System and method for compensating for arterial pressure sensor positioning

Abstract

The present disclosure relates generally to systems and methods for compensating for arterial pressure sensor positioning. Various system configurations can be used to calibrate a pressure transducer to automatically account for pressure attributable to the vertical distance between the phlebostatic axis and the pressure transducer. Various system configurations can be used to detect a vertical distance between the phlebostatic axis and a pressure transducer and to adjust pressure readings accordingly. Various system configurations can be used to position a pressure transducer at the phlebostatic axis.

Description

SYSTEM AND METHOD FOR COMPENSATING FORARTERIAL PRESSURE SENSOR POSITIONINGBACKGROUND

[0001] Arterial lines are placed to obtain real-time blood pressure and to allow for arterial blood gas sampling. Figure 1 provides an example of a prior art system 100 that may be used to measure arterial pressure. System 100 includes a recording device 101, a pressure transducer 103 that is connected to the recording device 101 via a cable 102, and pressure tubing 104 that is connected between pressure transducer 103 and the arterial line. One or more 3-way stopcocks 105 may be positioned on or in communication with pressure tubing 104.

[0002] System 100 also includes a pressure infuser 111 that is connected to pressure transducer 103 via tubing 112. Tubing 112 may couple to pressure infuser 111 via a drip chamber 113. A clamp 114 may be positioned on tubing 112 to control flow of fluid therethrough.

[0003] Pressure transducer 103 is positioned at the phlebostatic axis 123 (which corresponds roughly with the position of the right atrium and aortic root and is identified as the intersection between line 121 representing the mid-point, anterior-posterior chest wall and line 122 representing the fourth intercostal space at the sternum) and connected to pressure infuser 111. Pressure infuser I l l is pressurized to 300mmHg, and the flow is throttled by a flow restrictor in pressure transducer 103 to a rate of about 3 ml / hr. The purpose of the flow rate of 3ml / hr is to keep pressure tubing 104 free from air bubbles, and to keep blood from backing up into the catheter and creating an occlusion. Pressure transducer 103 is zeroed to atmosphere to allow the measurement of a gauge pressure of the aorta.

[0004] There are various problems with these current techniques. For example, a good pressure waveform can be lost due to an air bubble, catheter kinking, an occlusion, etc. Also, constant adjusting of the transducer height may be necessary as the patient is repositioned or the bed is inclined or declined. It is also time consuming to set up the tubing, transducer, pressure infusion, etc.

[0005] The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one example technology area where some implementations described herein may be practiced.SUMMARY

[0006] The present disclosure relates generally to systems and methods for compensating for arterial pressure sensor positioning. Various system configurations can be used to calibrate a pressure transducer to automatically account for pressure attributable to the vertical distance between the phlebostatic axis and the pressure transducer. Various system configurations can be used to detect a vertical distance between the phlebostatic axis and a pressure transducer and to adjust pressure readings accordingly. Various system configurations can be used to position a pressure transducer at the phlebostatic axis.

[0007] In some embodiments of the present disclosure, a system for compensating for arterial pressure sensor positioning may include a pressure transducer, an arterial line coupled to the pressure transducer, and a fluid column coupled to the pressure transducer.

[0008] In some embodiments, a top of the fluid column may be positioned at the phlebostatic axis.

[0009] In some embodiments, the pressure transducer may be positioned at a height below the phlebostatic axis.

[0010] In some embodiments, the pressure transducer may generate pressure readings indicative of arterial pressure that account for the height at which the pressure transducer is positioned below the phlebostatic axis.

[0011] In some embodiments, the system may further include a pressure monitoring device that receives the pressure readings from the pressure transducer.

[0012] In some embodiments of the present disclosure, a system for compensating for arterial pressure sensor positioning may include a pressure transducer that is configured to generate pressure readings indicative of arterial pressure and a pressure monitoring device that is configured to receive the pressure readings from the pressure transducer.

