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Pulmonary Function Tests in Very Low Birth Weight Infants Screened for Pulmonary Hypertension: A Pilot Study
John D Adair1, Brendan Kelly2, Diane Schilling1
1Division of Neonatology, Department of Pediatrics, Oregon Health & Science University, Portland, OR.
Insights
Very low birth weight (VLBW) infants with pulmonary hypertension show higher respiratory system resistance and lower compliance. These pulmonary function test findings highlight differences in lung mechanics for VLBW infants with this condition.
Area of Science:
- Neonatal Medicine
- Pediatric Pulmonology
- Respiratory Physiology
Background:
- Pulmonary hypertension is a serious complication in very low birth weight (VLBW) infants.
- Pulmonary function tests (PFTs) are crucial for assessing lung function in this vulnerable population.
- Understanding the impact of pulmonary hypertension on respiratory mechanics is essential for management.
Purpose of the Study:
- To compare PFTs, specifically respiratory system resistance (Rrs) and compliance (Crs), in VLBW infants with and without pulmonary hypertension.
- To identify potential PFT markers for pulmonary hypertension in VLBW infants.
Main Methods:
- A cohort of VLBW infants (born ≤1500 g) requiring respiratory support were screened for pulmonary hypertension at 34-38 weeks postmenstrual age (PMA).
- Pulmonary hypertension was defined by estimated pulmonary arterial or right ventricular pressure.
- Rrs and Crs were measured using the single breath occlusion technique and functional residual capacity via nitrogen washout.
Main Results:
- Twelve VLBW infants with pulmonary hypertension and 39 without were analyzed.
- Infants with pulmonary hypertension had significantly lower birth weight.
- Significantly higher Rrs (119 vs 78 cmH2O/L/s) and lower Crs/kg (0.71 vs 0.92 mL/cmH2O/kg) were observed in infants with pulmonary hypertension.
Conclusions:
- VLBW infants with pulmonary hypertension exhibit significantly increased Rrs and decreased Crs compared to those without.
- These findings suggest distinct respiratory system mechanics in VLBW infants with pulmonary hypertension.
- Further research is needed to phenotype infants with evolving bronchopulmonary dysplasia and pulmonary hypertension.
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.
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