Physiologic tourniquet with safety circuit

An electrically operated physiologic tourniquet system, comprising:

• an inflatable and deflatable cuff;
• selector means for displaying to an operator selections of initial time limits and for permitting the operator to select one of the displayed initial time limits and to change the selected one of the initial time limits;
• configuration register means for enabling an operator to record in a memory the selected initial time limit and for periodically determining whether the operator has changed the selected initial time limit, wherein the memory retains the last recorded initial time limit irrespective of whether power to the system is interrupted;
• 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.

A physiologic tourniquet system comprising:

• an inflatable and deflatable cuff for encircling and applying pressure to a limb;
• at least one pressure source selectably pneumatically connected to the cuff;
• at least one exhaust line selectably connected to the cuff;
• a microprocessor that determines when to inflate the cuff, deflate the cuff, or regulate the pressure in the cuff, and that produces a cuff mode signal having one of a plurality of predefined signals indicative of whether to inflate, deflate or regulate the pressure in the cuff;
• a first inlet valve responsive to a first inlet valve actuation signal and a first inlet valve deactuation signal from the microprocessor, wherein the first inlet valve is opened by the first inlet valve actuation signal to pneumatically connect the pressure source to the cuff, or deactuated by the first inlet valve deactuation signal to close the pneumatic connection between the cuff and pressure source;
• a first inlet valve status output signal from the first inlet valve to indicate whether the first inlet valve is actuated or deactuated;
• and
• a safety circuit that monitors the cuff mode signal and the first inlet valve status output signal for undesired combinations of cuff mode signal and first inlet valve status output signal and produces a fault signal if an undesired combination is detected.

A physiologic tourniquet system comprising:

• an inflatable and deflatable cuff for encircling and applying pressure to a limb;
• at least one pressure source selectably pneumatically connected to the cuff;
• at least one exhaust line selectably connected to the cuff;
• a microprocessor that determines when to inflate the cuff, deflate the cuff, or regulate the pressure in the cuff, and that produces a cuff mode signal having one of a plurality of predefined signals indicative of whether to inflate, deflate or regulate the pressure in the cuff;
• a first exhaust valve responsive to a first exhaust valve actuation signal and a first exhaust valve deactuation signal from the microprocessor, wherein the first exhaust valve is opened by the first exhaust valve actuation signal to pneumatically connect the cuff to the exhaust line, or deactuated by the first exhaust valve deactuation signal to close the pneumatic connection between the cuff and the exhaust line;
• a first exhaust valve status output signal from the first exhaust valve to indicate whether the first exhaust valve is actuated or deactuated;
• and
• a safety circuit that monitors the cuff mode signal and the first exhaust valve status output signal for undesired combinations of cuff mode signal and first exhaust valve status output signal and produces a fault signal if an undesired combination is detected.

A physiologic tourniquet system, comprising:

• an inflatable and deflatable cuff;
• a microprocessor that determines when to inflate the cuff, deflate the cuff, or regulate the pressure in the cuff, and that produces a cuff mode signal having one of a plurality of predefined levels indicative of whether to inflate, deflate or regulate the pressure in the cuff;
• a regulator responsive to the cuff mode signal for inflating the cuff, deflating the cuff and regulating the pressure in the cuff;
• and
• a safety circuit operable independently of the microprocessor and responsive to the cuff mode signal and having a plurality of stored levels for the cuff mode signal, wherein the safety circuit operates by comparing the level of the cuff mode signal to the plurality of levels for the cuff mode signal and produces a microprocessor fault signal when the cuff mode signal level does not correspond to one of the sets of stored levels.

An electrically operated physiologic tourniquet system, comprising:

• an inflatable and deflatable cuff for encircling and applying pressure to a limb;
• a pressure source for supplying pressurized gas to the cuff;
• first and second valves through which the pressure source is independently connected to the cuff;
• regulator means for producing a cuff mode signal and first and second inlet valve actuation signals;
• and
• wherein the pressure source is selectively pneumatically connected to the cuff through actuation of the first or second valves by the regulator means, and a safety circuit senses preset undesired combinations of the cuff mode signal and actuation of the first and second valves, and produces a fault signal in response to detection of any of the undesired combinations;
• and
• wherein the cuff is connected to an exhaust line through actuation of separate third or fourth valves by the regulator means, and the safety circuit senses preset undesired combinations of the cuff mode signal and actuation of the third and fourth valves, and produces the fault signal in response to detection of any of the undesired combinations of the cuff mode signal and actuation of the third and fourth valves.