创伤后呼吸机相关肺炎发病机制探讨

Pathogenesis of post-traumatic ventilator-associated pneumonia

目的探讨创伤后机械通气患者口咽部菌群变化在呼吸机相关肺炎（ventilator-as-sociatedpneumonia，VAP）内源性发病机制中的作用。方法收集45例创伤后发生VAP的患者，在人工气道建立后1，3，7和14d收集患者的口咽部分泌物、声门下分泌物、深部气道痰液以及胃液进行培养和药敏检测，同时收集患者的大便进行球杆比和真菌检测，对比其声门下分泌物、痰液、胃液和口咽部分泌物菌群的一致率。结果VAP患者的病原菌主要为G^-菌，随着机械通气时间的延长，声门下分泌物、痰液和胃液病原学培养的阳性率逐渐升高，声门下分泌物、痰液、胃液和口咽部分泌物菌种的一致率明显上升；并且随着机械通气天数的增加，培养产β-内酰胺酶阳性（ESBL＋）的细菌和多重耐药菌的例数也明显增加。结论口咽部菌群变化与创伤后VAP的发生关系密切，胃内细菌常逆向定植于口咽部，胃-咽-下呼吸道的逆行感染为VAP的重要感染途径。

Objective To study the role of changes of oropharyngeal microflora in pathogenesis of post-traumatic ventilator-associated pneumonia （VAP）. Methods Forty-five patients with post-trau- matic VAP treated with intubation and mechanical ventilation were involved in the study. Microbiologic cultures and drug-sensitivity test of oropharyngeal secretions, subglottic secretions, sputum from deep air- way and gastric fluid samples were performed at days 1, 3, 7 and 14 after mechanical ventilation. The stool samples were collected to detect the coccus and bacillus ratio and the fungus. The concordance rate of microflora among subglottic secretions, sputum, gastric fluid and oropharyngeal secretions were com- pared. Results The main pathogens for VAP patients were gram-negative bacilli. The study showed an increase in aspects of the positive rate of etiology cultures of subglottic secretions, sputum and gastric fluid samples, the concordance rate of microflora among subglottic secretions, sputum, gastric fluid and oropharyngeal secretions and the number of ESBL ＋ and multi-resistant bacteria, along with the prolonged mechanical ventilation. Conclusions The changes of oropharyngeal microflora are closely associated with the development of VAP. The enterobacteria in the gastric cavity always reversely colonize in the oro- pharynx and the retrograde stomach-pharynx-lower respiratory tract infection is a major infection route of VAP.