Bronchopulmonary dysplasia in very low birth weight subjects and lung function in late adolescence.

OBJECTIVES: The purpose of this work was to determine the relationship between lung function in late adolescence and bronchopulmonary dysplasia, to establish whether lung function changed more from earlier in childhood in those with bronchopulmonary dysplasia, and to assess the effect of different definitions of bronchopulmonary dysplasia on respiratory outcome. METHODS: Subjects were composed of 147 survivors of birth weight <1500 g from the Royal Women's Hospital (Melbourne, Australia) born during 1977-1982 and who had lung function tests at a mean age of 18.9 years. Of the 147 subjects, 33 (22%) had bronchopulmonary dysplasia in the newborn period. Lung function was measured according to American Thoracic Society guidelines. RESULTS: All of the lung function variables reflecting airflow were substantially diminished in the bronchopulmonary dysplasia group, but lung volumes were not significantly different. More subjects in the bronchopulmonary dysplasia group had reductions in airflow in the clinically significant range (eg, forced expired volume in 1 second/forced vital capacity ratio <75%; bronchopulmonary dysplasia: 42.4% [14 of 33]; and no bronchopulmonary dysplasia: 16.4% [18/114]). Results were not substantially affected after adjustment for confounding variables, including intrauterine growth restriction or birth weight. Compared with earlier in childhood, the forced expired volume in 1 second/forced vital capacity ratio deteriorated more in bronchopulmonary dysplasia subjects between 8 and 18 years. Lung function results varied little with different definitions of bronchopulmonary dysplasia. CONCLUSIONS: Subjects of very low birth weight with bronchopulmonary dysplasia in the newborn period have poorer lung function in late adolescence than those without bronchopulmonary dysplasia, and their lung function may be deteriorating at a more rapid rate.

Adverse effects of smoking on respiratory function in young adults born weighing less than 1000 grams.

OBJECTIVE: To determine whether active smoking has an adverse impact on respiratory function of young adults of extremely low birth weight (ELBW; birth weight <1000 g). METHODS: This was a cohort study of 60 consecutive ELBW survivors who were born during 1977-1980 at Royal Women's Hospital, Melbourne, Australia. Respiratory function was measured on 44 (73%) of the subjects at a mean age of 20.2 years (standard deviation: 1.0 year). Respiratory function had also been measured on 42 of the 44 subjects at 8 years of age. Respiratory function was compared between the 14 smokers and the 30 nonsmokers. RESULTS: Several respiratory function variables reflecting airflow (the forced expired volume in 1 second [FEV(1)]/forced vital capacity [FVC] ratio; flow rates at 75%, 50%, and 25% of vital capacity; and mid-expiratory flow from 25% to 75% of vital capacity) were significantly diminished in smokers. The proportion with a clinically important reduction in the FEV(1)/FVC ratio (<75%) was significantly higher in smokers (64%) than in nonsmokers (20%). There was a significantly larger decrease in the FEV(1)/FVC ratio between ages 8 and 20 years in the smokers (mean change: -8.2%; 95% confidence interval: -14.1% to -2.4%) CONCLUSIONS: Active smoking by young adult survivors of ELBW is associated with reduced respiratory function.

Blood pressure in late adolescence and very low birth weight.

OBJECTIVES: To determine whether blood pressure (BP) differed between very low birth weight (VLBW; birth weight 2499 g) subjects in late adolescence, and to determine whether growth restriction in utero was related to BP in VLBW survivors at this age. METHODS: This was a cohort study of 210 preterm survivors with birth weights <1501 g born from January 1, 1977, to March 31, 1982, and 60 randomly selected NBW subjects from the Royal Women's Hospital, Melbourne. BP was measured at 18+ years of age in 156 (74%) VLBW subjects and 38 (63%) NBW subjects with both a standard mercury sphygmomanometer and an ambulatory BP monitor. RESULTS: VLBW subjects had higher sphygmomanometer systolic and diastolic BPs than NBW subjects (mm Hg; mean difference [95% confidence interval]; systolic, 8.6 [3.4, 13.9]; diastolic, 4.3 [1.0, 7.6]). VLBW subjects also had significantly higher mean systolic ambulatory BPs (mm Hg; mean difference [95% confidence interval]) for the 24-hour period (4.7 [1.4, 8.0]), and for both the awake (5.0 [1.6, 8.5]) and asleep (3.6 [0.04, 7.1]) periods. There were no significant differences between the birth weight groups for any ambulatory diastolic BPs. Within the VLBW subjects, there was no significant relationship between birth weight standard deviation score and any measure of BP. CONCLUSIONS: BP was significantly higher in late adolescence in VLBW survivors than in NBW subjects. Growth restriction in utero was not significantly related to BP in VLBW survivors.