• Xiao-Yan Wu, Ying-Zi Huang, Huo-Gen Liu, Dong-Ya Huang, Rui Tang, and Hai-Bo Qiu.
• Department of Critical Care Medicine, Nanjing Zhongda Hospital, Southeast University School of Clinical Medicine, Nanjing 210009, China (Wu XY, Huang YZ, Liu HG, Huang DA, Tang R, Qiu HB); Subei People's Hospital & Clinical Medical School, Yangzhou University ,Yangzhou 225001, China (Wu XY).
• World J Emerg Med. 2011 Jan 1; 2 (4): 296-301.

BackgroundPulmonary stretch reflex plays an important role in regulation of respiratory movement. This study aimed to evaluate the effect of pulmonary stretch reflex on lung injury in rabbits with acute respiratory distress syndrome (ARDS).MethodsARDS rabbits were given intratracheal infusion of hydrochloric acid and ventilated with neurally adjusted ventilatory assistance (NAVA) with a tidal volume (VT) of 6 mL/kg and the electrical activity of diaphragm (EAdi)-determined positive end expiratory pressure. After isolation of the bilateral vagus nerve trunk, the rabbits were randomized into two groups: sham operation (SHAM) group (n=5) and bilateral vagotomy (VAG) group (n=5). Gas exchange and respiratory mechanics were detected at baseline, after lung injury and 1, 2, and 3 hours after ventilation respectively. Pulmonary permeability index, pathological changes and inflammatory response were also measured.ResultsCompared with the SHAM group, PaO2/FiO2 in the VAG group decreased significantly 2 and 3 hours after ventilation (P<0.05). There was no significant difference in PaCO2 between the SHAM and VAG groups (P>0.05), and the VAG group had a high VT, peak pressure (Ppeak), and mean pressure (Pm) compared with the SHAM group 1, 2, 3 hours after ventilation (P<0.05). Compared to the SHAM group, dead space fraction (VD/VT) and respiratory system elastance (Ers) in the VAG group increased (P<0.05) and static pulmonary compliance (Cst) decreased markedly (P<0.05) after ventilation for 3 hours. Lung wet/dry weight ratio (W/D) (8.4±1.2 vs. 6.6±1.0), lung injury score (6.3±1.8 vs. 3.8±1.3), tumor necrosis factor-α (TNF-α) (779±372 pg/mL vs. 355±130 pg/mL) and interleukin-8 (IL-8) (169±21 pg/mL vs. 118±17 pg/mL) increased significantly in the VAG group compared with the SHAM group (P<0.05).ConclusionLung injury is aggravated after bilateral vagotomy, demonstrating that pulmonary stretch reflex may have protective effect on the lung.

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