Dual mode non-invasive blood pressure measurement

Abstract

This specification describes a method and system for linear pressure non-invasive blood pressure (NIBP) measurement suitable for various cuff sizes. In an embodiment, an adapter hose that connects the cuff to the NIBP device is dynamically identified. An embodiment provides a restriction in at least one of the valves of the device to allow controlled release of air from the NIBP device during the cuff inflation process.

Description

[Technical field]

[0001] The present disclosure relates to monitoring physiological parameters, and more particularly, to methods and systems for obtaining blood pressure measurements and / or monitoring blood pressure using measurements from a non-invasive blood pressure (NIBP) device. [Background technology]

[0002] Non-invasive blood pressure (NIBP) is an important physiological parameter measured by nearly all bedside monitors sold worldwide. Ambulatory blood pressure (ABP) measurement deploys NIBP measurement capabilities in a small, wearable recorder to obtain continuous measurements of a patient during the patient's daily activities. Referring to FIG. 1, a conventional ambulatory blood pressure measurement system 100 is shown. The system 100 includes a cuff 115 and a tube 110 that provides pneumatic communication between an air bladder in the cuff 115 and an air pump positioned in a housing 105. A valve 120 is positioned to selectively release air from the air bladder of the cuff 115. The housing 105 further includes a measurement system that detects pressure oscillations from the cuff 115 to generate blood pressure measurements, including diastolic and systolic measurements. Diastolic and systolic refer to the relaxation and contraction of the heart muscle, with the relaxation period being diastolic and the contraction period being systolic, and the balance between the two determining a person's blood pressure.

[0003] A conventional NIBP measurement is obtained by rapidly inflating a flexible cuff, such as cuff 115 of FIG. 1, positioned around a patient's limb. Rapid inflation is accomplished by using a pump to force air into the cuff, and pumping is maintained until the cuff pressure rises to a pressure level significantly above the systolic value of standard blood pressure, which may be determined by monitoring the patient's pulse and continuing to inflate the cuff to a point approximately 30 mmHg above the point at which the patient's pulse disappears. In an oscillometric measurement, the patient's pulse does not actually disappear as in auscultatory measurements made by a clinician with a stethoscope. In some devices, rapid inflation is achieved by using a pump to force air into the cuff, and maintaining pumping until the cuff pressure rises to a pressure level significantly above the previous measurement. In one example, if the patient's previous measurement was 120 / 80, the device inflates to the previous systolic plus 35 mmHg (so, in this example, 155 mmHg). Once that elevated pressure level is reached, the air pump is turned off and the cuff is gradually deflated in a controlled manner. The cuff pressure is reduced in small pressure steps, usually around 8 millimeters of mercury (mmHg). At each step, a measurement of the pressure oscillation is made. The cuff oscillations, which correspond to the arterial pulsation, are then analyzed to determine the blood pressure. The point of maximum oscillation corresponds to the mean intra-arterial pressure. During decompression, a measurement is made against a target blood pressure, which is either a default value depending on the patient type or based on previous measurements.

[0004] Conventional NIBP devices typically include two valves that control the bleed of air from the cuff. Generally, each valve is configured such that when activated, the valve is in a closed position to make the cuff airtight, and when power is removed or the valve is not activated, the valve transitions to an open state to allow air to bleed from the cuff. Two valves are typically used because the first valve acts as the actual deflation mechanism, while the second valve acts as a backup in case the first valve fails. Additionally, the second valve can be used to provide a mechanism to more quickly release or remove pressure from the cuff upon completion of a measurement.

[0005] Another approach to NIBP measurement is the use of a "linear compression" system. In contrast to conventional reduced pressure NIBP systems, where measurements are taken only during deflation after the cuff is fully inflated, linear compression systems take measurements during cuff inflation. A special pneumatic configuration between the valve and pump allows for controlled inflation and deflation of the cuff's internal chamber. The main advantages of linear compression measurements include faster measurements, reduced maximum cuff pressure, and reduced ambient noise from the pump. Because the pump is operated at a low RPM to activate the device and slowly inflate the cuff, the pump is also relatively quiet compared to conventional full speed measurements. These features, alone or in combination, increase patient comfort as the intensity and duration of the "squeezing" of the arm is reduced and loud noise from the pump during full speed operation is minimized. Linear compression measurement methods and devices are less traumatic for use in children or patients with weaker anatomy. Additionally, measurements can be taken more quickly by clinicians, typically about 30% faster.

[0006] Linear pressure NIBP devices can provide the patient with the benefits of speed and comfort, but the task of controlling inflation rate is difficult with small cuff sizes, such as small adults (cuff size 12 cm x 22 cm) or children (4 cm x 8 cm to 9 cm x 18 cm). Inflation rate can be varied by adjusting the pump speed or revolutions per minute (RPM). Since pump RPM increases with increasing applied voltage, pump speed can be further modified with the drive voltage applied across the terminals of the pump. A voltage threshold is associated with the current pressure of each NIBP device, below which the pump cannot rotate or is in a "dead head" condition. Application of a voltage approximately 10% above the threshold can be considered to induce a low RPM of the pump. For small cuffs, a low pump speed is required to obtain an effective inflation rate of 3 mmHg to 6 mmHg per beat. At this low flow rate, the pump tends to become unstable as the applied voltage is near the lower limit of the speed at which the pump can rotate. This instability makes reliable control of the inflation rate of small cuffs difficult. Furthermore, when the pump RPM is low, i.e., within 10% above the deadhead threshold, the frequency of the pump perturbation approaches the upper frequency limit of the range of interest for pulse wave discrimination (10 Hz), and the noise from the pump begins to obscure the signal of interest (the pulse wave). Thus, the magnitude of the perturbation to the pressure signal from the pump can obscure the pulse wave signal that the NIBP device is attempting to measure. Summary of the Invention [Problem to be solved by the invention]

