Presurgical pulmonary function tests in the first few days of life in neonates with congenital heart disease, a pilot study.

OBJECTIVE: To compare early pulmonary function tests (PFTs) in neonates with critical congenital heart disease (CHD) compared to a historical reference group. DESIGN: Infants ≥ 37 weeks gestation with critical CHD were studied within the first few days of life, prior to cardiac surgery, and compared to data from a published reference group of healthy term neonates without CHD, studied at the same institution. Passive respiratory resistance (Rrs) and compliance (Crs) were measured with the single breath occlusion technique following specific acceptance criteria. The study was powered for a 30% difference in Rrs. RESULTS: PFTs in 24 infants with CHD were compared to 31 historical reference infants. There was no difference in the Rrs between the groups. The infants with CHD had a significantly decreased Crs (1.02 ± 0.26 mL/cmH2O/kg versus 1.32 ± 0.36; (p < 0.05; mean ± SD)). CONCLUSIONS: Further prospective studies are required to quantify early PFTs in infants with CHD of different phenotypes.

Presurgical Pulmonary Function Tests in the First Few Days of Life in Neonates with Congenital Heart Disease, A Pilot Study.

Objective: To compare early pulmonary function tests (PFTs) in neonates with critical congenital heart disease (CHD) compared to a historical reference group. Design: Infants > 37 weeks gestation with critical CHD were studied within the first few days of life and prior to cardiac surgery and compared to data from a published reference group. Passive respiratory resistance (Rrs) and compliance (Crs) were measured with the single breath occlusion technique following specific acceptance criteria. The study was powered for a 30% difference in Rrs. Results: PFTs in 24 infants with CHD were compared to 31 historical reference infants. There was no difference in the Rrs between the groups. The infants with CHD had a significantly decreased Crs (1.02 ± 0.26 mL/cmH2O/kg versus 1.32 ± 0.36; (p < 0.05; mean ± SD)). Conclusions: Further prospective studies are required to quantify early PFTs in infants with CHD of different phenotypes.

Perioperative Improvement in Pulmonary Function in Infants with Congenital Diaphragmatic Hernia.

OBJECTIVE: The objective of this study was to compare serial changes in pulmonary function in contemporary infants with congenital diaphragmatic hernia managed with a gentle ventilation approach. STUDY DESIGN: Observational cohort, single-center study of infants ≥350/7 weeks gestation at delivery with congenital diaphragmatic hernia. Functional residual capacity (FRC), passive respiratory compliance, and passive respiratory resistance were measured presurgical and postsurgical repair and within 2 weeks of discharge. A 1-way analysis of variance for repeated measures was used to evaluate the change in FRC, passive respiratory compliance, and passive respiratory resistance over these repeated measures. RESULTS: Twenty-eight infants were included in the analysis with a mean gestational age of 38.3 weeks and birth weight of 3139 g. We found a significant increase in FRC across the 3 time points (mean in mL/kg [SD]: 10.9 [3.6] to 18.5 [5.2] to 24.2 [4.4]; P < .0001). There was also a significant increase in passive respiratory compliance and decrease in passive respiratory resistance. In contrast to a previous report, there were survivors in the current cohort with a preoperative FRC of <9 mL/kg. The mean FRC measured at discharge was in the range considered within normal limits. Sixteen infants had prenatal measurements of the lung-to-head ratio, but there was no relationship between the lung-to-head ratio and preoperative or postoperative FRC measurements. CONCLUSIONS: Infants with congenital diaphragmatic hernia demonstrate significant increases in FRC and improvements in respiratory mechanics measured preoperatively and postoperatively and at discharge. We speculate these improvements are due to the surgical resolution of the mechanical obstruction to lung recruitment and that after achieving preoperative stability, repair should not be delayed given these demonstrable postoperative improvements.

Pulmonary Function Tests in Very Low Birth Weight Infants Screened for Pulmonary Hypertension: A Pilot Study.

OBJECTIVE: To compare pulmonary function tests (PFTs), specifically respiratory system resistance (Rrs) and compliance (Crs), in very low birth weight (VLBW) infants with and without pulmonary hypertension. STUDY DESIGN: Infants were included who underwent PFTs at 34-38 weeks postmenstrual age (PMA) as part of our pulmonary hypertension screening guidelines for infants born at ≤1500 g requiring respiratory support at ≥34 weeks PMA. One pediatric cardiologist reviewed and estimated right ventricular or pulmonary arterial pressure and defined pulmonary hypertension as an estimated pulmonary arterial pressure or right ventricular pressure greater than one-half the systemic pressure. Rrs and Crs were measured with the single breath occlusion technique and functional residual capacity with the nitrogen washout method according to standardized criteria. RESULTS: Twelve VLBW infants with pulmonary hypertension and 39 without pulmonary hypertension were studied. Those with pulmonary hypertension had significantly lower birth weight and a trend toward a lower gestational age. There were no other demographic differences between the groups. The infants with pulmonary hypertension had significantly higher Rrs (119 vs 78 cmH2O/L/s; adjusted P = .012) and significantly lower Crs/kg (0.71 vs 0.92 mL/cmH2O/kg; P = .04). CONCLUSIONS: In this pilot study of VLBW infants screened for pulmonary hypertension at 34-38 weeks PMA, those with pulmonary hypertension had significantly increased Rrs and decreased Crs compared with those without pulmonary hypertension. Additional studies are needed to further phenotype infants with evolving BPD and pulmonary hypertension.