Continuous Measurement of Arterial Blood Gas Status during Total Hip Replacement: A Prospective Study

The arterial blood gas chemistry was measured continuously in ten patients during primary cemented total hip replacement in order to define more precisely the patterns of changes in blood gases during various stages of the operation. All ten patients demonstrated significant drops in P_aO₂ after femoral cement implantation and nine of the ten after acetabular cement implanation. The mean drop in P_aO₂ following acetabular cement expressed as mean ± SD was 18±8 mmHg (16±6%) (P<0.05) and femoral cement application was 25±11 mmHg (23±9%) (P<0.05). For changes in P_aO₂ there were corresponding drops in SpO₂ in all patients with the femoral cement and in eight patients with the acetabular cement. The mean drop in SpO₂ following the application of acetabular and femoral cements respectively were 1.7±1.5% and 3±2.45%. No changes in blood P_aO₂ were observed during dislocation of the hip joint or reaming of acetabulum and femur. In vitro studies revealed no effect of the liquid monomer or the cured cement on the performance of the Clark electrode of the sensor. We suggest that significant drops in P_aO₂ occur with both acetabular and femoral cement implantation and that the derangements in blood P_aO₂ last longer than detected by pulse oximetry following cement implantation.