[0007] Thus, there is a need for a method and system for non-invasive blood pressure measurement that can overcome one or more of the shortcomings of current standard and linear pressure NIBP devices. In particular, there is a need for an NIBP system that can operate at low flow rates while maintaining a substantially constant inflation rate. There is also a need for an NIBP system that can reliably produce the required constant flow rates with small cuff sizes. There is also a need for an NIBP system that minimizes the frequency of pump perturbations when operating the pump at applied voltages at or near the pump's lower voltage limits. [Means for solving the problem]

[0008] The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools, and methods that are intended to be exemplary and illustrative, and not limiting in scope.

[0009] The present specification discloses a blood pressure monitoring system comprising: a housing; a controller positioned within the housing; a pump positioned within the housing, the pump in communication with the controller, the controller configured to activate the pump and stop the pump; a pressure sensor and analysis system positioned within the housing, the pressure sensor and analysis system in data communication with the controller; a first hose defined by a first inner diameter; a first cuff configured to connect to the first hose; a second hose defined by a second inner diameter; a second cuff configured to connect to the second hose; a cuff connector adapted to be coupled to the first hose or the second hose; and at least two valves positioned within the housing, a first valve of the at least two valves configured to allow a first air flow rate and a second valve of the at least two valves configured to allow a second air flow rate, the controller adapted to activate at least one or both of the first valve and the second valve based on whether the cuff connector is coupled to the first hose and the first cuff or the cuff connector is coupled to the second hose and the second cuff.

[0010] Optionally, the first inner diameter of the first hose is larger than the second inner diameter of the second hose. Optionally, the cuff connector is coupled to the first hose or the second hose via at least one adapter. Optionally, the first cuff is configured to fit onto a limb of an adult or pediatric patient. Optionally, the second cuff is configured to fit onto a limb of a neonatal patient.

[0011] Optionally, at least one of the first cuff and the second cuff is configured to wrap around a patient's limb, and at least one of the first cuff and the second cuff is in air flow communication with a pump and configured to receive air when the pump is actuated by the controller.

[0012] Optionally, the first and second valves are identical, with the restriction configured to restrict airflow in a flow passage of the first valve. Optionally, the first valve is smaller than the second valve such that airflow through the first valve is restricted compared to airflow through the second valve. Optionally, during deflation of the second cuff, the controller is configured to cause the first valve to be open during at least a portion of said deflation. Optionally, during deflation of the second cuff, the controller is configured to cause the first valve and the second valve to be open during at least a portion of said deflation.

[0013] Optionally, the cuff connector includes a female rectus connector.

[0014] Optionally, the blood pressure monitoring system further comprises a monitor that displays information regarding at least one of the blood pressure measurement, the status of the first hose connected to the first cuff, the status of the second hose connected to the second cuff, the status of the first cuff or the second cuff coupled to the cuff connector, and / or whether an adapter is attached to the cuff connector.

[0015] Also disclosed herein is a method of determining a patient's blood pressure using a non-invasive blood pressure (NIBP) device, the NIBP device including a controller positioned within a housing, a cuff connector, a first hose having a first inner diameter and adapted to be connected to the first cuff and configured to be coupled to the cuff connector, a second hose having a second inner diameter and adapted to be connected to the second cuff and configured to be coupled to the cuff connector, a pump in fluid communication with the cuff connector, and at least two valves, a first valve of the at least two valves configured in an open configuration to allow a first air flow rate and a second valve of the at least two valves configured in an open configuration to allow a second air flow rate, the first air flow rate being less than the second air flow rate. and a valve, the method including the steps of coupling at least one of a first cuff and a second cuff to a cuff connector; applying the first cuff or the second cuff to a limb of the person; operating a controller to determine whether the cuff connector is coupled to the first cuff or the second cuff; operating the controller to actuate a pump, whereupon the pump pumps air into the first cuff or the second cuff positioned on the limb of the person; and operating the controller to open and / or close the first valve and / or the second valve based on whether the first cuff or the second cuff is coupled to the cuff connector and whether the controller is inflating or deflating the first cuff or the second cuff.

[0016] Optionally, the method further comprises operating the controller to determine whether the first hose is connected to the first cuff or the second hose is connected to the second cuff.

[0017] Optionally, the first inner diameter of the first hose is greater than the second inner diameter of the second hose.

[0018] Optionally, the cuff connector is coupled to the first hose or the second hose via at least one adapter.

[0019] Optionally, the first cuff is configured to fit on a limb of an adult or pediatric patient and the second cuff is configured to fit on a limb of a neonatal patient. Optionally, during inflation of the first cuff, the first cuff is fitted on the limb of an adult patient and the controller is configured to close the first and second valves during said inflation. Optionally, if a blood pressure determination is performed during inflation of the first cuff and the first cuff is fitted on the limb of a pediatric patient, the controller is configured to at least partially open the first valve and close the second valve during said inflation. Optionally, if a blood pressure determination is performed during deflation of the second cuff, the controller is configured to open the first valve during at least a portion of said deflation. Optionally, if a blood pressure determination is performed during deflation of the first cuff, the controller is configured to open the first valve and the second valve.

[0020] Optionally, the method further comprises detecting pressure oscillations in the first or second cuff during inflation or deflation of the first or second cuff to determine a blood pressure of the person.

