[Changes of arterial blood gas indexes of free-field primary blast lung injury of pigs and its application value].

To observe the changes of arterial blood gas indexes in pigs with the free-field primary blast lung injury (PBLI) model, and to explore the value of arterial blood gas indexes in predicting moderate to severe PBLI.Nine adult healthy Landrace pigs were selected to construct the pig free-field PBLI model. Arterial blood samples were taken 15 minutes before the explosion (before injury) and 10, 30, 60, 120, and 180 minutes after the explosion (after injury). Arterial blood gas indexes and pulse oxygen saturation (SpO2) were measured, compare the changes of blood gas analysis indexes and SpO2 levels at different time points, and observe the changes of gross injury scores and pathological injury scores of lung tissue. Analyze the correlation between the blood gas indicators.As time prolonged, at each time point, pH, arterial partial pressure of oxygen (PaO2), and SpO2 were lower than those before the injury, and blood lactic acid (Lac) and arterial partial pressure of carbon dioxide (PaCO2) were higher than those before the injury. Compared with that before the injury, the pH value in the blood decreased significantly 10 minutes after the injury (7.39±0.06 vs. 7.46±0.02, P < 0.05), and the Lac increased significantly (mmol/L: 3.61±2.89 vs. 1.10±0.28, P < 0.05), and lasts until 180 minutes after injury (pH value: 7.37±0.07 vs. 7.46±0.02, Lac (mmol/L): 2.40±0.79 vs. 1.10±0.28, both P < 0.05); while PaO2 and SpO2 decreased significantly at 180 minutes after injury [PaO2 (mmHg, 1 mmHg = 0.133 kPa): 59.40±10.94 vs. 74.81±9.39, P < 0.05; SpO2: 0.75±0.11 vs. 0.89±0.08, P < 0.05], PaCO2 increased significantly (mmHg: 56.17±5.38 vs. 48.42±4.93, P < 0.05). Correlation analysis showed that the gross injury score of lung blast injury animals was positively correlated with the pathological injury score (r = 0.866, P = 0.005); PaO2 and SpO2 were positively correlated (r = 0.703, P = 0.000); pH value and Lac were negative Correlation (r = -0.400, P = 0.006); pH value is negatively correlated with PaCO2 (r = -0.844, P = 0.000).This study successfully established a large mammalian free-field PBLI model, arterial blood gas analysis is helpful for the early diagnosis of PBLI, whether SpO2 can be used to evaluate the severity of lung injury remains to be further verified.