[0013] In some embodiments, the system may further include a first transmitter positioned at the pressure transducer, a second transmitter positioned at the phlebostatic axis, and a plurality of sensors that receive signals from the first and second transmitters, the signals being used to calculate a height at which the pressure transducer is positioned below the phlebostatic axis. The pressure monitoring device is configured to use the calculated height to determine an arterial pressure from the pressure readings.

[0014] In some embodiments, the system may further include a control box positioned at the phlebostatic axis and a shape sensing fiber that is connected between the control box and the pressure transducer, the control box being configured to calculate a height at which the pressure transducer is positioned below the phlebostatic axis using the shape sensing fiber. The pressure monitoring device is configured to use the calculated height to determine an arterial pressure from the pressure readings.

[0015] In some embodiments, the system may further include a first reference positioned at the pressure transducer, a second reference positioned at the phlebostatic axis, and a camera that is configured to calculate a height at which the pressure transducer is positioned below the phlebostatic axis using the first and second references. The pressure monitoring device is configured to use the calculated height to determine an arterial pressure from the pressure readings.

[0016] In some embodiments, the system may further include a first barometer sensor positioned at the pressure transducer and a second barometer sensor positioned at the phlebostatic axis. The pressure monitoring device is configured to calculate a height at which the pressure transducer is positioned below the phlebostatic axis using the first and second barometer sensors and to use the calculated height to determine an arterial pressure from the pressure readings.

[0017] In some embodiments, the pressure monitoring device is configured to receive a first pressure reading when the pressure transducer is positioned at the phlebostatic axis and a second pressure reading when the pressure transducer is positioned at a height below the phlebostatic axis and to determine an arterial pressure from subsequent pressure readings using the first and second pressure readings.

[0018] In some embodiments, the arterial pressure may be determined by subtracting the first and second pressure readings from the subsequent pressure readings.

[0019] In some embodiments, the pressure transducer includes an accelerometer and a gyroscope, and wherein the pressure monitoring device is configured to calculate a height at which the pressure transducer is positioned below the phlebostatic axis using the accelerometer and the gyroscope and to use the calculated height to determine an arterial pressure from the pressure readings.

[0020] In some embodiments, the system may further include a second pressure transducer and a fluid column that is connected to the second pressure transducer, a top of the second fluid column being positioned at the phlebostatic axis. The pressure monitoring device receives pressure readings from the first and second pressure transducers, the pressure monitoring device being configured to determine arterial pressure from the pressure readings from the first pressure transducer by using the pressure readings from the second pressure transducer to account for a height at which the first pressure transducer is positioned below the phlebostatic axis.

[0021] In some embodiments, the pressure transducer may be positioned within the artery.

[0022] In some embodiments, the system may further include a sensor positioned at the phlebostatic axis. The sensor may be configured to detect a height at which the pressure transducer is positioned below the phlebostatic axis.

[0023] In some embodiments, the system may further include a magnetic sensor positioned at one of the pressure transducer or at the phlebostatic axis and one or more Hall sensors positioned at the other of the pressure transducer or the phlebostatic axis. The pressure monitoring device is configured to calculate a height at which the pressure transducer is positioned below the phlebostatic axis using the magnetic sensor and the one or more Hall sensors and to use the calculated height to determine an arterial pressure from the pressure readings.

[0024] In some embodiments of the present disclosure, a method for determining arterial pressure may include using a pressure transducer to obtain pressure readings, determining a height of the pressure transducer below the phlebostatic axis, and determining arterial pressure from the pressure readings and the height.

[0025] In some embodiments, the pressure transducer may be connected to an arterial line and to a fluid column, a top of the fluid column being positioned at the phlebostatic axis.

[0026] In some embodiments, determining the arterial pressure from the pressure readings and the height may include configuring the pressure transducer to cause the pressure readings to account for the height.

[0027] In some embodiments, determining the arterial pressure from the pressure readings and the height may include calculating a component of the pressure readings that is attributable to the height.

