胃液小颗粒成分对误吸性肺损伤的影响

The role of gastric small particles in the pathogentsis of aspiration lung injury

目的 研究胃液小颗粒成分对误吸性肺损伤的影响及其发生的机制。方法 32只雄性新西兰白兔麻醉后随机分成四组,吸入不同物质入组（n=8）生理盐水（NS）,pH=5.3;B组（n=8）盐酸（HC1）,pH=1.25;C组（n=8）胃液小颗粒+NS,pH=5.3:D组（n=8）胃液小颗粒+HC1,pH=125。以 1.25ml/kg的剂量经气管导管注入兔肺,测定基础状态及吸入后1h、2h、3h、4h、5h、6h血浆IL-8及吸入后1h、3h、6h的PaO2,动物处死后,测定左上叶肺湿于重比（W/D）,并行右肺灌洗,测定肺泡灌洗液（BALF）中总蛋白、PMN/WBC、IL-8水平。结果（1）B、C、D组PaO2在吸入后1h内明显下降,B组较C组下降明显（P<0.05）,且在随后的6h仍维持在低水平,C组逐渐好转,至6h已基本恢复至基础水平;D组PaO2下降较其他各组更为显著（P<0.05）。（2）与 A组相比,其他3组BALF中总蛋白浓度、PMN/WBC及肺W/D均显著升高（P<0.05）;C组较B组显著升高（P<005）,D组较B、C组升高程度更为明显（P<0.05）。3）A、B两组血浆IL-8水平在整个观察期无明显改变,而C、D组分别于吸入后3h、4h开始升高,至吸入后6h仍维持在高水平。结论 吸入胃液小颗粒可导致与吸入盐酸性质、程度不同的肺损伤,这种差异可能与IL-8的不同表达程度有关。

Objective The purpose of this study was to determine the role of aspiration of HCI and/ or gastric small particles in the pathogenesis of aspiration lung injury. Methods Thirty-two New Zealand male rabbits weighting 2.0-2.5kg were anesthetized with diazepam and ketamine. The animals were randomly divided into four groups of 8 each: in group A normal saline ( NS, pH = 5.3) was instilled into the lungs; in group B HCI (pH= 1.25); in group C gastric small particles in NS was instilled into the lungs and in group D gastric small particles in HCI was instilled. Gastric small particles were prepared according to the methods of Davidson BA , et al. The volume of fluid instilled into the lungs was 1.2ml· kg-1 in the four groups. Blood samples were taken at 0,1,2,3,4,5 and 6 h after aspiration for determination of plasma IL-8 level. PaO2 was measured before and 1, 3, 6, h after aspiration. The animals were killed 6 h after aspiration. The wet/dry weight ratio of left upper lobe and the levels of total protein and IL-8 and polymorphonuclear(PMN) counts of bronchoalveolar lavage fluid (BALF) from right lung were measured. Results 1. PaO2 decreased dramatically in group B, C and D at 1 h after aspiration, especially in group B and D. PaO2 returned to normal level at 6h after aspiration in group C, but remained low in group B and D. 2. PMN counts and levels of total protein and IL-8 of BALF and W/D ratio were significantly higher in group B, C and D than those in group A especially in group C and D. 3. There was no significant change in plasma IL-8 level after aspiration in group A and B. Plasma IL-8 level began to increase significantly at 3 h after aspiration in group C and at 4 h in group D (P < 0.05) . Conclusion Aspiration of gastric small particles can cause lung injury different from that caused by HCI and IL-8 may play a role in that difference.