RIGHT-SIDED PULMONARY APLASIA - LONGITUDINAL LUNG-FUNCTION STUDIES IN2 CASES AND COMPARISON TO RESULTS FROM TERM HEALTHY NEONATES

Agenesis of the right lung was diagnosed prenatally in two neonates bo rn at 36 and 37 weeks, respectively. Computed tomographic scans and ma gnetic resonance imaging indicated that both cases had a Type 2 pulmon ary agenesis, which was confirmed later by bronchoscopy. Both patients were clinically stable during the neonatal period. Serial pulmonary f unction tests revealed a decrease in specific respiratory system compl iance (sCrs) in both neonates and a marked discrepancy between functio nal residual capacity measured by the nitrogen washout technique (FRCN 2) and by plethysmography (FRCpleth) on follow-up. Early decrease of r espiratory system compliance (Crs) and increase of respiratory system resistance (Rrs) in one infant preceded the onset of tracheal stenosis , which remained asymptomatic until the age of 8 weeks, when the infan t developed acute respiratory failure requiring intubation and mechani cal ventilation with high airway pressures. Aortopexy, implantation of a tissue expander into the right hemithorax, and laser ablation of fi brotic tissue at the site of tracheal stenosis were performed to achie ve successful extubation. The second infant remained asymptomatic. Val ues for lung mechanics and volumes for both infants with pulmonary apl asia were as follows: Crs, 3.43 and 10.60 mL.kPa(-1).kg(-1); sCrs, 0.2 3 and 1.28 kpa(-1); Rrs, 11.1 and 7.4 kpa.s.L-1; FRCN2, 14.9 and 10.2 mL.kg(-1); FRCpleth, 28.2 and 25.8 mL.kg(-1); FRCN2: FRCpleth ratio, 0 .56 and 0.54 for patients 1 and 2, respectively. These values differed considerably from results of a control group of nine term healthy neo nates (Crs, 10.0 +/- 1.8 mL.kPa(-1).kg(-1); sCrs, 0.43 +/- 0.08 kpa(-1 ); Rrs, 5.10 +/- 0.55 kpa.s.L-1; FRCN2, 24.0 +/- 2.5 mL.kg(-1); FRCple th, 31.1 +/- 6.0 mL.kg(-1); FRCN2:FRCpleth ratio, 0.78 +/- 0.10). In c onclusion, serial assessment of lung mechanics and pulmonary gas volum es detects airway obstruction early in neonates with unilateral lung a genesis. Bronchoscopy is recommended. Along with conventional surgical procedures, an expandable implant may improve management or prevent r espiratory failure in selected cases. Pediatr Pulmonol. 1998; 26:138-1 44. (C) 1998 Wiley-Liss, Inc.