A solid state recorder for ambulatory monitoring of pulmonary-artery pressure

A compact, portable recording system has been developed to record pulmonary-artery pressure in ambulatory patients. A transducer mounted on the tip of a conventional cardiac catheter is inserted percutaneously and positioned in the main pulmonary artery. Analogue circuitry, including peak and trough detectors, pre-processes the pressure/voltage waveform to yield sampled values for the systolic and diastolic pressures. Systolic and diastolic values sampled every 30 s are digitized and stored in CMOS semiconductor memory. Data acquired over a prolonged period is transferred to a microcomputer for permanent storage and subsequent analysis. Five patients were each successfully monitored for at least 24 h. The zero-level drift was less than 1% and gain stability was also better than 1% over 48 h. This device allows practical, safe, reliable and prolonged pressure recording and has wide-ranging clinical potential.