-time renal blood flow index is above the baseline index value and the high real-time renal blood flow index values ​​as variables in estimating the AKI risk score for the patient 10.

[0078] Renal blood flow monitors use continuous Doppler flow measured in the renal, hepatic, or portal veins, and can measure the venous excess ultrasound score (VEXUS) from the Doppler flow waveform characteristics in these vessels. Blood flow monitors can continuously measure VEXUS, which is useful clinical information for determining venous congestion and elevated right atrial pressure.

[0079] Discussion of Possible Embodiments The following is a non-exclusive description of possible embodiments of the present invention.

[0080] The renal blood flow monitor includes an ultrasound transducer probe with a two-dimensional array of transducer elements. An adhesive patch is connected to the ultrasound transducer probe and configured to attach the ultrasound transducer probe to a patient and maintain contact between the patient and the ultrasound transducer probe without an operator. A beamformer is configured to drive the two-dimensional array of transducer elements, causing the two-dimensional array of transducer elements to emit multiple ultrasound beams from the two-dimensional array of transducer elements, and to track Doppler flow signals of the patient's renal blood flow relative to the array of transducer elements.

[0081] The renal blood flow monitor of the preceding paragraph may additionally and / or alternatively optionally include any one or more of the following features, configurations, and / or additional components in the paragraphs below:

[0082] In embodiments of the renal blood flow monitor described above, the renal blood flow monitor further includes a system memory storing monitoring software code, and a processor configured to execute the monitoring software code to determine a characteristic associated with the patient's renal blood flow and to monitor the characteristic associated with the patient's renal blood flow over time.

[0083] In the foregoing renal blood flow monitor embodiment, the renal blood flow monitor further includes a display in communication with the processor for receiving and showing continuous readings of the Doppler flow signal from the ultrasound transducer probe and a representation of a characteristic associated with the patient's renal blood flow.

[0084] In the aforementioned renal blood flow monitor embodiment, the monitoring software code includes renal blood flow index monitoring software code, and the processor is configured to execute the renal blood flow index monitoring software code to estimate a renal blood flow index from a Doppler flow signal of the renal blood flow and to establish a baseline value for the patient's renal blood flow index from the Doppler flow signal sensed by the ultrasound transducer probe.

[0085] In the foregoing renal blood flow monitor embodiment, the processor is further configured to execute renal blood flow index monitoring software code and to output a representation of the patient's renal blood flow index to the display.

[0086] In the foregoing renal blood flow monitor embodiments, the renal blood flow index comprises a venous impedance index (VII), a renal resistive index (RRI), and / or a venous exaggerated ultrasound (VExUS) score.

[0087] In the aforementioned renal blood flow monitor embodiment, the monitoring software code includes renal blood flow monitoring software code, and the processor is configured to execute the renal blood flow monitoring software code to estimate renal blood flow from the renal blood flow Doppler flow signal and output a representation of the patient's renal blood flow on a display.

[0088] In embodiments of the renal blood flow monitor described above, the monitoring software code includes acute kidney injury (AKI) monitoring software code, and the processor is configured to execute the AKI monitoring software code to establish a baseline value for the patient's renal blood flow from renal blood flow Doppler flow signals sensed by the ultrasound transducer probe; continuously monitor the renal blood flow Doppler flow signals sensed by the ultrasound transducer probe throughout the duration of the patient's surgical procedure, medical procedure, or medical observation; estimate a real-time acute kidney injury risk score for the patient from the renal blood flow Doppler flow signals; and output a representation of the patient's real-time acute kidney injury risk score on a display.

[0089] In embodiments of the renal blood flow monitor described above, the renal blood flow monitor further includes an organ recognition algorithm configured to distinguish the renal blood flow signal from non-renal blood flow signals based on waveform characteristics of the renal blood flow signal.

[0090] In the aforementioned renal blood flow monitor embodiment, the organ recognition algorithm includes a system memory storing organ recognition software code and a processor configured to execute the organ recognition software code, perform waveform analysis of the patient's Doppler flow signals sensed by the ultrasound transducer probe, extract waveform characteristics of the Doppler flow signals, compare the waveform characteristics of the Doppler flow signals to a lookup table of renal blood flow waveform characteristics and non-renal blood flow waveform characteristics, and output a decision score indicative of whether the Doppler flow signals are from renal blood flow or non-renal blood flow.

[0091] In the foregoing renal blood flow monitor embodiment, the renal blood flow monitor further includes a display in communication with the ultrasound transducer probe control module and the organ recognition algorithm for receiving and showing continuous readings of the Doppler flow signal from the ultrasound transducer probe and a representation of the decision score from the organ recognition algorithm.

[0092] In the previously described embodiment of the renal blood flow monitor, the ultrasound transducer probe operates at a center frequency between 0.5 MHz and 4.0 MHz and penetrates more than 15 cm into the patient.

[0093] In the aforementioned renal blood flow monitor embodiment, the array of transducer elements of the ultrasound transducer probe is sized to cover one or more acoustic windows in the patient in at least one of two dimensions, the acoustic window of the patient being defined as an area of ​​the patient where ultrasound transmission is substantially unattenuated compared to its immediate surroundings.

[0094] In the foregoing renal blood flow monitor embodiment, the array of transducer elements of the ultrasound transducer probe is sized to extend across at least two intercostal spaces of the patient in at least one of two dimensions.

[0095] In the aforementioned renal blood flow monitor embodiment, each transducer element in the array of transducer elements of the ultrasound transducer probe includes an element width and a length, both of which are greater than one wavelength in soft tissue of the ultrasound waves emitted by the array of transducer elements.

[0096] In the embodiments of the renal blood flow monitor described above, the renal blood flow monitor further includes a coupling layer that includes a couplant that enables transmission of ultrasonic energy between the patient's skin and the ultrasound transducer probe.

[0097] In the aforementioned renal blood flow monitor embodiment, the renal blood flow monitor further includes a system memory that stores the beamformer as flow signal tracking software code, and a processor configured to execute the flow signal tracking software code and continuously monitor the Doppler flow signals of the renal blood flow sensed by the ultrasound transducer probe throughout the duration of the patient's surgery, medical procedure, or medical observation.

[0098] A method for monitoring a patient's renal blood flow is disclosed. The method includes positioning an ultrasound transducer probe over the patient's abdomen. The ultrasound transducer probe includes a two-dimensional array of transducer elements. The patient's abdomen is scanned by the two-dimensional array of transducer elements, and a beamformer drives the array of transducer elements to find and sense Doppler flow signals of the patient's renal blood flow. The ultrasound transducer probe is attached to the patient's abdomen by an adhesive patch connected to the ultrasound transducer probe at a location on the patient's abdomen where the Doppler flow signals of the patient's renal blood flow are found. The beamformer and the array of transducer elements track the Doppler flow signals of the patient's renal blood flow and continuously sense the Doppler flow signals of the patient's renal blood flow during surgery, medical procedures, or medical observations without an ultrasound operator.

[0099] The method of the preceding paragraph may additionally and / or alternatively optionally include any one or more of the following features, configurations, and / or additional components in the paragraphs below.

[0100] In an embodiment of the aforementioned method, the step of track scanning the Doppler flow signal of the patient's renal blood flow with a beamformer and an array of transducer elements includes the steps of emitting a set of sequential beams from the array of transducer elements and tracking the center of renal blood flow relative to the array of transducer elements, focusing each beam from the set of beams at a different location, and adjusting the position of the set of beams with the beamformer over the center of renal blood flow to maintain the Doppler flow signal of the patient's renal blood flow.

[0101] In an embodiment of the aforementioned method, the step of track scanning the Doppler flow signal of the patient's renal blood flow with the beamformer and the array of transducer elements includes measuring an estimate of the location of the renal blood flow with the beamformer, inputting the estimate of the location of the renal blood flow into a prediction filter, and determining a predicted trajectory of the location of the renal blood flow based on the estimate of the location of the renal blood flow and based on the patient's respiratory frequency.

