幼猪机械通气中异氟醚或七氟醚混合一氧化氮吸入的安全性

The safety of inhalation of volatile anesthetic mixed with nitric oxide during mechanical ventilation in piglets

目的研究吸入异氟醚或七氟醚混合一氧化氮(NO)在幼猪机械通气中的安全性。方法36头幼猪随机分为6组:Ⅰ组(对照组):单纯机械通气;Ⅱ组(NO组):吸入20ppmNO;Ⅲ组(异氟醚组):吸入1.3MAC异氟醚;Ⅳ组(异氟醚+NO组):吸入1.3MAC异氟醚及20ppmNO;Ⅴ组(七氟醚组)吸入1.3MAC七氟醚;Ⅵ组(七氟醚+NO组)吸入1.3MAC七氟醚及20ppmNO。用麻醉机行间歇正压通气4h,测定各组机械通气前、机械通气1、2、3、4h(T0、T1、T2、T3、T4)的呼吸频率(RR)、呼吸系统总顺应性(Crs)、气道压力(Paw)、潮气量(VT)、分钟通气量(MV)以及呼末二氧化碳分压(PETCO2);测定T0、T2、T4时点动脉血高铁血红蛋白(MetHb)和亚硝酸根(NO2-/NO3-)水平;处死动物后比较各组肺组织湿/干重比、支气管肺泡灌洗液(BALF)中饱和磷脂/总磷脂(DSPC/TPL)及饱和磷脂,总蛋白(DSPC/TP)、肺表面张力和白细胞计数,并行肺组织损伤评分。结果Ⅲ、Ⅳ、Ⅴ、Ⅵ组BALF中DSPC/TP及肺表面张力较Ⅰ组下降(P<0.05),通气结束时Crs较通气前下降(P<0.05),而Ⅱ组无显著性变化(P>0.05);与通气前比较,各组通气结束时MetHb与:NO2-/NO3-水平无变化,各组BALF中白细胞计数、肺组织损伤评分、肺泡扩张度和湿/干重比之间比较差异无统计学意义。结论1.

Objective To investigate the safety of inhalation of isoflurane (ISO) or sevoflurane (SEVO) mixed with nitric oxide (NO) during mechanical ventilation.Methods Thirty-six healthy piglets of both sexes weighing 7-11 kg were randomly allocated to one of 6 groups ( n = 6 each): (1) control group was mechanically ventilated with O2; (2) NO group inhaled 20 ppm NO; (3) ISO group inhaled 1.3 MAC isoflurane; (4) ISO + NO group 1.3 MAC isoflurane + 20 ppm NO; (5) SEVO group inhaled 1.3 MAC sevoflurane and (6) SEVO + NO group inhaled 1.3 MAC sevoflurane + 20 ppm NO. The animals were mechanically ventilated with IPPV (VT 10 ml·kg-1 , RR 30-40 bpm, I: E 1:2) for 4 h in the all 6 groups. The animals were premedicated with atropine 0.02 mg·kg-1 i.m. . The Ⅳ line was established for fluid and drug administration. An additional dose of ketamine 10 mg·kg-1 was given i.v. before tracheostomy. 4F S-G catheter was placed in pulmonary artery via right internal jugular vein for hemodynamic monitoring. Femoral artery was cannulated for BP monitoring and collection of artrerial blood samples. MAP, HR, CVP, right ventricular pressure (RVP), PCWP, MPAP and total compliance of respiratory system (Crs), Paw, VT and PET CO2 were recorded before (T0 ) and at 1, 2, 3, 4 h of ventilation (T1-4). Blood samples were taken at T0 , T2 and T4 for determination of Met Hb and NO2- /NO3- . The animals were killed at the end of 4 h mechanical ventilation and the lungs were removed for determination of wet/dry(W/D) lung weight ratio, broncho-alveolar lavage fluid (BALF) and microscopic examination. BALF was collected for determination of surface tension and concentrations of saturated phosphate (DSPC) , total phosphate (TPL) total protein (TP) and white cell count. Results Crs was significantly decreased at the end of ventilation (T4 ) as compared with the baseline (T0) in group 3,4,5 and 6, while there was no significant change in Crs in group 1 and 2. DSPC/TP was significantly lower in group 3,4,5 and 6 than in group 1 ( P < 0.05) , There were no significant changes in the level of MetHb and NO2- /NO3- at the end of ventilation (T4) as compared with the baseline (T0) in the all 6 groups. There was no significant difference in W/D ratio, WBC count in BALF, lung injury scores and alveolar expansion among the 6 groups ( P > 0.05 ) . Conclusion 1.3 MAC isoflurane or sevoflurane mixed with 20 ppm NO can be used safely during mechanical ventilation.