| Background:Meconium aspiration syndrome(MAS) is a major cause of respiratory morbidity and mortality in neonates. The pathophysiology of MAS is very complicated,including pulmonary inflammation,suifactant inactivation and increased oxygen free radical.MAS can induce acute lung injury,respiratory distress, air leak and persistent pulmonary hypertension of newborn(PPHN).With the improvement in perinatal care, the morbidity of MAS has decreased significantly, but little is known about the number of MAS cases in proportion to the total number of neonatal admission in a tertiary hospital in China. Therefore, collecting and analyzing the clinical data of MAS is of great importance.Inhaled nitric oxide (iNO) has recently been proved to be a selective pulmonary vasodilator, and it can improve oxygenation and inhibit lung inflammation. But NO is also a free radical,it can rapidly combine with superoxide to form the potent oxidant,the peroxynitrite(ONOO-),which inhibit pulmonary surfactant function by lipid peroxidation and damage surfactant proteins.To protect against lung injury induced by oxygen free radicals, we investigated the effects of antioxidants on the lung injury following meconium aspiration.Recombinant human superoxide dismutase(rhSOD) can scavenge reactive oxygen species and alleviate lung injury.Previous studies have indicated that intrathacheal administration of rhSOD is well tolerated with significantly increasing in SOD concentrations and activity in serum,tracheal aspirates and urine within 3 days in premature infants with RDS. And rhSOD can also inhibit inflammation. Little isknown of the effects of rhSOD on the expression of cytokine mRNA in acute lung injury following meconium aspiration.Surfactant consists of phospholipids and proteins. Its function is to reduce surface tension at the air-liquid interface. And surfactant proteins(SP) play an important role in reducing surface tension. Among SPs,SP-B is the most effective substance in promoting rapid spread of surfactant phospholipids.Little is known about rhSOD and iNO on the effect of SP-B mRNA expression following meconium aspiration.In our present studies ,we collected and analyzed the clinical data of MAS to investigate the morbidity trend, complication, the factors relevant to the mortality of MAS.On the other hand ,we estabilished an infant rat model of acute lung injury following meconium aspiration and examined the effects of rhSOD combined with iNO .The aim is to provide possible therapeutic strategies for clinical treatment of this disease.Part1 The clinical retrospective analyse of MASObjective:To investigate the morbidity trend, complication, the factors relevant to the mortality of MAS.Methods: Clinical data of MAS from 1996 to 2003 in the children's hospital of zhejiang university school of medicine were collected and divided into two groups, the first four-year group and the last four-year group. The morbidity trend , complication, mortality between two groups were compared .The risk factors of death induced by MAS in NICU was analyzed.Result: The patients of MAS in proportion to total in-patient neonates appeared decline, there was a great difference between two groups(p<0.01), but the proportion of patients with complication or death to the patients of MAS have no difference between the first four-year group and the last four-year group(p>0.05),The differences of the proportion of patients with PPHN or air leak between death and survive groups were significant (p<0.01).Conclusion: (l)The morbidity of MAS appeared decline,(2)MAS is easy to develop complications including PPHN and air leak,which were related to the high mortality.Part 2 The effect of iNOand rhSOD on the level of MIP-1 a and SP-B mRNA in acute lung injury of infantrats following meconium aspirationObjective: To evaluate the protective effects and possible mechanism of intrathacheal administration of rhSOD combined with inhaled nitric oxide in infant rats acute lung injury following meconium aspiration.Methods: 40 he...
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