Abstract Rationale Extreme preterm birth is a recognized risk factor for reduced pulmonary function over an individual’s lifetime. We recently identified lower respiratory muscles forces in adolescents and adults born preterm. Here, we aimed to evaluate the neonatal factors contributing to the decreased respiratory muscle forces after preterm birth. Methods Preterm participants aged 12-40 years of age were recruited from the Parkland Hospital Neonatal ICU Registry (Dallas County, Texas). Healthy term-born participants were recruited from the surrounding area. All participants completed pulmonary function testing including maximal voluntary ventilation (MVV) measured with a Sensormedics Vmax 229 Pulmonary Function instrument. Predicted values were calculated with Global lung initiative (GLI) race-neutral reference equations. Maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) maneuvers were conducted with a Marshalltown pressure gauge, with best of 3 maneuvers recorded. Handgrip testing was conducted in both hands to determine maximal voluntary contraction using the Northstar echo grip (JTECH Medical, Midvale, UT). Statistical tests included Fisher’s exact and Unpaired T-tests. Multiple linear regression using Prism software. (Version 10, GraphPad Software Inc., La Jolla, CA). Results Participants included 105 preterm and 48 term individuals. Baseline characteristics, pulmonary function results and multivariate analysis are presented in the attached Table 1. Overall, spirometry and lung volumes were similar between preterm and term participants. All respiratory muscle force measurements were significantly lower in the preterm compared to the term group (MIP: 81.3±20.7 vs 71.3±27.6 mmHg, MEP: 88.7±34.9 vs 63.3±28.2 mmHg, MVV: 90.2±19.4 vs 75.8±20.5% term vs preterm, respectively). Multivariate models were constructed to further explore the differences in pulmonary muscle pressure measurements between the two groups. The strongest multivariate models included sex, BMI, and gestational age to predict MIP (R2 = 0.31, P 0.001), MEP (R2 = 0.25, P 0.001) and MVV (R2 = 0.13, P = 0.0002). Other neonatal factors described in table 1 when compared or added to gestational age were not found to be as predictive. MIP, MEP, and MVV also correlated well with hand grip, demonstrating multisite skeletal muscle weakness. Conclusions Individuals born premature demonstrated significantly lower respiratory muscle forces compared to a term born control population. Multivariate analysis revealed a potential relationship between gestational age and respiratory muscle strength even after controlling for sex and BMI differences. This abstract is funded by: Southwestern Health Resources Academic Affiliation Committee, Award from the American Heart Association, Doris Duke Charitable Foundation, and the Harry S. Moss Heart Trust
Wall et al. (Fri,) studied this question.