Greetings,
We hosted another wonderful group of trainees in May who hailed from Ft. Collins, Colorado; Worthington, Ohio; Danville, Pennsylvania; and Franklin, Tennessee. It is a glorious time of the year here in Charlottesville, with warm days, cool nights, and no humidity (yet). It takes some resolve to turn the car away from the mountains and come to work on beautiful spring mornings when the hills and streams are beckoning… Our journal club this month promises to be another article that will provoke much discussion in the future, and one with potential to alter how we provide nutrition support in the ICU.
May Citation:
Rice TW, Mogan S, Hays MA, et al. Randomized trial of initial trophic versus full-energy enteral nutrition in mechanically ventilated patients with acute respiratory failure. Crit Care Med. 2011;39(6):1-8.
Summary:
This was a randomized unblinded study of patients in acute respiratory failure that were randomized to receive either trophic (10 mL/hr) or full feedings for 6 days. The full feeding rate was calculated as 25-30 kcal/kg ideal body weight/day of non-protein energy and 1.2-1.6 g/kg ideal body weight/day of protein. Patients received a feeding formula and tube position as determined by the nutrition consultant and primary team, respectively. Supplemental protein in excess of enteral nutrition formula was not allowed. After 6 days the trophic feeding group had their nutrition provision increased to meet the full calculated needs. Elevated gastric residual volumes (GRV) were defined as greater than 300 mL. GRV’s were checked every 6 hours while feeding rates were increased and every 12 hours thereafter if the patient was receiving trophic feeding, or once the final rate was achieved.
The primary outcome of the study was ventilator-free days to day 28.
Secondary endpoints were 28-day and hospital mortality, organ-failure free days, ICU-free days, hospital-free days to day 28, GI intolerance (diarrhea, GRV > 300mL, abdominal distension/cramping, constipation, vomiting) and new infections.
Inclusion and Exclusion Criteria were:
Inclusion Criteria:
- Mechanical ventilation expected to last at least 72 hours.
- Presence of, or primary physician’s intent to place, an enteral feeding tube and begin enteral feeds
Exclusion criteria
- More than 48 hours elapsed since inclusion criteria met
- Patient, legal representative, or physician refuses consent or is unavailable to provide consent
- Patient, legal representative, or physician not committed to full support (Exception: a patient who will receive all supportive care except for attempts at resuscitation from cardiac arrest will not be excluded)
- Presence of malignant or irreversible condition and estimated 28 day mortality greater than 50%
— Poorly controlled neoplasms
— HIV infection with CD4 count < 50 and known end stage process such as progressive multifocal
leukencephalopathy, systemic mycobacterium avium infection)
— Prior cardiac arrest requiring CPR without fully demonstrated neurologic recovery
— New York Heart Association Class IV Cardiac Exercise Limitation
- Severe or Refractory Shock
— Dopamine infusion at rate > 15 mcg/kg/min
— Dobutamine infusion at rate > 15 mcg/kg/min
— Epinephrine or norepinephrine infusion at rate > 30 mcg/min
— Phenylephrine infusion at rate > 50 mcg/min
— Milrinone infusion at rate > 0.5 mcg/kg/min
— Vasopressin infusion at any rate
— Intra-aortic balloon pump
- Chronic Respiratory Disease that requires home oxygen or results in severe exercise restriction (unable to climb stairs or perform household duties), secondary polycythemia, or ventilator dependence
- Moribund patients not expected to survive 24 hours from start of enteral nutrition (as decided by primary medical team)
- Child-Pugh score > 9 (1)
- Presence of partial or complete mechanical bowel obstruction, or ischemia, or infarction
- Current parenteral nutrition use or intent to use within 7 days
- Severe malnutrition with BMI < 18.5 and/or loss of > 30% total body weight in the previous 6 months
- Neuromuscular disease impairing the ability to ventilate spontaneously
— Amyotrophic lateral sclerosis
— Guillain-Barre Syndrome
— Myasthenia Gravis
— Upper spinal cord injury at level C5 or above
— Kyphoscoliosis or chest wall deformity resulting in severe exercise restriction (unable to climb stairs or perform household
duties), secondary polycythemia, or ventilator dependence
- Laparotomy expected within 7 days
- Unable to raise head of bed 45 degrees
- 30% total body surface area burns
- Absence of GI tract/short bowel syndrome (defined as entire length of small bowel totaling 4 feet or less)
- Presence of high-output (> 500 cc/day) enterocutaneous fistula
- Age < 13 years
- Allergy to enteral formula
Major Results reported by authors:
During the 6-year study period 1187 patients met inclusion criteria, but only 290 did not have exclusion criteria. Ultimately 200 patients consented and were randomized with 98 patients receiving trophic and 102 patients receiving full-energy nutrition. Baseline characteristics of the groups were similar and we noted that majority of subjects were overweight with mean BMI 28.7.
