Enteral nutrition with eicosapentaenoic acid, gamma-linolenic acid, and antioxidants reduces alveolar inflammatory mediators and protein influx in patients with acute respiratory distress syndrome.

OBJECTIVE

Previously, we showed that acute respiratory distress syndrome patients fed an enteral diet containing eicosapentaenoic acid and gamma-linolenic acid and elevated antioxidants (EPA+GLA; Oxepa) had significantly reduced pulmonary inflammation, increased oxygenation, and improved clinical outcomes. In a subset of acute respiratory distress syndrome patients from this trial, we performed a preliminary examination of the potential mechanisms underlying these clinical improvements by retrospectively testing the hypothesis that enteral feeding with EPA+GLA could reduce alveolar-capillary membrane protein permeability and the production of interleukin (IL)-8, IL-6, tumor necrosis factor-alpha, and leukotriene B4 that are responsible, in part, for pulmonary inflammation.

DESIGN

Prospective, randomized, double-blind, controlled clinical trial.

SETTING

Intensive Care Unit of the Ohio State University Medical Center.

PATIENTS

A total of 67 patients were enrolled who met defined criteria for acute lung injury/acute respiratory distress syndrome.

INTERVENTIONS

A total of 43 of 67 evaluable patients randomly received either EPA+GLA or an isonitrogenous, isocaloric standard diet that was tube fed at a minimum caloric delivery of 75% of basal energy expenditure times 1.33 for at least 4 to 7 days.

MEASUREMENTS AND MAIN RESULTS

Bronchoalveolar lavage (BAL) was performed at baseline and study days 4 and 7 to obtain BAL fluid (BALF) for measurement of total protein, ceruloplasmin, and transferrin, total neutrophil count, IL-8, IL-6, tumor necrosis factor-alpha, and leukotriene B4. Oxygenation, measured as Pao2/Fio2, was assessed before BAL. Patients fed EPA+GLA had a significant reduction in BALF ceruloplasmin and IL-8 during the study as compared with patients fed the control diet. BALF levels of total protein, neutrophils, and leukotriene B4 tended to decrease in EPA+GLA patients over the course of the study as compared with control patients. BALF levels of IL-6 declined similarly during the study in both groups. A trend toward a reduction in BALF tumor necrosis factor-alpha was observed on study day 7 in the EPA+GLA group as compared with control patients. Significant improvements in oxygenation (Pao2/Fio2) occurred in EPA+GLA patients on study day 4 as compared with controls. Correlation analysis revealed significant relationships between BALF neutrophil counts and indices of alveolar-capillary membrane protein permeability, IL-8, and leukotriene B4.

CONCLUSIONS

This preliminary investigation showing a decrease in BALF levels of IL-8 and leukotriene B4 and the associated reduction of BALF neutrophils and alveolar membrane protein permeability in acute respiratory distress syndrome patients fed EPA+GLA support, in part, the potential mechanisms underlying the previously described clinical improvements with this diet. Additional controlled studies are needed to confirm these findings.