新生兔机械通气并氧吸入肺损伤的实验研究

Experimental Study of Ventilator-Induced Lung Injury and Oxygen Inhalation in Newborn Rabbits

目的研究新生兔机械通气并氧吸入肺损伤的病理改变及肺灌洗液白细胞的变化规律。方法将108只新生兔随机分为高氧、低氧组;每组又分为高吸气峰压(HPIP)、中吸气峰压(MPIP)和低吸气峰压(LPIP)共6组进行机械通气。于通气后1、3、6h3个时间点活杀取肺,行肺灌洗液细胞计数、沉渣涂片细胞分类,测定肺湿干比并结合病理切片分析。结果机械通气6h内,白细胞计数在高氧、低氧通气后均高于对照,且在HPIP通气中白细胞计数明显高于MPIP、LPIP(Pa<0.05);低氧通气、MPIP通气及对照组细胞反应以巨噬细胞为主;淋巴细胞反应与给氧方式无关,但与肺受到的机械牵拉力有关,以HPIP组最高(P<0.05);分叶核细胞数高氧组高于低氧组,MPIP组低于HPIP及LPIP组(Pa<0.05)。肺损伤评分及病理分级肺损伤高氧组重于低氧组,HPIP组及LPIP组重于中压力组。病理片均有膨胀不均一的肺泡,低压力通气肺不张重,高压力通气肺出血、肺大泡明显。结论新生兔机械通气时,低压力通气易致肺不张损伤,高压力通气易致肺气压伤,适当的压力能减轻肺损伤。细胞数的改变随通气策略不同而不同。

Objective To investigate the pathological change of ventilator - induced lung injury and oxygen inhalation and the regularity of white blood cell changes in broncho alveolar lavage fluid（BALF）. Methods One hundred and eight newborn rabbits were divided randomly into two groups according to high concentration oxygen （FiO2 = 1. 0） and low concentration oxygen （FiO2 = 0. 45 ）. Each group was sub-divided into three parts：high peak inspiratory pressure group （HPIP）, moderate peak inspiratory pressure group （MPIP）and low peak inspiratory pressure group （LPIP）. All rabbits were given mechanical ventilation（MV） and killed to obtain lungs at 1, 3, 6 hours after trail respectively. Cells in BALF were counted and the percentage of WBC was classified in sediment film. The ratio of wet to dry of lungs was detected, at the same time,pathological section was analyzed. Results The findings were demonstrated within 6 hours in newborn rabbits by MV. The white blood cell count ventilated with hyperxia or hypoxia groups was higher than that of control group（ no MV） ;and that of HPIP group was higher than that of MPIP and LPIP groups （ Pα 〈 0. 05 ）. The main percentage of WBC in BALF was macrophage in hypoxia or MPIP ventilation or that in control group. The percentage of leukomonocyte had irrelative with oxygen concentration, but it concerned with the lung mechanical stretch and the mean value was maximum under the condition of HPIP ventilation （ P 〈 0. 05 ） ; Compared to hypoxia groups , segmented cell in hyperxia groups was higher. The percentage of segmented cell of MPIP groups significantly decreased than that of HPIP and LPIP groups （ Pα 〈 0. 05 ）. Pathological ranking and score in newborn rabbits lung manifested that the lung injury in hyperxia groups was more severe than that of hypoxia groups. The lung injury of MPIP ventilation groups was lightest in all of experiment groups. All experiment rabbits pathological section had alveoli pulmonum heterogeneity inflation. There were obviously part pulmonary atelectasis in LPIP groups and pulmonary hemorrhage and pulmonary bullae formation in HPIP group. Conclusions When newborn rabbits suffer from MV,atelectasis is likely in the LPIP ventilation and barotrauma in the HPIP ventilation. Only MV with the MPIP can reduce the lung injury. Different cell responsees in BALF are determined by the different ventilation way.