[0028] In some embodiments of the present disclosure, a system for compensating for arterial pressure sensor positioning may include a pressure transducer that is configured to generate pressure readings, an arterial line coupled to the pressure transducer, a fluid column coupled to the pressure transducer, and a pressure monitoring device that is configured to output an arterial pressure from the pressure readings, the arterial pressure accounting for a height at which the pressure transducer is positioned below the phlebostatic axis.

[0029] It is to be understood that both the foregoing general description and the following detailed description are examples and explanatory and are not restrictive of the invention, as claimed. It should be understood that the various embodiments are not limited to the arrangements and instrumentality illustrated in the drawings. It should also be understood that the embodiments may be combined, or that other embodiments may be utilized and that structural changes, unless so claimed, may be made without departing from the scope of the various embodiments of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0030] Example embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0031] Figure 1 illustrates a prior art system that can be used to monitor arterial pressure;

[0032] Figures 2A and 2B provide an example of a system for compensating for arterial pressure sensor positioning that is configured in accordance with one or more embodiments of the present disclosure;

[0033] Figure 3 provides an example of a system for compensating for arterial pressure sensor positioning that is configured in accordance with one or more embodiments of the present disclosure;

[0034] Figure 4 provides an example of a system for compensating for arterial pressure sensor positioning that is configured in accordance with one or more embodiments of the present disclosure;

[0035] Figure 5 provides an example of a system for compensating for arterial pressure sensor positioning that is configured in accordance with one or more embodiments of the present disclosure;

[0036] Figure 6 provides an example of a system for compensating for arterial pressure sensor positioning that is configured in accordance with one or more embodiments of the present disclosure;

[0037] Figures 7A and 7B provide an example of a system and method for compensating for arterial pressure sensor positioning in accordance with one or more embodiments of the present disclosure; and

[0038] Figure 8 provides an example of a system for compensating for arterial pressure sensor positioning that is configured in accordance with one or more embodiments of the present disclosure.DESCRIPTION OF EMBODIMENTS

[0039] Figure 2A provides an example of a system 200 for compensating for arterial pressure sensor positioning that is configured in accordance with one or more embodiments of the present disclosure. System 200 includes a pressure transducer 210 that is positioned proximal to the arterial line 240. As shown in Figure 2B, pressure transducer 210 can include a diaphragm 211 and circuitry 212 for measuring differences in pressures on opposing sides of diaphragm 211. Arterial line 240 can be connected to a distal end of pressure transducer 210 and a fluid column 220 can be connected to the proximal end of pressure transducer 210. Accordingly, the pressure of blood in arterial line 240 will be incident on the distal side of diaphragm 211 and the pressure of the fluid in fluid column 220 will be incident on the proximal side of diaphragm 211.

[0040] An arm band 230 may be used to secure and stabilize fluid column 220 on the patient’s arm. A top 220a of fluid column 220 (e.g., the highest point of the fluid in fluid column 220) can be positioned at the phlebostatic axis 123. With top 220a of fluid column 220 at the phlebostatic axis 123 and pressure transducer 210 in its intended / desired position, but with diaphragm 211 not exposed to arterial pressure, pressure transducer 210 can be zeroed. This could be accomplished using a stopcock on arterial line 240 or prior to coupling arterial line 240 to pressure transducer 210. Then, diaphragm 211 can be exposed to the arterial pressure (e.g., by opening the stopcock, attaching arterial line 240, etc.). The pressure measurements that pressure transducer 210 then provides will accurately represent the arterial pressure as long as top 220a of fluid column 220remains at or near the phlebostatic axis 123, which will typically be the case when the patient is lying in a hospital bed. Pressure transducer 210 can be configured to relay these pressure measurements to a pressure monitoring device 250 via a wired connection, a wireless connection, or both.