[0021] Optionally, the method further includes identifying an anomaly when the controller is inflating the first cuff or inflating the second cuff, and closing at least one of the first and second valves during the depressurization process using the controller. Optionally, operating the controller to determine whether the first or second cuff is coupled to the cuff connector includes opening the first valve, operating the pump for a first time period, measuring a first amplitude of air pressure pulses caused by operation of the pump after the first time period, operating the pump for a second time period, measuring a second amplitude of air pressure pulses caused by operation of the pump after the second time period, calculating a function of the first and second amplitudes, and determining based on an output of the function whether at least one of the first and second hoses is coupled to the cuff connector, whether at least one of the first and second hoses is kinked, whether the first hose is connected to the first cuff, or whether the second hose is connected to the second cuff.

[0022] Optionally, the function is an average of the first and second amplitudes. Optionally, each of the first and second periods is between 10 ms and 100 ms, preferably 50 ms. Optionally, the method further comprises a time interval between the first and second periods. Optionally, operating the pump comprises operating at a duty cycle in a range equal to 90% to 100%. Optionally, determining whether the first hose is connected to the first cuff or the second hose is connected to the second cuff comprises opening the first and second valves during the first period, operating the pump at a duty cycle in a range of 30% to 50% after the first period, measuring the first amplitude, and determining at least one of whether the first hose is connected to the first cuff and whether the second hose is connected to the second cuff based on the first amplitude. Optionally, the determining includes concluding that a first hose is connected to a first cuff if the amplitude has a first value and that a second hose is connected to a second cuff if the amplitude has a second value, the first value being less than the second value.

[0023] These and other embodiments herein are explained in more depth in the following figures and detailed description.

[0024] These and other features and advantages of the present specification will be appreciated as they become better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings. [Brief description of the drawings]

[0025] [Figure 1] 1 shows a conventional NIBP system. [Diagram 2] 1 shows a schematic diagram of an exemplary blood pressure measurement system according to an embodiment of the present disclosure. [Figure 3A] 11 is a flowchart illustrating an exemplary sequence of operations performed to verify cuff connection, according to embodiments herein. [Figure 3B]4 is a flow chart illustrating a first set of steps of an exemplary blood pressure measurement method according to one embodiment of the present invention. [Figure 3C] 4 is a flow chart illustrating a second set of steps of an exemplary blood pressure measurement method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] In various embodiments, the present disclosure provides a method and system for monitoring physiological characteristics of a patient using a non-invasive blood pressure (NIBP) monitor. The NIBP device performs measurements in two modes. The mode is selected based on the patient. The device verifies that the selected mode corresponds to the type of cuff used with the selected patient. In operation, an adapter with two hoses is removably attached to the cuff connector of the NIBP device. The first hose is configured to connect to a cuff for NIBP measurement of an adult / pediatric patient, while the second hose is configured to interface with a cuff for a neonatal patient. Each hose has a different inner diameter that provides a different resistance to air flow therethrough. The different resistances are detected by the NIBP system to determine / verify whether an adult / pediatric or neonatal type patient is connected. Before each measurement, a check is performed on the monitor integrated with the NIBP device to verify the presence of an adapter and, if one is present, that the adapter is connected to the correct cuff type that matches the patient settings. If no adapter is attached or the wrong hose is attached to the cuff, no measurement is performed and a message regarding the mismatch is communicated to the user.

[0027] Furthermore, once the NIBP device is able to distinguish whether the patient is an adult / pediatric or neonatal patient, the measurement method is adjusted to measure using a step-deflate process or an on-inflate process. Thus, an embodiment of the NIBP system can perform measurements with a normal adult / pediatric cuff in one mode and a very small neonatal cuff in another mode. Measurements in neonatal mode are performed using a conventional inflation and deflating process. In one embodiment, the pneumatic configuration of the NIBP device has a specially designed restricted flow path configuration that allows for controlled deflation suitable for the small neonatal cuff size. The restricted flow path makes it easy to control the deflating process to obtain accurate pressure control for the small neonatal cuff. Furthermore, the high speed operation of the pump shifts the aerodynamic noise from the pump to higher frequencies and away from the pulse signal of interest, allowing it to be effectively filtered. Measurements in adult / pediatric mode can be performed using a step-deflate or deflating process of NIBP measurement. In some embodiments, the step-deflate measurement mode is preferably used for speed and comfort, and the deflating mode is preferred for adult / pediatric measurements as a fallback in case the step-deflate measurement fails.

[0028] This specification covers multiple embodiments. The following disclosure is provided to enable those skilled in the art to practice the invention. The words used in this specification should not be construed as a general disclaimer of one particular embodiment, nor should they be used to limit the scope of the claims beyond the meaning of the terms used in this specification. The general principles defined in this specification can be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Furthermore, the terms and expressions used are for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present invention is to be accorded the widest scope encompassing many alternatives, modifications, and equivalents consistent with the principles and features disclosed. For the sake of clarity, details of technical content known in the art related to the present invention have not been described in detail so as not to unnecessarily obscure the present invention.

[0029] In the present specification and claims, the words "comprises," "includes," and "having," and variations thereof, do not necessarily limit the elements in the list with which the word may be associated. It should be noted that any feature or component described in this specification in connection with a particular embodiment can be used with other embodiments unless otherwise stated.

