Personalized tourniquet apparatus

• US 9,814,467 B2
• Filed: 04/25/2015
• Issued: 11/14/2017
• Est. Priority Date: 07/10/2014
• Status: Active Grant

• Current Assignee: Western Clinical Engineering Ltd.
• Original Assignee: Western Clinical Engineering Ltd.
• Inventors: McEwen, James A., Jameson, Michael, Jeyasurya, Jeswin, Glinz, Kenneth L.
• Primary Examiner(s): LYNCH, ROBERT A
• Application Number:
  US14/696,401
• Publication Number:
  US 20160008005A1
• Time in Patent Office: 934 Days
• CPC Class Codes: A61B 17/132 Tourniquets sphygmomanometer A61B5/022
• CPC Class Codes: A61B 17/1322 comprising a flexible encircling member A61B17/135 takes precedence
• CPC Class Codes: A61B 17/135 inflatable for measuring blood pressure A61B5/022; inflatable pressure pads A61F5/34
• CPC Class Codes: A61B 17/1355 Automated control means therefor
• CPC Class Codes: A61B 2017/00017 Electrical control of surgical instruments
• CPC Class Codes: A61B 2017/00022 Sensing or detecting at the treatment site
• CPC Class Codes: A61B 2017/00119 alarm; indicating an abnormal situation
• CPC Class Codes: A61B 2017/00199 with a console, e.g. a control panel with a display
• CPC Class Codes: A61B 2090/0807 Indication means
• CPC Class Codes: A61B 2505/05 Surgical care
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02233 Occluders specially adapted therefor tourniquets A61B17/132
• CPC Class Codes: A61B 90/92 coded with colour
• CPC Class Codes: A61B 90/98 using electromagnetic means, e.g. transponders

Abstract

Disclosed is a method and apparatus for regulating tourniquet cuff pressure based on a personalized tourniquet pressure (PTP) to facilitate safe performance of a surgical procedure. The apparatus includes a dual-purpose tourniquet cuff adapted to encircle a region of a patient limb to provide both a sensor during a pre-surgical time period and an effector during a surgical time period. An effector module communicates pneumatically with an inflatable bladder of the cuff for maintaining pressure in the bladder near a PTP during the surgical time period to safely stop penetration of arterial blood past the cuff. A pulsation sensor that communicates pneumatically with the inflatable bladder during the pre-surgical time period senses and characterizes pressure pulsations that are indicative of penetration of arterial blood into the region of the limb encircled by the cuff. A PTP estimator is responsive to the pulsation sensor for producing an estimate of the PTP, such that the estimate of the PTP is a function of the sensed pulsations.

Claims

1. An apparatus for regulating tourniquet cuff pressure based on a personalized tourniquet pressure (PTP), comprising:

a sensor module for estimating a limb occlusion pressure (LOP) by determining an estimated LOP equal to a minimum pressure at which penetration of blood past an applied tourniquet cuff is stopped, and measuring a pulsation characteristic associated with the LOP,

a controller for establishing a PTP by determining a second pressure that is greater than the LOP and that corresponds to a second pulsation characteristic that differs by a predetermined percentage from the pulsation characteristic associated with the LOP; and

an effector module operable during a surgical time period for maintaining pressure in an applied tourniquet cuff near the PTP.

2. The apparatus of claim 1 wherein the pulsation characteristic is indicative of a shape of the pulsation.

3. The apparatus of claim 1 wherein the pulsation characteristic is a maximum amplitude of pulsation.

4. The apparatus of claim 1 wherein the predetermined percentage is a function of a magnitude of the estimated LOP.

5. The apparatus of claim 1 wherein the sensor module is operable also to sense a characteristic of blood that penetrates past the applied tourniquet cuff.

6. The apparatus of claim 1 wherein the sensor module is also operable to sense in an inflatable bladder of the cuff a characteristic of pulsation.

7. An apparatus for regulating tourniquet cuff pressure based on a personalized tourniquet pressure (PTP), comprising a controller operable during a pre-surgical time period for:

estimating a limb occlusion pressure (LOP) by determining a minimum pressure at which penetration of blood past an applied tourniquet cuff is stopped;

measuring a pulsation characteristic associated with the LOP;

establishing a PTP by determining a second pressure that is greater than the LOP and that corresponds to a second pulsation characteristic that differs by a predetermined percentage from the pulsation characteristic associated with the LOP; and

regulating the tourniquet cuff pressure during a surgical time period to maintain a surgical pulsation characteristic near the second pulsation characteristic.

8. The apparatus of claim 7 wherein the pulsation characteristic is indicative of a shape of the pulsation.

9. The apparatus of claim 7 wherein the pulsation characteristic is a maximum amplitude of pulsation.

10. The apparatus of claim 7 wherein the predetermined percentage is a function of a magnitude of the estimated LOP.

11. The apparatus of claim 7 wherein the controller for estimating the LOP includes sensing a characteristic of blood that penetrates past the applied tourniquet cuff.

12. The apparatus of claim 7 wherein the controller for estimating the LOP includes sensing in an inflatable bladder of the cuff a pulsation characteristic.

