Observation On The Dose Of Methylprednisolone Improving Lung Injury In Swine With Paraquat Intoxication

Objective:To observe influence of different doses of methylprednisolone on acute lung injury caused by paraquat intoxication. Methods:Models of ALI/ARDS were made by an intraperitoneal injection of a large dose of 20% PQ solution 20 millilitres in swine. Then 16 swine were randomly divided into 4 groups: control group(group A), 5mg/kg of methylprednisolone group(group B), 15mg/kg of methylprednisolone group(group C), and 30mg/kg of methylprednisolone group(group D). All groups were based on the conventional rehydration for drug intervention, after modeling, group B, group C, and group D were respectively input methylprednisolone 5mg/kg, 15mg/kg and 30mg/kg. Arterial blood samples were collected for blood gas analysis before modeling and at 0, 12, 24, 36 hours after modeling. Heart rate(HR), extravascular lung water index(EVLWI) were measured by PICCO(pulse indicator continuous cardiac output). swine were executed after medication for 36 hours and lung tissue was obtained by punctureneedle to produce lung biopsy, then observed the pathological changes of lung tissue in the microscope. Results:1. models were made in 3.7 to 5.3 hours after intraperitoneal injection of PQ solution. Heart rate(HR) and mean arterial pressure(MAP) in group A kept going up. At the model was made, heart rate(HR) and mean arterial pressure(MAP) rise in other three groups, but decreased after medication, there was significant difference in all groups at the same time point(P<0.05). 2. extravascular lung water index(EVLWI), semi-quantitative score of lung tissue pathology and pulmonary vascular permeability index(PVPI) kept going up in group A. in other three groups,At the model was made, extravascular lung water index(EVLWI), semi-quantitative score of lung tissue pathology and pulmonary vascular permeability index(PVPI) went up(P<0.05), at the 12 h point, EVLWI and semi-quantitative score of lung tissue pathology declined, especially in group D(P<0.05), then they began to rise, at the 24 h point, compared with group B and C, group D changed the least(P<0.05), but at the 36 h point, group C was the one that made minimal change(P<0.05). After medication, there was no significant change about PVPI in all groups. 3. Oxygenation index in group A decreased during the experiment. Oxygenation index in other there groups decreased at the model was made, After medication, at the 12 h point, oxygenation index rise, group D changed the most(P<0.05), then it began to decline, at the 24 h point, compared with group B and C, group D changed the least(P<0.05), but at the 36 h point, group C was the one that made minimal change(P<0.05). 4. After medication for 36 h, correlation analysis showed that EVLWI were negatively associated with oxygenation index(r=-0.427, P=0.022) and positively associated with semi-quantitative score of lung tissue pathology(r=0.903, P= 0.034). Conclusion:(1) Methylprednisolone can obviously relieve lung injury caused by paraquat poisoning, but the dosage should be decided by the degree of lung injury, not blindly using high-dose glucocorticoids.(2) EVLWI can reflect the degree of lung injury caused by paraquat intoxication...