Seawater versus freshwater induced direct lung injury<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

古秒宁　肖金仿　黄毅然　傅卫军　林春水　周伟　徐建设　陈晔明　王元占

GU Miao-ning，XIAO Jin-fang，HUANG Yi-ran，et al．Department of SICU and Anesthesiology，Nanfang Hospital，First Military Medical University，Guangzhou 510515，China

Abstract

　　Objective：To compare the seawater and freshwater induced direct lung injury in a canine model.

　　Methods：Sixteen healthy mongrel dogs of both sexes，weighing 11.8-16.4kg were randomly assigned to one of three groups：groups S seawater（n＝6）；group F freshwater（n＝6） and group C control（n＝4）.The animals were anesthetized with intravenous 3％ pentobarbital sodium （30mg/kg）. Spontaneous breathing was maintained after tracheal intubation. In groups S and F Swan-Ganz catheter was inserted into the 3rd order bronchus of diaphragmatic lobe of right lung under direct vision with fiberoptic bronchoscope and seawater or freshwater（10ml/kg×body weight×1/6） was irrigated at 1.0-1.5 kPa（irrigation pressure）within 2min. In group C no irrigation was performed. Femoral artery was cannulated for BP monitoring. MAP，HR，VT，RR，Blood gases，electrolytes，acid-base balance and LDH and ALP activity in bronchoalveolar fluid （BAF） and blood were determined before irrigation and 5min，10min，30min，1h，2h，3h and 4h after irrigation. Lung tissue was obtained 4h after irrigation for light and electron microscopic examination.

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　　Results：There was no significant difference in blood gases，electrolytes，acid-base balance and hemodynamics among the three groups（P>0.05）. Bronchoscopic examination showed that bronchi in irrigated area were filled with BAF to different degree. In group S LDH and ALP activities in BAF were persistently increased after irrigation. LDH and ALP activities in BAF and blood LDH activity were significantly higher in group S than those in group F （P<0.01）. Macroscopic examination showed that the irrigated area was edematous and congestive with localized bleeding. Light microscopic examination showed alveolar edema and collapse and massive neutrophil infiltration. Pulmonary hemorrhage was seen in four animals in group S and one animal in group F. Electron microscopic examination showed that type II alveolar epithelial cells were injured，alveolar septa were thickened with platelet adhered to capillary wall.

　　Conclusion：Both seawater and freshwater produce direct lung injury. The direct lung injury induced by seawater is severer.

　　Key words： Seawater；Fresh water；Lung；Wounds and injuries；Disease models，animal

　　海水和淡水淹溺肺损伤动物模型的建立是研究其机制和治疗的基础。既往研究海水淹溺肺损伤模型都表现为持续性的低氧血症和酸中毒为主的病理生理特性，因此认为海水的损伤性作用、低氧血症和酸中毒是海水淹溺肺水肿肺损伤主要原因^[1，2]。以往的研究结果证明在排除低氧血症和酸中毒的影响下海水作为单独效应的原发性致伤因素可造成直接肺损伤^[3]。本研究的目的是建立直接肺损伤模型比较海水和淡水直接损伤的特点。

材料和方法

　　海水取自广东海域内伶仃洋，其采集、运输、分析按国家海水水质标准HY003-91的规定执行。其中主要电解质的含量为（mmol/L）： Na⁺ 381，K⁺ 8.1，Cl^- 465，Ca²⁺ 5.02；淡水采集定点塘水，氯化物含量0.1％～0.2％。

　　实验分组和模型的建立　选择普通级健康杂种犬共16只，体重11.8～16.4kg，犬龄2.4～4.2岁，雌雄不拘，随机分为肺段海水灌注模型组（S组）、肺段淡水灌注模型组（F组）和空白对照组（E组），模型组每组6只，对照组4只。

　　三组犬禁食12h，3％戊巴比妥钠（30mg/kg）静脉麻醉，直视下气管插管后维持自主呼吸。S、F组在支气管纤维镜引导下将替代灌注管（Swan-Ganz导管）置入目标肺叶--右肺隔叶的三支气管开口处备用。

