Lung Function and Exercise Capacity in Young Adults Born Prematurely

Abstract

Vrijlandt EJ, Gerritsen J, Boezen HM, Grevink RG, Duiverman EJ. Am J Respir Crit Care Med. 2006;173:890–896 PURPOSE OF THE STUDY. To determine long-term effects of prematurity on lung function (volumes, diffusing capacity) and exercise capacity in ex-preterm infants compared with healthy peers. STUDY POPULATION. Preterm participants (n = 42) and healthy term controls (n = 48) were recruited for lung-function and exercise tests. METHODS. Part of a prospective nationwide Dutch study, children born in 1983 with a gestational age of <32 weeks and/or a birth weight under 1500 g were followed up to 19 years of age. Measurements included spirometry, diffusing capacity (DLco), and bicycle ergometer test. RESULTS. Most lung-function measurements were within the reference ranges for both groups. Preterm birth was associated with lower forced expiratory volume in 1 second (preterm infants: 95% predicted; controls: 110% predicted) and DLcosb, single breath corrected for hemoglobin (88% predicted vs 96% predicted compared with control subjects at follow-up). Exercise capacity was 15% lower in ex-preterm infants than in control subjects. The anaerobic threshold, maximum minute ventilation, and maximum heart rate as percentage predicted were significantly lower in ex-preterm infants compared with control subjects. CONCLUSIONS. Long-term effects of prematurity were airway obstruction and a lower diffusing capacity compared with control subjects, although mean lung-function parameters were within the reference ranges. Ex-preterm infants had a lower exercise level, which could not be explained by impaired lung function or smoking habits but might be a result of impaired physical fitness. REVIEWER COMMENTS. We all see ex-preterm patients in our practices, and there have been conflicting data on lung function as adolescents. No previous studies on exercise capacity have been performed. Without the control group included, one could have concluded that almost all participants had lung-function measurements within the reference ranges. Ex-preterm infants reported fewer hours of exercise per week than the control subjects, which might explain their lower level of physical fitness. Diminished exercise capacity did not seem to be a result of impaired lung function or limited ventilation. We might want to encourage all children who were born prematurely to participate in more physical activity and sports at an early age, because this might possibly improve the exercise performance of those in this group.