RESUMEN
BACKGROUND: A tourniquet is usually used for total knee replacement arthroplasty (TKR) to provide a bloodless surgical field. However, hemodynamic and metabolic changes result from the ischemia after application of a tourniquet. Moreover, the hemodynamic and metabolic effects of tourniquet application during both TKR under general anesthesia have been rarely reported. METHODS: Fifteen patients undergoing both TKR were studied during general anesthesia. Hemodynamic and metabolic parameters were measured before inflating the tourniquet, just before release of the tourniquet and 3, 6, 15 min after tourniquet release. Stroke volume (SV), cardiac index (CI), systemic vascular resistance (SVR) and end-tidal CO2 (ETCO2) were measured using a non-invasive cardiac output monitor. RESULTS: Mean arterial pressure (MAP) decreased after tourniquet release, but was not different from MAP before tourniquet inflation. After tourniquet release, central venous pressure, SVR, arterial pH, bicarbonate and calcium decreased significantly (P <0.05), and heart rate, CI, ETCO2, PaCO2 and potassium increased significantly (P <0.05). But, the hemodynamic and metabolic changes after tourniquet release in the subsequent TKR were not affected by those after tourniquet release in the antecedent TKR. CONCLUSIONS: During both TKR, although there was no difference in the hemodynamic and metabolic changes after tourniquet release between the antecedent and the subsequent TKR, there were significant hemodynamic and metabolic changes after tourniquet release. These findings indicate the need for more active hemodynamic and metabolic monitoring in patients with a compromised cardiopulmonary function.