[Effect of hemodynamics on transdiaphragmatic central venous pressure: experiments with rapid bleeding and rapid...

Effects of hemodynamics which would be a possible problem in monitoring diaphragm function through transdiaphragmatic central venous pressure were studied experimentally. Mongrel dogs were anesthetized and allowed to breath spontaneously. (1) Rapid exsanguination (30 ml/kg. body), (2) rapid infusion (15 ml/kg. body) were performed. Superior vena cava mean pressure (PSVC) and inferior vena cava mean pressure (PIVC) were measured and pressure changes during respiration (delta P) were recorded. Changes in the transdiaphragmatic central venous pressure (delta PDI = delta PIVC - delta PSVC) were calculated. And hemodynamic parameters (heart rate, cardiac output, mean arterial pressure, PSVC, PIVC) were measured simultaneously. The delta P and hemodynamic parameters were measured before and after (1) or (2). As the results, no significant changes were observed in delta PDI even if hemodynamics changed. The results suggest that measurement of transdiaphragmatic central venous pressure can be employed clinically as a parameter for monitoring diaphragm function to detect hemodynamic changes which are less serious than those appeared by mass bleeding or excess fluid transfusion.