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University of Virginia Health System

Nutrition Support E-Journal Club

July 2007

Greetings,

We had a great July nutrition support traineeship with trainees from Greenwood SC, Woodbridge VA, San Antonio TX, and Duluth MI.  The picture below is from our traineeship evening out.

This month we did something a little unusual in that we re-reviewed an article we had discussed before (October 05).  We have several new team members, but the real reason was that staff had just returned from a conference where this study was quoted several times as "evidence" of the need to provide full calories to ICU patients.

July Citation: 

  • Villet S, Chiolero RL, Bollmann MD, et al. Negative impact of hypocaloric feeding and energy balance on clinical outcome in ICU patients. Clinical Nutrition 2005;24(4):page 502-509.

Summary: 

This was a prospective, observational study that utilized the data from 48 patients (out of 962 admissions) in a surgical ICU with a length of stay of at least 5 days.  Data from 669 patient days were utilized.  The feeding protocol of the intensive care unit was to begin early enteral feeding within 48 hours for malnourished patients, those with multiple injury, or requiring abdominal surgery for GI tumor.  In the remaining patients considered unlikely to tolerate oral intake within 5 days, the protocol was to reach goal feeding by day 4.  Parenteral nutrition (PN) was used when enteral nutrition (EN) was contraindicated or "when difficult EN causes obvious energy deficit." 

Energy goals were set at 1.3 X REE (indirect calorimetry), or at 30 kcal/kg when indirect calorimetry was not possible.  Energy deficit (calories delivered - estimated energy needs) were calculated daily, and then calculated as weekly as a total energy deficit and cumulative imbalance.

Inclusion and Exclusion Criteria were:

The study enrolled consecutive patients staying for more than 5 days in a surgical ICU of a tertiary hospital.  Exclusion criteria were major burns and short stay (<5 days).

Major Results reported by authors:

The authors reported that the average calorie deficit was 1270 calories/day in the first week and 625 calories/day in week 2.  Mean time to initiate feeding was 3.1 days (+/- 2.2 days); there were a total of 101 patient days (15%) without feeding.  Five patients were classified as malnourished; 18 other patients were identified as meeting criteria for early EN.  However, only 11 patients actually received early feeding.  Seventy-five percent (n = 36) of patients received only EN, 23% (n = 11) received PN + EN, and 2% (n =1) received only PN.

The cumulative calorie deficit was significantly associated with ICU length of stay (p<0.001).  The calorie deficit for the first 7 days, as well as the total calorie deficit, was significantly associated with both total and infectious complications.  Calorie deficit was not significantly associated with mortality.  Of note: èPlasma proteins (albumin and prealbumin) did not correlate with nutrition delivery, but were inversely related to the inflammatory status. ç

Author's Conclusions:

A negative calorie balance correlated with increasing number of complications, particularly infections.  Delayed initiation of nutrition support produces energy deficits that are not compensated for later.  The total nutrition deficit may be a useful indicator of nutrition status, but requires further testing. 

Evaluation:

Intuitively, the concept of calorie deficit has appeal as an indicator of nutrition status - if you are fed inadequately for long enough you become malnourished, and (perhaps) share the poor outcome that has been associated with malnutrition in other populations.  However, this is NOT a randomized study - it is observational, and therefore can describe only associations, and as a result, it is not possible to make cause-and-effect conclusions.  There is no way to control for all the factors relating to severity of illness without randomizing two large groups.  The concern is that it may not be the calorie deficit itself that determines the outcome; it may just be that patients with poor outcome unavoidably receive less nutrition, whether by GI intolerance, or because they require more procedures, test, lines, codes, etc. 

It would be inappropriate to quote this study as evidence that hypocaloric, protein-sparing feeding should not be used in the ICU.  Purposeful, hypocaloric feeding with increased protein and full micronutrient provision is quite different metabolically than when patients are essentially semi-starved of all nutrients when feedings are held or not tolerated.

That said, the concept of caloric deficit might be a valid marker of nutrition status.  The problem is that we just have no way of knowing how large of a calorie deficit is required before patient outcome is affected.  Some observational studies have reported that there were no significant differences between critically ill patients who received full nutrition support and those who received only 50% of nutrition goals.  Furthermore, other studies have reported improved outcomes in the groups who received fewer calories.

Our Take home message:

The concept of calorie deficit is an interesting one, but this study only points to the need for double-blind trials (with adequate numbers of both malnourished and well-nourished patients), comprised of early full nutrition delivery versus delayed, partial, or no nutrition.

This study provides additional evidence that prealbumin and albumin have nothing to do with the amount of nutrition you provide to critically ill patients.

Other News:

•1)     Check out the latest Practical Gastroenterology articles/info at:

http://www.uvadigestivehealth.org/ 
Scroll down to GI Nutrition on the far left column and click on link
This leads to a pull down menu with links within the GI nutrition site including the Nutrition Articles in Practical Gastroenterology.  May's articles are:

•1)      Corbett E.  Intravenous Fluids: It's More Than Just "Fill‘ Er Up!"  Practical Gastroenterology 2007;XXXI(7):44.

•2)      Barrett J, Gibson P.  Clinical Ramifications of Malabsorption of Fructose and Other Short-chain Carbohydrates Practical Gastroenterology 2007;XXXI(8):51.

Joe Krenitsky MS, RD

Carol Parrish RD, MS

PS - Please feel free to forward this on to friends and colleagues.