Effects of dexmedetomidine on responses to tourniquet in patients undergoing lower extremity surgery with peripheral nerve block / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effects of dexmedetomidine on responses to tourniquet in patients undergoing lower extremity surgery with peripheral nerve block.Methods Eighty American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients of both sexes,aged 22-63 yr,weighing 47-81 kg,scheduled for elective foot surgery under ultrasound-guided popliteal sciatic nerve block combined with saphenous nerve block,were divided into 2 groups (n =40 each) using a random number table method:control group (group C) and dexmedetomidine group (group D).Dexmedetomidine was intravenously infused for 10 min in a dose of 1 μg/kg in group D,and the equal volume of normal saline was given instead in group C.Blood samples were taken from the internal jugular vein before using the tourniquet (T0) and at 30 and 60 min after releasing the tourniquet (T1-2) for determination of the levels of c-reactive protein (CRP),tumor necrosis factor-alpha (TNF-α),methane dicarboxylic aldehyde (MDA) and superoxide dismutase (SOD) in plasma.The time to responses to tourniquet,tourniquet tolerance time and tourniquet tolerance period were recorded.The occurrence of hypotension,bradycardia and nausea and vomiting was also recorded.Results Compared with the baseline at T0,the concentrations of plasma CRP,TNF-α and MDA were significantly increased and the activity of plasma SOD was decreased at T1,2 in the two groups (P＜0.05).Compared with group C,the concentrations of plasma CRP,TNF-α and MDA were significantly decreased and the activity of plasma SOD was increased at T1,2,the time to responses to tourniquet,tourniquet tolerance time and tourniquet tolerance period were prolonged,and the incidence of bradycardia was increased in group D (P＜0.05).Conclusion Dexmedetomidine can reduce responses to tourniquet in patients undergoing lower extremity surgery with peripheral nerve block.