[0030] In some embodiments, the system includes at least one processor (not shown) that controls the operation of the entire system and its components. It is further understood that the at least one processor is capable of processing program instructions, has a memory capable of storing program instructions, and employs software consisting of a plurality of program instructions to perform the processes described herein. In one embodiment, the at least one processor is a computing device capable of receiving, executing, and transmitting a plurality of program instructions stored in a volatile or non-volatile computer readable medium. Thus, in various embodiments, the computing device is used to receive and process data signals and may include an input / output controller, at least one communication interface, and a system memory. The system memory may include at least one random access memory (RAM) and at least one read only memory (ROM). These elements communicate with the processor or central processing unit (CPU) to enable the operation of the computing device.

[0031] In an embodiment, the system is coupled to at least one display that displays information about at least one patient parameter and the operation of the system through a GUI. The GUI also presents various menus that allow the user to configure the settings according to their requirements.

[0032] In various embodiments, the computing device may be a conventional stand-alone computer, or the functionality of the computing device may be distributed across a network of computer systems and architectures. In some embodiments, execution of sequences of program instructions or codes stored in one or more non-volatile memories may cause the CPU of the computing device to perform or enable various functions, processes, and algorithms, such as obtaining blood pressure measurements and / or monitoring blood pressure using measurements from a non-invasive blood pressure (NIBP) device. In alternative embodiments, hardwired circuitry may be used in place of or in combination with software instructions for implementation of the processes of the systems and methods described herein. Thus, the described systems and methods are not limited to any particular combination of hardware and software.

[0033] In embodiments, the present disclosure provides an NIBP device configured to interface with cuffs for measuring physiological parameters of adult or pediatric patients, as well as relatively small cuffs configured for neonatal patients, the device being further configured to allow BP measurements for different types of patients using different methods.

[0034] FIG. 2 illustrates a configuration of an NIBP device or system 200 according to some embodiments herein. A controller 204, including one or more electrical circuits, memory, and processors integrated on one or more printed circuit boards, may be positioned within an enclosure or housing 202. A display or monitor 206, such as a touch screen display, may also be integrated with the system 200. In some embodiments, the display 206 may allow a user to enter patient settings and select an operating mode of the system 200, display the mode selected by the system 200, and communicate anomalies or concordances identified by the system 200 in addition to measurements monitored by the system 200. The housing 202 further includes an air pump 210 and a pressure sensor and analysis system 213, which also includes one or more electrical circuits, memory, and processors integrated on one or more printed circuit boards. Both the air pump 210 and the pressure sensor and analysis system 213 are in electrical communication with the controller 204 and the monitor 206. The pressure sensor and analysis system 213 is positioned within the manifold 208 which provides a path for air to be pumped by the pump 210 to at least two valves 218 and 220. The pressure sensor and analysis system generates an analog voltage corresponding to the air pressure developed within the manifold 208 which is sampled by an analog to digital converter to provide a measure of the pressure. The pressure sensor and analysis system 213 is also in communication with the controller 204 which is configured to implement a linear pressure blood pressure measurement process as described below.

[0035] The NIBP system 200 includes a single front panel connector port 216 (in one embodiment, a female rectus connector port), and a first adapter hose 212 and a second adapter hose 214. In an embodiment, the proximal end of the first adapter hose 212 or the second adapter hose 214 is connected to the connector port 216. In one embodiment, the distal end of the first adapter hose 212 is configured to connect to an adult / pediatric patient cuff, while the distal end of the second adapter hose 214 is configured to interface with a cuff for neonatal measurements. In an embodiment, the second adapter hose 214 is neonatal while the first adapter hose 212 is adult, since neonatal cuffs have different pressure safety limits (approximately 150 mmHg vs. 300 mmHg for adults) and different adapters at the cuff ends. In an embodiment, the adapters positioned on the neonatal cuff are smaller in diameter than those of the adult cuff. The neonatal adapter hose 214 has a smaller and narrower inner diameter than the adult adapter hose 212, which has a relatively larger inner diameter. In some embodiments, the first adapter hose 212 and the second adapter hose 214 are equal in length. In some embodiments, the first adapter hose 212 and the second adapter hose 214 are unequal in length to one another. In some embodiments, the first adapter hose 212 and the second adapter hose 214 are each between 6 feet and 10 feet in length. In embodiments, the first adapter hose 212 and the second adapter hose 214 plug into a common cuff connector port 216 on the front panel of the system 200.

[0036] The adapter hose 212 and the adapter hose 214 have different inner diameters and present different flow resistances to the system 200. In one embodiment, the adapter hose 212 for use with an adult has an inner diameter of 1 / 8 inch. In one embodiment, the adapter hose 214 for use with a neonatal setting has an inner diameter of 1 / 16 inch. Prior to operating the system 200 for a measurement, a check is performed by pumping air from the pump 210 and measuring the flow resistance measured by the pressure sensor and analysis system 213. In an embodiment, the HIBP system 200 is "fault tolerant" by having at least two pressure transducers to ensure that if one transducer fails, the second (backup) transducer will not expose the patient to dangerous pressures. The measured flow resistance is an indication of the proper connection of the cuff to the adapter and the type of hose (212 or 214) to which the cuff is connected. The type of adapter hose is used as the basis for selecting the operating mode of the system 200 or verifying the mode selected by the user in the patient settings. If the system 200 detects that neither the adapter hose 212 nor the adapter hose 214 is attached to the cuff, or that the wrong type of adapter hose is attached, no measurement will be taken and a message will be displayed on the monitor 206 informing the user of the discrepancy.

