The effect of prolonged tourniquet application on serum bicarbonate

Many clinicians believe that prolonged tourniquet application lowers the serum bicarbonate concentration in samples drawn from that limb, but this effect has never been examined prospectively.

To test the effect of prolonged tourniquet application before phlebotomy on serum bicarbonate concentration in healthy adults.

We drew blood samples from 27 healthy adult volunteers without a tourniquet and again 1, 3, and 5 minutes after applying a blood pressure cuff and inflating it to the mean arterial pressure.

The mean bicarbonate concentration was 27.3 +/- 2.26 mmol/L (standard deviation) at baseline, 27.7 +/- 2.39 mmol/L at 1 minute, 27.7 +/- 2.05 mmol/L at 3 minutes, and 27.7 +/- 1.96 mmol/L at 5 minutes. The mean change in bicarbonate concentration from baseline was -0.04 +/- 1.02 mmol/L at 1 minute, 0.44 +/- 1.05 mmol/L at 3 minutes, and 0.44 +/- 1.31 mmol/L at 5 minutes. The mean lactate concentration was 1.1 +/- 0.28 mmol/L at baseline, 1.3 +/- 0.65 mmol/L at 1 minute, 1.2 +/- 0.52 mmol/L at 3 minutes, and 1.2 +/- 0.36 mmol/L at 5 minutes. The mean change in lactate concentration from baseline was 0.15 +/- 0.67 mmol/L at 1 minute, 0.11 +/- 0.11 mmol/L at 3 minutes, and 0.12 +/- 0.37 mmol/L at 5 minutes.

Prolonged tourniquet application before phlebotomy does not lower the serum bicarbonate concentration in healthy adults.