Long-term parenteral nutrition in cystic fibrosis.

The effects of parenteral nutrition (PN) with high lipid content were studied in 18 cystic fibrosis patients in this pilot investigation. The patients were randomly assigned to one of two groups. During the first 4-mo period, group 1 received PN and group 2 received routine therapy. During the second 4-mo period, PN was discontinued in group 1 and instituted in group 2. When the effect of PN was considered for both treatment groups, its general effect was to increase body fat content with little or no impact on respiratory function, exercise tolerance, or recurrent infections. However, subsequent analysis and clinical observation suggested that patients receiving PN responded in two seemingly distinct patterns: some demonstrated apparent clinical improvement and benefit, and others did not. A positive response in pulmonary and exercise function was closely correlated to a rise in serum dihomo-gamma-linolenic acid (DHLA) concentrations during PN. Pulmonary function improved in patients who normalized their DHLA levels (vital capacity increased from 2.2 +/- 0.3 to 2.6 +/- 0.3 area %, p < 0.05), whereas those who continued to have undetectable levels of DHLA deteriorated (forced expiratory volume in 1 s decreased from 0.7 +/- to 0.6 +/- 0.1, p < 0.001). PN applied to malnourished patients with cystic fibrosis results in beneficial effects in a subgroup characterized by the presence of DHLA in serum; for the group as a whole, the positive effects are minimal.