[0037] Upon connecting the housing 202 to the cuff via the cuff connector 216, the pump 210 is actuated to pump air into the cuff. The pump 210 is controlled by modulating the voltage applied across the terminals of the pump 210. As the duty cycle increases, the increased applied voltage provides more "throttle" to the pump 210. Inflation of the cuff is controlled by a first valve 218 and a second valve 220, which in one embodiment are high flow valves. The first valve 218 and the second valve 220 are provided in the path of the pumped air in the manifold 208 from the pump 210 to the cuff connector 216, which pumps air into the connected cuff via the first adapter hose 212 or the second adapter hose 214. In some embodiments, the first valve 218 and the second valve 220 have the same structure. In one embodiment, the inlet of first valve 218 is modified with flow restriction 222 so that the restricted first flow valve 218 can function similarly to a valve designed with a narrow orifice to more precisely control the flow rate through first valve 218. In some embodiments, one of the valves, such as first valve 218, is configured with a narrow flow path relative to high flow valve 220. By way of example, when unrestricted, first valve 218 is a high flow valve with an inner diameter of 0.04 inches to 0.08 inches, preferably about 0.066 inches, and when restricted, the inner diameter of first valve 218 is reduced to a diameter of 0.05 inches to 0.020 inches, preferably about 0.012 inches.

[0038] The cuff connected via connector 216 is rapidly inflated to a pressure of 50 mmHg with pump 210 running at full speed. In one embodiment, a 12V pump is used, so applying 12V to the pump provides maximum RPM. Lower effective applied voltages below 12V result in slower pump operation. During inflation, pressure sensor and analysis system 213 captures the pressure waveform at 220Hz. The module takes the differential value of the pressure and then applies a low pass filter to generate a differential waveform with a frequency below 10Hz. Several features are extracted from the pressure and the low pass filtered differential waveform. In an embodiment, some exemplary features extracted are shown in Table 1.

[0039] [Table 1]

[0040] Hose detection and cuff size determination FIG. 3A illustrates an exemplary method implemented by the system 200 for identifying the connection of the adapter hose 212 or adapter hose 214 and therefore the type of cuff connected thereto. The presence and / or type of the attached cuff can be detected by detecting the presence and type of the adapter hose. The adapter hose detection process is initiated at the beginning of each blood pressure measurement. When a measurement is requested, the system automatically verifies that the hose is present and that it matches the patient type, as described below. If the hose is not present, a first error type message is displayed and no measurement is performed. If an incorrect adapter hose is detected, a second error type message is displayed. The hose detection process includes a primary hose detection phase and a secondary hose detection phase. As described above, the second adapter hose 214 is relatively smaller than the first adapter hose 212, and the second adapter hose 214 with a smaller inner diameter is configured to interface with a neonatal cuff. The first adapter hose 212 is configured to interface with a cuff for use with adult or pediatric NIBP.

[0041] 2 and 3A simultaneously, in step 302, a primary phase is initiated by opening the first valve 218 fitted with the flow restrictor 222 and closing the valve 220, which in one embodiment is a high flow valve. In an embodiment, the first valve 218 fitted with the flow restrictor 222 is referred to as a restrictor valve. In step 304, a first pressure pulse is generated in the manifold 208 by operating the pump 210 at 100% duty cycle during a first period. In one embodiment, the pump 210 is operated for a first period of time that is between 10 milliseconds and 100 milliseconds, preferably 50 milliseconds (ms). The pressure continues to rise for a short period of time that is approximately equal to a few samples after the pump 210 is turned off, and after waiting that period, in step 306, a first pulse amplitude of the generated first pulse is measured. In some embodiments, this waiting period is in the range of 20 ms to 40 ms. The measured pressure measured by the pressure sensor and analysis system 213 indicates the flow resistance due to back pressure generated by the first adapter hose 212 or the second adapter hose 214 whose distal end is connected to the cuff. In step 308, after measuring the amplitude of the first pulse, the system 200 generates a second pulse by operating the pump for a second period of time between 20 milliseconds and 100 milliseconds, preferably 50 milliseconds (ms). In some embodiments, the first and second periods are of equal duration, preferably 50 ms. In step 310, the amplitude of the generated second pulse is measured after waiting a short period of time after the pump 210 is turned off. In some embodiments, the short period of time ranges from 20 ms to 40 ms. In step 312, the controller processes the recorded amplitudes of the first and second pulses to obtain an average pulse amplitude. The average pulse amplitude value is used to determine the type of adapter hose and / or the condition of the hose connected to the cuff connector 216.

[0042] In some embodiments, an average value above 40 mmHg indicates that the connected hose is kinked. In embodiments, an average value between 20 mmHg and 40 mmHg indicates that the second adapter hose 214 (for neonates) is connected. Additionally, an average value below 20 mmHg and above 3.5 mmHg indicates that the first adapter hose 212 (for adult) is connected. Additionally, an average value below 3.5 mmHg indicates that the hose is not connected to the connector 216. If the hose is not connected, the amplitudes of the first and second pulses used to calculate the average value are within 1 mmHg. If the first adapter hose 212 is connected, the amplitudes of the first and second pulses used to calculate the average value are within 10 mmHg. If the second adapter hose 214 is connected, the amplitudes of the first and second pulses used to calculate the average value are within 10 mmHg. Note that a large difference between the amplitudes of the first and second pulses may indicate that the recorded data is unreliable. In this case, the primary phase of the hose detection process may be repeated. In some embodiments, the primary phase of the detection process is repeated up to two times before a failure to identify the cuff / hose combination is reported. In step 314, the average pulse amplitude is used to determine whether the distal end of either the first adapter hose 212 or the second adapter hose 214 is connected to a cuff, and if so, which hose / cuff combination has been detected.

