[Hemodynamic and renal effects of high epidural clonidine doses in dogs]

There are no studies reporting renal effects promoted by high epidural clonidine doses. This study aimed at evaluating hemodynamic and renal effects of high epidural clonidine doses in dogs.

This double-blind randomized study involved 20 animals anesthetized with sodium thiopental and fentanyl, which were distributed in two groups: Group 1 or placebo (n = 10), receiving 0.2 mL.kg-1 saline, and Group 2 or clonidine (n = 10), receiving 0.2 mL.kg-1 of a solution with 50 microg.mL-1 clonidine in the epidural space. The following hemodynamic parameters were evaluated: heart rate (HR): beat.min-1; mean blood pressure (MBP): mmHg; pulmonary capillary wedge pressure (PCWP): mmHg; cardiac output (CO): L.min-1; and systolic volume (SV): mL. The following renal function parameters were also evaluated: renal blood flow (RBF) mL.min-1; renal vascular resistance (RVR): mmHg.mL-1; urinary minute volume (UMV): mL.min-1; creatinine clearance (C Cr): mL.min-1; para-aminohippurate clearance (C PAH): mL.min-1; filtration fraction (FF); sodium clearance (C NA): mL.min-1; potassium clearance (C K): mL.min-1; sodium fractional excretion (FE NA): %; sodium urinary excretion (U NA V): microEq.min-1; potassium urinary excretion (U K V): microEq.min-1. Experiment consisted of three 20-minute moments. Data were collected at 10 minutes of each moment and diuresis was measured in the beginning and end of each moment. At the end of M1, clonidine or saline were epidurally injected. After 20 minutes data were repeated in M2 and M3.

Epidural 10 microg.kg-1 clonidine in dogs has promoted significant changes with decreased heart rate and cardiac output and increased sodium para-aminophurate clearance/cardiac output ratio.

In our conditions and doses, clonidine has not promoted renal function changes, but has decreased hemodynamic parameters (heart rate and cardiac output).