[0041] More particularly, the height (h) between the phlebostatic axis 123 and the position of pressure transducer 210 is a parameter in the pressure applied by fluid column 220 and by the blood in arterial line 240 to diaphragm 211. In each case, this pressure is equal to pgh where p is the density of blood, g is the acceleration of gravity, and h is the vertical distance between the phlebostatic axis 123 and pressure transducer 210. By positioning top 220a of fluid column 220 at the phlebostatic axis 123 and zeroing pressure transducer 210 prior to connecting arterial line 240, the pressure of the blood attributable to the height (h) can be offset by the pressure of fluid column 220 so that the pressure measurement reflects only the arterial pressure. The following equation may represent this pressure: Ptransducer = Partery + pgharte - pghfiuid column. In system 200, pghfiuid column will equal and therefore offset pgh;irtL.r>.

[0042] System 200 may provide various benefits. For example, because pressure transducer 210 can be positioned at the insertion point, the distance between the artery and pressure transducer 210 is minimized which can result in more accurate pressure waveforms. This shorter distance can also minimize the risk of air bubbles. System 200 is also easier to connect and disconnect given that there may only be a single cable or even a wireless connection between pressure transducer 210 and pressure monitoring device 250.

[0043] In some embodiments, a system for compensating for arterial pressure sensor positioning may be configured to detect / calculate the height (h) between the phlebostatic axis 123 and pressure transducer 210 and to automatically adjust pressure measurements based on thisheight. For example, by knowing the height (h), pressure transducer 210 and / or pressure monitoring device 250 can calculate the pressure that fluid column 220 applies to diaphragm 211 (pghfluid column) and the pressure attributable to the height (h) that the arterial blood applies to diaphragm 211 (pghartery) and then use such pressures to calculate the arterial pressure (Partery). Figures 3-6 provide some examples of systems that function in this manner.

[0044] Figure 3 provides an example of a system 300 for compensating for arterial pressure sensor positioning that is configured in accordance with one or more embodiments of the present disclosure. System 300 may include pressure transducer 210 that is connected to arterial line 240. Alternatively, pressure transducer 210 could be positioned in the artery, in the catheter or otherwise positioned to be capable of sensing the arterial pressure. Additionally, system 300 can include a first transmitter 301a, a second transmitter 301b, and a plurality of sensors 302. First transmitter 301a can be positioned at pressure transducer 210 (or more particularly, at the point where arterial line 240 connects to pressure transducer 210 or where pressure transducer 210 is subject to the arterial pressure) and second transmitter 301b can be positioned at the phlebostatic axis 123 (e.g., on the arm of the patient, on the bed, etc.). Sensors 302 can be positioned around the patient such as on the walls or ceiling of the room. First and second transmitters 301a, 301b can be configured to transmit signals that sensors 302 can use to triangulate the location of the transmitters to thereby calculate the height (h). Accordingly, in some embodiments, at least three sensors 302 may be used.

[0045] Figure 4 provides an example of a system 400 for compensating for arterial pressure sensor positioning that is configured in accordance with one or more embodiments of the present disclosure. System 400 may include pressure transducer 210 that is connected to arterial line 240. Alternatively, pressure transducer 210 could be positioned in the artery, in the catheter or otherwisepositioned to be capable of sensing the arterial pressure. Additionally, system 400 can include a control box 410 positioned at the phlebostatic axis 123 that is connected to pressure transducer 210 via a shape sensing fiber 411. For example, control box 410 could be positioned on a pole, the bed, or other structure near the patient. Control box 410 can be configured to use shape sensing fiber 411 to detect the height (h). In particular, control box 410 can detect the shape of shape sensing fiber 411 and can use the detected shape to calculate the vertical distance (h) between control box 410 and the end of shape sensing fiber 411 which is positioned at pressure transducer 210.

[0046] In some embodiments, a sensor may be positioned at the phlebostatic axis and used to detect the height (h). For example, a sensor may be configured to detect the height (h) by calculating the relative height between its known position at the phlebostatic axis and the detected position of pressure transducer. This sensor could detect this relative height using vision (e.g., as a camera), via light or another signal emitted from pressure transducer 210, or in some other manner. In some embodiments, the sensor may be configured to automatically move up and down to stay level with the phlebostatic axis.

