Respiratory functions in adolescents hospitalized for anorexia nervosa: A prospective study

Objective: To examine the effects of malnourishment on the respiratory system of adolescents with anorexia nervosa (AN) hospitalized for medical stabilization. Method: Prospective study. Study group: hospitalized adolescents with recent onset (\ 1 year) AN. Control group: adolescents hospitalized for other diagnoses. Excluded: participants with lung disease. Results: Patients' characteristics (mean 6 SD) for the AN (n = 16) and the control group (n = 13) on admission were: age: 15.0 +/- 1.7 vs. 15.2 +/- 1.4 years, p = 0.7; body mass index (BMI): 15.5 +/- 2.3 vs. 19.8 +/- 2.9 kg/ m 2, p\ 0.001; venous pH 7.34 +/- 0.02 vs. 7.38 +/- 0.03, p \ 0.001; PCO2 53.3 +/- 4.1 vs. 42.5 +/- 3.1 mm Hg, p\ 0.001; and HCO3 28.7 +/- 2.0 vs. 25.3 6 2.4 meq/ L, p \ 0.001, respectively. There were no significant differences in nocturnal respiratory rates, pulse-oximetry oxygen saturations, or end-tidal CO2. Pulmonary function tests (PFTs) in adolescents with AN revealed no obstructive, restrictive, or significant pulmonary vascular disease except for lower peak expiratory flow rates (PEFRs). During hospitalization (12.3 +/- 3.8 days), their weight, BMI, mean nocturnal heart rate, and respiratory rate increased significantly, while their venous PCO2 and HCO3 decreased significantly without significant changes in PFTs. Discussion: Adolescents with recent onset AN, admitted for medical stabilization, demonstrate hypercapnia despite normal PFTs, except for decreased PEFRs. These could result from decreased respiratory muscle strength and/or abnormal control of breathing. (C) 2011 by Wiley Periodicals, Inc.