[0043] In an embodiment, the average pulse amplitude is compared to a predefined threshold of pulse amplitude stored by the controller 204. In some embodiments, the predefined threshold is derived by measuring the amplitude of prototype pulses and allowing a sufficient margin to reasonably distinguish all conditions. The first and second pulse amplitudes may also be compared. In an embodiment, the controller 204 is configured to compare the average pulse amplitude to a predefined threshold of pulse height / amplitude to identify whether the first adapter hose 212 or the second adapter hose 214 is connected to the cuff. The neonatal adapter hose 214 will have a larger pulse amplitude compared to the adult adapter hose 212 due to a smaller inner diameter resulting in less possible air flow.

[0044] Additionally, in another situation, when neither the first adapter hose 212 nor the second adapter hose 214 is connected to the cuff, the recorded average pulse amplitude has a very small value. In yet another situation, when the first adapter hose 212 or the second adapter hose 214 is kinked or otherwise anomaly, the recorded average pulse amplitude has a large value. Example values ​​for the various situations are provided above.

[0045] Once the connection and presence of the cuff is detected, the system 200 executes a second phase. FIG. 3B is a flow chart illustrating an exemplary sequence of processes executed by the system 200 in the second phase, according to some embodiments herein. In step 320, both the first valve 218 and the second valve 220 are initially opened for a period of time, after which both the first valve 218 and the second valve 220 are closed. In an embodiment, this period may be in the range of 10 milliseconds to 20 milliseconds (ms). In one embodiment, the first valve 218 and the second valve 220 are opened for 15.6 ms. In step 322, the pump 210 is pulsed with a duty cycle of 30% to 50%, preferably 40%, while the valves 218 and 220 are open. In step 324, the observed pressure pulse amplitude is recorded. In step 326, the recorded pulse amplitude is compared to the average pulse amplitude observed during the primary detection phase. As described above with respect to FIG. 3A, the first phase identifies whether a hose (first adapter hose 212 or second adapter hose 214) is connected or not. The second phase is now used to determine the type of hose connected (first adapter hose 212 or second adapter hose 214). In step 328, if the pulse amplitude is less than the average pulse amplitude measured in the primary phase, a "failure to detect" the adapter hose is reported. Thus, if the primary and secondary determinations do not match, the measurement is aborted.

[0046] Additionally, if the adapter hose being measured is kinked or defective resulting in irregular or uneven back pressure, the measurement will not be completed. In one embodiment, the user is notified by a combination of audio, visual, or audiovisual alerts. The visual alert may be in the form of a message displayed on the monitor 206. The user may physically inspect the hose to check if the cuff is connected to the hose and that it is not kinked.

[0047] In step 330, if the pulse amplitude is equal to or greater than the average pulse amplitude of the primary phase, the pulse is compared to a predefined threshold to determine one of several different cuff connections. In some embodiments, if the pulse amplitude is less than 25 mmHg, the connected hose is identified as the first adapter hose 212, and if the pulse amplitude is equal to or greater than 25 mmHg, the connected hose is identified as the second adapter hose 214. The adult adapter hose 212 will have a smaller pulse amplitude compared to the neonatal adapter hose 214. In step 332, at the end of the secondary hose detection phase, the system 200 reports the identified adapter hose type. In some embodiments, the process described in FIG. 3A and FIG. 3B is completed in less than one second. The system 200 then proceeds to measure NIBP based on the type of cuff connected. The measurement method is different for the first adapter hose 212 / associated cuff and the second adapter hose 214 / associated cuff.

[0048] HIBP measurement Upon completion of the secondary detection phase, if it is determined that the adapter hose is connected to a corresponding cuff for the selected measurement mode (given in the patient setup), measurement begins in step 340 as described in Figure 3C. Figure 3C illustrates an exemplary method performed by the system 200 based on identification of the adapter hose and thus the cuff type (small corresponding to a neonatal cuff and connected to the second adapter hose 214 or large corresponding to an adult / pediatric cuff and connected to the first adapter hose 212) according to embodiments herein.

[0049] In step 342, the patient type and the adapter hose type are identified according to the process described in connection with Figures 3A, 3B, and 3C. Referring simultaneously to Figures 2 and 3C, if in step 342 it is determined that the hose 212 is connected to a corresponding cuff for an adult / pediatric patient, the method proceeds to step 344. In step 344, a linear pressurization measurement of BP is performed. During the measurement, both valves 218 and 220 remain closed. Since the first adapter hose 212 is larger than the second adapter hose 214 (the second adapter hose is designed for neonatal patients), the first adapter hose 212 can accommodate a variety of cuff sizes. The first adapter hose 212 can have corresponding cuff sizes ranging from small cuff sizes for adult and pediatric patients or children, which are still larger than the cuff sizes available for neonatal patients, to relatively large cuff sizes suitable for adults. Therefore, it is also desirable to be able to distinguish between adult and pediatric patients while connected to the first adapter hose 212. NIBP measurement methods are different for adult and pediatric patients. For smaller cuff sizes, such as pediatric / children's, the restrictor valve 218 may optionally be left open during linear inflation measurements to allow better pump control.

