Transcutaneous oxygen tension measurements during methacholine challenge of prematurity in infants with chronic lung disease

Chronic lung disease (CLD) of prematurity may be caused by a number of insults during mechanical ventilation, including barotrauma and hyperoxia. To evaluate bronchial hyperresponsiveness (BHR) in infants with CLD of prematurity, we measured changes in transcutaneous oxygen tensions (tcPO₂) during methacholine inhalation challenge. Twelve infants with CLD and 22 age-matched children without respiratory diseases were enrolled in this study (ages—5 to 36 months; mean age—16.2 months). Serial doses of methacholine were doubled until a 10% decrease in tcPO₂ from baseline was reached. The cumulative dose of methacholine inhaled by the time tcPO₂ had been reached (Dmin-PO₂) was considered to represent the dose at which reactivity to methacholine (RO₂meth) had occurred. In the CLD group, Dmin-PO₂ (3.50 ± 0.1 log.milli-units) was significantly lower than in the preterm control infant group (4.31 ± 0.2 log·milli-units) and the term infant group (4.21 ± 0.1 log.milli-units) (P = 0.004, P < 0.001). Dmin-PO₂ in the preterm control infant group was not significantly different than in the term infant group (P > 0.5). These results suggest that infants who require additional therapeutic oxygen and mechanical ventilation during the early months of life are at risk of developing early-onset, long-lasting respiratory disease that is related to an acquired BHR. Pediatr Pulmonol. 1998; 25:338–342. © 1998 Wiley-Liss, Inc.