Abstract

A blood pressure system which cycles through an inflation cycle and a deflation cycle during which systolic and diastolic blood pressure in a patient is automatically measured. The blood pressure system basically comprises an inflatable pressure cuff system for accomplishing occlusion and the subsequent opening of an artery in a patient being monitored, and an electrical system for increasing and decreasing the pressure in the cuff under servo loop control and for displaying the systolic and diastolic measurements. A pressure transducer produces an electrical signal indicative of the actual pressure in the cuff. A solenoid valve permits selective pressure decrease during the deflation cycle. A rotary vane compression pump provides pressure increase during the inflation cycle. During the inflation cycle, pressure increase in the cuff is accomplished by a servo control loop comprising the transducer, the pump, and an inflate/deflate controller. During the deflation cycle, pressure decrease in the cuff is accomplished by a servo control loop comprising the transducer, the controller, and the solenoid valve. In both the inflation cycle and the deflation cycle, the controller receives the signal from the transducer and produces an error signal indicative of the difference between the actual rate of change of pressure in the cuff and a desired rate of change of pressure. Additional circuitry in the controller variably duty cycle modulates the error signal to produce a control signal. In the inflation cycle, the control signal actuates the pump to increase the pressure. In the deflation cycle, the control signal actuates the solenoid valve to decrease the pressure.