Air aspirated from the venous system during total hip replacement.

In order to demonstrate the presence of air embolism during total hip replacement surgery six patients, chosen at random, were examined with an ultrasound probe placed over the right atrium. In five patients, the characteristic double cardiac sound coming from the ultrasound probe changed into an irregular rattling sound as the femoral cement started generating its maximum hardening heat. In two patients this change was also heard simultaneously with the insertion of the femoral prosthesis. In four patients in whom catheters were placed in the right atrium it was possible to aspirate a maximum of 3 ml air from the right atrium. During the cementation of acetabulum, no change in the signal, coming from the ultrasound probe, was registered. It is probable that air is formed in the venous system during the insertion and cementation of a femoral prosthesis. The resulting air embolism is presumed to be the cause of the massive, but generally very brief impairment of the central circulation and the lungs seen during a hip arthroplasty. In the case of patients undergoing anaesthesia with N2O, the N2O should be removed before the cementation, it is also recommended that the right atrium be catheterised, in order to reduce the risk of this complication.