Diaphragmatic fatigue and its recovery are influenced by cardiac output.

The effects of cardiac output (Qt) on diaphragmatic blood flow (Qdi) and diaphragmatic fatigue and its recovery were studied in dogs. Qdi was estimated by measurement of the left inferior phrenic arterial blood flow (QdiL). There was a significant positive correlation between % Qt and % QdiL. Transdiaphragmatic pressure (Pdi) was significantly smaller in the lowered Qt group than the control at the end of fatigue, and the speed of recovery from the fatigue was also significantly slower in the lowered Qt group. It is concluded that Qt was considered to play an important role in the pathogenesis of diaphragmatic fatigue and its recovery in the mechanically ventilated dogs.