George K. Grimble

Enteral nutrition in intensive care patients: a practical approach

Severe protein-calorie malnutrition is a major problem in many intensive care (ICU) patients due to the increased catabolic state often associated with acute severe illness and the frequent presence of prior chronic wasting conditions. Nutritional support is thus an important part of the management of these patients. Over the years, enteral nutrition (EN) has gained considerable popularity, due to its favorable effects on the digestive tract and its lower cost and rate of complications compared to parenteral nutrition. However, clinicians caring for ICU patients are often faced with contradictory data and difficult decisions when having to determine the optimal timing and modalities of EN administration, estimation of patient requirements, and choice of formulas. The purpose of this paper is to provide practical guidelines on these various aspects of enteral nutritional support, based on presently available evidence.

Enteral nutrition in intensive care patients: a practical approach. Working Group on Nutrition and Metabolism, ESICM. European Society of Intensive Care Medicine.

Severe protein-calorie malnutrition is a major problem in many intensive care (ICU) patients due to the increased catabolic state often associated with acute severe illness and the frequent presence of prior chronic wasting conditions. Nutritional support is thus an important part of the management of these patients. Over the years, enteral nutrition (EN) has gained considerable popularity, due to its favorable effects on the digestive tract and its lower cost and rate of complications compared to parenteral nutrition. However, clinicians caring for ICU patients are often faced with contradictory data and difficult decisions when having to determine the optimal timing and modalities of EN administration, estimation of patient requirements, and choice of formulas. The purpose of this paper is to provide practical guidelines on these various aspects of enteral nutritional support, based on presently available evidence.

Effect of providing fortified meals and between-meal snacks on energy and protein intake of hospital patients

This study aimed to evaluate whether food fortification and snacks could increase the energy and protein intakes of hospital patients. The control group of 82 consecutive admissions on medical, elderly care and orthopaedic wards ate freely from the hospital menu. Subsequently, an intervention group of 62 patients were offered fortified food and snacks, providing an extra 22.2|g protein/day and 966 kcal/day in addition to the standard menu. Fortification significantly increased energy intake in the intervention group (P = 0.007, independent samples t-test), having the greatest effect on groups with the lowest energy intake, that is male and female orthopaedic, female medical and female elderly patients (84 cent of total). The increases in energy intake were 21.3 cent, 21.4 cent, 23 cent and 19.6 cent respectively. Although the increased energy and protein intake represented 25.6 cent and 22.5 cent respectively, of the supplements given, and suggested that wastage was high, it was nevertheless sufficient to remove energy deficit. We therefore propose that provision of fortified food and snacks is a convenient method of improving the nutritional intakes of hospital patients.

Artificial nutrition support in hospitals in the United Kingdom — 1991: Second national survey

Objective - to determine current clinical practice of nutrition support in hospitals in the UK and to determine whether there have been any apparent changes in practices since 1988. Design - An 81 question survey about enteral and parenteral nutriton was sent to all District Dietitians registered with the British Dietetic Association. Information was collected additionally from pharmacists and clinicians. Results - 61.2% of questionnaires distributed were completed and returned. 32.5% of respondents had access to nutrition support teams, compared with 27% in 1988. The documentation of usage of nutrition support was poor, only 33% being able to accurately quantify administation of enteral nutrition, and 53% parenteral nutrition. Since 1988 the number of respondents using peripheral parenteral nutrition had doubled to 15%. Those using percutaneous gastrostomies had increased from 6% to 74%. Those using respiratory enteral diet formulations had quadrupled to 33%. There have been no other apparent major changes in nutrition support practice in the UK, in the last 3 years. Conclusions - Despite increasing awareness about the role of artificial nutrition support, and the value of Nutrition Support Teams there has been little or no progress in the provision or monitoring of support in the last 3 years. This has important implications when considering audit of such practices.

Effect of peptide chain length on absorption of egg protein hydrolysates in the normal human jejunum

The influence of the peptide chain length of partial enzymic hydrolysates of protein on nitrogen and amino acid absorption was studied in 12 subjects using a jejunal perfusion technique. Three hydrolysates of egg white and an equivalent amino acid mixture were perfused at 30 mmol/L and 100 mmol/L in two separate experiments. Two hydrolysates (OH1 and OH2) contained mainly dipeptides and tripeptides, whereas the third (OH3) comprised tripeptide to pentapeptides as judged chromatographically. Nitrogen absorption was significantly slower from the higher chain length mixture, OH3, than from the short chain mixtures, OH1 and OH2, at both concentrations. Similarly, several amino acid residues were absorbed less well from OH3 than from OH1 and OH2. These data demonstrate that the chain length of heterogeneous mixtures of peptides affects absorption of nitrogen and individual amino acid residues, and suggest that brush border hydrolysis of tetrapeptides and pentapeptides limits absorption from enzymic hydrolysates of protein which simulate the composition of the postprandial luminal contents.

