Effects of prone ventilation in rats with pulmonary acute lung injury

Abstract

Objective To investigate the effects of prone ventilation in rats with lipopolysaccharide (LPS) induced pulmonary acute lung injury (ALI). Methods Totally 32 male Sprague-Dawley rats were randomly divided into four groups, 8 rats in each group: control group, pulmonary ALI group, supine position group (ALIS) and prone position group (ALIP). Rats in the ALI, ALIS, and ALIP groups were given 6 mg/kg LPS intratracheally to build the ALI rat model. After 24 h, rats in the ALIS and ALIP groups were were mechanically ventilated for 4 h in supine or prone positions. After that, PaO2 and PaCO2 of arterial blood, lung tissue wet/dry weight ratio (W/D), tumour necrosis factor-alpha (TNF-α) and interleukin-6(IL-6) concentrations in serum were compared in these four groups, and lung tissue morphometric analysis was inverstigated under light microscope at the same time. Results Compared with the control group, PaO2 were significantly lower in the ALI, ALIS and ALIP groups (F = 57.369, P < 0.001); PaCO2 in the ALI and ALIS groups were obviously higher (F = 8.448, P < 0.001); lung tissue W/D ratio, as well as the levels of TNF-α and IL-6 in serum were significantly higher in the ALI, ALIS and ALIP groups (F = 13.609, 6.443, 23.849; P = 0.001, 0.017, < 0.001). Compared with the ALI group, PaO2 in the ALIS and ALIP groups was significantly higher, but lung tissue W/D ratio, TNF-α and IL-6 in serum were obviously lower in these two groups (all P< 0.05). Compared with the ALIS group, except PaO2 was higher [(83 ± 6) mmHg vs. (71 ± 5) mmHg], PaCO2 [(50 ± 7) mmHg vs. (58 ± 6) mmHg, P < 0.05], lung tissue W/D ratio [(4.65 ± 0.56) vs. (4.82 ± 0.41), P < 0.05, TNF-α and IL-6 in serum [(293 ± 68) ng/L vs. (366 ± 44) ng/L; (358 ± 39) ng/L vs. (440 ± 38) ng/L; all P < 0.05] were obviously lower in the ALIP group. Meanwhile under light microscope, compared with the ALIS group, hyper-inflated areas were less (F = 63.423, P < 0.001), normal areas were larger (F = 73.229, P < 0.001) on the ventral side in the ALIP group. Also, normal and hyper-inflated area were greater (F = 61.871, P < 0.001; F = 9.800; P = 0.001) when the collapsed area was less (F = 68.586, P < 0.001) on the dorsal side in the ALIP group. Conclusion In LPS-induced pulmonary ALI rats model, the prone ventilation improved gas exchange, decreased pulmonary edema with attenuate inflammatory responses. Key words: Prone ventilation; Acute lung injury; Lipopolysaccharides; Rat, Sprague-Dawley