A method of controlling an external counterpulsation apparatus includes selecting a patient treatment pressure; outputting a signal corresponding to the selected treatment pressure; detecting a pressure of a compressed fluid reservoir; comparing the selected treatment pressure to the compressed fluid reservoir pressure; and controlling a pressure regulator valve based on a difference between the patient treatment pressure and the compressed fluid reservoir pressure. The compressed fluid reservoir pressure may be decreased when the compressed fluid reservoir pressure is greater than a preset difference from the patient treatment pressure, particularly by venting the compressed fluid reservoir to atmosphere. The compressed fluid reservoir pressure may be necessary when the compressed fluid reservoir pressure is less than a preset difference from the patient treatment pressure, particularly by operating a compressor.