Pulmonary function in older children and young adults with gastroesophageal reflux.

A wide variety of types of pulmonary diseases and respiratory symptoms have been associated with gastroesophageal reflux (GER). Asthma, chronic bronchitis, bronchiectasis, and pulmonary fibrosis have all been linked to GER, but causal mechanisms have been difficult to establish. To characterize pulmonary function abnormalities in older children and young adults (age 7-23 years) with GER, lung function was evaluated in 22 patients being treated for reflux. The patients were divided into two groups: nine subjects (Group 1) had no history of pulmonary symptoms. Thirteen subjects (Group 2) had known pulmonary disease; all had diagnosed asthma, and five had a history of recurrent pneumonia. Lung volumes and spirometry were measured. Airway reactivity was assessed by measuring change in flows following isocapneic hyperventilation of subfreezing air. The presence of "small airway" disease was assessed by air-helium flow volume curves and the single breath oxygen test. Lung size, as indicated by measurement of total lung capacity, was normal in all patients. Flow rates, density dependence of maximal expiratory flow, single breath oxygen test, and tests of airway reactivity were abnormal only in Group 2 patients and were normal in the Group 1 patients. That not all children with GER have abnormal pulmonary function suggests that, if there is a causal relationship between GER and lung disease, it is multi-factorial in nature. Children with GER who do have lung disease have evidence of airway obstruction, maldistribution of ventilation, and increased airway reactivity, but do not have restricted lung volumes.