[0102] In an embodiment of the aforementioned method, measuring an estimate of the location of renal blood flow by the beamformer includes measuring, by the beamformer, the difference in integrated power spectra between individual beams of the set of sequential beams to estimate the azimuth and elevation angles of the location of renal blood flow relative to the array of transducer elements; estimating, by the beamformer, the distance of the blood flow from the array of transducer elements in the distance dimension by collecting, by the array of transducer elements and the beamformer, a plurality of distance samples along the distance dimension, by the beamformer calculating, by the beamformer, an integrated power spectrum for each of the plurality of distance samples, by the beamformer assigning, by the beamformer, a likelihood of containing renal blood flow to each of the plurality of distance samples, and by the beamformer calculating an estimate of the center of renal blood flow from the plurality of distance samples.

[0103] In an embodiment of the aforementioned method, the method further includes the steps of: making the likelihood of containing renal blood flow proportional to the integrated power spectrum for each of the plurality of distance samples by the beamformer; and calculating, by the beamformer, an estimate of the center of renal blood flow from the plurality of distance samples by selecting the distance sample of the plurality of distance samples having the largest integrated power spectrum.

[0104] In an embodiment of the foregoing method, the method further includes measuring the patient's respiratory frequency with a respiratory monitor connected to the patient, and inputting the patient's respiratory frequency from the respiratory monitor into a predictive filter.

[0105] In an embodiment of the foregoing method, the predictive filter comprises a Kalman filter.

[0106] In an embodiment of the foregoing method, the method further includes continuously outputting a plot of the Doppler flow signal of the patient's renal blood flow to a display in communication with the ultrasound transducer probe during surgery, medical treatment, or medical observation without an ultrasound operator.

[0107] In an embodiment of the foregoing method, the method further includes communicating the Doppler flow signals sensed by the ultrasound transducer probe to a processor configured to execute monitoring software code stored on the system memory; determining, by the processor executing the monitoring software code, characteristics associated with the patient's renal blood flow from the Doppler flow signals of the renal blood flow sensed by the ultrasound transducer probe; and continuously monitoring, by the processor executing the monitoring software code, the Doppler flow signals of the renal blood flow and the characteristics associated with the patient's renal blood flow during surgery, medical treatment, or medical observation of the patient.

[0108] In an embodiment of the foregoing method, the method further includes continuously outputting a plot of the Doppler flow signal of the patient's renal blood flow and a representation of characteristics associated with the patient's renal blood flow to a display in communication with the processor during the patient's surgery, medical procedure, or medical observation.

[0109] In an embodiment of the aforementioned method, the monitoring software code includes renal blood flow monitoring software code, and the processor executes the renal blood flow monitoring software code to estimate renal blood flow from the renal blood flow Doppler flow signal, continuously monitor the renal blood flow during the patient's surgery, medical procedure, or medical observation, and output a representation of the patient's renal blood flow over time to a display.

[0110] In an embodiment of the foregoing method, the monitoring software code includes renal blood flow index monitoring software code, and the processor executes the renal blood flow index monitoring software code to estimate a renal blood flow index from a Doppler flow signal of the renal blood flow, establish a baseline value for the patient's renal blood flow index from the Doppler flow signal sensed by the ultrasound transducer probe, continuously monitor the renal blood flow index during the patient's surgery, medical procedure, or medical observation, and output a representation of the patient's renal blood flow index over time on a display.

[0111] In an embodiment of the foregoing method, the monitoring software code includes renal resistive index (RRI) monitoring software code, and the processor executes the RRI monitoring software code to estimate the patient's RRI from a Doppler flow signal of renal blood flow, establish a baseline value for the patient's RRI from the Doppler flow signal sensed by the ultrasound transducer probe, continuously monitor the patient's RRI during the patient's surgery, medical procedure, or medical observation, and output a representation of the patient's RRI over time on a display.

[0112] In an embodiment of the aforementioned method, the monitoring software code includes venous impedance index (VII) monitoring software code, and the processor executes the VII monitoring software code to estimate the patient's VII from a Doppler flow signal of renal blood flow, establish a baseline value for the patient's VII from the Doppler flow signal sensed by the ultrasound transducer probe, continuously monitor the patient's VII during the patient's surgery, medical procedure, or medical observation, and output a representation of the patient's VII over time on a display.

[0113] In an embodiment of the foregoing method, the monitoring software code includes venous excess ultrasound (VExUS) monitoring software code, and the processor executes the VExUS monitoring software code to estimate a patient's VExUS score from a Doppler flow signal of renal blood flow, establish a baseline value for the patient's VExUS score from the Doppler flow signal sensed by the ultrasound transducer probe, continuously monitor the patient's VExUS score during the patient's surgery, medical procedure, or medical observation, and output a representation of the patient's VExUS score over time on a display.

[0114] In an embodiment of the foregoing method, the monitoring software code includes acute kidney injury (AKI) monitoring software code, and the processor executes the AKI monitoring software code to establish a baseline value for the patient's renal blood flow from renal blood flow Doppler flow signals sensed by the ultrasound transducer probe, continuously monitor the renal blood flow Doppler flow signals sensed by the ultrasound transducer probe throughout the duration of the patient's surgical procedure, medical procedure, or medical observation, estimate a real-time acute kidney injury risk score for the patient from the renal blood flow Doppler flow signals, and output a representation of the patient's real-time acute kidney injury risk score on a display.

[0115] In an embodiment of the foregoing method, the method further includes verifying, by a processor executing the monitoring software code, the identity of the Doppler flow signal of the patient's renal blood flow using an organ recognition algorithm based on waveform characteristics of the Doppler flow signal.

[0116] In an embodiment of the aforementioned method, verifying by the processor executing the monitoring software code the identity of the Doppler flow signal of the patient's renal blood flow based on waveform characteristics of the Doppler flow signal using an organ recognition algorithm includes comparing by the processor executing the monitoring software code the waveform characteristics of the Doppler flow signal to a waveform lookup table, the waveform lookup table being a table of renal blood flow waveform characteristics and non-renal blood flow waveform characteristics.

[0117] In embodiments of the foregoing methods, the waveform look-up table is pre-populated with waveforms obtained from prior measurements from a population and / or the waveform look-up table contains information from the patient gathered prior to the operation, medical procedure, or medical observation by a processor executing the monitoring software code scanning with an ultrasound transducer probe each organ of the patient that will be monitored during the operation, medical procedure, or medical observation.

[0118] In embodiments of the foregoing methods, the waveform characteristics of the Doppler flow signal include the signal-to-noise ratio (SNR), integrated power spectrum, spectral envelope, pulsatility, and / or spectral bandwidth of the Doppler flow signal.

[0119] In an embodiment of the foregoing method, the method further includes outputting a quality grade / index to a display indicating the probability that the Doppler flow signal is from the patient's renal blood flow or from the patient's non-renal blood flow, and continuously communicating the quality grade / index as an input into a predictive filter during operation, medical procedure, or medical observation.

[0120] In embodiments of the foregoing methods, an ultrasound transducer probe senses Doppler flow signals of the patient's renal blood flow from the patient's renal artery, from the patient's renal vein, or from both the renal artery and renal vein.

[0121] The organ blood flow monitor includes an ultrasound transducer probe with a two-dimensional array of transducer elements. An adhesive patch is connected to the ultrasound transducer probe and configured to attach the ultrasound transducer probe to a patient. A beamformer is configured to drive the two-dimensional array of transducer elements, causing the two-dimensional array of transducer elements to emit multiple ultrasound beams from the two-dimensional array of transducer elements, and to track target organ blood flow signals relative to the array of transducer elements.

[0122] The organ blood flow monitor of the preceding paragraph may additionally and / or alternatively optionally include any one or more of the following features, configurations, and / or additional components in the paragraphs below:

[0123] In embodiments of the organ blood flow monitor described above, the organ blood flow monitor further includes a system memory storing target organ flow index monitoring software code; and a processor configured to execute the target organ flow index monitoring software code to establish a baseline value for the patient's target organ flow from the target organ blood flow signals sensed by the ultrasound transducer probe, continuously monitor the target organ blood flow signals sensed by the ultrasound transducer probe throughout the duration of a surgical procedure on the patient, and estimate a real-time target organ blood flow index for the patient from the target organ blood flow signals.

