Effect of dexmedetomidine added to ropivacaine administered locally on prevention of tourniquet-related hypertension in patients undergoing total knee arthroplast / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effect of dexmedetomidine added to ropivacaine administered locally on prevention of tourniquet?related hypertension in the patients undergoing total knee arthroplast. Methods Ninety patients of both sexes, aged 58-74 yr, weighing 60-78 kg, of American Society of Anesthesiologists physical statusⅠ?Ⅲ, scheduled for elective unilateral total knee arthroplast, were randomly divided into 3 groups ( n=30 each) using a random number table: ropivacaine group ( group R) , dexmedetomidine added to ropivacaine administered locally group ( group D + R ) , and dexmedetomidine administered intravenously + ropivacaine group ( group Div+R ) . Femoral nerve block:0.5% ropivacaine 15 ml was injected in group R; the mixture ( 15 ml) of 0. 5% ropivacaine 20 ml plus dexmedetomidine 60 μg was injected in group D+R; 0.5% ropivacaine 15 ml was injected in group Div+R. Lateral femoral cutaneous nerve block: 0.5% ropivacaine 5 ml was injected in group R; the mixture 5 ml was injected in group D+R; 0.5% ropivacaine 5 ml was injected in group Div+R. General anesthesia was induced after the end of nerve block. In group Div+R, dexmedetomidine was infused as a bolus of 0.5 μg∕kg over 10 min starting from anesthesia induction, followed by an infusion of 0.4 μg·kg-1 ·h-1 until 30 min before the end of surgery. A tourniquet was applied and inflated ( 266-304 mmHg) within 90 min. Before induction of anesthesia ( T0 ) , and at 0, 15, 30, 45, 60, 75 and 90 min after the tourniquet was inflated ( T1?7 ) , mean arterial pressure and heart rate were recorded. The occurrence of hypertension, hypotension, tachycardia and bradycardia was recorded when the tourniquet was inflated. Agitation was assessed and scored after removal of the endotracheal tube. The time for recovery of breathing, emergence time, and time for removal of the endotracheal tube were recorded. Results Compared with group R, the mean arterial pressure and heart rate were significantly decreased at T1?7 in D+R and Div+R groups, the incidence of hypertension and tachycardia was decreased, the incidence of bradycardia was increased, and agitation score was decreased in D+R and Div+R groups ( P0.05). There was no significant difference in the time for recovery of breathing, emergence time, and time for removal of the endotracheal tube between the three groups ( P>0.05 ) . Conclusion Dexmedetomidine added to ropivacaine administered locally can exert effect on prevention of tourniquet?related hypertension in the patients undergoing total knee arthroplast, and the effect is similar to that of dexmedetomidine administered intravenously.