胸段硬膜外阻滞对油酸致猪急性肺损伤的作用

Effects of thoracic epidural Mockade on acute lung injury induced by oleic acid in piglets

目的观察胸段硬膜外阻滞对油酸致猪急性肺损伤(ALI)的作用。方法16只健康幼猪,体重30-35kg,随机分为2组(n=8):生理盐水组(S组)及罗哌卡因组(R组)。麻醉后气管插管,机械通气,吸入氧浓度100％,经颈内静脉持续输注油酸,直至动脉血氧分压(PaO2)≤200mm Hg。ALI制备成功后即刻R组经T3,4硬膜外导管注入0．25％罗哌卡因5ml,随后以2ml/h的速率持续输注4h, S组给予等量生理盐水,分别于麻醉操作完成后稳定30min(基础值)、ALI模型制备成功后即刻(T0)、硬膜外腔输注罗哌卡因(或生理盐水)1、2、3、4h记录平均动脉压(MAP)、平均肺动脉压(MPAP)、肺毛细血管楔压(PCWP)、PaO2、心排血量(CO)、肺内分流率(Qs／Qt)、肺血管阻力(PVR)和体循环血管阻力(SVR)。罗哌卡因输注4h时处死动物,取左肺下叶,分别在光镜和电镜下观察肺组织形态学及超微结构。结果油酸可导致MPAP、PVR、SVR、Qs／Qt升高,CO、PaO2降低,并可使肺组织的形态学及超微结构发生病理改变,胸段硬膜外阻滞在一定程度上抑制油酸引起的上述改变。结论胸段硬膜外阻滞可减轻油酸致猪急性肺损伤。

Objective To investigate the effects of thoracic epidural blockade on acute lung injury （ALI） induced by oleie acid in piglets. Methods Fourteen healthy piglets of either sex, weighing 30-35 kg were used in this study, Anesthesia was induced with ketamine and thiopental, and maintained with IV infusion of thiopental and fentanyl and intermitten IV boluses of pancuronium after tracheal intubation, The animals were mechanically ventilated （FiO2 = 1, VT = 10-15 ml·kg^-1 , RR = 16 bpm, I ： E = 1 ： 2）, The catheter was inserted at T3-4 interspace and advanced 5 cm into the epidural space cephalad, The internal carotid artery was caunulated for BP monitoring and blood sampling. Swan-Ganz catheter was placed in pulmonary artery via right internal jugular vein, Oleic acid 0.1 ml·kg^-1 in 20 ml of normal saline was infused via internal jugular vein, ALI was considered to have been induced when PaO2/FiO2≤200 mmHg, Arterial blood gases, MAP, MPAP, PVR, SVR, CO, Qs/Qt were measured and calculated before induction of ALI （baseline）, when ALI was induced （To） and at 1, 2, 3, 4 h after T0（T3-4）, The animals were randomly divided into 2 groups： group A received 0.25% repivacaine 5 ml via epidural catheter at To followed by infusion of 0.25% repivacaine at 2 ml·h^-1 for 4 h, and group B received normal saline instead of repivacaine, The animals were killed at 4 h after epidural repivacaine, The lungs were removed for light and electron microscopic examination. Results Intravenous oleic acid caused significant increase in MPAP, PVR, SVR and Qs/Qt and decrease in CO and PaO2, and produced ultramicrostructural pathologic changes of the lung tissue. Thoracic epidural blockade significantly, improved respiratory function and attenuated the damage to the lung ultramicrestructure. Conclusion Thoracic epidural blockade can attenuate oleic acidinduced ALI.