Lung function in developing lambs: is it affected by preterm birth?
Children born before term often have reduced lung function, but the effects of preterm birth alone are difficult to determine owing to iatrogenic factors such as mechanical ventilation. Our objective was to determine the effects of preterm birth alone on airway resistance, airway reactivity, and ventilatory heterogeneity as an index of intrapulmonary gas mixing. Preterm birth was induced in sheep 12 days before term; controls were born at term (∼147 days). Lung function was assessed at 8 wk postterm. To assess medium-large airway function we measured airway resistance and reactivity to carbachol. Multiple breath N2 washout (MBW) was used to assess ventilatory heterogeneity in conducting (Scond) and acinar (Sacin) airways. Baseline airway resistance and responsiveness to carbachol were similar in preterm and term lambs. Airway responsiveness to carbachol was greater in females than males (P < 0.05), and baseline airway resistance tended to be higher in females than males (P = 0.06). The