Influence of catheter position on blood pressure values in the pulmonary artery of the dog.

Abstract

In measuring pulmonary arterial pressure with special catheters in 19 dogs, anesthetized with morphine-urethane, mean pressure differences of 2.2±0.7 (\(\bar x\)±sx) mmHg (=9% of lateral pressure) were obtained between lateral pressure and total pressure at normal flow rates, and of 9.1±2.7 mmHg (=19% of lateral presure) at maximal flow rates. The transition from laminar to turbulent flow alters the relation between catheter measured kinetic energy and kinetic energy calculated by electromagnetically measured flow. There was, howver, no significant difference between lateral pressure and downstream pressure for\(\bar V\) Vk. This is incompatible withBurton's statement to the effect that downstream pressure is significantly lower than lateral pressure, and that this fact results in serious consequences for calculation and interpretation of pulmonary vascular resistance and distensibility of the pulmonary vascular bed. In experiments on models, local turbulences at the catheter opening pointing downstream could be demonstrated and are believed to cause this phenomenon.