Pulmonary Artery Pressure Measurements in Surgical Patients

In 23 patients, Swan-Ganz catheters for the measurement of the pulmonary artery pressure (PAP) were introduced on the day before elective vascular surgery. The following parameters were measured: pulmonary artery mean pressure (PAMP), pulmonary capillary wedge pressure (PCWP), pulmonary artery end-diastolic pressure (PAED), central venous pressure (CVP), arterial blood pressure (BP), pulse, plasma colloid osmotic pressure (COP) and blood volume. Pre-operatively, resting pressures and pressures during exercise and fluid infusion were measured. Continuous pressure measurements were made during induction of anaesthesia and operation and during the first 24 postoperative hours. The pre-operative PAP was an important parameter among those contra-indicating operation, particularly so in 5 patients, in 3 of whom the ultimate decision was made as a direct consequence of PAP. In one case, a sudden marked increase in PAP preceded all other signs of severe deterioration in the patient's condition by some 7 hours. In the period of apnoea immediately prior to and during endotracheal intubation, PAP and CVP rises were as marked as during the pre-operative exercise test. This exercise was strenuous, and the exercise PAP is thought to give perhaps the most reliable expression of the cardiac reserve. Finally, PAP was found to be a substantially more sensitive parameter of blood loss and adequacy of replacement than CVP.