Background: In chronic obstructive pulmonary disease (COPD), body mass index (BMI) is an important predictor of survival. Little is known about the prevalence of malnutrition or longitudinal changes of BMI in patients undergoing noninvasive positive-pressure ventilation (NPPV).
Methods: In a cohort study of 141 patients with COPD and severe chronic respiratory failure (mean forced expiratory volume in the first second [FEV1] 0.80 +/- 0.27 L, mean P(aCO2) 55.6 +/- 8.8 mm Hg), we investigated nutritional status in relation to respiratory impairment. Changes in BMI were evaluated at 6 and 12 months after initiation of NPPV.
Results: Malnutrition, indicated by a BMI of < 20 kg/m2, was found in 20.6% of the patients. BMI was significantly correlated with the severity of respiratory impairment, especially with hyperinflation (residual volume divided by total lung capacity, r = -0.55, p < 0.001). In malnourished patients (BMI < 20 kg/m2) there was a significant increase in body weight after 6 months (6.2 +/- 12.5%, p < 0.05) and 12 months (12.8 +/- 16.0%, p < 0.01), whereas there were no significant changes in the overall study population. Furthermore, there was no correlation between changes in BMI and changes in blood-gas values, lung function, or inspiratory muscle function, either in the entire patient group or in the subgroup of malnourished patients.
Conclusions: In COPD with chronic respiratory failure, malnutrition is common and strongly related to hyperinflation. After initiation of NPPV, a significant weight gain is observed in malnourished COPD patients.