Calculation of irrigant absorption by measurement of breath alcohol level during transurethral resection of the prostate.

If ethanol is added to the irrigant used in transurethral resection of the prostate, absorption of the fluid can be immediately detected by measuring the ethanol concentration in the expired breath. During 90 resections where the irrigant contained 1.5% glycine and 1% ethanol, the breath alcohol level was compared with the amount of irrigant absorbed as determined by volumetric measurement. The results showed that the expired-breath ethanol level depended not only on the volume of irrigant absorbed but also on the rate of ethanol diffusion in the total body water, which increased with the ethanol concentration. By applying a derived mathematical model the absorption could be estimated from the breath alcohol level at any time during surgery, with a median deviation of 19% from the measured value.