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Objective: To observe the cryogenic gas mechanical ventilation on canine body temperature, respiratory mechanics, blood gas parameters and lung histopathology, and to explore a new method of lowering body temperature and respiration of the method. Methods: 18 healthy male mongrel dogs were randomly divided into two groups, namely hypothermia group, normothermia group. Underwent endotracheal intubation mechanical ventilation, hypothermia group and normal group were pass gas at 4 ℃ and 25 ℃ ambient temperature gases, two respiratory parameters are set to: VT = 15ml/kg; RR = 15bpm; I: E = 1:2 . Dog timer is started immediately after intubation (ie 0min as baseline), continuous observation 240min. 0min 30min to 240 min each time point were nine dogs were observed and recorded nasopharyngeal temperature, axillary temperature, blood temperature. Take 0min, 30min, 1h, 2h, 3h, 4h time points were five dogs were observed and recorded arterial blood gas data (PaO2, PaCO2, PH) and respiratory mechanics data (Raw, PIP, Cstat). 0min, 2h, 4h blood of three time points were measured by ELISA IL-6, TNF-α concentrations. Finally in lung tissue pathological changes were observed under light microscope. Results: hypothermia group and the normal body temperature of groups of different ventilation time (nasopharyngeal temperature, axillary temperature, blood temperature) difference was not statistically significant (P gt; 0.05); during mechanical ventilation, PaO2 30min after hypothermia group was significantly lower than normal group ( 367.02 ± 17.10vs388.69 ± 10.99mmHg) (P lt; 0.05); hypothermia group and the normal group PO2 30min point unless there is a difference, the other time points were undifferentiated groups PO2 (P gt; 0.05); Low group and the normal group at each time point in PaCO2, PH and various respiratory mechanics parameters (Raw, Ppeak, Cstat) were not significantly different (P gt; 0.05). At 2h, 4h time points hypothermia group and normal group, IL-6 levels were significantly higher than baseline values (P lt; 0.05), the ventilation 2h, 4h time points hypothermia group IL-6 concentrations were (0.29 ± 0.02,0.28 ± 0.02) ng · mL-1 were significantly lower than normal temperature group corresponding time points (0.31 ± 0.33, 0.30 ± 0.03) ng · mL-1; 2h time point at normothermia group hypothermia group and TNF-α concentrations were significantly higher than baseline values ( P lt; 0.05), but the two groups at each time point the concentration of TNF-α was no significant difference (P gt; 0.05); hypothermia group cumulative average rating of lung tissue (2.44 ± 1.03) was significantly lower than normal group (4.01 ± 1.31) , the difference was statistically significant (P = 0.012). Conclusion: cold gas of mechanical ventilation on canine systemic temperature (hypothermia) had no significant effect; cryogenic gas mechanical ventilation on canine blood gas exchange and respiratory mechanics had no significant effect; mechanical ventilation compared with gas at room temperature 4 ℃ for gas mechanical ventilation can inhibit inflammatory cytokines (IL-6) secretion, reduce lung tissue damage.
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