胸部爆震伤致兔急性呼吸窘迫综合征模型的建立及相关因素分析

目的 构建室内胸部爆震伤致兔急性呼吸窘迫综合征(ARDS)模型并分析其发生机制及早期死亡原因,为研究肺爆震伤早期预警体系和治疗方法提供依据.方法 按照不同炸药量和致伤距离所产生的压强,将60只新西兰大白兔按随机数字表法分为5个致伤组和1个无致伤对照组.伤后观察存活率和组织病理学,并监测病理生理学指标、肺含水量.结果 冲击波压强低于1 210.5 mm Hg(1 mm Hg=0.133 kPa,A、B组)时,肺损伤较轻,表现为点状肺挫伤,肺简明损伤评定分级法(ALS)均在2级内,动物伤后24 h内全部恢复,长期存活无并发症.冲击波压强高于2 036.1 mm Hg(D、E组)时,肺损伤过重,表现为广泛的肺挫伤、肺门撕裂伤和肺内大血肿,AIS均大于5级,动物于伤后1 h内全部死亡.冲击波压强为1 917.3 mm Hg(C组)时,肺表现为广泛而恒定的挫伤,累及4个肺叶以上,AIS 4～5级,伤后6 h内出现动脉氧分压下降;肺组织可见肺泡壁水肿,部分肺泡壁断裂,肺泡融合;肺泡内充满大量炎性细胞,偶见透明膜形成.与对照组比较,C组兔致伤6 h肺湿/干重比值即显著升高(6.46±0.24比3.98±0.19,P＜0.01),血浆及支气管肺泡灌洗液(BALF)中肿瘤坏死因子-α(TNF-α)和白细胞介素-6(IL-6)即明显升高血浆TNF-α(ng/L):328.89±6.26比62.12±2.98,BALF TNF-α(ng/L):164.87±4.59比29.51±1.12;血浆IL-6(ng/L):128.51±4.13比19.32±1.53,BALF IL-6(ng/L):94.97±1.14比22.72±0.19,均P＜0.05].结论 在1 917.3 mm Hg爆炸压强的密闭环境下,冲击伤可诱导兔发生ARDS;TNF-α及IL-6参与爆震伤致ARDS的形成与发展;特定环境下,肺脏破裂致气胸为早期死亡原因,而冲击波致循环系统功能紊乱也是引起早期死亡的重要原因.

Abstract：

Objective To reproduce acute respiratory distress syndrome (ARDS) model in rabbit induced by chest blast injury and to analyze the pathogenesis and causes of early death in order to provide the basis for the early diagnosis of lung blast injury and its early-warning system to facilitate an early treatment.Methods Sixty healthy New Zealand white rabbits were divided into six groups according to the different explosion distance with the random number table method. The survival rate and its resulting pathological changes were observed and patho-physiological indexes and lung fluid content were determined at sequential time points post-explosion. Results Shock wave pressure less than 1 210. 5 mm Hg (1 mm Hg=0. 133 kPa,group A, B) resulted in limited injury to the lung within grade-2 as assessed with the abbreviated injury scale (AIS). The rabbits in these groups recovered soon and survived without any complication. Shock pressure higher than 2 036. 1 mm Hg (group D, E) caused severe injuries to the lung, including deep laceration, disruption of lung hilus and large hematoma in the lung, and the injury severity of lungs was assessed above grade-5 as assessed with AIS. All rabbits died within 1 hour post-explosion. The groups described above failed to meet the demand of an ARDS model for the present study. Shock wave pressure at 1 917. 3 mm Hg (group C) produced extensive contusion from grade-4 to grade-5 as assessed with AIS. The rabbits survived in poor general condition, and arterial partial pressure of oxygen (PaO2) lowered within 6 hours. Pathological examination showed extensive and constant multi-focal bleeding involving more than four lobes. The alveolar wall was edematous, with partial rupture and alveolar fusion in lung tissues was observed in the group C. Alveoli were filled with inflammatory cells, and hyaline membrane was formed occasionally. Compared with control group, the wet to dry weight ratio (W/D) in lungs increased obviously (6.46±0. 24 vs. 3. 98±0. 19, P＜ 0. 01) in group C within 6 hours postinjury. The contents of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in plasma and bronchoalveolar lavage fluid (BALF) were also increased distinctly compared with the control group TNF-α (ng/L) in plasma: 328. 89± 6.26 vs.62.12±2. 98, TNF-α (ng/L) in BALF: 164.87±4.59 vs. 29. 51±1.12; IL-6 (ng/L) in plasma: 128. 51±4.13 vs. 19.32±1.53: IL-6 (ng/L) in BALF: 94.97±1.14 vs. 22.72±0. 19, all P＜0. 05]. Conclusion In an airtight environment, rabbit ARDS model can be reproduced successfully by blast injury with 1 917.3 mm Hg explosion pressure; TNF-α and IL-6 are involved in the pathogenesis and development of ARDS in blast injury. Pneumothorax as a result of lung rupture is the chief reason for early death and dysfunction of circulatory system is also an important reason in producing early death.

