Effects Of Controlled Hypotension Induced By Isoflurane On Postoperative Cognitive Dysfunction And Inflammatory Factors

Objectives:To investigate the effects of controlled hypotension induced by isoflurane on postoperative cognitive dysfunction and inflammatory factors of TNF-a and IL-6.Methods:Forty patients, ASAⅡ-Ⅲ, scheduled for surgery aging from 30 to 60, were divided into two groups randomly. GroupⅠwas composed of twenty patients undergoing controlled hypotension induced by isoflurane inhaled anesthesia. The other twenty patients named GroupⅡwere not received hypotension. Excluded standards: patients with serious cardiac, hepatic, pulmonary or renal diseases; patients with diseases of central nervous system; patients with cognitive dysfunction or inflammatory diseases before operation. Anesthesia methods:midazolam 0.1mg·kg-1, propofol 1.5-2.0 ml·kg-1, fentanyl 3-5μg·kg-1, cisatracurium 0.15 mg·kg-1. Then, the patients had mechanical ventilation after tracheal intubation. Anesthesia was maintained by propofol 4-6mg·kg-1h-1 and atracurium 0.5mg·kg-1h-1 with intermittent injection of fentanyl. Controlled hypotension in GroupⅠ, lasted for 40 minutes, was induced by isoflurane with mean arterial pressure (MAP) 25-30% lower. GroupⅡtook no special treatment. The data, included SBP, DBP, MAP, HR, SPO2 was recorded at designated time points: before anesthesia(T0);after anesthesia before hypotension (T1);time to begin CH immediately(T2);time to reach scheduled BP (T3);CH lasted for 30min(T4);time to stop CH(T5);after have stopped CH for 30min(T6), Similarly, before anesthesia(T0);the operation lasted for 10min (T1),15 min(T2),30min (T3),60min (T4),70min(T5),100min(T6) in groupⅡ. Neuropsychology assessment was measured using MMSE preoperative and 24 hours postoperative. Simultaneously, blood samples were taken at T1, T4, T6 to test the levels of TNF-αand IL-6.Results:1.There were no differences in baseline values between the two groups(P>0.05).During the induced hypotension(T3,T4,T5),the MAP values of groupⅠwere maintained at 71%-73% of the baseline value and were much lower than that of T0.There were no remarkable differences among each time point of groupⅡ.Heart rate decreased slightly in both groups at T1 without significance(P>0.05).HR in groupⅠincreased at T3,T4,T5 and was higher than that of T0(P<0.05).No differences were indicated at each time point in groupⅡ.2. No cognitive dysfunction was showed in both groups before operations. Both mean MMSE scores decreased 24 hours after operations significantly (P<0.05). Between the two groups, there were no differences in MMSE preoperative or postoperative.25% of the patients (5 patients) showed POCD in groupⅠ, compared with 15%(3 patients) in groupⅡ. But there were no statistic significance between them (P>0.05).3. The concentrations of IL-6 and TNF-a increased slowly in both groups from T1 to T6.The differences of IL-6 and TNF-a at T1 between groupⅠandⅡwere not obvious (P>0.05).By contrast, the concentrations of IL-6 in groupⅠwere lower than that in groupⅡat T4 and T6 (P<0.05), so were the concentrations of TNF-a at T6.Conclusion:It shows that controlled hypotension induced by isoflurane is a good and easy way to achieve bloodlessness, although It may cause reflex tachycardia.It may not increase the risk of postoperative cognitive dysfunction with the MAP 30% lower; to some extent, it may decrease the concentrations of IL-6 and TNF-a.