[Efficacy of low doses of heparin to postoperative changes of blood gases after abdominal surgery (author's transl)].

Arterial hypoxaemia near critical values may occur during the postoperative period after surgery under general anaesthesia. Mainly alterations of ventilation/perfusion ratio seem to be the cause for this disorder. In this study we examined the effect of low-dose-heparin in improving pulmonary perfusion and consequently reduction of postoperative hypoxaemia. In 22 elderly patients both male and female we found no significant differences in oxygen tension compared to a control group of 19 patients. In both groups duration and degree of postoperative hypoxaemia were equal with minima on the first respectively second postoperative day. As in both groups there were no significant differences in other parameters further influencing oxygen supply--such as haemoglobin, haematocrit, pH and mean arterial blood pressure--we do not believe that disturbances of perfusion caused by microembolism are mainly responsible for postoperative hypoxaemia. Likewise low dose heparin seems to have no effect on postoperative hypoxaemia.