Experimental study on acute respiratory distress syndrome and analysis of relevant factors in rabbits subjected to thoracic blast trauma

Objective To reproduce acute respiratory distress syndrome (ARDS) model in rabbit induced by chest blast injury and to analyze the pathogenesis and causes of early death in order to provide the basis for the early diagnosis of lung blast injury and its early-warning system to facilitate an early treatment.Methods Sixty healthy New Zealand white rabbits were divided into six groups according to the different explosion distance with the random number table method. The survival rate and its resulting pathological changes were observed and patho-physiological indexes and lung fluid content were determined at sequential time points post-explosion. Results Shock wave pressure less than 1 210. 5 mm Hg (1 mm Hg=0. 133 kPa,group A, B) resulted in limited injury to the lung within grade-2 as assessed with the abbreviated injury scale (AIS). The rabbits in these groups recovered soon and survived without any complication. Shock pressure higher than 2 036. 1 mm Hg (group D, E) caused severe injuries to the lung, including deep laceration, disruption of lung hilus and large hematoma in the lung, and the injury severity of lungs was assessed above grade-5 as assessed with AIS. All rabbits died within 1 hour post-explosion. The groups described above failed to meet the demand of an ARDS model for the present study. Shock wave pressure at 1 917. 3 mm Hg (group C) produced extensive contusion from grade-4 to grade-5 as assessed with AIS. The rabbits survived in poor general condition, and arterial partial pressure of oxygen (PaO2) lowered within 6 hours. Pathological examination showed extensive and constant multi-focal bleeding involving more than four lobes. The alveolar wall was edematous, with partial rupture and alveolar fusion in lung tissues was observed in the group C. Alveoli were filled with inflammatory cells, and hyaline membrane was formed occasionally. Compared with control group, the wet to dry weight ratio (W/D) in lungs increased obviously (6.46±0. 24 vs. 3. 98±0. 19, P＜ 0. 01) in group C within 6 hours postinjury. The contents of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in plasma and bronchoalveolar lavage fluid (BALF) were also increased distinctly compared with the control group TNF-α (ng/L) in plasma: 328. 89± 6.26 vs.62.12±2. 98, TNF-α (ng/L) in BALF: 164.87±4.59 vs. 29. 51±1.12; IL-6 (ng/L) in plasma: 128. 51±4.13 vs. 19.32±1.53: IL-6 (ng/L) in BALF: 94.97±1.14 vs. 22.72±0. 19, all P＜0. 05]. Conclusion In an airtight environment, rabbit ARDS model can be reproduced successfully by blast injury with 1 917.3 mm Hg explosion pressure; TNF-α and IL-6 are involved in the pathogenesis and development of ARDS in blast injury. Pneumothorax as a result of lung rupture is the chief reason for early death and dysfunction of circulatory system is also an important reason in producing early death.