Effects of different doses of dexmedetomidine on stress responses of hypertensive patients undergoing thoracic surgery / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effects of different doses of dexmedetomidine on stress responses of the hypertensive patients undergoing thoracic surgery and find the uptimal infusion rate of dexmedetomidine in decreasing stress responses.Methods Sixty hypertensive patients of both sexes,aged 45-64 yr,weighing 65-80 kg,of American Society of Anesthesiologists physical status Ⅰ or Ⅱ,were divided into 4 groups (n =15 each) using a random number tablecontrol group (group C) and 3 different doses of dexmedetomidine groups (D1-3 groups).In D1,D2 and D3 groups,dexmedetomidine 0.2,0.3 and 0.4 μg · kg 1 · h 1 were intravenously infused until 30 min before the end of surgery,respectively,starting from 15 min before induction of anesthesia.The equal volume of normal saline was given instead of dexmedetomidine in group C.Before administration of dexmedetomidine (T0),at 1 min after endotracheal intubation (T1),at skin incision (T2) and immediately after extubation (T3),venous blood samples were collected for determination of epinephrine and norepinephrine concentrations in plasma (using high-performance liquid chronatography) and blood glucose concentrations.The development of adverse effects such as bradycardia,hypotension and respiratory depression was recorded.Results Compared with group C,epinephrine and norepinephrine concentrations in plasma and blood glucose concentrations were significantly decreased at T1-3 in D1,D2 and D3 groups,the incidence of bradycardia and hypotension was significantly increased in group D3 (P＜0.05),and no significant change was found in the incidence of bradycardia or hypotension in D1 and D2 groups (P＞0.05).There were no significant differences in epinephrine and norepinephrine and concentrations in plasma and blood glucose concentrations at each time point between group D1,group D2 and group D3 (P ＞ 0.05).Conclusion The optimal infusion rates of dexmedetoinidine are 0.2 and 0.3μg · kg-1 · h-1 in decreasing stress responses of the hypertensive patients undergoing thoracic surgery.