BIRTH-WEIGHT AND EARLY LUNG COMPLIANCE AS PREDICTORS OF SHORT-TERM OUTCOME IN PREMATURE-INFANTS WITH RESPIRATORY-DISTRESS SYNDROME

In addition to birth weight (BW), respiratory mechanics measured durin g the first week of life have been reported to predict outcome in vent ilated newborn infants with respiratory distress syndrome (RDS). Most measuring techniques are invasive, requiring the placement of an oesop hageal tube or balloon. in the present study the compliance (Crs) and resistance (Rrs) of the total respiratory system were measured without an oesophageal tube, using a commercially available system (PEDS; MAS Inc., Hatfield, Pa.). The Grs and Rrs were determined once, within 24 hours of birth, in 28 preterm infants requiring mechanical ventilatio n for RDS. Variables such as gestational age (GA) and BW were also eva luated for their predictive role in outcome. Poor outcome was defined as death from respiratory failure or the development of bronchopulmona ry dysplasia (BPD) at 28 days. All non-survivors died of refractory re spiratory failure, at a median age of 6 days. The median Crs of the 21 survivors was 0,5 ml/cm H2O and of the non-survivors 0,21 ml/cm H2O ( P = 0,01). Crs below 0,45 ml/cm H2O predicted 15 of the 16 infants who either developed BPD or died (positive predictive value 100%; negativ e predictive value 92%; sensitivity 94%; specificity 100%). Nine survi vors, who subsequently developed BPD, had a median Grs of 0,38 ml/cm H 2O. Their Crs was significantly lower than that of the infants without evidence of BPD (Crs = 0,61 ml/cm H2O) (P = 0,01). All of the 12 babi es without BPD who survived had median Crs values above 0,45 ml/cm H2O . The median Rrs of the 9 infants with BPD (96 cm H2O/I/s) was also si gnificantly higher than the Rrs value of the non-BPD group (59 cm H2O/ I/s) (P = 0,05). When stepwise multiple logistic regression was applie d to predict outcome, the only variable that could be entered at a 0,0 5 level of significance was BW. Uncorrected compliance entered the sec ond step, but did not reach statistical significance. We conclude that in premature infants with RDS; BW is a strong predictor of outcome. A lthough determination of the Crs within the first 24 hours after birth did not add significance to this predictive model, it was nevertheles s a useful parameter to determine respiratory morbidity and mortality.