Continuous monitoring of irrigating fluid absorption during transurethral surgery

We have designed an automatic detector system for noninvasive monitoring of irrigating fluid absorption during transurethral resection of the prostate. Ethanol, which is used as a tracer for the fluid, is measured in the expired breath of the patient. The breath ethanol monitor can be used both in the awake patient and during general anaesthesia. A lap-top computer controls the monitor and calculates the fluid absorption 1-3 times per min and uses the pattern of ethanol changes to indicate whether the fluid is being taken by the intra- and/or extravascular route. The monitor has been used in routine operations for one year. The interpretation of absorption routes was checked by control methods or by evaluation of the postoperative breath-ethanol curve. We found the indicated absorption to be correct in all resections with absorption large enough for the monitor to present an interpretation.