Pulmonary capillary arterial pressure pulse in man.

In 1948, Hellems, Haynes, Dexter, and Kinney, using venous and arterial catheterization in dogs obtained pressure recordings from both sides of the pulmonary capillary bed. The method consisted in wedging the tip of a cardiac catheter into a small branch of the pulmonary artery and of the pulmonary vein respectively, and recording the mean blood pressures in the obstructed vascular bed distal to the catheter tip. They felt that these pressures were " close approximations of the true capillary pressure" and the term capillary pressure is now' widely used for the mean pressure obtainable by occluding a small branch of the pulmonary artery. Shortly afterwards, it was shown by Lagerloef and Werkoe (1949) that in man the tracings recorded on the arterial side of the capillary bed were of typical venous shape and closely resembled the tracings from the right (and left) atrium. They concluded that in the manometric system thus constructed not only capillary pulsations but also those from the venous side of the vascular bed were transmitted through the capillaries. It seemed, therefore, of interest to investigate the type of curve obtainable by obstructing a small branch of the pulmonary vein. Accordingly this was done in five cases of atrial septal defect, and the tracings thus recorded resembled in many ways arterial pulsations. Since Lagerloef and Werkoe called their curves from the arterial side the " pulmonary capillary venous pressure pulse " (PCV) we should like to name the curves from the venous side of the capillary bed the " pulmonary capillary arterial pressure pulse " (PCA). Methods. Cardiac catheterization was performed in the usual way. Cournand catheters No. F6-9 with the hole on the tip were used and connected with Tybjaerg-Hansen's capacitive manometer. Pressure tracings were recorded on Elmquist-triplex, together with electroand phono-cardiograms. The damping of the manometer system was critical. In order to eliminate artefacts due to catheter movements, damping was further increased by the electric'al filter III on the amplifier. The mean pressures were highly overdamped'curves using filter V. The zero point for all pressures was 5 cm. below the sternal angle, with the patient in the recumbent position. Immediately after pressure recording blood samples were drawn in the usual way and oxygen analyses were carried out using Van Slyke's method. To obtain pulmonary capillary arterial pressures the catheter was advanced through the right and left atrium and into a pulmonary vein under fluoroscopic control. The patient was then asked to take a deep breath, and the tip of the catheter was pushed further into the vein so as to obstruct its lumen.