[0124] In the foregoing organ blood flow monitor embodiment, the organ blood flow monitor further includes a display in communication with the processor for receiving and showing continuous readings of the target organ blood flow signal from the ultrasound transducer probe and a representation of the patient's real-time target organ blood flow index.

[0125] In embodiments of the organ blood flow monitor described above, the organ blood flow monitor further includes a system memory storing organ blood flow monitoring software code, and a processor configured to execute the organ blood flow monitoring software code and to estimate the target organ blood flow from the target organ blood flow signal.

[0126] In the previously described organ blood flow monitor embodiment, the organ blood flow monitor further includes a display in communication with the processor for receiving and showing continuous readings of the target organ blood flow signal from the ultrasound transducer probe and a representation of the target organ blood flow rate of the patient.

[0127] In embodiments of the organ blood flow monitor described above, the organ blood flow monitor further includes a system memory storing organ injury monitoring software code; and a processor configured to execute the organ injury monitoring software code, establish a baseline value for the patient's organ flow from the target organ blood flow signals sensed by the ultrasound transducer probe, continuously monitor the target organ blood flow signals sensed by the ultrasound transducer probe throughout the duration of the surgical procedure on the patient, and estimate a real-time organ injury risk score for the patient from the target organ blood flow signals.

[0128] In embodiments of the organ blood flow monitor described above, the organ blood flow monitor further includes a display in communication with the processor for receiving and showing continuous readings of the target organ blood flow signal from the ultrasound transducer probe and a representation of the patient's real-time organ injury risk score.

[0129] In the previously described organ blood flow monitor embodiment, the ultrasound transducer probe operates at a center frequency between 0.5 MHz and 4.0 MHz and penetrates more than 15 cm into the patient.

[0130] In the aforementioned organ blood flow monitor embodiment, the array of transducer elements of the ultrasound transducer probe is sized to cover one or more acoustic windows in the patient in at least one of two dimensions, the acoustic window of the patient being defined as an area of ​​the patient where ultrasound transmission is substantially unattenuated compared to its immediate surroundings.

[0131] In the previously described organ blood flow monitor embodiment, the array of transducer elements of the ultrasound transducer probe is sized to extend across at least two intercostal spaces of the patient in at least one of two dimensions.

[0132] In the aforementioned organ blood flow monitor embodiment, each transducer element in the array of transducer elements of the ultrasound transducer probe includes an element width and a length, both of which are greater than one wavelength in soft tissue of the ultrasound waves emitted by the array of transducer elements.

[0133] In the aforementioned organ blood flow monitor embodiment, the system memory and processor further include organ recognition software code configured to distinguish target organ blood flow signals from non-target blood flow signals based on waveform characteristics of the target organ blood flow signals.

[0134] In the aforementioned organ blood flow monitor embodiment, the processor is configured to execute organ recognition software code to perform waveform analysis of the patient's flow signal sensed by the ultrasound transducer probe, extract waveform characteristics of the flow signal, compare the waveform characteristics of the flow signal to a look-up table of blood flow waveform characteristics of various organs, and output a decision score to a display indicating whether the flow signal is from target organ blood flow or non-target blood flow.

[0135] In embodiments of the organ blood flow monitor described above, the organ blood flow monitor further includes a coupling layer that includes a couplant that enables transmission of ultrasonic energy between the patient's skin and the ultrasound transducer probe.

[0136] A method for monitoring organ blood flow in a target organ of a patient during surgery, a medical procedure, or medical observation is disclosed. The method includes positioning an ultrasound transducer probe over the patient's abdomen, the ultrasound transducer probe including a two-dimensional array of transducer elements. The target organ location of the patient is scanned by the two-dimensional array of transducer elements and a beamformer driving the array of transducer elements to find a Doppler flow signal of the patient's organ blood flow. The ultrasound transducer probe is attached to the patient by an adhesive patch connected to the ultrasound transducer probe at the target organ location where the Doppler flow signal of the patient's organ blood flow is found. The beamformer track-scans the Doppler flow signal of the patient's organ blood flow and continuously senses the Doppler flow signal of the patient's organ blood flow during surgery, a medical procedure, or medical observation without repositioning the ultrasound transducer probe.

[0137] The method of the preceding paragraph may additionally and / or alternatively optionally include any one or more of the following features, configurations, and / or additional components in the paragraphs below.

[0138] In an embodiment of the aforementioned method, the step of track scanning the Doppler flow signal of the patient's organ blood flow with a beamformer and an array of transducer elements includes the steps of emitting a set of sequential beams from the array of transducer elements and tracking the center of the organ blood flow relative to the array of transducer elements, focusing each beam from the set of beams at a different location, and adjusting the position of the set of beams with the beamformer over the center of the organ blood flow to maintain the Doppler flow signal of the patient's organ blood flow.

[0139] In an embodiment of the foregoing method, the method further includes continuously outputting a plot of a Doppler flow signal of the patient's organ blood flow to a display in communication with the ultrasound transducer probe while the ultrasound transducer probe is attached to the patient by an adhesive patch.

[0140] In an embodiment of the aforementioned method, the method further includes the steps of communicating the Doppler flow signals sensed by the ultrasound transducer probe to a processor configured to execute target organ blood flow index monitoring software code stored on a system memory; establishing, by the processor, a baseline value for organ blood flow of the target organ from the Doppler flow signals of the target organ blood flow sensed by the ultrasound transducer probe; continuously monitoring, by the processor, the Doppler flow signals of the organ blood flow of the target organ sensed by the ultrasound transducer probe throughout the duration of the surgical procedure, medical procedure, or medical observation; and estimating, by the processor, a real-time target organ blood flow index of the patient from the Doppler flow signals of the organ blood flow of the target organ.

[0141] In an embodiment of the aforementioned method, the method further includes the steps of communicating Doppler flow signals sensed by the ultrasound transducer probe to a processor configured to execute target organ injury monitoring software code stored on a system memory; establishing, by the processor, a baseline value for organ blood flow of the target organ from the organ blood flow Doppler flow signals sensed by the ultrasound transducer probe; continuously monitoring, by the processor, the organ blood flow Doppler flow signals sensed by the ultrasound transducer probe throughout the duration of the surgical procedure, medical procedure, or medical observation; and estimating, by the processor, a real-time target organ injury risk score for the patient from the organ blood flow Doppler flow signals of the patient's target organ.

[0142] In an embodiment of the foregoing method, the method further includes continuously outputting to a display in communication with the processor a plot of the organ blood flow Doppler flow signal of the patient's target organ and a representation of the patient's real-time target organ blood flow index for the duration of the surgical procedure, medical procedure, or medical observation.

[0143] In an embodiment of the foregoing method, the method further includes continuously outputting to a display in communication with the processor a plot of the Doppler flow signal of the organ blood flow of the patient's target organ and a representation of the patient's real-time target organ injury risk score for the duration of the surgical procedure, medical procedure, or medical observation.

[0144] In an embodiment of the foregoing method, the method further comprises verifying the identity of the Doppler flow signal of the patient's organ blood flow with an organ recognition algorithm based on waveform characteristics of the Doppler flow signal.

[0145] The renal blood flow monitor includes an ultrasound transducer probe and an adhesive patch connected to the ultrasound transducer probe for attaching the ultrasound transducer probe to the patient. The renal blood flow monitor further includes an organ recognition algorithm configured to distinguish the renal blood flow signal from non-renal blood flow signals based on waveform characteristics of the renal blood flow signal.

[0146] The renal blood flow monitor of the preceding paragraph may additionally and / or alternatively optionally include any one or more of the following features, configurations, and / or additional components in the paragraphs below:

[0147] In the previously described renal blood flow monitor embodiment, the ultrasound transducer probe includes a two-dimensional array of transducer elements.

