| Background and ObjectiveRheumatic heart disease often leads to serious complications, such as cardiac insufficiency and cerebral embolism. At present, the surgical treatment is still gives priority to with artificial valve replacement.Surgical method has been very mature, But the surgery success are inseparable with brain protection during operation. In valve replacement surgery, right against the chest bone, the aorta, vena cava intubation and intracardiac operation are strong stimulus.Patients were in the intense stress, and sympathetic nerve in a state of hyperthyroidism, easy to cause hemodynamic instability and increase cardiovascular complications during perioperative. As a result, there is important to restrain stress reaction at maximum and maintain stable hemodynamic. In addition, cardiopulmonary bypass(CPB) is a kind of traumatic assistive technology, it can cause different degree of brain injury In valve replacement surgery, including primary brain injury and secondary brain injury. CPB brain injury combined with surgical trauma stress, often caused of postoperative cognitive dysfunction in patients, and seriously affected recovery of operation and quality of life. Therefore, it is important to take effective measures to reduce brain damage in valve replacement surgery of brain. Dexmedetomidine(Dex) is the high selectivity of alpha 2 agonists adrenaline, it has the characteristics of sedative and analgesic, anti-sympathetic nerve. It can reduce stress reaction and provide stable hemodynamics duing operation. It can maintain the myocardial oxygen supply and demand balance, stable hemodynamics in coronary artery bypass surgery. A large number of animal experiments confirmed that Dex can provide nerve protective effect. In clinical studies,it have confirmed that Dex can reduce postoperative cognitive dysfunction after laparoscopic surgery in elderly patients. Dex has been widely applied in the clinical, whether it can reduce the level of endothelin-1, markers of brain injured S100β and MBP, and perioperative brain damage is uncertain.Materials and methods50 patients with marked enhancement of heart valve replacement were randomly divided into group C(control group) and group D(Dex group). All patients were inducted in the same way: midazolam 0.06 mg/kg, Citrate sufentanil injection1μg/kg, etomidate 0.3 mg/kg, syn-benzenesulfonic acid Atracurium 0.3mg/kg. Mechanical ventilation was started after intubation. After the induction of anesthesia, the patients in group D were received Dex 1μg/kg(10 minutes), then 0.5μg/kg/h until the end of surgery, and the patients in group C were received with the same amount of sodium chloride injection. The two groups were maintained with same combined inhaled and intravenous anesthesia. Heart rate(HR), systolic blood pressure(SBP), and diastolic blood pressure(DBP) were recored at dosing(T1), 10 min after dosing(T2), 5 min after cutting off thr skin(T3), straight on the breast bone(T4), 20 minutes after jumping(T5) and the end of operatiom(T6). Blood samples were taken before induction(T5), 5 min after stopping cycle(T1), the end of operatiom(T2), 6 h after operation(T3) and 24 h after operation(T4) for the determination of the level of plasma noradrenaline(NE), endothelin-1,S100β and MBP by ELISA. Arterial blood gas analysis and blood glucose were measured at the same points.Results1.Dex on the effect of hemodynamics,stress reaction and endothelin-11.1 hemodynamicsCompared with T1,SBP,DBP were significantly increased at T3、T4 in group C(P < 0.05) and were significantly increased at T1 in group D. Compared with group C, SBP、DBP were significantly higher at T2,but were significantly lower at T3, T4 in group D(P < 0.05).Compared with T1, HR were significantly increased at T3、T4 in group C(P < 0.05) but were significantly reduced at T3、T4 in group D(P < 0.05). Compared with group C, HR were significantly lower at T3、T4 in group D(P < 0.05).1.2 stress reaction and endothelin-11.2.1 stress reactionNE at each time point in two groups after extracorporeal circulation were significantly higher Compared with T0(P < 0.05); Compared with group C, NE reduced significantly at T2-4 in group D(P < 0.05). Blood glucose at T1, T2 and T3 in two groups were significantly higher compared with T0(P < 0.05); Compared with group C, blood glucose at T1, T2 and T3 was lower in group D(P < 0.05).2 Dex on the effect of markers of brain damage and postoperative cognitive function1.2.2 endothelin-1Compared with T0, ET-1were significantly increased at T1-4 in two groups(P < 0.05).2.1 markers of brain damageS100β were significantly increased at T1-4 in two groups compared with T0(P < 0.05); Compared with group C, S100β at T2, T3 were significantly lower in group D(P < 0.05).Compared with T0, MBP were significantly increased at T2-4 in two groups(P < 0.05). Compared with group C, MBP were significantly lower at T2 and T4(P < 0.05).Conclusions1 Injection of dex at the bolous of 1μg/kg after induction of anesthesia and then continuous infusion of 0.5μg/kg/h in the valve replacement under CPB can reduce intraoperative stress response and the level of endothelin-1, and provide stable hemodynamics.2 Dex can reduce markers of brain injury of the level of S100β and MBP, provide brain protection. |
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