ObjectiveThe high incidence of lower lobe collapse in adult intensive care patients is well described. We aimed to document the incidence and distribution of acute lobar collapse in the pediatric intensive care setting. The influence of anatomical and pathophysiological differences between the adult and pediatric respiratory tract will be considered.DesignRetrospective review of chest radiograph series.SettingTertiary referral center for pediatric intensive care and the Department of Diagnostic Radiology in a large teaching hospital in England.PatientsCohort of 160 patients receiving intensive care during a 2-yr period (age range, 6 days-18 yrs; median, 23 months).InterventionsNoneMeasurements and Main ResultsTwenty-four of 160 children (15%) developed acute lobar collapse during their intensive care unit admission. Isolated right upper lobe collapse occurred in 14 patients, right upper lobe in association with one or more other lobes in five patients, and lobar collapse other than the right upper lobe in five patients. The development of lobar collapse and, in particular, right upper lobe collapse was associated with a lower median age (no collapse, 26 months; lobar collapse, 8 months; right upper lobe collapse, 4 months). Lobar collapse was significantly associated with the requirement for mechanical ventilation during admission (chi-square, 12.18; p = .005). It was observed in association with both high and low endotracheal tube positions.ConclusionThe predominance of upper lobe and, in particular, right upper lobe collapse observed in pediatric intensive care patients contrasts with the high incidence of lower lobe collapse in their adult counterparts. Multiple interrelated factors are likely to be contributory and include the following: a) anatomical and physiological differences between adults and children; b) the pathophysiology of childhood respiratory disease; c) more critical positioning of endotracheal tubes in younger patients and their movement with patient positioning. (Crit Care Med 1999; 27: 1594-1597)