Clinical Effect Analysis Of Dexmedetomidine Infusion Undergoing Cardiac Valve Replacement Surgery

【Objective】To estimate the effects of dexmedetomidine infusion on blood pressure, heart rate,bispectral index(BIS), cognitive function, the adverse reactions and consumption ofanaesthetic drug, blood glucose concentration undergoing cardiac valve replacementsurgery.【Methods】Prospective,randomized placebo parallel control trial conducted in the first affiliatedhospital of soochow university from May2013to February2014. Forty five patients (ASAⅡ or Ⅲ, NYHA Ⅱ or Ⅲ, aged18～65yr) undergoing cardiac valve replacementsurgery were randomly divided into group dexmedetomidine (group D1and group D2),control group (group C). Group D1received dexmedetomidine0.5μg/kg over15min,group D2received dexmedetomidine0.5μg/kg over15min and contiuning to receivedexmedetomidine0.5μg/kg/h until completing the procedure, group C received the samevolume of normal saline before the induction of anesthesia. Patients were preferred to givepropofol at rate of1mg/s until the valve of BIS reach to60at the beginning of anestheticinduction. Then three groups accept the same method of anesthetic induction. Heart rate(HR), mean arterial pressure (MAP), and bispectral index (BIS) were recorded at baseline(T1),5,10,15minutes (T2～T4) after drug infusion, the end of propofol dosage (T5),before intubation (T6),1minutes after intubation (T7), after skin incision (T8), aftersternotomy (T9). Blood glucose was measured at baseline (T1), after sternotomy (T9),10minutes after termination of cardiopulmonary bypass (T10) and the end of operation (T11).At the time of1day before operation,4days and7days after operation, cognitive functionwas evaluated by the mini-mental state examination (MMSE). The adverse reactions(hypotension, hypertension, bradycardia, tachycardia, postoperative cognitive decline) andconsumption of propofol and fentanyl during operation were also recorded.【Results】1.There were no apparently differences between three groups in age, sex, weight, left ventricular ejection fraction, Cardiopulmonary flow time,operation time, the cardiacfunction classification, the types of surgery(P＞0.05).2. Mean arterial pressure and Heart rate: Compared with group C, MAP wassignificantly lower in group D1and group D2at T4,T8,T9(P＜0.05). The numerical ofthree groups at T4,T8,T9were (84±14,73±11,80±12)mmHg in group D1;(84±9,76±11,74±13) mmHg in groupD2;(95±11,85±10,91±14) mmHg in group C. In groupC, HR at T3～T9was apparently higher than group D1(P＜0.05). The HR at T3～T9were (75±14,70±15,69±13,62±11,69±13,64±10,71±9)bpm in group D2;(87±18,84±18,83±14,76±15,86±18,80±16,81±12) bpm in group C. HR at T4～T9was apparently higher than group D2(P＜0.05). The HR at T4～T9in group D2were (72±13,70±13,64±14,68±14,63±13,65±13) bpm; The HR at T4～T9in group Cwere (84±18,83±14,76±15,86±18,80±16,81±12) bpm. There were three patientswith hypertension, three patients with hypotension, two patients with tachycardia and onepatient with bradycardia in group C; one patient with hypertension, five patients withhypotension, one patient with tachycardia and two patients with bradycardia in group D1;seven patients with hypotension, one patient with tachycardia and two patients withbradycardia in group D2. There were no difference between three groups in incidence ofadverse reaction(P＞0.05).3. Sedation: Compared with group C, BIS was significantly lower in group D1andgroup D2at T3, T4(P＜0.05). The numerical of three groups at T3, T4were84.0±3.5,78.1±3.3(group D1);82.9±4.4,76.4±7.7(group D2);93.7±2.7,92.6±3.3(group C).4. Anesthetic dosage: The consumption of propofol at anesthetic induction and totalwere significantly higher in group C than group D1and group D2(P＜0.05), also the totalconsumption of propofol in group D2was lower than group D1(P＜0.05). Theconsumption of propofol at anesthetic induction and total were0.78±0.27mg/kg,397±1.7mg in group D2;0.87±0.28mg/kg,487±93mg in group D1;1.49±0.40mg/kg,601±141mg in group C. The Dosage of fentanyl in group C was much higher than groupD2(18.5±4.2vs22.5±2.5μg/kg，P＜0.05).5. Blood glucose concentration: The blood glucose concentration of all the threegroups at T10, T11were higher than T1(P＜0.05), The numerical of three groups at T10,T11were (9.5±2.2,11.2±1.8)mmol/L in group D1;(8.8±1.2,10.0±1.2) mmol/L in group D2;(9.7±2.0,11.7±1.7) mmol/L in group C. The blood glucose concentration ofgroup D2at T11lower than group C(10.0±1.2vs11.7±1.7mmol/L, P＜0.05).6. Cognitive function: Two patients in group C, one patint in group D1and group D2could not been included for cognitive function score due to under sedation after operation.The valve of MMSE of all three groups were lower than before operatioin at the time offour days after operatioin(P＜0.05), also the valve of MMSE in group D2was higher thangroup C at T12(26.9±0.8vs25.8±1.2分，P＜0.05). There were three patinets withpostoperative cognitive decline in group D1, and two patients in group D2, five patients ingroup C four days after operation. There were two patinets with postoperative cognitivedecline in group D1, and one patient in group D2, three patients in group C seven daysafter operation. But there were no differences between the three groups (P＞0.05).【Conclusion】1. Dexmedetomidine infusion undergoing valve replacement surgery was beneficialfor reducing the volatility of blood pressure and heart rate caused by surgical stimulation.2. Dexmedetomidine infusion undergoing valve replacement surgery was beneficialfor reducing the consumption of propofol, furthermore the dexmedetomidine infusionmethod of load dosage and maintenance dose (0.5μg/kg+0.5μg/kg/h) could reduce theconsumption of fentanyl, and was better for reducing the total dosage of propofol throughthe operation than only load dosage (0.5μg/kg).3. Dexmedetomidine infusion of load dosage and maintenance dose (0.5μg/kg+0.5μg/kg/h) undergoing valve replacement surgery could reduce the change range of bloodglucose concentration, improve operative cognitive function.