Nutrition in chronic critical illness

First international meeting of early career investigators: Current opportunities, challenges and horizon in critical care nutrition research

BACKGROUND

Appropriate nutritional support is a key component of care for critically ill patients. While malnutrition increases complications, impacting long term outcomes and healthcare-related costs, uncertainties persist regarding optimal provision of nutritional support in this setting.

METHODS

An international group of healthcare providers (HCPs) from critical care specialties and nutrition researchers convened to identify knowledge gaps and learnings from studies in critical care nutrition. Clinical research needs were identified in order to better inform future nutrition practices.

RESULTS

Challenges in critical care nutrition arise, in part, from inconsistent outcomes in several large-scale studies regarding the optimal amount of calories and protein to prescribe, the optimal time to initiate nutritional support and the role of parental nutrition to support critically ill patients. Furthermore, there is uncertainty on how best to identify patients at nutritional risk, and the appropriate outcome measures for ICU nutrition studies. Given HCPs have a suboptimal evidence base to inform the nutritional management of critically ill patients, further well-designed clinical trials capturing clinically relevant endpoints are needed to address these knowledge gaps.

CONCLUSIONS

The identified aspects for future research could be addressed in studies designed and conducted in collaboration with an international team of interdisciplinary nutrition experts. The aim of this collaboration is to address the unmet need for robust clinical data needed to develop high-quality evidence-based nutritional intervention recommendations to better inform the future management of critically ill patients.

Prediction of Prolonged ICU Stay in Cardiac Surgery Patients as a Useful Method to Identify Nutrition Risk in Cardiac Surgery Patients: A Post Hoc Analysis of a Prospective Observational Study

BACKGROUND

Cardiovascular surgery patients with a prolonged intensive care unit (ICU) stay may benefit most from early nutrition support. Using established scoring systems for nutrition assessment and operative risk stratification, we aimed to develop a model to predict a prolonged ICU stay ≥5 days in order to identify patients who will benefit from early nutrition interventions.

METHODS

This is a retrospective analysis of a prospective observational study of patients undergoing elective valvular, coronary artery bypass grafting, or combined cardiac surgery. The nutrition risk was assessed by well-established screening tools. Patients' preoperative EuroSCORE (European System for Cardiac Operative Risk Evaluation), primary disease, and intraoperative cardiopulmonary bypass (CPB) time were included as independent variables in a multivariate logistic regression analysis to predict a prolonged ICU stay (>4 days).

RESULTS

The number of cardiac surgery patients included was 1193. Multivariate analysis revealed that for prediction of ICU stay >4 days, both Nutritional Risk Screening 2002 (area under the curve (AUC): 0.716, P = .020) and Mini Nutritional Assessment (MNA) score (AUC: 0.715, P = .037) were significant, whereas for prediction of ICU stay >5 days, only the MNA score showed significant results (AUC: 0.762, P = .011).

CONCLUSION

Present data provide first evidence about the combined use of EuroSCORE, primary disease, CPB time, and nutrition risk screening tools for prediction of prolonged ICU stay in cardiac surgery patients. If prospectively evaluated in adequately designed studies, this model may help to identify patients with prolonged ICU stay to initiate early postoperative nutrition therapy and thus, facilitate an enhanced recovery.

Body composition in patients with stable chronic obstructive pulmonary disease: comparison with malnutrition in healthy smokers

OBJECTIVE

Although malnutrition (body mass index (BMI)<18.5kg/ m(2)) has been associated with impaired health status in patients with chronic obstructive pulmonary disease (COPD), the effects of body composition (body fat and protein percentage) in patients with COPD have not been clearly demonstrated.

MATERIALS AND METHODS

A total of 180 stable patients with COPD at the stages of moderate, severe, very severe, and 50 healthy subjects were included in this prospective study. All subjects underwent a clinical evaluation, spirometry tests, anthropometric measurements and blood analysis.

RESULTS

Frequency of underweight was higher in COPD (11.7%) patients than the control group (8%). The frequency of underweight increased as the severity of COPD worsens. There was body decomposition (protein or fat depletion) in not only all underweight patients but also some normal/overweight COPD patients, as well as in the healthy subjects. Deterioration in FEV1 (L), and FEV1/FVC was more evident in underweight patients with protein and fat depletion compared to normal/overweight patients (p=0.004, and p=0.005). Inspiratory and expiratory respiratory muscle power was lower in under-weight patients with depletion than in normal/overweight patients (p=0.02, and p=0.01). DLCO and DLCO/VA were significantly lower in underweight patients than in normal/overweight patients (p=0.003, and p=0.004), they were also lower in normal/overweight patients with depletion than in normal/overweight patients with no depletion (p=0.01, and p=0.07). Normal/overweight patients with protein depletion had the most frequent number of exacerbations than others (p=0.04).

CONCLUSION

These results show that the body decomposition is important in patients with COPD. Assessment of body composition should be a part of nutritional assessment besides BMI in patients with COPD.