[0148] In an embodiment of the renal blood flow monitor described above, the renal blood flow monitor further includes a system memory storing a beamformer with flow signal tracking software code, a processor configured to execute the beamformer and flow signal tracking software code to emit multiple beams from the array of transducer elements, track Doppler flow signals of renal blood flow relative to the array of transducer elements, and continuously monitor the Doppler flow signals of renal blood flow sensed by the ultrasound transducer probe throughout the duration of the patient's surgery, medical procedure, or medical observation, and a coupling layer over the ultrasound transducer probe including a couplant material for forming contact between the skin and the ultrasound transducer probe.

[0149] In the aforementioned renal blood flow monitor embodiment, the organ recognition algorithm includes a waveform lookup table of renal blood flow waveform characteristics and non-renal blood flow waveform characteristics, and a waveform analyzer module that performs waveform analysis of the patient's Doppler flow signals sensed by the ultrasound transducer probe, extracts the waveform characteristics of the Doppler flow signals, compares the waveform characteristics of the Doppler flow signals with the lookup table, and outputs a decision score indicative of whether the Doppler flow signal is from renal blood flow or non-renal blood flow.

[0150] In the previously described renal blood flow monitor embodiment, the renal blood flow monitor further includes a display in communication with the ultrasound transducer probe, the beamformer, and the organ recognition algorithm for receiving and showing continuous readings of the Doppler flow signal from the ultrasound transducer probe and a decision score from the organ recognition algorithm.

[0151] In embodiments of the renal blood flow monitor described above, the renal blood flow monitor further includes a system memory storing acute kidney injury (AKI) monitoring software code; and a processor configured to execute the AKI monitoring software code to establish a baseline value for the patient's renal blood flow from the renal blood flow Doppler flow signals sensed by the ultrasound transducer probe, continuously monitor the renal blood flow Doppler flow signals sensed by the ultrasound transducer probe throughout the duration of the surgical procedure on the patient, estimate a real-time acute kidney injury risk score for the patient from the renal blood flow Doppler flow signals, and output a representation of the patient's real-time acute kidney injury risk score on a display.

[0152] The renal blood flow monitor includes an ultrasound transducer probe with an array of transducer elements. An adhesive patch is connected to the ultrasound transducer probe and configured to connect the ultrasound transducer probe to a patient. The renal blood flow monitor further includes a system memory storing beamformer software code and a processor in communication with the ultrasound transducer probe and the system memory. The processor is configured to execute the beamformer software code to beam scan the patient with the array of transducer elements and find a Doppler flow signal of the patient's renal blood flow.

[0153] The renal blood flow monitor of the preceding paragraph may additionally and / or alternatively optionally include any one or more of the following features, configurations, and / or additional components in the paragraphs below:

[0154] In the aforementioned embodiment of the renal blood flow monitor, the processor is configured to execute beamformer software code to track scan the patient's renal blood flow by emitting multiple beams from the array of transducer elements and tracking the center of renal blood flow relative to the array of transducer elements, adjust the position of the beams of the beam scan over the center of renal blood flow, and maintain a Doppler flow signal of the patient's renal blood flow.

[0155] In the foregoing renal blood flow monitor embodiment, the renal blood flow monitor further includes a display in communication with the ultrasound transducer probe and the processor for receiving and showing continuous readings of the Doppler flow signal from the ultrasound transducer probe.

[0156] In the previously described embodiment of the renal blood flow monitor, the ultrasound transducer probe operates at a center frequency between 0.5 MHz and 4.0 MHz and penetrates more than 15 cm into the patient.

[0157] In the previously described renal blood flow monitor embodiment, the array of transducer elements of the ultrasound transducer probe is sized in length to cover one or more acoustic windows in the patient, the acoustic window of the patient being defined as an area of ​​the patient where ultrasound transmission is substantially unattenuated compared to its immediate surroundings.

[0158] In the previously described renal blood flow monitor embodiment, the array of transducer elements of the ultrasound transducer probe is sized in length to extend across at least two intercostal spaces of the patient.

[0159] In the aforementioned renal blood flow monitor embodiment, each transducer element in the array of transducer elements of the ultrasound transducer probe includes an element width and a length, both of which are greater than one wavelength of ultrasound emitted by the array of transducer elements.

[0160] In the aforementioned renal blood flow monitor embodiment, the array of transducer elements of the ultrasound transducer probe includes a pitch that defines an inter-element spacing between adjacent transducer elements, the pitch being greater than one wavelength of ultrasound emitted by the array of transducer elements.

[0161] In the aforementioned renal blood flow monitor embodiment, the system memory stores acute kidney injury (AKI) monitoring software code, and the processor is configured to execute the AKI monitoring software code to establish a baseline value for the patient's renal blood flow from renal blood flow Doppler flow signals sensed by the ultrasound transducer probe, continuously monitor the renal blood flow Doppler flow signals sensed by the ultrasound transducer probe throughout the duration of a surgical procedure on the patient, estimate a real-time acute kidney injury risk score for the patient from the renal blood flow Doppler flow signals, and output a representation of the real-time acute kidney injury risk score on a display.

[0162] The blood flow monitor includes an ultrasound transducer probe with a two-dimensional array of transducer elements. An adhesive patch is connected to the ultrasound transducer probe and configured to attach the ultrasound transducer probe to a patient. The blood flow monitor further includes both a system memory storing beamformer software code and a processor in communication with the ultrasound transducer probe and the system memory. The processor is configured to execute the beamformer software code to steer a beam and scan the patient with the array of transducer elements to find a Doppler flow signal of a target blood flow in the patient.

[0163] The blood flow monitor of the preceding paragraph may additionally and / or alternatively optionally include any one or more of the following features, configurations, and / or additional components in the paragraphs below:

[0164] In the blood flow monitor embodiment described above, the processor is configured to execute beamformer software code to track scan a target blood flow in the patient by emitting multiple beams from the array of transducer elements and tracking a center of the target blood flow relative to the array of transducer elements, adjust the position of the beams of the beam scan over the center of the target blood flow, and maintain a Doppler flow signal of the target blood flow in the patient.

[0165] In the foregoing blood flow monitor embodiment, the blood flow monitor further includes a display in communication with the ultrasound transducer probe and the processor for receiving and showing continuous readings of the Doppler flow signal from the ultrasound transducer probe.

[0166] In the blood flow monitor embodiment described above, the ultrasound transducer probe operates at a center frequency between 0.5 MHz and 4.0 MHz and penetrates more than 15 cm into the patient.

[0167] In the previously described blood flow monitor embodiment, the array of transducer elements of the ultrasound transducer probe is sized in length to cover one or more acoustic windows within the patient, the acoustic window of the patient being defined as an area of ​​the patient where ultrasound transmission is substantially unattenuated compared to its immediate surroundings.

[0168] In the blood flow monitor embodiment described above, the array of transducer elements of the ultrasound transducer probe is sized in length to extend across at least two intercostal spaces of the patient.

[0169] In the previously described blood flow monitor embodiment, each transducer element in the array of transducer elements of the ultrasound transducer probe includes an element width and a length, both of which are greater than one wavelength of ultrasound emitted by the array of transducer elements.

[0170] In the aforementioned blood flow monitor embodiment, the array of transducer elements of the ultrasound transducer probe includes a pitch that defines an inter-element spacing between adjacent transducer elements, the pitch being greater than one wavelength of ultrasound emitted by the array of transducer elements.

[0171] In the aforementioned blood flow monitor embodiment, the system memory stores specific organ injury (SOI) monitoring software code, and the processor is configured to execute the SOI monitoring software code to establish a baseline value for the patient's specific organ blood flow from the specific organ blood flow Doppler flow signals sensed by the ultrasound transducer probe, continuously monitor the specific organ blood flow Doppler flow signals sensed by the ultrasound transducer probe throughout the duration of the surgical procedure on the patient, estimate a real-time specific organ injury risk score for the patient from the renal blood flow Doppler flow signals, and output a representation of the real-time specific organ injury risk score on a display.

