Time-limited physiologic tourniquet

• US 5,911,735 A
• Filed: 12/19/1996
• Issued: 06/15/1999
• Est. Priority Date: 01/29/1990
• Status: Expired due to Term

• Current Assignee: Zimmer Orthopaedic Surgical Products (Zimmer Biomet Holdings, Inc.)
• Original Assignee: James A. Mcewen, Michael Jameson
• Inventors: McEwen, James A., Jameson, Michael
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US08/769,661
• Time in Patent Office: 908 Days
• Field of Search: 606/201, 606/202, 600/499, 600/490, 600/493-6
• US Class Current: 606/201
• CPC Class Codes: A61B 17/1355 Automated control means therefor
• CPC Class Codes: A61B 2505/05 Surgical care
• CPC Class Codes: A61B 2560/02 Operational features
• CPC Class Codes: A61B 5/1106 to assess neuromuscular blockade, e.g. to estimate depth of anaesthesia
• CPC Class Codes: A61B 5/6828 Leg
• CPC Class Codes: A61B 5/6829 Foot or ankle
• CPC Class Codes: A61B 5/7435 Displaying user selection data, e.g. icons in a graphical user interface

Abstract

A configuration register is incorporated into an electrically powered tourniquet apparatus for enabling an operator to change the values of parameters initially employed at the time of the next use of the apparatus, such as the initial pressure settings and elapsed time limits. These changed initial values of parameters are stored in memory and remain there despite inadvertent or intentional interruption of electrical power to the apparatus. An event register provides capability for recording the occurrence of events (cuff inflation, cuff deflation, etc.) and for relating the occurrence of the events to hazards and undesirable outcomes such as nerve damage associated with tourniquet usage.

Claims

1. An electrically operated physiologic tourniquet system, comprising:

an inflatable and deflatable cuff attachable to a limb to encircle the limb at a location so that pressure is applied to the limb at the location when the cuff is inflated and wherein the system includes pressure control means for inflating and deflating the cuff to control the pressure applied by the cuff to the limb to stop blood flow into the limb distal to the cuff;

selector means for permitting an operator to select an initial time limit during which pressure is to be applied to the limb;

configuration register means for enabling an operator to record in a memory the selected initial time limit, wherein the memory retains the last recorded initial time limit irrespective of whether power to the system is interrupted;

the configuration register means including;

selector read means for periodically determining whether the operator has changed the initial time limit and for recording in memory a clock time indicating when the operator changed the initial time limit; and

timing means for retrieving from the memory at the beginning of each use of the system the last recorded initial time limit, for monitoring a time period, and for alerting the operator when the time period equals the time limit.

2. The system of claim 1 wherein the selector means includes operator interface means for displaying to an operator only one of two or more menu selections from which the operator may select the initial time limit.

3. A physiologic tourniquet system, comprising:

a pressurizing cuff for encircling and applying pressure to a limb;

selector means for producing a reference time signal indicative of a reference time period, wherein the selector means retrieves a recorded time period from an electrically powered configuration register and permits an operator to select either the retrieved time period or another time period as the reference time period;

configure mode means for enabling the operator to produce a configure mode signal that indicates a selected one of a plurality of operating modes;

electrically powered register means responsive to the configure mode signal and the reference time signal and operable for selectively recording the time period corresponding to the level of the reference time signal for the selected operating mode, and further operable for retaining the recorded time period when electrical power is not supplied to the electrically powered configuration register;

cuff pressure control means responsive to the reference time signal for controlling the pressure in the cuff to stop blood flow into the limb distal to the cuff, for monitoring the time period during which the pressure is controlled, and for comparing the monitored time period to the reference time period corresponding to the reference time signal and for producing both an alarm signal and a time event signal when the monitored time period equals the reference time period; and

event register means responsive to the time event signal and the reference time signal for automatically storing in memory the operator-selected level of the reference time signal when the time event signal is produced and for enabling an operator to selectively display the stored level of the reference time signal, thereby to determine subsequently the reference time period corresponding to the displayed level of the reference time signal.

4. The physiologic tourniquet system as described in claim 3 wherein the event register means comprises a memory operable in combination with a printer so as to produce for the operator a printed record of the reference time period indicated by the recorded level of the reference time signal.

5. The physiologic tourniquet system as described in claim 3 wherein the event register means includes a memory operable in combination with a port configured to transfer a signal indicative of the stored recorded level of the reference time signal to the port for receipt by an apparatus that may be connected to the port.

6. A physiologic tourniquet system, comprising:

a pressurizing cuff for encircling and applying pressure to a limb;

selector means for producing a reference time signal indicative of a reference time period, wherein the selector means retrieves a recorded time period from an electrically powered configuration register and permits an operator to select either the retrieved time period or another time period as the reference time period;

configure mode means for enabling the operator to produce a configure mode signal that indicates a selected one of a plurality of operating modes;

electrically powered register means responsive to the configure mode signal and the reference time signal and operable for selectively recording the reference time period corresponding to the level of the reference time signal for the selected operating mode, and further operable for retaining the recorded time period when electrical power is not supplied to the electrically powered configuration register; and

control means responsive to the reference time signal for controlling the pressure applied by the cuff to the limb, for monitoring the time interval during which the pressure is controlled, for comparing the monitored time interval to the reference time period indicated by the level of the reference time signal, and for producing a time alarm signal when the monitored time interval equals the reference time period

wherein the control means includes recommended cuff pressure means for determining the minimum cuff pressure in the cuff suitable for preventing blood flow past the cuff within the limb to which the cuff is applied, for determining as a function of the minimum cuff pressure a recommended cuff pressure to be applied by the cuff, and for controlling the pressure applied by the cuff near the recommended cuff pressure during the time interval.

7. The system of claim 6 and including alarm means responsive to the time alarm signal for producing an alarm detectable by an operator when the time alarm signal is produced.