A.S.P.E.N. 1990 research workshop on energy metabolism

Estimating energy expenditure in critically ill adults and children

Designing effective nutrition support regimens for critically ill patients requires an understanding of the energy needs of each patient. Many disease processes result in elevated caloric requirements, whereas some clinical procedures and medications may diminish the metabolic response. Experienced clinicians are unable to predict the extent to which trauma or injury will affect energy requirements for an individual. Both under- and overfeeding a critically ill patient may prolong hospitalization and increase morbidity and mortality. Applying equations that were originally developed for healthy nonhospitalized individuals to predict the energy requirements of critically ill patients will often result in significant errors and may lead to provision of inappropriate nutritional support. The measurement of resting energy expenditure by indirect calorimetry is a valuable tool and can be used to predict energy requirements for most spontaneously breathing critically ill patients, but may lead to spurious results in mechanically ventilated pediatric patients. In the complex and rapidly changing context of critical illness, individualized assessment of energy requirements is crucial. Whichever technique is used initially to assess energy requirements, sequential monitoring and constant reassessment of each patient is essential to provide the appropriate nutritional care regimen. The purpose of this article is to review the equations for estimating and the techniques, practical aspects, and interpretation of measuring energy expenditure in critically ill patients.

Nutritional support in alcoholic cirrhotic patients improves host defenses

BACKGROUND

Malnutrition is usual in patients with alcoholic liver disease and is associated with a poor outcome. Nutritional support decreases nutrition-associated complications.

AIM

To demonstrate that nutritional support in ambulatory alcoholic cirrhotic patients improves host defenses.

METHODS

Thirty-one male outpatients with alcoholic cirrhosis CHILD-PUGH B or C were included. Twenty-five subjects completed six months consuming daily a nutritional supplement (Ensure, 1000 Kcal and 35 g protein), in addition to their regular diet. At entrance and every three months, a clinical assessment, nutritional evaluation and indirect calorimetry were performed. Liver function tests and LPS-induced monocyte production of cytokines, salivary secretory IgA, lactulose/mannitol ratio and breath hydrogen tests were also measured in these intervals. Delayed cutaneous hypersensitivity and IgG and IgM antibody response to endotoxin were assessed at entrance and at the end of the study.

RESULTS

Patients drank 85% of the provided supplement as an average. REE, total body fat and serum albumin increased, basal breath hydrogen decreased and cellular immunity improved significantly during the follow up period (p< or =0.03). All the other parameters remained unchanged throughout the study. Six patients (16.2%) died during the study, five due to upper gastrointestinal bleeding.

CONCLUSION

Nutritional support in alcoholic cirrhotic patients improves nutritional status and cell mediated immunity.

Hypoglycaemia in spinal muscular atrophy

Repeated episodes of hypoglycaemia were observed in two girls with spinal muscular atrophy. During a 12 h fast blood glucose fell to 3.4 and 2.7 mmol/L, respectively. One girl developed hypoglycaemia and ketonuria. Reduced gluconeogenesis was probably the cause of hypoglycaemia in these patients who had a muscle mass of about 10% of bodyweight (normal 30-40%). Hypoglycaemia must be suspected and treated when patients with severe muscle wasting due to chronic neuromuscular disorders are admitted comatose. In our experience this condition is often regarded as respiratory insufficiency.

Nutritional parameters observed during 28-day infusion of recombinant human tumor necrosis factor-alpha

In conjunction with a Phase I investigation of the antineoplastic activity of recombinant human tumor necrosis factor-alpha (TNF-alpha), administered as a 28-day continuous infusion, selected nutritional parameters were evaluated to identify any effect that might be attributed to the TNF infusion. Seven clinically stable men with a variety of tumor types were studied. None had clinical or laboratory evidence of significant malnutrition before entry into the study. Five patients received 10 micrograms of recombinant human TNF-alpha per square meter per day and two patients received 25 micrograms/m2 per day. Indirect calorimetry assessment of resting energy expenditure, body weight, serum TNF concentration, and laboratory analysis of common nutritional markers (albumin, prealbumin, and triglycerides) were performed at baseline, day 14, day 28, and 2 weeks (day 42) after completion of the infusion. There were no statistically significant differences by analysis of variance observed in any parameter during the study period compared with baseline values and values on day 42. Also, there were no differences between any parameters when stratified by dose administered, although the number of patients studied was small. Measured serum TNF concentrations ranged from 0.02 to 1.56 ng/mL and did not correlate with study day or dose of TNF infused. No correlation was observed between serum TNF concentrations and resting energy expenditure. Although others have reported significant metabolic changes associated with acute administration of TNF in humans and animals, our experience does not support a hypermetabolic state in patients receiving low daily dose, long-term (28-day) continuous infusion of recombinant human TNF-alpha, a state that may be consistent with many neoplastic conditions.

Cytokine mediators of malnutrition: clinical implications

During the past decade, the relationships that exist between inflammatory cytokines and the metabolic changes associated with critical illness have been the focus of extensive research efforts. Alterations in protein metabolism, characterized by increased peripheral protein catabolism and increased hepatic synthesis of acute-phase proteins, have been reported with tumor necrosis factor, interleukin-1, and interleukin-6 administration in animals and humans. Hyperlipoproteinemia has also been observed, particularly in association with increases in very-low-density lipoproteins and hepatic fatty acid synthesis. The release of counter-regulatory hormones in response to cytokine activity contributes to these metabolic changes as well. An understanding of the complex interactions of cytokines as mediators of intermediary metabolism is important to clinicians caring for critically ill patients.

Predicted and measured resting energy expenditure in healthy young women

Basal energy expenditure (BEE) was either measured by indirect calorimetry or predicted by different formulae in 104 young women: 74 lean and overweight subjects (normal weight, NWt) and 30 obese subjects. The predictive equations were based on weight alone (Owen, FAO-1, Schofield-1) or on weight and height (Harris-Benedict, Mifflin, Kleiber, and again FAO-2 and Schofield-2). With the exception of the Owen equation all the equations over-estimated measured BEE in both study groups. The ratio between measured and predicted value (% MP) varied between 102.3 (Owen) and 87.7 (Kleiber) in the NWt subjects and between 113.2 (Owen) and 89.3 (Schofield-1) in the obese subjects. The range including 95% of the predicted-measured differences (PMdiff) was larger than 1700 kJ/d in the NWt group and 2300 kJ/d in the obese group. In both study groups most of the equations showed a significant relationship between PMdiff and/or % MP with body weight and the magnitude of BEE. In conclusion, these equations are of little help in predicting BEE in a single subject and should be used with caution when assessing energy requirements in populations or groups of subjects.