Effect of low-dose heparin prophylaxis on arterial oxygen tension after high laparotomy

The effect of low doses of heparin (5000 units of sodium heparin every 12 hours for 5 days) on arterial oxygenation was studied in 24 patients in the postoperative period after upper abdominal surgery. Another 24 patients served as a control group. The arterial oxygen tension was the same in both groups preoperatively and was equally significantly reduced during the 1st postoperative day. During the 2nd day, oxygen tension rose in the heparin-treated group to values which no longer differed significantly from the peroperative level. In the control group the significant reduction persisted until the 4th postoperative day. The arterial carbon-dioxide tension did not differ between the groups, neither did it vary significantly between days. There were no clinical signs of large pulmonary embolism during the postoperative period, chest X-ray was normal in all patients examined and a photoscan was normal in 23 of 24 subjects studied. Low-dose heparin treatment may apparently shorten the period of postoperative hypoxaemia, probably by counteracting both large pulmonary emboli and microthromboembolism.