The Clinical Application Of Dexmedetomidine Combined With Sodium Nitroprusside In Controlled Hypotension Durning Endovascular Graft Exclusion

Background and ObjectiveIn cardiovascular surgery, aordic dissection is a very dangerous disease with a risk of rupture at any time, a high mortality, and a high incidence of postoperative cognitive dysfunction. Now with the improvement of living level and popularization of disease such as hypertension, hyperlipidemia, coronary heart disease and diabetes,the incidence of aortic dissecting is rising year by year.Aordic dissection can be divided into three types, and aordic dissection of DeBakey? type is the indication of endovascular graft exclusion(EVGE). The key point of anesthesia is controlled hypotension when stent graft released during EVGE, for the purpose of achieving accurate positioning. Sodium nitroprusside(SNP) is a common drug used in controlled hypotension with benefits of low-cost and high effectiveness, but it also exists side-effects that have a negative impact on surgery and postoperative cognitive function, such as reflex tachycardia, rebound hypertension, resistance, cyanide poisoning, coronary steal, increased intracranial pressure, pulmonary shunt increase,platelet dysfunction and so on. Therefore, it's necessary to find a safer and moreeffective management program for controlled hypotension.Dexmedetomidine(DEX) is a highly selective ?2-adrenoreceptor agonist, and mainly excited ?2A receptor of brain stem, spinal cord and hypothalamus at low-dose,resulting in anti-sympathetic and sedation, suppression of norepinephrine release,enhance of vagus nerve activity, and causing decreased heart rate and blood pressure.At present, dexmedetomidine has been reported to use in controlled hypotension during endoscopic sinus surgery, spinal surgery and neurosurgery. However, there has not systematic research about application of dexmedetomidine as a hypotension agent in EVGE. This study focused on the efficacy and safety of dexmedetomidine combined with sodium nitroprusside during controlled hypotension and its impact on postoperative cognitive function in EVGE, so as to provide theoretical basis for clinical treatment optimization.MethodsForty patients who was undergoing EVGE, 32 males and 8 females, aged 27 to79 years old, ASA II or III grade, were randomly divided into 2 groups(n=20each):SNP group and DEX combined with SNP group. In SNP+DEX Group, DEX was infused in 15 min with a dose of 1 ?g/kg before induction, then continued at a speed of 0.5 ?g/kg?min,and stopped at 30 min before the end of surgery, while patients in SNP group received the same amounts of saline. SNP was administrated to maintain controlled hypotension at the time of skin inclusion. SBP, HR and RPP were recorded at the following time points: before administration of DEX(T0), after administration of DEX(T1), before administration of SNP(T2), 5(T3), 10(T4)min after administration of SNP, 5(T5), 10(T6)min after stopping administration of SNP. The time of reaching the target SBP, the total average dosage of SNP, the precision of graft localization, the MMSE score before and after surgery, the incidence of adverse reactions and POCD were also recorded.1. Baseline characteristics were similar for all patients between groups in sex,age, weight, and operation time(P>0.05).2. Compared to the time point of T2, the SBP at the time point of T5~T6 in SNP group and SNP+DEX group were significantly increased, the HR at the time point of T3~T6 in SNP group were also significantly increased(P<0.05). When compared with SNP group, the SBP at the time point of T6, HR and RPP at T3~T6 in SNP+DEX group were significantly decreased(P<0.05).3. The time of reaching the target SBP in SNP+DEX group was significantly shorter than in SNP group, the total average dosage of SNP in SNP+DEX group was significantly lower than in SNP group(P<0.05), there was no statistically significant in terms of graft localization precision(P>0.05).4. The incidence of tachycardia and postoperative agitation were significantly decreased in SNP+DEX group(P<0.05), there was no statistically significant in terms of endoleak, bradycardia, and delayed recovery(P>0.05).5. Compared with SNP+DEX group, MMSE score in SNP group after surgery was significantly lower and the incidence of POCD was higher(P<0.05).Conclusion1. Dexmedetomidine combined with sodium nitroprusside can inhibit reflex tachycardia, rebound hypertension and reduce the value of RPP to some extent.2. The application of dexmedetomidine and sodium nitroprusside in controlled hypotension can shorten the time of reaching the target SBP, reduce the total average dosage of SNP, but has no effects on operation time, the precision of graft localization and the incidence of endoleak.3. Dexmedetomidine combined with sodium nitroprusside can reduce the incidence of tachycadia, postoperative agitation and POCD, and doesn't increase the risk of delayed recovery and bradycardia.4. The application of dexmedetomidine and sodium nitroprusside in controlled hypotension during EVGE is effective and safe,it's a better treatment optimization in Resultsclinic.