[Postoperative hypoxia and hyperfibrinolysis in patients after total knee replacement]

It was revealed that postoperative hypoxia had occurred frequently in patients after total knee replacement (TKR) in our preliminary study. Since we speculated that pulmonary embolism was the cause of the hypoxia, we investigated the relationship between PaO2 and D-dimer in patients after TKR and high tibial osteotomy (HTO). A total of 13 patients with the diagnosis of osteoarthritis were studied. Ten patients underwent TKR and three received HTO under subarachnoid block. Arterial oxygen tension and D-dimer were unchanged in patients who had undergone HTO. Even on the 5th postoperative day, five of the ten patients after TKR revealed a decrease in oxygen tension by more than 10% compared with the preoperative control (hypoxia group). In the other patients after TKR, a decrease of oxygen tension on the 5th postoperative day was under 10% (non-hypoxia group). There was a positive correlation between a decrease of PaO2 and a value of D-dimer in all of the patients who had undergone TKR and HTO. Although no patient developed dyspnea clinically, one patient in hypoxia group was diagnosed as pulmonary embolism in the scintigram. It is likely that pulmonary embolism is the cause of postoperative hypoxia in patients after TKR.