[0172] While the present invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is not intended that the invention be limited to the particular embodiments disclosed, but rather that the invention will include all embodiments falling within the scope of the appended claims. [Explanation of symbols]

[0173] 10 patients 11 Monitoring System 11K Monitoring System 11L Monitoring System 12 Renal Blood Flow Monitor 12K Renal Blood Flow Monitor 12L Liver Blood Flow Monitor 14 Ultrasonic transducer probe 14A Ultrasonic Transducer Probe 14B Ultrasonic Transducer Probe 14K Ultrasonic Transducer Probe 14L Ultrasonic Transducer Probe 16 adhesive patches 17 Ultrasonic front-end circuit 18 System Processors 20 System Memory 22 Software Code 24 Probe cable 25 Analog Signals 26 Analog-to-Digital Converter (ADC) 28 Display 30 Transducer Probe Control Module 32 Injury Monitoring Module 34 User Interface 36 Doppler plot 36A First Plot 36B Second Plot Plot of 36K Doppler flow signal 36L Plotting the Doppler Flow Signal 38 Injury Score Indicators 38A Primary Injury Score Indicator 38B Second Injury Score Indicator 38K Injury Score Indicator 38L Injury Score Indicator 40 Abdomen 42L left kidney 42R Right kidney 44 Liver 46 Spleen 48 Beamformer 49 Predictive Filters 50 Array 51 Respiratory Monitor 52 Transducer Element 54a, 54b, 54c ribs 56a, 56b, 56c signal beam 58 Organ Recognition Algorithm 60 Decisive Score 62 Waveform Analyzer 64 waveform lookup tables 98 Renal Blood Flow Monitoring Software Code 100 Renal Blood Flow Index Monitoring Software Codes EL element length EP Pitch EW Element width BW Doppler signal of blood flow in the renal artery RA DF Doppler flow signal OW Outgoing Signal PL probe length PW Probe width RA renal artery RV renal vein RW Doppler signal of blood flow in the renal vein RV W1 First acoustic window W2 Second acoustic window

Claims

1. an ultrasonic transducer probe including a two-dimensional array of transducer elements; an adhesive patch connected to the ultrasound transducer probe and configured to attach the ultrasound transducer probe to a patient and maintain contact between the patient and the ultrasound transducer probe without an operator; and a beamformer that drives the two-dimensional array of transducer elements, the beamformer configured to cause the two-dimensional array of transducer elements to emit a plurality of ultrasound beams from the two-dimensional array of transducer elements and to track Doppler flow signals of renal blood flow of the patient relative to the array of transducer elements; and and renal blood flow monitors.

2. a system memory for storing monitoring software code; Executing the monitoring software code; determining a characteristic associated with the renal blood flow of the patient; a processor configured to monitor the characteristic associated with the renal blood flow of the patient over time; 10. The renal blood flow monitor of claim 1, further comprising:

3. 3. The renal blood flow monitor of claim 2, further comprising a display in communication with the processor for receiving and showing continuous readings of the Doppler flow signal from the ultrasound transducer probe and a representation of the characteristic associated with the renal blood flow of the patient.

4. The monitoring software code renal blood flow index monitoring software code; the processor executing the renal blood flow index monitoring software code; estimating a renal blood flow index from the Doppler flow signal of the renal blood flow; 4. The renal blood flow monitor of claim 3, configured to establish a baseline value for the renal blood flow index of the patient from the Doppler flow signal sensed by the ultrasound transducer probe.

5. 5. The renal blood flow monitor of claim 4, wherein the processor is further configured to execute the renal blood flow index monitoring software code and output a representation of the renal blood flow index of the patient to the display.

6. 6. The renal blood flow monitor of claim 5, wherein the renal blood flow index comprises a venous impedance index (VII), a renal resistive index (RRI), and / or a venous exaggerated ultrasound (VExUS) score.

7. The monitoring software code renal blood flow monitoring software code; the processor executing the renal blood flow monitoring software code; estimating renal blood flow from the Doppler flow signal of the renal blood flow; 10. The renal blood flow monitor of claim 3 or 6, configured to output a representation of the renal blood flow rate of the patient to the display.

8. The monitoring software code Includes acute kidney injury (AKI) monitoring software code, the processor executes the AKI monitoring software code; establishing a baseline value for the patient's renal blood flow from the Doppler flow signal of the renal blood flow sensed by the ultrasound transducer probe; continuously monitoring the Doppler flow signal of the renal blood flow sensed by the ultrasound transducer probe throughout the duration of the patient's surgery, medical procedure, or medical observation; estimating a real-time acute kidney injury risk score for the patient from the Doppler flow signal of the renal blood flow; 8. The renal blood flow monitor of claim 3, configured to output a representation of the patient's real-time acute kidney injury risk score on the display.

9. 10. The renal blood flow monitor of claim 1, further comprising an organ recognition algorithm configured to distinguish the renal blood flow signal from non-renal blood flow signals based on waveform characteristics of the renal blood flow signal.

10. The organ recognition algorithm a system memory storing organ recognition software code; Executing the organ recognition software code; performing a waveform analysis of the Doppler flow signal of the patient sensed by the ultrasound transducer probe; extracting waveform characteristics of the Doppler flow signal; comparing the waveform characteristics of the Doppler flow signal to a lookup table of renal and non-renal blood flow waveform characteristics; a processor configured to output a decision score indicative of whether the Doppler flow signal is from renal blood flow or non-renal blood flow; 10. The renal blood flow monitor of claim 9, comprising:

11. 11. The renal blood flow monitor of claim 10, further comprising a display in communication with the ultrasound transducer probe control module and the organ recognition algorithm for receiving and showing continuous readings of the Doppler flow signal from the ultrasound transducer probe and a representation of the decision score from the organ recognition algorithm.

12. 12. The renal blood flow monitor of claim 1, wherein the ultrasound transducer probe operates at a center frequency between 0.5 MHz and 4.0 MHz and penetrates more than 15 cm into the patient.

13. 13. The renal blood flow monitor of claim 1, wherein the array of transducer elements of the ultrasound transducer probe is sized to cover one or more acoustic windows in the patient in at least one of the two dimensions, the acoustic window of the patient being defined as an area of ​​the patient where ultrasound transmission is substantially unattenuated compared to its immediate surroundings.

14. 14. The renal blood flow monitor of claim 1, wherein the array of transducer elements of the ultrasound transducer probe is sized to extend across at least two intercostal spaces of the patient in at least one of the two dimensions.

15. 15. The renal blood flow monitor of claim 13 or 14, wherein each transducer element in the array of transducer elements of the ultrasound transducer probe includes an element width and a length, both of which are greater than one wavelength in soft tissue of ultrasound emitted by the array of transducer elements.

16. 16. The renal blood flow monitor of claim 1, further comprising a coupling layer comprising a couplant that enables ultrasonic energy transmission between the patient's skin and the ultrasound transducer probe.