[0050] Therefore, an additional step can be used to determine the size of the cuff (adult or pediatric) when connected to the first adapter hose 212. Pediatric cuffs have a smaller cuff volume relative to adult cuffs. The distinction between adult and pediatric cuff sizes is based on the time it takes to inflate the cuff from zero to a lower target pressure through the first adapter hose 212. The longer the time, the larger the cuff, which corresponds to an adult cuff size. If an anomaly is identified in the measurement in step 346, the system 200 optionally proceeds to step 352 and performs a measurement using reduced pressure as a check method. An anomaly can be identified if the pressure measurement is irregular. In step 356, a measurement using the reduced pressure method is performed with both valves 218 and 220 closed during the measurement until the next "step" when they are opened. Once the measurement is completed, both valves 218 and 220 are opened to release the pressure. If there are no anomalies in step 346, the linear inflation measurement of step 344 is completed in step 350. As previously mentioned, if the cuff size is determined to be for a child (pediatric), a linear inflation measurement is performed with the flow restriction valve 218 open. By leaving the valve 218 open, a "small leak" is simulated, allowing the pump to run slightly faster and more controllable. Additionally, pump noise (air pressure) does not interfere with the measurement. On the other hand, if the cuff size is determined to be larger than for a child (pediatric), the restriction valve 218 is closed during the linear inflation measurement. In some embodiments, blood pressure is determined using an algorithm that analyzes the pressure pulse wave amplitude observed during cuff inflation. In some embodiments, the time it takes to inflate the cuff is also monitored. In embodiments, a robust estimate of the maximum pulse wave amplitude is obtained so that the measurement is reliable (assuming realistic conditions) and is not the result of motion artifacts or other disturbances. In embodiments, an estimate of the systolic pressure is obtained when the pulse wave amplitude reaches approximately 50% of the pulse wave maximum. Similarly, the diastolic pressure is estimated when the pulse wave amplitude reaches approximately 75% of its peak value.

[0051] However, if in step 342 it is determined that the hose 214 is connected to a corresponding cuff for a neonatal patient, the method proceeds to step 352 to begin a measurement with reduced pressure. Since the reduced pressure measurement is for a neonatal patient, in step 358 the first valve 218 is opened and the second valve 220 is closed during the bleed step of the measurement if it allows air to escape or escape during the deflation step. The valve 218 that remains open during the blood pressure measurement is a structure having a flow restriction structure 222 positioned in the exhaust path of the valve 218. In some embodiments, the exhaust path of the valve 218 is configured with a controlled orifice fitted with the restriction structure 222, which further allows for control of the inflation rate by limiting the amount of air released during inflation and deflation. In some embodiments, the size of the orifice of the exhaust path of the valve 218 is configured to be 0.012 inches when open. In embodiments, the restriction structure 222 is sized such that if the second valve 220 fails after the measurement, the restricted path allows the cuff to be safely deflated within the tolerance margin of the regulatory standard. In an embodiment, the regulatory standard is specified for the time it takes for an inflated system to reach 15 mmHg based on a volume of 500 mL, which may be approximately 30 seconds. In an embodiment, the restriction in the exhaust path of open valve 218 is configured such that the path doubles as a viable back-up pressure relief while allowing the pump to operate at higher PPM.

[0052] When restricted, the second valve 218 allows the pump 210 to operate at a higher RPM than would normally be the case with devices known in the prior art. The operation of the pump 210 at a high RPM is controlled by the controller. The high speed operation of the pump 210 shifts the aerodynamic noise from the pump 210 to a higher frequency and away from the pulse wave signal of interest, allowing it to be effectively filtered. The restricted path provided by the valve 218 facilitates control of the decompression process, providing accurate pressure control of the small neonatal cuff. Measurements in adult / pediatric mode can be performed using either the linear inflation or decompression process of NIBP measurement. In some embodiments, the linear inflation measurement mode is preferably used for speed and comfort, while the decompression mode is preferred for adult / pediatric measurements as a fallback in case the linear inflation measurement fails (reports an abnormality). In step 360, the measured value is communicated to the user. In some embodiments, the measurement data is displayed on the monitor 206.

[0053] The above examples are merely illustrative of the many applications of the system of the present invention. Although only a few embodiments of the present invention have been described herein, it should be understood that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the present invention. The present examples and embodiments should therefore be considered as illustrative rather than restrictive, and the present invention may vary within the scope of the appended claims.

Claims

1. 1. A blood pressure monitoring system comprising: Housing and a controller positioned within the housing; a pump positioned within the housing, the pump in communication with the controller, the controller configured to activate the pump and deactivate the pump; and a pressure sensor and analysis system positioned within the housing, the pressure sensor and analysis system in data communication with the controller; a first hose defined by a first inner diameter; a first cuff configured to connect to the first hose; a second hose defined by a second inner diameter; a second cuff configured to connect to the second hose; a cuff connector adapted to be coupled to the first hose or the second hose; at least two valves positioned within the housing, a first valve of the at least two valves configured to allow a first air flow rate and a second valve of the at least two valves configured to allow a second air flow rate, and the controller is configured to actuate at least one or both of the first valve and the second valve based on whether the cuff connector is coupled to the first hose and the first cuff or the cuff connector is coupled to the second hose and the second cuff; A blood pressure monitoring system comprising:

2. 2. The blood pressure monitoring system of claim 1, wherein the first inner diameter of the first hose is greater than the second inner diameter of the second hose.

3. 2. The blood pressure monitoring system of claim 1, wherein the cuff connector is coupled to the first hose or the second hose via at least one adapter.

4. 10. The blood pressure monitoring system of claim 1, wherein the first cuff is adapted to fit around a limb of an adult or pediatric patient.

5. 10. The blood pressure monitoring system of claim 1, wherein the second cuff is adapted to fit around a limb of a neonatal patient.

6. 2. The blood pressure monitoring system of claim 1, wherein at least one of the first cuff and the second cuff is configured to be wrapped around a patient's limb, and wherein at least one of the first cuff and the second cuff is in air flow communication with the pump and configured to receive air when the pump is actuated by the controller.

