DOI: 10.1097/CCM.0b013e31821b82bb
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PMID: 21685749
Issn Print: 0090-3493
Publication Date: 2011/07/01
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Excerpt
The study by Gadek et al (1) randomized 146 patients, 98 of whom were deemed evaluable (e.g., tolerated target feeding for 4 days). The evaluable patients who received the enriched formula experienced less pulmonary neutrophil recruitment, improved gas exchange, fewer days of ventilator support, and fewer new organ failures. An intent-to-treat analysis showed that the significant differences in clinical outcomes (time on ventilator; new organ failures) remained in favor of those patients receiving the enriched formula. Although the study was not powered for a mortality outcome, there was a trend in favor of the enriched formula in both the evaluable and the intent-to-treat groups (intent-to-treat analysis: mortality = 16% in patients receiving the enriched formula and 25% in patients receiving the unenriched formula; p = .165). The study by Singer and colleagues (2) randomized 100 patients at a single center. Patients receiving the enriched formula showed better oxygenation (at day 4, PaO2/Fio2 = 317.3 vs. 214.3; p = −.05) and lung compliance; there was no difference in mortality. The study by Pontes-Arruda and coworkers (3) enrolled 165 patients, of whom 103 were evaluable (an adequate feeding period of 4 days, etc.). All patients were ventilated and had severe sepsis (15 patients in the enriched group and only six in the standard group were in shock). The patients receiving the enriched formula experienced significantly better oxygenation, more ventilator-free days (13.2 vs. 5.8; p < .001), fewer organ failures, and lower 30-day mortality (22.7% vs. 52.1%; p = .037). Although an intent-to-treat analysis was not planned or provided, some of the available data suggests that the main conclusions might generally hold up. For example, in the 62 nonevaluated patients, there were 13 deaths before day 4 in 38 patients randomized to the unenriched formula and eight deaths before day 4 in 29 patients randomized to the enriched formula.
Based largely on these three studies, at least one expert panel recommended the use of enteral formula enriched with fish oils, borage oils, and antioxidants for patients with acute lung injury (4). It seems that this approach was never widely adopted, perhaps in part because the critical care community was aware of new studies being planned.
In this issue, the article by Stapleton et al (5) reports on an important investigation, which was aimed at testing whether fish oil (EPA and DHA) alone, without the additional supplements used in the other studies (γ-linolenic acid and antioxidant vitamins), could demonstrate efficacy. By design, this was a small phase II study powered to detect changes in biomarkers rather than assess clinical outcomes. The primary end point was bronchoalveolar lavage fluid interleukin-8 levels. Patients were randomized to receive either fish oil (n = 41) with an EPA dose approximately 25 greater than that received in the previously mentioned studies or placebo (n = 49) delivered every 6 hrs. All regular enteral or parental feeding, including substrate and timing, was fully at the discretion of the treating physician.
