Early vs Late Enteral Feeding of mechanically ventilated pateints: Results of a clinical trial
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Posted By: Elizabeth Sweetman
Posted Date: 13/01/09
Title: Early vs Late Enteral Feeding of mechanically ventilated pateints: Results of a clinical trial
Authors: Ibrahim EH, Mehringer L, Prentice D, Sherman G, Schaiff R, Fraser V, Kollef MH.
Reference: JPEN J Parenter Enteral Nutr. 2002 May-Jun;26(3):174-81.
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Abstract: BACKGROUND: This study sought to compare 2 strategies for the administration of enteral feeding to mechanically ventilated medical patients.
METHODS: The prospective, controlled, clinical trial was carried out in a medical intensive care unit (19 beds) in a university-affiliated, urban teaching hospital. Between May 1999 and December 2000, 150 patients were enrolled. Patients were scheduled to receive their estimated total daily enteral nutritional requirements on either day 1 (early-feeding group) or day 5 (late-feeding group) of mechanical ventilation. Patients in the late-feeding group were also scheduled to receive 20% of their estimated daily enteral nutritional requirements during the first 4 days of mechanical ventilation.
RESULTS: Seventy-five (50%) consecutive eligible patients were entered into the early-feeding group and 75 (50%) patients were enrolled in the late-feeding group. During the 5 five days of mechanical ventilation, the total intake of calories (2370 +/- 2000 kcal versus 629 +/- 575 kcal; p < .001) and protein (93.6 +/- 77.2 g versus 26.7 +/- 26.6 g; p < .001) were statistically greater for patients in the early-feeding group. Patients in the early-feeding group had statistically greater incidences of ventilator-associated pneumonia (49.3% versus 30.7%; p = .020) and diarrhea associated with Clostridium difficile infection (13.3% versus 4.0%; p = .042). The early-feeding group also had statistically longer intensive care unit (13.6 +/- 14.2 days versus 9.8 +/- 7.4 days; p = .043) and hospital lengths of stay (22.9 +/- 19.7 days versus 16.7 +/- 12.5 days; p = .023) compared with patients in the late-feeding group. No statistical difference in hospital mortality was observed between patients in the early-feeding and late-feeding groups (20.0% versus 26.7%; p = .334).
CONCLUSIONS: The administration of more aggressive early enteral nutrition to mechanically ventilated medical patients is associated with greater infectious complications and prolonged lengths of stay in the hospital. Clinicians must balance the potential for complications resulting from early enteral feeding with the expected benefits of such therapy.
Are the Results Valid?
1. Was the assignment of patients to treatments randomized? ( Was allocation concealment maintained?)
No. The authors state on page 175 "Patients admitted to the medical ICU on odd numbered days were assigned to the early-feeding group, and patients admitted on even-numbered days were assigned to the late-feeding group".
Due to the method of treatment allocation used for this trial, this trial can be considered to be a pseudo-randomised trial.
Pseudo-randomised trials tend to over-estimate treatment effects and may be subject to bias because trialists can predict and influence which treatment group a patient will enter into before consent is obtained.
2. Were all patients who entered the trial properly accounted for and attributed at its conclusion?
2a. Was followup complete?
Patient follow-up and its completeness within this trial is unclear. On page 177, the authors state that "189 consecutive patients requiring mechanical ventilation were evaluated for enrollment into the study". From these 189 patients, 27 were "excluded" and 150 patients at the end of the trial were analysed.
It is difficult to establish the timing of exclusion of the 27 patients i.e. whether they were excluded prior to or following entry into the trial.
2b. Were patients analyzed in the groups to which they were randomized?
Yes, the patients within this trial were analysed in the groups to which they were assigned.
3. Were patients, health workers, and study personnel blind to treatment?
No, the patients, health workers and study personnel were not blinded to the treatment groups within this trial.
4. Were the groups similar at the start of the trial?
Yes. On table 1, page 177, the authors demonstrate that both groups were similar in nearly all characteristics.
The lymphocyte count in patients in the early-feeding group was lower (1123 vs 1831, p = .010) than in patients in the late-feeding group.
5. Aside from the experimental intervention, were the groups treated equally?
Yes. As presented in table 11 (p. 177), the authors demonstrate that on the whole both patient groups were treated the same. The authors do mention that there was an increased use of Metoclopramide in the early-feeding group (13.3% vs 1.3%, p = .005) compared to the late-feeding group.
What are the Results?
1. How large was the treatment effect?
Important Note: Although the title reports this trial as 'Early vs Late', EN was actually started at the same time in both groups. One group received Early full goal nutritional support and the other group received Early restricted intake followed by Late full goal.
Primary Outcome Measure:
Ventilator associated pneumonia (VAP) was found to be significantly greater in the early-feeding group compared to the late-feeding group(49.3% vs 30.7%, p = .020)
VAP during the first 96 hours of mechanical ventilation: early-feeding group 25.3% vs late-feeding group 14.7%, p = .102
VAP after 96 hours of mechanical ventilation: early-feeding group 24.0% vs late-feeding group 16.0%, p = .221
Secondary Outcome Measures:
Early-feeding group vs late feeding group:
  • Duration of mechanical ventilation (6.1 +_ 6.2 days vs 5.7 +_ 8.2 days, p = .847)
  • Hospital mortality (20.0% vs 26.7%, p = .334)
  • Intensive care unit days (13.6 +_ 14.2 vs 9.8 +_ 7.4, p = .043)
  • Hospital length of stay (22.9 +_ 19.7 vs 16.7 +_ 12.5 days, p = .023)
  • Antibiotic days (12.4 +_ 9.9 days vs 7.5 +_ 6.1 days, p = > .001)
  • Diarrhea (Clostridium difficile-associated) (13.3% vs 4.0%, p = 0.42)
  • 2. How precise was the estimate of the treatment effect?
    Primary Outcome Ventilator associated pneumonia:
  • adjusted OR = 2.48, 95% confidence interval = 1.65 to 3.75, p = 0.027).
  • Will the Results Help Me In Caring For My Patients?
    1. Can the results be applied to my patient care?
    Due to the potential of allocation bias within this trial because of its pseudo-randomized design, the results presented in this study may be unreliable.

    The authors present some of the limitations of this study on page 180.
    2. Were all clinically important outcomes considered?
    3. Are the likely treatment benefits worth the potential harms and costs?
    Costs are not reported, the results may be unreliable. This question cannot be answered.

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    Early vs Late Enteral Feeding of mechanically ventilated pateints: Results of a clinical trial

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