Pulmonary Function of Survivors with Bronchopulmonary Dysplasia in Lampang Regional Hospital, Long Term Follow Up

Abstract

BACKGROUND: Bronchopulmonary dysplasia (BPD) is recognized as a major cause of significant pulmonary sequelae in infants with very low birth weight (VLBW), which may extend into adulthood. Previous studies have demonstrated the relationship between low lung function and future chronic obstructive pulmonary disease (COPD) risk. However, no study has been carried out concerning pulmonary function in VLBW BPD patients in Thailand.

OBJECTIVES: To demonstrate pulmonary function and determine possible modifiers in perinatal and postnatal periods that can worsen or ameliorate the pulmonary function outcomes of BPD in VLBW infants.

METHODS: A retrospective chart review was performed using the birth weight ≤1,500 gm and gestational age < 37 weeks of patients who were admitted to the NICU at Lampang Hospital and received follow-up regularly at the outpatient BPD clinic between October 1, 2006 and September 30, 2020. The demographics, clinical data and pulmonary function study results of 66 VLBW BPD patients were analyzed by Chi-square, t- test, linear regression analysis and Multivariate regression analysis.

RESULTS: A total of 55 patients (83%) performed adequate pulmonary function testing (PFT) according to American Thoracic Society and European Respiratory Society standards. The study population was 58% female and had a mean gestational age of 29.5±2.3 weeks with a mean birthweight of 1,111±219 grams. Spirometry was achieved at an average age of 9.1±2.2 years. The majority of patients with BPD (70.9%) performed normally on the pulmonary function test, while 12.7% of the patients exhibited the presence of restrictions as well as obstruction patterns, and only 3.7% had both. The pulmonary function parameters of the 55 patients were compared with a normal population using the Global lung Initiative (GLI) z-score. The mean forced expiratory volume in 1 s (FEV₁) GLI z-score -1.40, forced vital capacity (FVC) GLI z-score -0.82, FEV1/FVC ratio GLI z-score -1.13, forced expiratory flow at 25-75% (FEF _25-75%) GLI z-score -1.79 with lower value associated with oxygen requirement of initial hospital discharge (-0.47±0.12, p<0.001).

Conclusion: The majority of BPD patients in the study had normal pulmonary function results. Patients with severe BPD who required oxygen at the time of hospital discharge were associated with lower pulmonary function parameters.