[Haemodynamics and tolerance to hypoxia of the myocardium under 6%-oxygen ventilation following acute isovolaemic haemodilution in experimental animals (author's transl)].

1. In experiments on closed chest dogs in a control group and a group of previous isovolaemic haemodiluted dogs a cardiovascular stress was produced by means of reduction of inspiratory O2 content to 6% O2--2. Under haemodilution only small changes of the heart rate, aortic pressure and dp/dtmax occurred, pointing to a decreased sympathoadrenergic response. Augmentation of LVEDP and pulmonary artery pressure is considered to be related to left ventricular insufficiency.--3. According to haemodynamic changes myocardial O2 demand in the control group during hypoxia is increasedby 120% and in contrast remains unchanged after previous haemodilution.--4. Despite the reduced oxygen content under haemodilution severe arterial hypoxemia affects mean survival time of the animals (18.5 min and 21.5 min respectively) only little. However, there is a greater variation from 11 to 26 min in the haemodiluted animals.