Effect Of Lung Local Hypothermia And Low Tidal Volume Ventilation On Respiratory In Acute Respiratory Distress Syndrome Dogs

Objective:To study effects of body temperature, pneodynamics and Lung histopathology changes in acute respiratory distress syndrome (ARDS)dogs by lung local hypothermia and low tidal vloume mechanical ventilation, To search for a new ventilation method and its effect on respiratory mechanics.Methods:Tewnty-four healthy male dogs were randomly allocated to four groups (n=6),each group has six dogs, these are: local hypothermia and low tidal vloume mechanical ventilation, local hypothermia and traditional tidal volume ventilation, room temperature and low tidal volume ventilation,room temperature and traditional tidal volume ventilation. The animals were endotracheal intubated and mechanical ventilated with hypothermia (-2~0℃) and room air (25±0.5℃) respectively, low tidal volume and tratitional volume ventilation parameters were set as(VT=6ml/kg,RR=20bpm,I:E=1:2) and ( VT=12ml/kg, RR=12bpm, I:E=1:2 ) in each group. The respiratory mechanical parameters (Pplat, Raw , Cst , PaO2/FiO2 , PaCO2, HCO3-)were observed before oleic acid injection, at the time of ARDS and at 1h, 2h, 3h after ARDS, plasma cytokine(IL-6, TNF-α)concentration of blood were determined by ELISA at the time of 3h after ARDS, in the end, histopathologic changes of lung tissue were observed under light microscopy.Results:At the time after ARDS, the plateau pressure and airway resistance increased and lung compliance decreased significantly, after treatment with mechanical ventilation strategies, The Pplat, Raw, Cst of HL group were differences compared to HT group and RT Group (P <0.05), the Pplat, Raw, Cst of HL group have improved compared to RL group, but have no clear differences(P>0.05; at the time of 3h after ARDS, the PaO2 of HL group was significantly higher than other groups; after ARDS,the PaCO2, pH value of HL group were difference compared to the HT group (P <0.05); the HCO3- of each group were decreased after ARDS, at the time of 3h after ARDS, the HCO3- of HL group was difference compared to RT group; the IL-6, TNF-αconcentration and the degree of lung tissue injury of HL group was significantly lower than other groups. Conclusion:First, the lung local hypothermia and low tidal vloume ventilation can reduce the airway plateau pressure and airway resistance, improving pulmonary compliance.Second, the lung local hypothermia and low tidal volume lung ventilation can reduce the IL-6 , NTF-αlevels of the lung, reduce the severity of lung injury and improve oxygenation index and protect the lung tissue.