17. a system memory storing said beamformer as flow signal tracking software code; a processor configured to execute the flow signal tracking software code and to continuously monitor the Doppler flow signal of the renal blood flow sensed by the ultrasound transducer probe throughout the duration of the patient's surgical procedure, medical treatment, or medical observation; 10. The renal blood flow monitor of claim 1, further comprising:

18. 1. A method for monitoring renal blood flow in a patient, comprising: positioning an ultrasound transducer probe over the patient's abdomen, the ultrasound transducer probe including a two-dimensional array of transducer elements; scanning the abdomen of the patient with the two-dimensional array of transducer elements and a beamformer driving the array of transducer elements to find and sense a Doppler flow signal of the renal blood flow of the patient; attaching the ultrasound transducer probe to the patient's abdomen by an adhesive patch connected to the ultrasound transducer probe at a location on the patient's abdomen where the Doppler flow signal of the patient's renal blood flow is found; track scanning the Doppler flow signals of the renal blood flow of the patient with the beamformer and the array of transducer elements to continuously sense the Doppler flow signals of the renal blood flow of the patient during surgery, medical treatment, or medical observation without an ultrasound operator; A method comprising:

19. track scanning the Doppler flow signal of the renal blood flow of the patient with the beamformer and the array of transducer elements, emitting a set of sequential beams from the array of transducer elements and tracking the center of renal blood flow relative to the array of transducer elements; focusing each beam from the set of beams to a different location; adjusting the position of the set of beams by the beamformer over the center of the renal blood flow to maintain the Doppler flow signal of the renal blood flow of the patient; 20. The method of claim 18, comprising:

20. track scanning the Doppler flow signal of the renal blood flow of the patient with the beamformer and the array of transducer elements, measuring an estimate of the location of the renal blood flow with the beamformer; inputting the estimate of the location of the renal blood flow into a predictive filter; determining a predicted trajectory of the location of the renal blood flow based on the estimate of the location of the renal blood flow and based on the patient's respiratory frequency; 20. The method of claim 19, comprising:

21. Measuring an estimate of the location of the renal blood flow with the beamformer comprises: measuring, with the beamformer, differences in integrated power spectra between individual beams of the set of sequential beams to estimate azimuth and elevation angles of the location of the renal blood flow relative to the array of transducer elements; collecting a plurality of range samples along a range dimension with the array of transducer elements and the beamformer; calculating, by the beamformer, an integrated power spectrum for each of the plurality of range samples; by assigning, by the beamformer, a likelihood of containing the renal blood flow to each distance sample of the plurality of distance samples; and calculating, by the beamformer, an estimate of the center of renal blood flow from the plurality of distance samples; estimating, by the beamformer, a distance of the blood flow from the array of transducer elements in a distance dimension; 21. The method of claim 20, comprising:

22. making the likelihood of containing the renal blood flow proportional to the integrated power spectrum for each range sample of the plurality of range samples by the beamformer; calculating, by the beamformer, the estimate of the center of the renal blood flow from the plurality of distance samples by selecting the distance sample of the plurality of distance samples having a largest integrated power spectrum; 22. The method of claim 21, further comprising:

23. measuring the respiratory frequency of the patient with a respiratory monitor connected to the patient; inputting the respiratory frequency of the patient from the respiratory monitor into the predictive filter; 23. The method of any one of claims 20 to 22, further comprising:

24. 24. The method of any one of claims 20 to 23, wherein the predictive filter comprises a Kalman filter.

25. 25. The method of any one of claims 18 to 24, further comprising the step of continuously outputting a plot of the Doppler flow signal of the patient's renal blood flow to a display in communication with the ultrasound transducer probe during the surgical procedure, medical procedure, or medical observation without an ultrasound operator.

26. communicating the Doppler flow signals sensed by the ultrasound transducer probe to a processor configured to execute monitoring software code stored on a system memory; determining, by the processor executing the monitoring software code, characteristics associated with the renal blood flow of the patient from the Doppler flow signals of the renal blood flow sensed by the ultrasound transducer probe; continuously monitoring, by the processor executing the monitoring software code, the Doppler flow signal of the renal blood flow and the characteristic associated with the renal blood flow of the patient during a surgical procedure, medical treatment, or medical observation of the patient; 25. The method of any one of claims 18 to 24, further comprising:

27. 27. The method of claim 26, further comprising continuously outputting a plot of the Doppler flow signal of the patient's renal blood flow and a representation of the characteristic associated with the patient's renal blood flow to a display in communication with the processor during the surgical procedure, medical treatment, or medical observation of the patient.

28. the monitoring software code includes renal blood flow monitoring software code; the processor executing the renal blood flow monitoring software code; estimating renal blood flow from the Doppler flow signal of the renal blood flow; continuously monitoring the renal blood flow during the surgical procedure, medical treatment, or medical observation of the patient; 28. The method of claim 27, further comprising outputting a representation of the renal blood flow of the patient over time on the display.

29. the monitoring software code includes renal blood flow index monitoring software code; the processor executing the renal blood flow index monitoring software code; estimating a renal blood flow index from the Doppler flow signal of the renal blood flow; establishing a baseline value for the renal blood flow index of the patient from the Doppler flow signal sensed by the ultrasound transducer probe; continuously monitoring the renal blood flow index during the surgical procedure, medical treatment, or medical observation of the patient; 29. The method of claim 27 or 28, further comprising outputting a representation of the renal blood flow index of the patient over time on the display.

30. the monitoring software code includes renal resistive index (RRI) monitoring software code; the processor executes the RRI monitoring software code; estimating an RRI for the patient from the Doppler flow signal of the renal blood flow; establishing a baseline value for RRI for the patient from the Doppler flow signal sensed by the ultrasound transducer probe; continuously monitoring the RRI of the patient during the surgical procedure, medical treatment, or medical observation of the patient; 30. The method of any one of claims 27 to 29, wherein a representation of the RRI of the patient over time is output to the display.

31. the monitoring software code includes venous impedance index (VII) monitoring software code; the processor executes the VII monitoring software code; estimating VII of the patient from the Doppler flow signal of the renal blood flow; establishing a baseline value for the patient's VII from the Doppler flow signal sensed by the ultrasound transducer probe; continuously monitoring said VII of said patient during said surgical procedure, medical treatment, or medical observation of said patient; 31. The method of any one of claims 27 to 30, wherein a representation of the VII of the patient over time is output to the display.

32. the monitoring software code includes venous excess ultrasound (VExUS) monitoring software code; the processor executes the VExUS monitoring software code; estimating a VExUS score for the patient from the Doppler flow signal of the renal blood flow; establishing a baseline value for a VExUS score for the patient from the Doppler flow signal sensed by the ultrasound transducer probe; continuously monitoring the VExUS score of the patient during the surgical procedure, medical treatment, or medical observation of the patient; 32. The method of any one of claims 27 to 31, wherein a representation of the patient's VExUS score over time is output to the display.

33. the monitoring software code comprises acute kidney injury (AKI) monitoring software code; the processor executes the AKI monitoring software code; establishing a baseline value for the patient's renal blood flow from the Doppler flow signal of the renal blood flow sensed by the ultrasound transducer probe; continuously monitoring the Doppler flow signal of the renal blood flow sensed by the ultrasound transducer probe throughout the duration of the patient's surgery, medical procedure, or medical observation; estimating a real-time acute kidney injury risk score for the patient from the Doppler flow signal of the renal blood flow; 33. The method of any one of claims 27 to 32, wherein a representation of the real-time acute kidney injury risk score of the patient over time is output to the display.

34. 34. The method of any one of claims 27 to 33, further comprising verifying, by the processor executing the monitoring software code, the identity of the Doppler flow signal of the patient's renal blood flow using an organ recognition algorithm based on waveform characteristics of the Doppler flow signal.

35. verifying, by the processor executing the monitoring software code, the identity of the Doppler flow signal of the renal blood flow of the patient based on waveform characteristics of the Doppler flow signal with the organ recognition algorithm; 35. The method of claim 34, including comparing, by the processor executing the monitoring software code, the waveform characteristics of the Doppler flow signal to a waveform lookup table, the waveform lookup table being a table of renal blood flow waveform characteristics and non-renal blood flow waveform characteristics.

36. 36. The method of claim 35, wherein the waveform look-up table is pre-populated with waveforms obtained from prior measurements from a population and / or the waveform look-up table contains information from the patient gathered prior to the operation, medical procedure, or medical observation by the processor executing the monitoring software code scanning with an ultrasound transducer probe each organ of the patient that will be monitored during the operation, medical procedure, or medical observation.

37. 37. The method of claim 36, wherein the waveform characteristics of the Doppler flow signal include a signal-to-noise ratio (SNR), an integrated power spectrum, a spectral envelope, a pulsatility, and / or a spectral bandwidth of the Doppler flow signal.

38. outputting a quality grade / index to the display indicating the probability that the Doppler flow signal is from the patient's renal blood flow or from the patient's non-renal blood flow; continuously communicating said quality grade / index as an input into said predictive filter during said operation, medical procedure, or medical observation; 38. The method of any one of claims 35 to 37, further comprising:

39. 39. The method of any one of claims 18 to 38, wherein the ultrasound transducer probe senses the Doppler flow signal of the patient's renal blood flow from the patient's renal artery, from the patient's renal vein, or from both the renal artery and the renal vein.

