Methylmethacrylate plasma levels during total hip arthroplasty.

Methylmethacrylate (MMA) plasma concentrations were measured in 11 patients scheduled for total hip arthroplasty. After acetabular and after femoral cement implantation, sequential blood samples were withdrawn from pulmonary and radial artery catheters. The peak concentration of MMA (mean +/- standard error of the mean) in pulmonary artery blood occurred two minutes after cement implantation and was significantly higher after acetabulum (5.0 +/- 1.3 micrograms/ml) than after femoral cement insertion (1.9 +/- 0.6 micrograms/ml). The MMA peak in plasma was above 1 micrograms/ml in 13 cases, and the decrease fit a biexponential decay (r = 0.91). The initial half-life was 0.3 +/- 0.1 minutes, and the terminal half-life was 3 +/- 0.7 minutes. The areas under the curve (AUC) were determined for pulmonary (AUCpa) and radial (AUCra) plasma samples, and the ratio (AUCpa - AUCra)/AUCpa was computed: 55.1 +/- 7.8% of MMA was cleared during the transpulmonary passage. These results demonstrate that: (1) MMA could be determined after each cement implantation, (2) MMA plasma concentrations were higher after acetabulum than after femoral cement implantation, and (3) the half-life is short and the total pulmonary clearance is high.