Hypothermia associated with percutaneous nephrolithotomy.

OBJECTIVES: To characterize the perioperative fall in core body temperature associated with percutaneous nephrolithotomy, and to identify patients at greater risk of hypothermia.
METHODS: A retrospective review was undertaken of core body temperatures in 77 patients who underwent 95 percutaneous nephrolithotomy (PNL) procedures using room temperature irrigants over a 3 year period. Intraoperative temperature measurements were obtained via an esophageal thermistor probe.
RESULTS: Mean core body temperature fell from 36.7 degrees C preoperatively to 35.8 degrees C after retrograde manipulations and subsequent patient positioning before commencing the renal puncture. The mean core temperature fell an additional mean 1.0 degrees C during the percutaneous nephrolithotomy. This additional temperature drop was proportional to the length of the procedure. Female patients had a significantly greater decline in intraoperative core body temperature than male patients (p < 0.01). Obese patients preserved their preoperative temperature more efficiently. Blood loss and advanced age had no impact on the occurrence of hypothermia. Mean preoperative temperature was regained on average within 3 hours postoperatively.
CONCLUSIONS: Hypothermia occurs in the majority of patients undergoing PNL. Nearly an equivalent fall in temperature is seen during presurgical preparation, induction of anesthesia, and patient positioning as is seen during the surgical procedure itself. Efforts to preserve core body temperature both before and during the percutaneous procedure may reduce the degree of hypothermia and its potential complications.