Apparatus and method for estimating leakage in a surgical tourniquet system

• US 8,083,763 B2
• Filed: 02/10/2009
• Issued: 12/27/2011
• Est. Priority Date: 02/10/2009
• Status: Active Grant

• Current Assignee: Western Clinical Engineering Ltd.
• Original Assignee: Western Clinical Engineering Ltd.
• Inventors: McEwen, James A., Jameson, Michael, Gebert, Michael A., Cheung, William K. W.
• Primary Examiner(s): Redmann, Gregory J.
• Application Number:
  US12/368,789
• Publication Number:
  US 20100204726A1
• Time in Patent Office: 1,050 Days
• Field of Search: 73/40, 606/202
• US Class Current: 606/202
• CPC Class Codes: A61B 17/1355 Automated control means therefor
• CPC Class Codes: A61B 2017/00119 alarm; indicating an abnormal situation
• CPC Class Codes: A61B 2017/00132 Setting operation time of a device A61B2017/00123 takes precedence
• CPC Class Codes: A61B 2017/00199 with a console, e.g. a control panel with a display
• CPC Class Codes: A61B 2090/064 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61B 2090/0809 Indication of cracks or breakages

Abstract

Apparatus for estimating a magnitude of leakage from a surgical tourniquet system while pressure in a cuff of the system is regulated near a reference pressure.

Claims

1. A method of estimating the magnitude of gas leakage from a surgical tourniquet cuff during an operation time period when the cuff is applied to a patient'"'"'s limb and connected to a controllable pressure source of gas and when the cuff is pressurized with the gas to be within a reference pressure range suitable for occluding blood flow through the limb, the method comprising the steps of:

configuring the pressure source to be responsive to an applied electrical signal for directing gas to flow to the cuff at a flow rate corresponding to the electrical current level of the applied electrical signal;

correlating the current levels of the electrical signal applied to the pressure source with the corresponding gas flow rates to the cuff and saving that correlated information;

monitoring, during the operation time period, the current levels of the electrical signal applied to the pressure source;

using the correlated information for calculating the gas flow rate to the cuff during the operation time period; and

using the calculated gas flow rate for estimating a magnitude of gas leakage from the cuff.

2. The method of claim 1 including the step of accounting for a flow of gas intentionally vented from the cuff.

3. The method of claim 1 including the step of determining the trend in the magnitude of leakage by comparing two estimates of the magnitude of leakage.

4. The method of claim 1 including the steps of ranking the estimated magnitude of leakage and providing to a user an indication corresponding to that ranking

5. The method of claim 1 wherein the monitoring step includes monitoring the current levels of the electrical signal for a monitoring period that is greater than about two seconds.

6. The method of claim 1 wherein the monitoring step further comprises monitoring the current levels for a monitoring time period that is substantially greater than the time required for restoring the level of pressure in the cuff to be within the reference pressure range in response to instances when the cuff pressure moves out of that range as a result of a transient event that is not attributable to leakage.

7. The method of claim 1 including the step of:

storing a value indicative of the estimate of the magnitude of leakage;

communicating the stored value to a location remote from the cuff; and

presenting, subsequent to the operation time period, the stored value in a form perceptible by a user.

8. The method of claim 1 including the step of producing a leakage warning indication that is perceptible by a user if the estimate of the magnitude of leakage is greater than a predetermined hazardous level of leakage.