　　左股动脉切开置管连接Hewlett-Parkard呼吸循环监测仪连续监测MAP、ECG、RR、潮气量（VT）；麻醉后30min，S组在支气管纤维镜观察下，经Swan-Ganz导管参照Modell方法^[4]灌注海水，海水灌注量为10ml/kg×体重×1/6（占总肺1/6）^[5]，灌注压1～1.5kPa，2min灌完。灌注完毕纤维支气管镜检查，将溢出三级支气管开口处泡沫状液吸出，以免伤及临近肺段。F组灌注方式与S组相同，E组不灌注液体。

　　数据采集　S、F组分别于灌注前、灌注后5min、10min、30min、1h、2h、3h、4h记录以下数据（记录数据取3次平均值）。（1）MAP、HR。（2）RR、VT。（3）左股动脉抽血1ml查血气、血酸碱和电解质水平。（4）S、F组分别于海水、淡水灌注前、灌注后5min、10min、30min、1h、2h、3h、4h在纤维支气管镜下采集右隔叶支气管肺泡液（Bronchoalveolar fluid，BAF）和抽取股动脉血测定乳酸脱氢酶（LDH）和碱性磷酸酶（ALP）活性（速率法，OLYMPUS AU800，日本）。对照组数据采集时点同S、F组。所有样本在4℃以下条件保存送检。

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　　全肺海水灌注、单肺海水灌注和肺段海水灌注三种模型无论有无低氧血症和酸中毒发生，灌注区均发现了肺泡水肿和萎陷、肺出血、支气管上皮细胞呈片状脱落和肺泡上皮细胞损伤、大量的中性粒细胞侵润等组织病理学表现，证明了海水的直接肺损伤作用^[3]。本实验通过建立海水、淡水直接肺损伤模型对比研究，结果表明海水导致的肺出血比率高于淡水，证明了海水的直接肺损伤比淡水严重。有文献报道海水肺内灌注后血液的凝血酶功能和血小板的聚集功能下降与海水中的Mg²⁺浓度过高、低氧血症和酸中毒有关^[12]。本实验在排除了低氧血症和酸中毒的条件下，肺出血仍然发生，说明是海水及成份作用的结果。

　　综上所述，在排除了低氧血症和酸中毒的条件下，海水、淡水入肺后均可导致直接肺损伤，并且4h内不能发生逆转，海水的直接肺损伤作用较淡水更严重。

参考文献

1. Colden F St C. Tipton MJ. Scott RC. Immersion，near-drowning and drowning，Br J Anaesth　1997，79：214-232.

2. 董文度，刘新卷，傅更锋，等 兔海水淹溺肺水肿发生机制的实验研究 生物医学工程系杂志　2000，17：196-201.

3. 古秒宁，肖金仿，黄毅然，等 海水直接肺损伤犬模型的研究 第一军医大学学报　2003，23：201-205.

4. Modell JH，Gaub M，Moya F，et al. Physiologic effect of near drowning with chlorinated fresh water，distilled water and isotonic saline. Anesthesiology　1966，27：33-41.

5. 施新猷，主编 医学实验动物的特点及应用 现代医学实验动物学　第1版 北京：人民军医出版社　2000.119-127.

6. Modell JH，Graves SA，Ketover A. Clinical course of 91 consecutive near-drowning victims. Chest　1976，70：231-238.

7. Pearn JH. The management of near-drowning. Br Med J　1985，291：1447-1452.

8. Pearn JH. Secondary drowning in children. Br Med J　1980. 281：1103-1105.

9. Orlowski JP. Drowning，near-drowning，and ice-water submersions. Pediatic Clin North Am　1987，34：75-92.

10. Sogoloff H，Barrera R，Ginsberg R，et al. Unusual freshwater near-drowning syndrome in a hospitalized postlobectomy patient. Chest　2001，120：1021-1022.

11. 黄大有，主编 实验诊断的理论基础和临床意义 第3版 北京：人民卫生出版社　1985.201-236.

12. Miller RD，Brizica SM Blood，blood component，cocloid and autotransfusion therapy Anaesthesia　1981，12，885-889.