Metabolic changes after tourniquet release.

Abstract During routine capnography a rise of the end expiratory volume percentage CO2 was seen after releasing the tourniquet cuff in cases of orthopedic operations on the lower extremities under bloodless conditions. The patients were intubated and ventilated mechanically. In eight patients the relationship between this finding and the arterial bloodgas values were studied at one minute before and at one, ten and thirty minutes after releasing the tourniquet cuff. The end expiratory volume percentage CO2 increased from 4.21 +/- 0.22 to 4.83 +/- 0.26 one minute after releasing tourniquetischemia and even to 5.49 +/- 0.68 after three minutes. PaCO2 increased in one minute from 4.83 +/- 0.49 to 6.22 +/- 0.50 kPa (36.2 +/- 3.7 to 46.6 +/- 3.7 mm Hg). The pH, st. HCO-3 and base excess decreased in one minute from resp. 7.45 +/- 0.04, 27.16 +/- 1.04 mmol/l (mEq/l) and + 2.85 +/- 1.29 mmol/l (mEq/l) to 7.34 +/- 0.04, 24.75 +/- 1.16 mmol/l (mEq/l) and - 0.18 +/- 1.49 mmol/l (mEq/l). The capnographic values seems to reflect bloodgas changes. The findings were compared with recent literature.