The Protective Effect On Lung And Its Mechanism Of Dexmedetomidine In Patients With One-lung Ventilation

Objective:To explore the protective effect on lung and its mechanism of dexmedetomi-dine (Dex) in patients with one lung ventilation (OLV).Methods:Sixty patients undergoing elective resection of esophageal cancer were selected for the study, and they were divided into control group and observation group (dexmedetomidine hydrochloride given group),30 cases in each group. In both groups, the same method of anesthesia induction was adopted, and remifentanil, cis atracurium and propofol were continuously administered intravenously to maintain the anesthesia during operation. In observation group, a bolus of 1μg/kg of dexmedetomidine hydrochloride was administered intravenously at time of anesthesia induction and finished within 10min, followed by 0.5μg/kg-h to maintain the anesthesia. In Control group, same dose of saline were given by the same method, and it was stopped 30 min before the end of surgery. Venous blood samples were collected 10min before induction of anesthesia (TO), immediately after ventilation (T1),60min after ventilation (T2),90min after single-lung ventilation (T3),24h after operation(T4). The whole blood neutrophils (PMN) count was tested using a hematology analyzer, plasma myeloperoxidase (MPO) and xanthine oxidase (XOD) concentration at different time points (TO-T4), and plasma vascular endothelial growth factor (VEGF) and nitric oxide (NO) levels at (TO-T3) were tested using enzyme-linked immunosorbent (ELISA) assay, and arterial and central venous blood gas measurement were tested to calculate pulmonary shunt fraction (Qs/Qt). The amount of each drug used during the maintaining of anesthesia, operation time, intraoperative blood loss, single-lung ventilation time, waking time, urine volume and fluid used during surgery were recorded when the operation was over.Results:There were no significant difference of patients’general information, urine, fluid used, cis-atracurium dosage, operative time, single-lung ventilation time between the two groups (P> 0.05), but in observation group, the dose of remifentanil and propofol used were significantly less than those in control group, and waking time after drug stopped was significantly longer than that in control group (P<0.05). PMN count at time points T2-T4 in both groups was significantly higher than that at time point T0. There was no significant difference of PMN count between the two groups at time point T0(P> 0.05), but the PMN count in observation group at time points T2-T4 was significantly lower than that in control group (P<0.05); XOD and MPO concentration in both groups at time points T2-T4 was significantly higher than that at T0(P<0.05), but there was no significant difference between the two groups at TO (P> 0.05), whereas, XOD and MPO concentration levels in observation group at time points T2～T4 were significantly lower than those in control group (P<0.05); Qs/Qt in both groups at time points T1～T3 was significantly higher than that at TO (P<0.05), but there was no significant difference of Qs/Qt between the two groups at time points T0～T3 (P> 0.05); NO concentration was not significantly different between the two groups at time points TO and T1 (P> 0.05), but it was significantly higher in observation group than that in control group at time points T2, T3 (P <0.05); There was no significant difference of VEGF concentration at time points TO and T1(P> 0.05), but it was significantly higher at time points T2, T3 than that at time points TO in both groups, and it was significantly lower in observation group at time points T3 than that in control group (P<0.05).Conclusions:1. The use of dexmedetomidine and remifentanil can reduce the dose of propofol, it does no affect the dosage of cis atracurium and other muscular relaxant drugs, and it results in prolonged waking time.2. Peri-operative continuous infusion of dexmedetomidine hydrochloride can alleviate lung ischemia-reperfusion injury by reducing the concentration of serum MPO and XOD and PMN count, and it can reduce pulmonary vascular permeability, protect alveolar lining membrane and improve local oxygen supply to protect lung function.3. There was no significant effect of dexmedetomidine on pulmonary shunt fraction (Qs/Qt).4. Dexmedetomidine can reduce serum NO concentration of patients with esophageal cancer who need one lung ventilation, reduce the alveolar capillary permeabili-ty, and alleviate alveolar damage.