40. an ultrasonic transducer probe including a two-dimensional array of transducer elements; an adhesive patch connected to the ultrasound transducer probe and configured to attach the ultrasound transducer probe to a patient; and a beamformer that drives the two-dimensional array of transducer elements, the beamformer configured to cause the two-dimensional array of transducer elements to emit a plurality of ultrasound beams from the two-dimensional array of transducer elements and to track a target organ blood flow signal relative to the array of transducer elements; and Organ blood flow monitors, including:

41. a system memory storing target organ flow index monitoring software code; executing the target organ flow index monitoring software code; establishing a baseline value for target organ flow in the patient from the target organ blood flow signal sensed by the ultrasound transducer probe; continuously monitoring the target organ blood flow signal sensed by the ultrasound transducer probe throughout the duration of the surgical procedure on the patient; a processor configured to estimate a real-time target organ blood flow index for the patient from the target organ blood flow signal; 41. The organ blood flow monitor of claim 40, further comprising:

42. 42. The organ blood flow monitor of claim 41, further comprising a display in communication with the processor for receiving and showing continuous readings of the target organ blood flow signal from the ultrasound transducer probe and a representation of the real-time target organ blood flow index for the patient.

43. a system memory storing organ blood flow monitoring software code; a processor configured to execute the organ blood flow monitoring software code and to estimate target organ blood flow from the target organ blood flow signal; 41. The organ blood flow monitor of claim 40, further comprising:

44. 44. The organ blood flow monitor of claim 43, further comprising a display in communication with the processor for receiving and showing continuous readings of the target organ blood flow signal from the ultrasound transducer probe and a representation of the target organ blood flow rate in the patient.

45. a system memory storing organ injury monitoring software code; executing the organ injury monitoring software code; establishing a baseline value for organ flow in the patient from the target organ blood flow signal sensed by the ultrasound transducer probe; continuously monitoring the target organ blood flow signal sensed by the ultrasound transducer probe throughout the duration of the surgical procedure on the patient; a processor configured to estimate a real-time organ injury risk score for the patient from the target organ blood flow signal; and 41. The organ blood flow monitor of claim 40, further comprising:

46. 46. ​​The organ blood flow monitor of claim 45, further comprising a display in communication with the processor for receiving and showing continuous readings of the target organ blood flow signal from the ultrasound transducer probe and a representation of the real-time organ injury risk score for the patient.

47. 47. The organ blood flow monitor of any one of claims 40 to 46, wherein the ultrasound transducer probe operates at a center frequency between 0.5 MHz and 4.0 MHz and penetrates more than 15 cm into the patient.

48. 48. The organ blood flow monitor of any one of claims 40 to 47, wherein the array of transducer elements of the ultrasound transducer probe is sized to cover one or more acoustic windows in the patient in at least one of the two dimensions, the acoustic window of the patient being defined as an area of ​​the patient where ultrasound transmission is substantially unattenuated compared to its immediate surroundings.

49. 49. The organ blood flow monitor of any one of claims 40 to 48, wherein the array of transducer elements of the ultrasound transducer probe is sized to extend across at least two intercostal spaces of the patient in at least one of the two dimensions.

50. 50. The organ blood flow monitor of any one of claims 40 to 49, wherein each transducer element in the array of transducer elements of the ultrasound transducer probe includes an element width and a length, both of which are greater than one wavelength in soft tissue of ultrasound emitted by the array of transducer elements.

51. The system memory and the processor 51. The organ blood flow monitor of any one of claims 40 to 50, further comprising organ recognition software code configured to distinguish the target organ blood flow signal from non-target blood flow signals based on waveform characteristics of the target organ blood flow signal.

52. the processor executes the organ recognition software code; performing a waveform analysis of the patient's flow signal sensed by the ultrasound transducer probe; extracting waveform characteristics of the flow signal; comparing the waveform characteristics of the flow signal to a look-up table of blood flow waveform characteristics for various organs; 52. The organ blood flow monitor of claim 51, configured to output a decision score to the display indicative of whether the flow signal is from the target organ blood flow or from a non-target blood flow.

53. 53. The organ blood flow monitor of any one of claims 40 to 52, further comprising a coupling layer comprising a couplant that enables ultrasonic energy transmission between the patient's skin and the ultrasound transducer probe.

54. 1. A method for monitoring organ blood flow in a target organ of a patient during surgery, medical procedure, or medical observation, comprising: positioning an ultrasound transducer probe over the patient's abdomen, the ultrasound transducer probe including a two-dimensional array of transducer elements; scanning a target organ location of the patient with the two-dimensional array of transducer elements and a beamformer driving the array of transducer elements to find a Doppler flow signal of blood flow in the organ of the patient; attaching the ultrasound transducer probe to the patient by an adhesive patch connected to the ultrasound transducer probe at the target organ location where the Doppler flow signal of the organ blood flow of the patient is found; track scanning the Doppler flow signals of the organ blood flow of the patient with the beamformer to continuously sense the Doppler flow signals of the organ blood flow of the patient during the surgical procedure, medical procedure, or medical observation without repositioning the ultrasound transducer probe; A method comprising:

55. track scanning the Doppler flow signals of the organ blood flow of the patient with the beamformer and the array of transducer elements, emitting a set of sequential beams from the array of transducer elements and tracking a center of blood flow of the organ relative to the array of transducer elements; focusing each beam from the set of beams to a different location; adjusting the position of the set of beams by the beamformer over the center of the organ blood flow to maintain the Doppler flow signal of the organ blood flow of the patient; 55. The method of claim 54, comprising:

56. 56. The method of claim 54 or 55, further comprising continuously outputting a plot of the Doppler flow signal of the organ blood flow of the patient to a display in communication with the ultrasound transducer probe while the ultrasound transducer probe is attached to the patient by the adhesive patch.

57. communicating the Doppler flow signals sensed by the ultrasound transducer probe to a processor configured to execute target organ blood flow index monitoring software code stored on a system memory; establishing, by the processor, a baseline value for organ blood flow in the target organ from the Doppler flow signal of the target organ blood flow sensed by the ultrasound transducer probe; continuously monitoring, by the processor, the Doppler flow signal of the organ blood flow sensed by the ultrasound transducer probe in the target organ throughout the duration of the surgical procedure, medical procedure, or medical observation; estimating, by the processor, a real-time target organ blood flow index of the patient from the Doppler flow signal of the organ blood flow of the target organ; 57. The method of any one of claims 54 to 56, further comprising:

58. communicating the Doppler flow signals sensed by the ultrasound transducer probe to a processor configured to execute target organ injury monitoring software code stored on a system memory; establishing, by the processor, a baseline value for the organ blood flow of the target organ from the Doppler flow signal of the organ blood flow sensed by the ultrasound transducer probe; continuously monitoring, by the processor, the Doppler flow signal of the organ blood flow sensed by the ultrasound transducer probe in the target organ throughout the duration of the surgical procedure, medical procedure, or medical observation; estimating, by the processor, a real-time target organ injury risk score for the patient from the Doppler flow signal of the organ blood flow in the target organ of the patient; 58. The method of claim 57, further comprising:

59. 59. The method of claim 57 or 58, further comprising continuously outputting to a display in communication with the processor a plot of the Doppler flow signal of the organ blood flow of the target organ of the patient and a representation of the real-time target organ blood flow index of the patient for the duration of the surgical procedure, medical procedure, or medical observation.

60. 59. The method of claim 58, further comprising continuously outputting to a display in communication with the processor a plot of the Doppler flow signal of the organ blood flow of the target organ of the patient and a representation of the real-time target organ injury risk score of the patient for the duration of the surgery, medical procedure, or medical observation.

61. 61. The method of any one of claims 54 to 60, further comprising verifying the identity of the Doppler flow signal of the organ blood flow of the patient by an organ recognition algorithm based on waveform characteristics of the Doppler flow signal.