The average length of enteral nutrition was 5 days; the mean amount of feeding actually provided to the full calorie group was 1400 kcals, compared to 300 calories/day in the trophic group. The full feeding group received an average of 54 g protein vs 10 gm protein/day in the trophic feeding group.
There was no difference in the primary outcome or any other major hospital outcome between the two groups. There was also no difference in any outcome between the preplanned subgroups of acute lung injury-sepsis PNA, or BMI > 35. However, the researchers reported that they discovered that significantly more survivors in full feed group were able to be discharged to home rather than to a rehabilitation facility (68.3% for the full-energy group vs. 51.3% for the trophic group; p = .04).
There was a trend for more GI intolerance in full feed group 39 vs 26%, a trend to more feeding days with any episode of intolerance in days 1-6 , 34 vs 24% (full fed and trophic respectively). Diarrhea most common “GI intolerance” reported. In the first 6 days of the study the trophic group had a trend for less diarrhea (19% vs. 24% of feeding days; p = .08) and had significantly fewer episodes of elevated GRVs (2% vs. 8% of feeding days; p < .001).
Author’s Conclusions:
“Providing initial trophic enteral nutrition in mechanically ventilated patients with acute respiratory failure results in clinical outcomes similar to those of early advancement to full-energy enteral nutrition with fewer episodes of GI intolerance. Overall, these data suggest that a less aggressive feeding strategy during the initial stages of mechanical ventilation is not demonstrably worse than early advancement to full-energy enteral nutrition, although larger studies are needed to better determine the risks and benefits. Further study is needed to determine both optimal composition and timing of initiation of enteral nutrition in these patients and to clarify whether protein or micronutrient supplementation may confer added benefit.”
Evaluation:
This study provides data regarding one of the most basic concepts for ICU nutrition support – the question of whether we need to meet calorie and protein requirements in the early part of an ICU admission. In fact, considering that severely malnourished patients were excluded, the average BMI was 28.7 and the average length of feeding was only 5 days, it would be perfectly reasonable to ask if these patients needed any feeding. The short mean length of feeding time and time on the ventilator (5.6 days) suggests that many patients had either significantly improved or expired before they could accrue a significant nutrition deficit. Arguably, the full feeding group did not really receive full feedings, because they received a mean of 1400 calories/54 gm of protein which was only 17 total calories/kg and 0.6 g protein/kg of actual weight. However, they did receive substantially more nutrition than the trophic group without any apparent change in major outcomes.
The major limitation of this study of this study is that 200 patients is a small study size for a relatively mixed population studying ICU and hospital outcomes relative to a nutrition change. The much larger multicenter trial has recently met their full recruitment quota, so we can expect to see the results from a similar, but much larger study in the future.
The fact that significantly more survivors of the trophic-fed group required rehabilitation suggests that that there may be more long term sequelae for patients with metabolic stress that receive a calorie, and especially protein deficit, to prevent excessive wasting of lean muscle mass. It would require a much larger study to have sufficient numbers to allow examination of subgroups such as older patients, or those with mild to moderate malnutrition, to see if they are more negatively impacted by inadequate nutrition in the ICU.
Our group was not impressed with evaluation of diarrhea as a marker of feeding intolerance because of how commonly diarrhea is seen in the ICU related to cathartic, sorbitol-containing medications or contrast agent administration, without a link to enteral feeding administration. Constipation is not a function of enteral intolerance either, but rather bed rest, narcotics, fluid, etc.
Our Take Home messages:
1. This study suggests that attempting to meet nutrition goals during short-term respiratory failure does not appear to affect major outcomes compared to trophic feeding.
2. A much larger study that has just been completed should help to establish if short term nutrition deficits in the ICU affect needs for rehabilitation after hospitalization.
Other News:
See our website: www.ginutrition.virginia.edu for:
Upcoming Webinars for Spring/Summer 2011:
- May 24: Gastric versus Jejunal Feeding: Combining Data and Clinical Judgment—Joe Krenitsky, MS, RD
- June 14: Small Bowel Bacterial Overgrowth–Carol Parrish, MS, RD
- July 19: Feeding the Post-Surgical Patient–Kate Willcutts, MS, RD, CNSC
Latest Practical Gastroenterology article:
- Caruana P, Shah N. Hepatic Encephalopathy: Are NH4 levels and Protein Restriction Obsolete? Practical Gastroenterology 2011;XXXV(5):6.
Joe Krenitsky MS, RD
Carol Rees Parrish MS, RD
PS – Please feel free to forward on to friends and colleagues.