[0047] Figure 5 provides an example of a system 500 for compensating for arterial pressure sensor positioning that is configured in accordance with one or more embodiments of the present disclosure. System 500 may include pressure transducer 210 that is connected to arterial line 240. Alternatively, pressure transducer 210 could be positioned in the artery, in the catheter or otherwise positioned to be capable of sensing the arterial pressure. Additionally, system 500 can include a first visual reference 501a positioned at pressure transducer 210 and a second visual reference 501b positioned at the phlebostatic axis 123. System 500 may further include a camera 251, which could be part of pressure monitoring device 250, part of another computing device, or a standalonecamera. Camera 251 can be configured to capture images that include both first visual reference 501a and second visual references 501b and to calculate the height (h) from these images.

[0048] In variations of system 500, infrared references, as opposed to visual references, may be positioned at pressure transducer 210 and phlebostatic axis 123 and multiple infrared cameras may be used to determine the height (h) between the infrared references. For example, the infrared cameras may be oriented at two orthogonal directions and, based on the orthogonal directions and the detected relative positions between the infrared references, the height (h) may be calculated.

[0049] In some embodiments of system 500, camera 251 may be part of a smart phone. In such embodiments, a mobile application can be configured to use images captured by camera 251 to determine the height (h) based on the references appearing in the images. In some embodiments, system 500 may not include references. Instead, the mobile application can allow a user to specify the location of pressure transducer 210 and phlebostatic axis 123 in a captured image and may then determine the height (h) based on such input.

[0050] Figure 6 provides an example of a system 600 for compensating for arterial pressure sensor positioning that is configured in accordance with one or more embodiments of the present disclosure. System 600 may include pressure transducer 210 that is connected to arterial line 240. Alternatively, pressure transducer 210 could be positioned in the artery, in the catheter or otherwise positioned to be capable of sensing the arterial pressure. Additionally, system 600 can include a first barometer sensor 601a positioned at pressure transducer 210 and a second barometer sensor 601b positioned at the phlebostatic axis 123. First and second barometer sensors 601a and 601b can provide air pressure measurements (e.g., to pressure monitoring device 250 or another computing device) which can be used to calculate the height (h) based on differences in these air pressure measurements.

[0051] In variations of system 600, other types of sensors may be used. For example, a magnetic sensor can be positioned at either pressure transducer 210 or phlebostatic axis 123, and one or more Hall effect sensors can be positioned at the other location. The Hall effect sensor(s) can determine the direction and distance of the magnetic sensor. One of these sensors may also include a gyroscope that can determine the horizontal axis. Using the known horizontal axis and the detected direction and direction of the magnetic sensor from the Hall effect sensor(s), the height (h) can be calculated.

[0052] Figures 7A and 7B provide an example of a system 700 and method for compensating for arterial pressure sensor positioning that is configured in accordance with one or more embodiments of the present disclosure. System 700 may include pressure transducer 210 that is connected to arterial line 240. Alternatively, pressure transducer 210 could be positioned in the artery, in the catheter or otherwise positioned to be capable of sensing the arterial pressure. Additionally, pressure monitoring device 250 can be configured to receive a pressure reading (Pressurei) when pressure transducer 210 is positioned at the phlebostatic axis 123 and a pressure reading (Pressure ) when pressure transducer 210 is positioned at the intended / desired position. The pressure attributable to height (h) can then be calculated as Pressure? - Pressurei. Pressure monitoring device 250 can then calculate the arterial pressure from subsequent pressure readings while pressure transducer 210 is positioned at the intended / desired position by subtracting this pressure attributable to height (h) (i.e., Pressureartery = Pressuretransducer - Pressure? - Pressurei). A similar result could be accomplished by zeroing pressure transducer 210 when positioned at the phlebostatic axis 123 (i.e., making Pressurei equal to 0).

