Dexmedetomidine infusion is associated with enhanced renal function after thoracic surgery

Abstract

Study objective: To test the hypothesis that dexmedetomidine, a selective alpha-2 agonist, enhances urine flow rate and perioperative renal function, a post hoc analysis was conducted on a recently completed study of dexmedetomidine used as an adjunct to epidural analgesia after thoracotomy.

Design: Post hoc analysis of a randomized, placebo-controlled, double-blind clinical trial.

Setting: Tertiary-care university medical center.

Patients: 28 patients undergoing elective thoracotomy.

Interventions: Patients were prospectively randomized to receive a supplemental 24-hour intravenous infusion of either dexmedetomidine (0.4 microg kg(-1) h(-1), n = 14) or saline placebo (equivalent infusion rate, n = 14).

Measurements: Available renal parameters including urine output, calculated creatinine clearance (cCl(Cr)), daily serum creatinine level (S(Cr)), and the fractional change in S(Cr) level (DeltaS(Cr)%, [peak postoperative S(Cr) - baseline S(Cr)] / baseline S(Cr)) x 100) were recorded.

Main results: Values are expressed as means +/- SD. There were no significant differences in baseline values between the groups. The dexmedetomidine group had significantly greater cumulative urine output at postoperative hour 4 (473 +/- 35 vs 290 +/- 122 mL, P = 0.001) and 12 (1033 +/- 240 vs 822 +/- 234 mL, P = 0.02), although only 14% of the group received diuretic agents, compared with 43% in the control group. The dexmedetomidine group had significantly better preserved perioperative renal function compared with the control group, as assessed by DeltaS(Cr)% (0.04% decrease vs 21% increase, P = 0.0007) and cCl(Cr) (75.3 +/- 13.2 vs 62.5 +/- 15.5 mL/min, P = 0.02).

Conclusion: Dexmedetomidine infusion administered as a supplement to epidural analgesia induced diuresis in postthoracotomy patients with normal preoperative renal function and undergoing fluid restriction. Although this finding may represent simple reversal of a tubular antidiuresis, the lower DeltaS(Cr)% and preservation of cCl(Cr) suggest a beneficial effect on glomerular filtration compared with controls.