13. The apparatus of claim 7 further comprising an alarm condition detector for producing an alert if the surgical pulsation characteristic is outside a predetermined range.

14. An apparatus for regulating tourniquet cuff pressure based on a personalized tourniquet pressure (PTP), comprising:

a surgical tourniquet cuff having a bladder and configured to be applied to a patient'"'"'s limb at a location proximal to a surgical site on the limb;

a controller operable during a pre-surgical time period for;

estimating a minimum pressure at which penetration of blood past the applied tourniquet cuff is stopped by analyzing pressure pulsations in the bladder of the cuff that are associated with selected pressures in the bladder, thereby to identify a limb occlusion pressure (LOP) at the location and a first pulsation characteristic associated with the LOP;

establishing a PTP by determining a second pressure that is greater than the LOP and that corresponds to a second pulsation characteristic that differs by a percentage from the first pulsation characteristic associated with the LOP; and

maintaining pressure in the bladder of the applied tourniquet cuff near the PTP during a surgical time period.

15. The apparatus of claim 14 further comprising a noise sensor module for determining a noise level associated with pressure fluctuations in the bladder that are independent of the pressure pulsations analyzed for the estimation of LOP.

16. The apparatus of claim 15 wherein the controller is also operable to compensate for effects of a noise level above a threshold level.

17. The apparatus of claim 15 wherein the pressure fluctuations are associated with tremor-related muscle contractions during the pre-surgical time period.

18. The apparatus of claim 15 wherein the pressure fluctuations are associated with operation of a tourniquet pressure regulator for inflation of the bladder near the selected pressures during the pre-surgical time period.

19. The apparatus of claim 15 wherein the pressure fluctuations are associated with perioperative activity.

20. An apparatus for regulating tourniquet cuff pressure based on a personalized tourniquet pressure (PTP), comprising:

a surgical tourniquet cuff having a bladder and configured to be applied to a patient'"'"'s limb at a location proximal to a surgical site on the limb;

a controller operable during a pre-surgical time period for;

estimating a minimum pressure at which penetration of blood past the applied tourniquet cuff is stopped by analyzing pressure pulsations in the bladder of the cuff that are associated with selected pressures in the bladder, thereby to identify a limb occlusion pressure (LOP) at the location and a first pulsation characteristic associated with the LOP,

establishing a PTP by determining a second pressure that is greater than the LOP and that corresponds to a second pulsation characteristic that differs by a percentage from the first pulsation characteristic associated with the LOP, and

maintaining pressure in the bladder of the applied tourniquet cuff near the PTP during a surgical time period; and

a noise sensor module for determining a noise level associated with pressure fluctuations in the bladder that are independent of the pressure pulsations analyzed for the estimation of LOP;

wherein the controller establishes the PTP to be a first increment of pressure greater than the LOP if the noise level is below a first noise threshold.

21. The apparatus of claim 20 wherein the controller establishes the PTP to be a second increment of pressure greater than the first increment of pressure if the noise level is greater than the first noise threshold and less than a second noise threshold.

22. The apparatus of claim 21 wherein the controller for establishing the PTP establishes the PTP to be a predetermined default pressure if the noise level is greater than the second noise threshold.

23. The apparatus of claim 22 further comprising an alarm condition detector for producing an alert perceptible by a user if the noise level is greater than the second noise threshold.

24. An apparatus for regulating tourniquet cuff pressure based on a personalized tourniquet pressure (PTP) to facilitate safe performance of a surgical procedure, comprising:

a dual-purpose tourniquet cuff having an inflatable bladder adapted to encircle a patient limb;

a sensor module having a pulsation sensor communicating pneumatically with the inflatable bladder for sensing and characterizing pressure pulsations indicative of a limb occlusion pressure (LOP), thereby to identify a LOP equal to a minimum pressure at which penetration of blood past the cuff is stopped;

a PTP estimator responsive to the pulsation sensor for producing an estimate of a PTP, wherein the estimate of the PTP is a function of the LOP;

an effector module communicating pneumatically with the inflatable bladder of the dual-purpose cuff for maintaining pressure in the bladder near a PTP; and

a controller selectively operating the inflatable bladder in conjunction with the sensor module and the effector module.

25. The apparatus of claim 24 wherein the controller operates the inflatable bladder with the sensor module during a pre-surgical time period.

26. The apparatus of claim 24 wherein the controlleroperates the inflatable bladder with the effector module during a surgical time period.

27. The apparatus of claim 26 wherein the controller further operates the inflatable bladder with the sensor module for sensing and characterizing pressure pulsations during the surgical time period.

28. The apparatus of claim 24 further comprising an alarm condition detector producing an alert upon detection of an occlusion of pneumatic communication between the inflatable bladder and the sensor module.

29. The apparatus of claim 24 further comprising an alarm condition detector producing an alert upon detection of an occlusion of pneumatic communication between the inflatable bladder and the effector module.

30. The apparatus of claim 24 further comprising a cuff identification module for alerting a user in instances when the inflatable bladder is not part of a dual-purpose cuff.

31. The apparatus of claim 24 wherein the function is a percentage of the LOP.