[0053] A similar method could be used to calculate the arterial pressure when pressure transducer 210 includes an accelerometer and a gyroscope. In such cases, with pressure transducer210 positioned at the phlebostatic axis 123, a position calculated from readings of the accelerometer and gyroscope can be zeroed. Then, the height (h) could be calculated using subsequent readings of the accelerometer and gyroscope.

[0054] A similar method could be used to calculate the arterial pressure using a blood pressure cuff. The blood pressure cuff can be placed on the upper arm and used to measure blood pressure. The measured blood pressure can then be used to zero and calibrate pressure transducer 210. This process could be repeated periodically (e.g., each hour, once a day, whenever there is a significant change in mean arterial pressure, etc.) to automatically re-zero and calibrate pressure transducer 210.

[0055] Figure 8 provides an example of a system 800 for compensating for arterial pressure sensor positioning that is configured in accordance with one or more embodiments of the present disclosure. System 800 may be configured in a similar manner as system 200 except that pressure transducer 210 is not connected to arterial line 240. Instead, system 800 can include a second pressure transducer 810 that is connected to arterial line 240, positioned in the artery, positioned in the catheter or otherwise positioned to be capable of sensing the arterial pressure. In these embodiments, the pressure reported by pressure transducer 210 will be based on the height (h) and can be used to adjust the pressure reported by pressure reducer 810 to account for the height (h) at which pressure transducer 810 is positioned below the phlebostatic axis.

[0056] As stated above, pressure transducer 210 and / or 810 could be positioned within the artery as opposed to outside the body as is depicted, or in the catheter. In some embodiments, pressure transducer 210 and / or 810 could be a two-gage pressure transducer. In some embodiments, fluid column 220 could be secured to something other than the patient’s arm such as to the bed, a monitor pole, an IV pole, etc.

[0057] In some embodiments, a pressure transducer may be positioned at the phlebostatic axis 123. For example, the pressure transducer can be threaded up the artery to a position at the phlebostatic axis. From the radial artery, the pressure transducer could be threaded up to the brachial artery level with the phlebostatic axis. From the femoral artery, the pressure transducer can be advanced up to the aorta. Thus, there is no height difference between the phlebostatic axis and the pressure transducer. In such embodiments, the position of the pressure transducer can be determined by several technologies including Sherlock, ultrasound, etc.

[0058] In any of the above-described embodiments, techniques may be used to automatically alert a clinician when a change in mean arterial pressure occurs. For example, when pressure transducer 210 includes an accelerometer, the accelerometer can be used to detect when movement occurs. If movement is detected, but not change in mean arterial pressure is detected, the movement may be ignored. However, if no movement is detected when a change in mean arterial pressure is detected, the clinician may be alerted to check the patient. Also, if movement is detected along with a change in mean arterial pressure, the clinician may be alerted to re-zero pressure transducer 210 if necessary.

[0059] As another example, a system may be configured to detect when the bed is moved (e.g., reclined or inclined). When the bed is moved, the clinician may be alerted to check whether the phlebostatic axis may have changed. If so, the clinician may re-zero pressure transducer 210.

[0060] All examples and conditional language recited herein are intended for pedagogical objects to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. Although embodiments of the present inventions have beendescribed in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.

Claims

CLAIMSWhat is claimed:

1. A system for compensating for arterial pressure sensor positioning comprising: a pressure transducer; an arterial line coupled to the pressure transducer; and a fluid column coupled to the pressure transducer.

2. The system of claim 1, wherein a top of the fluid column is positioned at the phlebostatic axis.

3. The system of claim 2, wherein the pressure transducer is positioned at a height below the phlebostatic axis.

4. The system of claim 3, wherein the pressure transducer generates pressure readings indicative of arterial pressure that account for the height at which the pressure transducer is positioned below the phlebostatic axis.

5. The system of claim 4, further comprising: a pressure monitoring device that receives the pressure readings from the pressure transducer.

6. A system for compensating for arterial pressure sensor positioning comprising: a pressure transducer that is configured to generate pressure readings indicative of arterial pressure; and a pressure monitoring device that is configured to receive the pressure readings from the pressure transducer.