62. an ultrasonic transducer probe; an adhesive patch connected to the ultrasound transducer probe for attaching the ultrasound transducer probe to a patient; an organ recognition algorithm configured to distinguish renal blood flow signals from non-renal blood flow signals based on waveform characteristics of the renal blood flow signals; and renal blood flow monitors.

63. 63. The renal blood flow monitor of claim 62, wherein the ultrasound transducer probe includes a two-dimensional array of transducer elements.

64. a system memory storing a beamformer with flow signal tracking software code; executing the beamformer and the flow signal tracking software code; emitting a plurality of beams from the array of transducer elements and tracking the Doppler flow signal of the renal blood flow relative to the array of transducer elements; a processor configured to continuously monitor the Doppler flow signal of the renal blood flow sensed by the ultrasound transducer probe throughout the duration of the patient's surgery, medical procedure, or medical observation; a coupling layer on the ultrasound transducer probe including a couplant material for forming contact between the skin and the ultrasound transducer probe; 64. The renal blood flow monitor of claim 63, further comprising:

65. The organ recognition algorithm a waveform lookup table of renal and non-renal blood flow waveform characteristics; a waveform analyzer module that performs waveform analysis of the patient's Doppler flow signal sensed by the ultrasound transducer probe, extracts waveform characteristics of the Doppler flow signal, compares the waveform characteristics of the Doppler flow signal with the look-up table, and outputs a decision score indicative of whether the Doppler flow signal is from the renal blood flow or the non-renal blood flow; 65. The renal blood flow monitor of claim 64, comprising:

66. 66. The renal blood flow monitor of claim 65, further comprising a display in communication with the ultrasound transducer probe, the beamformer, and the organ recognition algorithm to receive and show continuous readings of the Doppler flow signal from the ultrasound transducer probe and the decision score from the organ recognition algorithm.

67. a system memory storing acute kidney injury (AKI) monitoring software code; Executing the AKI monitoring software code; establishing a baseline value for the patient's renal blood flow from the Doppler flow signal of the renal blood flow sensed by the ultrasound transducer probe; continuously monitoring the Doppler flow signal of the renal blood flow sensed by the ultrasound transducer probe throughout the duration of the surgical procedure on the patient; estimating a real-time acute kidney injury risk score for the patient from the Doppler flow signal of the renal blood flow; a processor configured to output a representation of the real-time acute kidney injury risk score for the patient on the display; and 67. The renal blood flow monitor of claim 66, further comprising:

68. an ultrasound transducer probe including an array of transducer elements; an adhesive patch connected to the ultrasound transducer probe and configured to connect the ultrasound transducer probe to a patient; a system memory storing beamformer software code; a processor in communication with the ultrasound transducer probe and the system memory, the processor configured to execute the beamformer software code to beam scan the patient with the array of transducer elements to find a Doppler flow signal of the patient's renal blood flow; and and renal blood flow monitors.

69. the processor executing the beamformer software code; track scanning the renal blood flow of the patient by emitting a plurality of beams from the array of transducer elements and tracking a center of the renal blood flow relative to the array of transducer elements; 69. The renal blood flow monitor of claim 68, configured to adjust a position of a beam of the beam scan over the center of the renal blood flow to maintain the Doppler flow signal of the renal blood flow of the patient.

70. 70. The renal blood flow monitor of claim 69, further comprising a display in communication with the ultrasound transducer probe and the processor for receiving and showing continuous readings of the Doppler flow signal from the ultrasound transducer probe.

71. 71. The renal blood flow monitor of claim 70, wherein the ultrasound transducer probe operates at a center frequency between 0.5 MHz and 4.0 MHz and penetrates more than 15 cm into the patient.

72. 72. The renal blood flow monitor of claim 71, wherein the array of transducer elements of the ultrasound transducer probe is sized in length to cover one or more acoustic windows in the patient, the acoustic window of the patient being defined as an area of ​​the patient where ultrasound transmission is substantially unattenuated compared to its immediate surroundings.

73. 72. The renal blood flow monitor of claim 71, wherein the array of transducer elements of the ultrasound transducer probe is sized in length to extend across at least two intercostal spaces of the patient.

74. 74. A renal blood flow monitor as described in claim 72 or 73, wherein each transducer element in the array of transducer elements of the ultrasound transducer probe includes an element width and a length, both of which are greater than one wavelength of ultrasound emitted by the array of transducer elements.

75. 75. The renal blood flow monitor of claim 74, wherein the array of transducer elements of the ultrasound transducer probe includes a pitch that defines an inter-element spacing between adjacent transducer elements, the pitch being greater than the one wavelength of the ultrasound emitted by the array of transducer elements.

76. the system memory storing acute kidney injury (AKI) monitoring software code, the processor executing the AKI monitoring software code; establishing a baseline value for the patient's renal blood flow from the Doppler flow signal of the renal blood flow sensed by the ultrasound transducer probe; continuously monitoring the Doppler flow signal of the renal blood flow sensed by the ultrasound transducer probe throughout the duration of the surgical procedure on the patient; estimating a real-time acute kidney injury risk score for the patient from the Doppler flow signal of the renal blood flow; 76. The renal blood flow monitor of claim 75, configured to output a representation of the real-time acute kidney injury risk score on the display.

77. an ultrasonic transducer probe including a two-dimensional array of transducer elements; an adhesive patch connected to the ultrasound transducer probe and configured to attach the ultrasound transducer probe to a patient; a system memory storing beamformer software code; a processor in communication with the ultrasound transducer probe and the system memory, the processor configured to execute the beamformer software code to steer a beam and scan the patient with the array of transducer elements to find a Doppler flow signal of a target blood flow in the patient; and blood flow monitor.

78. the processor executing the beamformer software code; track scanning the target blood flow in the patient by emitting a plurality of beams from the array of transducer elements and tracking a center of the target blood flow relative to the array of transducer elements; 78. The blood flow monitor of claim 77, configured to adjust a position of a beam of the beam scan over the center of the target blood flow to maintain the Doppler flow signal of the target blood flow in the patient.

79. 79. The blood flow monitor of claim 78, further comprising a display in communication with the ultrasound transducer probe and the processor for receiving and showing continuous readings of the Doppler flow signal from the ultrasound transducer probe.

80. 80. The blood flow monitor of claim 79, wherein the ultrasound transducer probe operates at a center frequency between 0.5 MHz and 4.0 MHz and penetrates more than 15 cm into the patient.

81. 81. The blood flow monitor of claim 80, wherein the array of transducer elements of the ultrasound transducer probe is sized in length to cover one or more acoustic windows in the patient, the acoustic window of the patient being defined as an area of ​​the patient where ultrasound transmission is substantially unattenuated compared to its immediate surroundings.

82. 82. The blood flow monitor of claim 81, wherein the array of transducer elements of the ultrasound transducer probe is sized in length to extend across at least two intercostal spaces of the patient.

83. 83. The blood flow monitor of claim 82, wherein each transducer element in the array of transducer elements of the ultrasonic transducer probe includes an element width and a length, both of which are greater than one wavelength of ultrasound emitted by the array of transducer elements.

84. 84. The blood flow monitor of claim 83, wherein the array of transducer elements of the ultrasonic transducer probe includes a pitch that defines an inter-element spacing between adjacent transducer elements, the pitch being greater than the one wavelength of the ultrasonic waves emitted by the array of transducer elements.

85. the system memory storing specific organ injury (SOI) monitoring software code, the processor executing the SOI monitoring software code; establishing a baseline value for the specific organ blood flow of the patient from the Doppler flow signal of the specific organ blood flow sensed by the ultrasound transducer probe; continuously monitoring the Doppler flow signal of the specific organ blood flow sensed by the ultrasound transducer probe throughout the duration of the surgical procedure on the patient; estimating a real-time organ-specific injury risk score for the patient from the Doppler flow signal of the renal blood flow; 85. The blood flow monitor of claim 84, configured to output a representation of the real-time organ-specific injury risk score on the display.

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