Arterial hypotension and hypoxaemia during total hip replacement: the importance of thromboplastic products, fat embolism and acrylic monomers.

Thirteen patients submitted to total hip replacement surgery by the Charnley technique were studied. Operations were performed under epidural analgesia with the patients awake and breathing air. During the surgical procedure, the magnitude of tissue-thromboplastic activity, the amount of fat globules, the presence of bone marrow cells and the concentrations of acrylic monomers were determined in the pulmonary arterial blood. Simultaneously, arterial blood gases and blood pressure were monitored. Marked reductions of the arterial blood pressure and arterial oxygen tension occurred after impaction of the femoral prosthesis, and minor depressions appeared after insertion of the acetabular prosthesis. A significant correlation was found between the release of tissue-thromboplastic products into the pulmonary circulation, i.e., products that initiate intravascular coagulation and the circulatory and respiratory reactions. The pulmonary fat droplets, per se, seem to be of minor importance, and the release of acrylic monomers is probably of no importance for these reactions.