Do volatile anaesthetics depress urine output?

Area of Science:

• Anesthesiology
• Nephrology
• Surgical Research

Background:

• Urine output reduction with isoflurane is known, but its specificity to volatile anesthetics is unclear.
• This study addresses whether volatile anesthetics have a unique effect on urine output during surgery.

Purpose of the Study:

• To compare the diuretic response to crystalloid volume loading during surgery under volatile anesthetics versus intravenous anesthesia.
• To determine if isoflurane and sevoflurane affect urine output differently than propofol.

Main Methods:

• Analysis of data from two randomized clinical trials: thyroid surgery (isoflurane vs. propofol) and hysterectomy (sevoflurane vs. propofol).
• Quantification of urine output and diuretic response to 1.7-1.8 L Ringer's lactate infusion using population volume kinetic analysis.
• Utilized plasma dilution measurements (hemoglobin, albumin) and urine output data for kinetic modeling.

Main Results:

• No statistically significant difference in urine output between isoflurane and propofol groups during thyroid surgery (P=0.50).
• No significant difference in urine output between sevoflurane and propofol groups during hysterectomy (P=0.81).
• Kinetic analysis, adjusted for volume, weight, and plasma expansion, showed no significant difference in diuretic response among the groups.

Conclusions:

• Isoflurane and sevoflurane do not exert a stronger diuretic effect than propofol.
• The observed reduction in urine output with volatile anesthetics is not specific and comparable to intravenous anesthesia effects.