| A deficiency or a dysfunction of pulmonary surfactant causes the neonatal respiratory distress syndrome (RDS). The incidence of RDS is inversely related to gestational age and birth weight, and the mortality of RDS rate is about 10 -40% in USA and 30 -50% in China. A diagnosis of RDS is usually dependent on typical chest radiogram and clinical features, and it' s difficult to make a diagnosis of RDS in the early stage, when pulmonary surfactant therapy may have better effect. In abroad reports on bedside pulmonary function test (PFT) in extremely low birth weight infants with RDS showed that PFT is helpful for diagnosis of RDS in first day, but the conclusion is not unification. We conduct the study that comparing PFT results between RDS group and non - RDS group aiming at demonstrating that PFT is effective in making a diagnosis of RDS in the very early stage. At the same time we investigated the dynamic changes of pulmonary function in infants with RDS in order to provide important clinical information.Patients and MethodsWe studied 42 preterm infants in our NICU. The RDS group included 21 infants and the other group included 21 infants without RDS. All the RDS infants needed conventional ventilation. Seven infants in non - RDS group also needed conventional ventilation. All the infants followed the NICU's routine policies. Equipment for bedsidePFT in preterm infants used the flow - through technique and esopha-geal pressure measurements. The infant was placed supine with the neck in neutral positions. For assessment of pulmonary function, e-sophageal pressure changes were measured using a catheter tip pressure transducer. We used two methods perform all the pulmonary function testing. When the infant was ventilated we inserted the VarFlex Flow Transducer between ventilator circuit and endotracheal tube adapter. When the infants breathed spontaneously we measured the flow using pneumotachometer through facemask. Daily measurements of pulmonary function were made in all babies during the first five days and then at one week of age. The pulmonary function parameters include lung dynamic compliance, work of breathing, airway resistance, tidal volume and minute ventilation.Statistical MethodsDifferences between groups were tested by means of t - tests. Differences were assessed for statistical significance using ANOVA for repeated measurements. All statistical computations were performed u-sing computer software SPSS10. 0 for windows. The pediatrician who made the diagnosis was unaware of the pulmonary function test results of the RDS infants.ResultsAll the RDS infants needed mechanical ventilation. Three infants died, and after seven infants'parents gived up, there were ten babies died. In non - RDS group seven babies ventilated with ventilator. Twobabies died, after their parents gived up. Significant differences were found between the RDS group and the non - RDS group with regard to the compliance in the first three days ( p <0. 01) . Significant differences were found between the RDS group and the non - RDS group with regard to work of breathing in first five days ( p < 0. 01). There were no significant differences with regard to the airway resistance. There were no significant differences with regard to the tidal volume and minute ventilation.DiscussionIn our investigation all the infants have respiratory distress symptoms soon after birth, and all the DOWNES SCORES for the infants were over 6. Because all the babies were premature, they had poor respiratory muscle function and respiratory control and they were easy to have respiratory failure. Because two group infants had different diseases, the RDS infants had worse pulmonary function than the non -RDS. Pulmonary function measurements are useful in identifying infants with RDS and predicting the prognoses. All the infants had lung diseases, which restricted their ventilation, and all of them had low tidal volume and minute ventilation. There was no significant difference between two groups, which was coincidence with clinic... |
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