[Preoperative oral dextromethorphan versus clonidine to prevent tourniquet-induced cardiovascular responses in orthopedic patients under general anesthesia]

ABSTRACT

Both preoperative oral dextromethorphan [DM] and IV clonidine attenuates arterial blood pressure and increases the heart rate during tourniquet inflation. Effect of preoperative oral clonidine on these variables was not investigated. We designed this study to compare the effect of preoperative oral DM or clonidine on hemodynamic changes during tourniquet inflation in patients undergoing lower limb surgery under general anesthesia. Seventhy-five patients were randomly assigned into three groups DM [n= 25 DM 30 mg], Clonidine [n= 25 clonidine 3 micro g/kg], and control [n= 25 placebo] groups. DM, clonidine, or placebo was given orally ninety minutes before induction of anesthesia. Systolic, Diastolic, Mean arterial blood pressure [SAP, DAP, MAP], and heart rate [HR] were measured at 0, 30, 45, 60 min after the start of tourniquet inflation, before tourniquet release [BTR], and 20 min after tourniquet deflation [20 ATR]. SAP, DAP, and MAP were significantly lower in the Clonidine group compared with control after 45, 60 min tourniquet inflation and at BTR [p<0.05]. Twenty minutes after deflation, DAP and MAP in the control group was still increased significantly compared with the clonidine group [P< 0.05]. Preoperative oral Clonidine 3 micro g/kg significantly prevented tourniquet-induced systemic arterial pressure increase in patients under general anesthesia better than oral DM