Effects of Meals on Respiratory Functions in Patients with Cystic Fibrosis

To determine the effect of meals on respiratory function in patients with chronic lung disease, we performed spirometry before and after a standard hospital lunch on 12 cystic fibrosis patients with varying severity of lung disease, as determined by Shwachman-Kulczcki (S-K) scores. The patients were monitored for oxygen saturation by ear oximetry before, during, and after the meal. The patient's ages ranged from 5 to 30 years (mean 16.8). The mean initial vital capacity was 58% of predicted, with a range of 22% to 89%. The mean initial oxygen saturation was 92%, with a range of 88% to 96%. Four patients had a decrease of 6% or more in their vital capacity. Four patients had a decrease of 3% or more in their oxygenation saturation. Three patients had decreases in both parameters. The mean initial vital capacity, oxygen saturation, and S-K score of the patients who experienced drops in vital capacity did not differ significantly from those of the other patients. However, the mean initial vital capacity of the patients who experienced drops in oxygen saturation was significantly lower than that of the other patients. Both groups had comparable mean oxygen saturation and S-K score. We conclude that some patients with chronic lung disease experience significant decreases in vital capacity and oxygen saturation during meals. A low vital capacity may predict the patients at risk for oxygen desaturation.