Elsevier

Clinical Nutrition

Volume 25, Issue 1, February 2006, Pages 51-59
Clinical Nutrition

ORIGINAL ARTICLE
Enteral nutrition delivery and energy expenditure in medical intensive care patients

https://doi.org/10.1016/j.clnu.2005.08.013Get rights and content

Summary

Background and aims

Delivery of enteral nutrition (EN) in critical illness is often inadequate. This prospective observational study addresses the implementation of enteral feeding in critically ill medical patients and its relation to energy expenditure.

Methods

All admissions to a university medical ICU over a period of one year were screened. Patients receiving EN for at least 7 days were followed up. The caloric target was a minimum of 20 kcal/kg/day. The feeding volume was increased daily by 500 ml and a maximum of 2000 ml/day was targeted to be achieved by day 4 of admission. Energy expenditure was measured with indirect calorimetry on day 3 or 5.

Results

Two hundred and thirtyone patients required artificial nutrition, of which 61 patients were enterally fed for ⩾7 days. This group was followed for a total of 750 feeding days. The gastric route was used at the start, with a post-pyloric feeding required during follow-up in 36.1% of patients due to high gastric residual. EN was interrupted in 32.1% of the feeding days. The daily administered volume was 86.2±30.4% of the prescribed. The mean enteral caloric supply in relation to energy expenditure was between 39.2±34.6% on day 1 and 83.1±31.1% on day 6. The targeted maximum feed volume was achieved on day 4 in 75.4% of the patients. Patients with a delayed target time had a higher mortality rate than those with a target time of <4 days (73.3% vs. 26.1%),

Conclusions

A high delivery-to-prescription rate could be achieved with a standardized enteral feeding protocol in critically ill medical patients. However, caloric delivery is much less than measured energy expenditure. Enteral feeding intolerance is associated with a high mortality rate.

Introduction

Nutritional support is important in the management of the critically ill patient when oral food intake is inadequate or not possible. Enteral nutrition (EN) has to a great extent replaced parenteral nutrition (PN) in intensive care medicine.1, 2 EN reverses the loss of gastrointestinal mucosal integrity,3, 4 maintains intestinal blood flow,5 preserves the IgA-dependent immunity6, 7 and contributes to the maintenance of host immune response.8 However, the clinical implication of these findings is not yet clear.9 Meta-analyses of clinical studies have reported that EN is associated with a lower risk of infection.10, 11, 12 There are also cost savings with EN as opposed to PN.13 Early EN is associated with a lower incidence of infections and a reduced length of hospital stay.14 Clear conclusions have been difficult to make due to the heterogeneity of nutritional studies.15 Despite existing controversies, nutrition should be administered by the enteral route whenever possible.9

A major concern with EN is the discrepancy between prescribed and delivered amount of nutrient, the major causes of which are diarrhea, vomiting or gastric stasis. Furthermore, enteral nutrient delivery is gradually increased in critically ill patients in order to avoid the possibility of gastrointestinal intolerance, so that a few days are required to achieve the caloric target. Administering the total nutritional requirement of mechanically ventilated medical patients starting on day 1 was associated with greater infectious complications and prolonged length of hospital stay compared to patients in whom a gradual approach was implemented.16 Despite the caloric deficiency, EN is still superior than PN so that non-energetic effects of EN, such as immune modulation or protection of the intestinal mucosal barrier, seem to be of greater value in the critically ill than the mere energetic supply.9

The issue of the better enteral access (gastric vs. post-pyloric route) is not yet settled. However, available evidence does not support the routine insertion of post-pyloric tubes as long as the gastric route is effective.17, 18, 19

EN is the standard feeding route in critically ill patients at the medical ICU of the University of Leipzig as long as there are no contraindications to this strategy. In this prospective observational study on critically ill medical patients, it was aimed to achieve the maximum enteral feed volume on day 4 of admission. We further report our experience with the implementation of EN in this patient population, compare data on delivery with energy expenditure measurements and discuss common problems associated with this strategy.

Section snippets

Patients and methods

All medical patients admitted to the medical ICU of the University of Leipzig between August 2001 and July 2002 were screened for an indication for artificial nutrition. Patients were considered in need of artificial nutrition if oral food intake was not possible. Contraindications to EN were continuous diarrhea (defined as more than 3 stools per day or the need for an incontinence bag), massive gastric stasis, paralytic ileus and acute upper gastrointestinal bleeding. A nasogastric tube was

Results

Seven hundred and thirty patients of Caucasian origin were admitted to the medical ICU during the study period. Forty eight patients (6.6%) were excluded because they were referred after a major surgical procedure within the last 2 weeks, thus considered surgical. Therefore, the analysis included 682 medical patients aged 63.0±16.9 years, of which 397 (58.2%) were men and 285 (41.8%) women. Their mean body weight was 76.5±17.2 kg with a body mass index (BMI) of 26.4±5.8. 6.9% of the patients had

Discussion

EN is physiologic and prevents atrophic changes of the intestinal mucosa.3, 4 The healthy enterally fed bowel is metabolically active and builds an effective barrier through peristalsis, secretory IgA, intact intercellular junctions, mucus and diverse inhibitory factors. Malnutrition, infection, chemotherapy, radiation, shock and total PN result in damage to this barrier.8, 28, 29, 30, 31 The injured bowel releases proinflammatory cytokines, which may trigger multiple organ dysfunction.32, 33

Acknowledgments

We would like to thank the staff of our medical ICU for the dedicated support in the implementation of the study and data collection.

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