[Registration and evaluation of blood pressure curves of the pulmonary artery with reference to various causes of error].

In about 250 experiments with male and female anesthetized mongrel dogs, measurements of right ventricle and pulmonary artery pressure were carried out. We used Goodale-Lubin-, micro- and Swan-Ganz-catheters. The pressure registration was done by usual equipment. The investigation was performed to evaluate the reason and the extent of disturbances, which affect the real and formal pressure curve in the arteria pulmonalis. The following results could be obtained: 1. The disturbances can lead to fluctuations of such extent, that a correct demarcation of normal and pathological values is impossible. 2. Of great influence on the results of measurements are preparation and registration (warm-up-time, amplification, closeness of pressure-system, unhurt catheters), factors relating to equipment and methods (air-bubbles in pressure-system, damping by filters, continuous infusion of the micro-catheter, level of zero-pressure), factors which occur during intravital measurement (pressure-drop along the arteria pulmonalis, influence of normal breathing, great intrapleural pressure changes, pressure damping in the catheter by thrombosis and external disturbances) and last not least positive and negative acceleration forces, which influence the diastolic and systolic pulmonary artery pressure. 3. Most of the defects and disturbances also occur, when the physical conditions of the equipment are correct. When the preparation and registration is conducted very carefully, all disturbances can be recognized, eliminated and corrected during the registration. 4. The main problems are caused by influence of normal and pathological intrapleural breathing pressures. By reasons of comparison it is necessary to select the pressure values to be used from a great number of real and formal correct pressure values. Besides it is necessary to have always in mind the transmural pressure in the evaluation of pulmonary artery pressures. 5. By consideration of these results it is possible to mark off the normal pressure zone of pulmonary artery pressure from the low pathological zone.