7. The system of claim 6, further comprising: a first transmitter positioned at the pressure transducer; a second transmitter positioned at the phlebostatic axis; and a plurality of sensors that receive signals from the first and second transmitters, wherein the signals are used to calculate a height at which the pressure transducer is positioned below the phlebostatic axis; wherein the pressure monitoring device is configured to use the calculated height to determine an arterial pressure from the pressure readings.

8. The system of claim 6, further comprising: a control box positioned at the phlebostatic axis; and a shape sensing fiber that is connected between the control box and the pressure transducer, wherein the control box is configured to calculate a height at which the pressure transducer is positioned below the phlebostatic axis using the shape sensing fiber; wherein the pressure monitoring device is configured to use the calculated height to determine an arterial pressure from the pressure readings.

9. The system of claim 6, further comprising: a first reference positioned at the pressure transducer; a second reference positioned at the phlebostatic axis; and a camera that is configured to calculate a height at which the pressure transducer is positioned below the phlebostatic axis using the first and second references; wherein the pressure monitoring device is configured to use the calculated height to determine an arterial pressure from the pressure readings.

10. The system of claim 6, further comprising: a first barometer sensor positioned at the pressure transducer; and a second barometer sensor positioned at the phlebostatic axis; wherein the pressure monitoring device is configured to calculate a height at which the pressure transducer is positioned below the phlebostatic axis using the first and second barometer sensors and to use the calculated height to determine an arterial pressure from the pressure readings.

11. The system of claim 3, wherein the pressure monitoring device is configured to receive a first pressure reading when the pressure transducer is positioned at the phlebostatic axis and a second pressure reading when the pressure transducer is positioned at a height below the phlebostatic axis and to determine an arterial pressure from subsequent pressure readings using the first and second pressure readings.

12. The system of claim 1 1 , wherein the arterial pressure is determined by subtracting the first and second pressure readings from the subsequent pressure readings.

13. The system of claim 3, wherein the pressure transducer includes an accelerometer and a gyroscope, and wherein the pressure monitoring device is configured to calculate a height at which the pressure transducer is positioned below the phlebostatic axis using the accelerometer and the gyroscope and to use the calculated height to determine an arterial pressure from the pressure readings.

14. The system of claim 3, further comprising: a second pressure transducer; and a fluid column that is connected to the second pressure transducer, a top of the fluid column being positioned at the phlebostatic axis; wherein the pressure monitoring device receives pressure readings from the first and second pressure transducers, the pressure monitoring device being configured to determine arterial pressure from the pressure readings from the first pressure transducer by using the pressure readings from the second pressure transducer to account for a height at which the first pressure transducer is positioned below the phlebostatic axis.

15. The system of claim 3, wherein the pressure transducer is positioned within the artery.

16. The system of claim 3, further comprising: a sensor positioned at the phlebostatic axis, the sensor being configured to detect a height at which the pressure transducer is positioned below the phlebostatic axis.

17. The system of claim 3, further comprising: a magnetic sensor positioned at one of the pressure transducer or at the phlebostatic axis; and one or more Hall sensors positioned at the other of the pressure transducer or the phlebostatic axis; wherein the pressure monitoring device is configured to calculate a height at which the pressure transducer is positioned below the phlebostatic axis using the magnetic sensor and the one or more Hall sensors and to use the calculated height to determine an arterial pressure from the pressure readings.

18. A method for determining arterial pressure comprising: using a pressure transducer to obtain pressure readings; determining a height of the pressure transducer below the phlebostatic axis; and determining arterial pressure from the pressure readings and the height.

19. The method of claim 18, wherein the pressure transducer is connected to an arterial line and to a fluid column, a top of the fluid column being positioned at the phlebostatic axis.

20. The method of claim 18, wherein determining the arterial pressure from the pressure readings and the height comprises configuring the pressure transducer to cause the pressure readings to account for the height.

Images