Cooling effect from absorption of prewarmed irrigating fluid in transurethral prostatic resection.

Thirty patients were studied over 10-min periods in the course of transurethral prostatic resection with measurements of rectal temperature and fluid absorption. Glycine with or without ethanol was used as the irrigant. The changes in the body temperature as reflected in oesophageal and rectal measurements in 5 of the patients were almost identical. Seven of the 30 patients became hyponatraemic and absorbed an average of 1328 ml of glycine solution. They had a significantly greater drop in rectal temperature than patients with little or no fluid absorption. This cooling effect occurred despite prewarming of the irrigant medium to 37 degrees C, which can be explained by a decrease in fluid temperature when the bag is being emptied. It was concluded that absorption of irrigating fluid is a mechanism that promotes heat loss during transurethral operations.