7. 2. The blood pressure monitoring system of claim 1, wherein the first valve and the second valve are identical, and a restriction is configured to restrict air flow in a flow passage of the first valve.

8. 2. The blood pressure monitoring system of claim 1, wherein the first valve is smaller than the second valve such that air flow through the first valve is restricted compared to air flow through the second valve.

9. 6. The blood pressure monitoring system of claim 5, wherein during deflation of the second cuff, the controller is configured to cause the first valve to open during at least a portion of the deflation.

10. 6. The blood pressure monitoring system of claim 5, wherein during deflation of the second cuff, the controller is configured to cause the first valve and the second valve to be open during at least a portion of the deflation.

11. 10. The blood pressure monitoring system of claim 1, wherein the cuff connector comprises a female rectus connector.

12. 10. The blood pressure monitoring system of claim 1, further comprising a monitor that displays information regarding at least one of a blood pressure measurement, a status of the first hose connected to the first cuff, a status of the second hose connected to the second cuff, a status of the first cuff or the second cuff coupled to the cuff connector, and / or whether the adapter is attached to the cuff connector.

13. 1. A method of determining a patient's blood pressure using a non-invasive blood pressure (NIBP) device, the NIBP device comprising: a controller positioned within a housing; a cuff connector; a first hose having a first inner diameter adapted to be connected to a first cuff and configured to be coupled to the cuff connector; a second hose having a second inner diameter adapted to be connected to a second cuff and configured to be coupled to the cuff connector; a pump in fluid communication with the cuff connector; and at least two valves, a first valve of the at least two valves configured to allow a first air flow rate in an open configuration and a second valve of the at least two valves configured to allow a second air flow rate in an open configuration, the first air flow rate being less than the second air flow rate, coupling at least one of the first cuff and the second cuff to the cuff connector; applying the first cuff or the second cuff to a limb of the person; operating the controller to determine whether the cuff connector is coupled to the first cuff or the second cuff; operating the controller to activate the pump, which upon activation pumps air into the first cuff or the second cuff positioned on the person's limb; operating the controller to open and / or close the first valve and / or the second valve based on whether the first cuff or the second cuff is coupled to the cuff connector and whether the controller is inflating or deflating the first cuff or the second cuff. The method includes:

14. 14. The method of claim 13, further comprising the step of operating the controller to determine whether the first hose is connected to the first cuff or the second hose is connected to the second cuff.

15. 14. The method of claim 13, wherein the first inner diameter of the first hose is greater than the second inner diameter of the second hose.

16. 14. The method of claim 13, wherein the cuff connector is coupled to the first hose or the second hose via at least one adapter.

17. 14. The method of claim 13, wherein the first cuff is configured to fit onto the limb of an adult or pediatric patient and the second cuff is configured to fit onto the limb of a neonatal patient.

18. 20. The method of claim 17, wherein the first cuff is placed on a limb of an adult patient during inflation of the first cuff, and the controller is configured to close the first valve and the second valve during the inflation.

19. 20. The method of claim 17, wherein a blood pressure determination is performed during inflation of the first cuff, and when the first cuff is placed on a limb of a pediatric patient, the controller is configured to cause the first valve to be at least partially open and the second valve to be closed during the inflation.

20. 20. The method of claim 17, wherein if blood pressure determination is performed during deflation of the second cuff, the controller is configured to cause the first valve to be open during at least a portion of said deflation.

21. 20. The method of claim 17, wherein the controller is configured to open the first valve and the second valve if a blood pressure determination is performed during deflation of the first cuff.

22. 14. The method of claim 13, further comprising detecting pressure oscillations in the first cuff or the second cuff during the inflation or deflation of the first cuff or the second cuff to determine a blood pressure of the person.

23. 14. The method of claim 13, further comprising identifying an anomaly when the controller is inflating the first cuff or inflating the second cuff, and causing at least one of the first valve and the second valve to close during a decompression process using the controller.

24. 15. The method of claim 14, wherein the step of operating the controller to determine whether the first cuff is coupled to the cuff connector or the second cuff is coupled to the cuff connector comprises: opening the first valve; operating the pump for a first time period; measuring a first amplitude of an air pressure pulse caused by operation of the pump after the first period of time; operating the pump for a second period of time; measuring a second amplitude of an air pressure pulse caused by operation of the pump after the second period of time; calculating a function of the first amplitude and the second amplitude; determining whether at least one of the first hose and the second hose is coupled to the cuff connector, whether at least one of the first hose and the second hose is kinked, whether the first hose is connected to the first cuff, or whether the second hose is connected to the second cuff based on an output of the function; The method includes:

25. 25. The method of claim 24, wherein the function is an average of the first amplitude and the second amplitude.

26. 25. The method of claim 24, wherein each of the first and second periods is between 10 ms and 100 ms, preferably 50 ms.

27. 25. The method of claim 24, further comprising a time interval between the first period and the second period.

28. 25. The method of claim 24, wherein operating the pump includes operating at a duty cycle in a range equal to 90% to 100%.

29. 25. The method of claim 24, wherein the step of determining whether the first hose is connected to the first cuff or the second hose is connected to the second cuff comprises: opening the first valve and the second valve during the first period; operating the pump at a duty cycle in the range of 30% to 50% after the first period of time; measuring the first amplitude; determining, based on the first amplitude, at least one of whether the first hose is connected to the first cuff and whether the second hose is connected to the second cuff; The method includes:

30. 30. The method of claim 29, wherein the determining step includes concluding that the first hose is connected to the first cuff if the amplitude has a first value and that the second hose is connected to the second cuff if the amplitude has a second value, the first value being less than the second value.

Images