Assessment of an Automated Chemiluminescence Nitrogen Analyzer for Routine Use in Clinical Nutrition

An automated method of chemiluminescence analysis of nitrogen used routinely for 4 yr. Liquid samples (urine, enteral, and parenteral feeds) required simple dilution, whereas feces required a modified acid-digestion procedure, before analysis. For urine samples, the coefficient of variation was within batch from 0.9-3.6%, and between batch 4.3-7.6%. At a sample injection rate of 2 microliter/sec, the useful dynamic range, for urine diluted 1:200, was 0-14 g N/liter. Precision for fecal nitrogen analysis was 3.8-6.7% for samples of low to high nitrogen content. The correlation between this technique and an established Kjeldahl method for fecal analysis was studied (r = 0.96, slope = 1.30). The discrepancy between the methods was due to inefficient conversion of nitrogen to NH4+ during Kjeldahl digestion of feces, rather than systematic errors in chemiluminescence analysis. Reliability was as good as for other automated clinical analyzers and sample cost was ca. 0.22 pounds. It has proved possible to analyze approximately 80 samples in the working day. The efficiency of measuring 24-hr urine urea-nitrogen (UUN) and total urine nitrogen (TUN) in patients on general wards was measured. Results were obtained on 87% of TPN days, but large variations were noted in UUN/TUN from less than 30% to greater than 90% (average 75.7%) in patients receiving TPN, and from less than 55% to 100% (average 83.8%) in patients receiving enteral nutrition. In contrast, UUN/TUN was 87.0% and 84.0% in healthy subjects, fasted or receiving iv nutrition, respectively. We therefore expect that clinical nutritionists will find increasing applications for this method of nitrogen analysis.

Nutritional support in critically ill children.

BACKGROUND & AIMS Enteral nutrition is the feeding method of choice during critical illness, but in some cases as few as 25% are fed appropriately. The aim was to retrospectively review the administration of nutrition to critically ill children. METHODS The notes of 95 children over the age of 1 year who were in PICU>or=3 days were reviewed and information related to the delivery of nutrition was obtained. RESULTS Fifty-nine per cent were fed within 24h of admission. Enteral nutrition was administered 54% of the time, 10% required parenteral nutrition and 9.5% received no nutritional support. Children only received a median 58.8 (range 0-277)% of their energy requirements, which could not be optimised until the 10th intensive care day. Energy intake was greater when supplemented with parenteral nutrition. Parenteral nutrition administration was interrupted 3 times while enteral nutrition was stopped 264 times, mainly to allow other clinical procedures to take place. For 75% of the study time, children had abnormal bowel patterns. Seventy-nine per cent were constipated for 3-21 days and 43% had diarrhoea of unknown aetiology. CONCLUSION This was a retrospective study to describe the efficiency of nutritional support in critically ill children. We have shown that it is possible to administer enteral nutrition safely. However, the difference between desirable intake and actual intake achieved suggests that a more pro-active approach should be adopted.

Can energy expenditure be predicted in critically ill children

Objective To determine whether critically ill children are hypermetabolic and to calculate whether predictive equations are appropriate for critically ill children. Design Prospective, clinical study. Setting Pediatric intensive care unit. Patients A total of 57 children (39 boys) aged 9 months to 15.8 yrs. Interventions None. Measurements and Main Results The median resting energy expenditure measurement measured by indirect calorimetry was 37.2 (range, 11.9–66.6) kcal·kg−1·day−1. This was significantly lower than would be predicted using either the Schofield (42.7 [26.9–65.4] kcal·kg−1·day−1) or Fleisch equations (42.8 [20.9–66.2] kcal·kg−1·day−1, p < .001) but significantly higher than the White equation developed specifically for pediatric intensive care units (26.2 [8.5–70.1] kcal·kg−1·day−1, p < .0001). Methods comparison analysis showed the limits of agreement were −484 to 300, −461 to 319, and −3.2 to 854 kcal/day, respectively. Multivariate analysis indicated the following factors contribute to hypometabolism and hypermetabolism: age (p = .006), sex (p = .034), time spent in the pediatric intensive care unit (p = .001), diagnosis (p = .015), weight (p = .009), temperature (p = .04), continuous infusion for sedation (p = .04), and neuromuscular blockade (p = .03). Conclusions Children do not become hypermetabolic during critical illness. These data suggest that agreement between resting energy expenditure and the predictive equations are so broad that they are inappropriate for use in critically ill children.

Nucleotides as immunomodulators in clinical nutrition

Dietary nucleotides, like glutamine, have attracted attention as a key ingredient missing from nutritional formulae for many years. They are the building blocks of tissue RNA and DNA and of ATP and their presence in breast milk has stimulated research in babies which has indicated that supplementation of infant formula milk leads to improved growth and reduced susceptibility to infection. Animal studies have confirmed some of these data. In particular, dietary nucleotides modulate immune function, promote faster intestinal healing and have trophic effects on the intestine of parenterally-fed rats which are similar to those resulting from glutamine supplementation, but at much lower intakes. Nucleotide supplementation has also been shown to improve some aspects of tissue recovery from ischaemia/reperfusion injury or radical resection. There is, however, a fundamental paradox. The intestine and liver possess powerful homeostatic mechanisms which degrade intake of purines and pyrimidines (i.e. salvage) and replace it with de novo synthesised output. It is possible that peripheral tissues receive only small amounts of nucleotides of dietary origin. Previously, nucleotides have been proposed as being conditionally-essential nutrients that provide an adequate supply of purines and pyrimidines for nucleic acid synthesis in neonates or in the stressed patient. This review explores this puzzle in the light of recent data from nutritional studies and from research into purinergic signalling in the intestine, heart and cells of the immune system. We propose that dietary nucleotides should be considered within a pharmacological and metabolic framework.

Position paper of the ESICM Working Group on Nutrition and Metabolism

The metabolic changes associated with critical illness involve several pathways acting at different steps of the utilization of nutritive substrates. The understanding of the role of these pathways and of their complex regulation has led to the development of new strategies for the metabolic and nutritional management of critically ill patients, including the development of new products for nutritional support. The rationale for changing the profile of nutritional support solutions by adding novel substrates is also discussed. This review focuses on the metabolic specificities of critically ill patients and also includes an analysis of the adequacy of tools to monitor the metabolic status and the adequacy of the nutritional support.