Weight loss composition is one-fourth fat-free mass: a critical review and critique of this widely cited rule

Maximizing fat loss while preserving lean tissue mass and function is a central goal of modern obesity treatments. A widely cited rule guiding expected loss of lean tissue as fat-free mass (FFM) states that approximately one-fourth of weight loss will be FFM (i.e. ΔFFM/ΔWeight = ∼0.25), with the remaining three-fourths being fat mass. This review examines the dynamic relationships between FFM, fat mass and weight changes that follow induction of negative energy balance with hypocaloric dieting and/or exercise. Historical developments in the field are traced with the 'Quarter FFM Rule' used as a framework to examine evolving concepts on obesity tissue, excess weight and what is often cited as 'Forbes' Rule'. Temporal effects in the fractional contribution of FFM to changes in body weight are examined as are lean tissue moderating effects such as ageing, inactivity and exercise that frequently accompany structured low-calorie diet weight loss protocols. Losses of lean tissue with dieting typically tend to be small, raising questions about study design, power and applied measurement method reliability. Our review elicits important questions related to the fractional loss of lean tissues with dieting and provides a foundation for future research on this topic.

Enteral nutrition discontinuation and outcomes in general critically ill patients

OBJECTIVE

To determine the relationship between enteral nutrition discontinuation and outcome in general critically ill patients.

MATERIALS AND METHODS

All patients admitted to a mixed intensive care unit in a tertiary care hospital from May-August 2009 were screened for an indication for enteral nutrition. Patients were followed up until leaving the intensive care unit or a maximum of 28 days. The gastrointestinal failure score was calculated daily by adding values of 0 if the enteral nutrition received was identical to the nutrition prescribed, 1 if the enteral nutrition received was at least 75% of that prescribed, 2 if the enteral nutrition received was between 50-75% of that prescribed, 3 if the enteral nutrition received was between 50-25% of that prescribed, and 4 if the enteral nutrition received was less than 25% of that prescribed.

RESULTS

The mean, worst, and categorical gastrointestinal failure scores were associated with lower survival in these patients. Age, categorical gastrointestinal failure score, type of admission, need for mechanical ventilation, sequential organ failure assessment, and Acute Physiologic and Chronic Health Evaluation II scores were selected for analysis with binary regression. In both models, the categorical gastrointestinal failure score was related to mortality.

CONCLUSION

The determination of the difference between prescribed and received enteral nutrition seemed to be a useful prognostic marker and is feasible to be incorporated into a gastrointestinal failure score.

Moderate glucose control results in less negative nitrogen balances in medical intensive care unit patients: a randomized, controlled study

Introduction

Hyperglycemia and protein loss are common in critically ill patients. Insulin can be used to lower blood glucose and inhibit proteolysis. The impact of moderate insulin therapy on protein metabolism in critically ill patients has not been evaluated. We compared urinary nitrogen excretion, nitrogen balance, serum albumin concentrations, prealbumin concentrations, and clinical outcomes between patients receiving moderate insulin therapy (MIT) and conventional insulin therapy (CIT) in a medical ICU.

Methods

Patients were randomly divided into groups and treated with MIT (glucose target 120 to 140 mg/dl) or CIT (glucose target 180 to 200 mg/dl). Calories and protein intake were recorded each day. On days 3, 7 and 14, the 24-hour urinary nitrogen excretion, nitrogen balance, and serum albumin and prealbumin concentrations were measured. Clinical outcomes data were collected.

Results

A total of 112 medical ICU patients were included, with 55 patients randomized to the MIT group and 57 patients randomized to the CIT group. Patients treated with MIT showed a trend towards increased nitrogen balance (P = 0.070), significantly lower urinary nitrogen excretion (P = 0.027), and higher serum albumin (P = 0.047) and prealbumin (P = 0.001) concentrations than patients treated with CIT. The differences between the two groups were most significant on day 3, when all factors showed significant differences (P < 0.05).

Conclusions

Moderate glucose control results in less negative nitrogen balances in medical ICU patients. Differences are more significant in the early stages compared with the late stages of critical illness.

Trial registration

ClinicalTrial.Gov NCT 01227148

To return or to discard? Randomised trial on gastric residual volume management

BACKGROUND

The control of gastric residual volume (GRV) is a common nursing intervention in intensive care; however the literature shows a wide variation in clinical practice regarding the management of GRV, potentially affecting patients' clinical outcomes. The aim of this study is to determine the effect of returning or discarding GRV, on gastric emptying delays and feeding, electrolyte and comfort outcomes in critically ill patients.

METHOD

A randomised, prospective, clinical trial design was used to study 125 critically ill patients, assigned to the return or the discard group. Main outcome measure was delayed gastric emptying. Feeding outcomes were determined measuring intolerance indicators, feeding delays and feeding potential complications. Fluid and electrolyte measures included serum potassium, glycaemia control and fluid balance. Discomfort was identified by significant changes in vital signs.

RESULTS

Patients in both groups presented similar mean GRV with no significant differences found (p=0.111), but participants in the intervention arm showed a lower incidence and severity of delayed gastric emptying episodes (p=0.001). No significant differences were found for the rest of outcome measurements, except for hyperglycaemia.

CONCLUSIONS

The results of this study support the recommendation to reintroduce gastric content aspirated to improve GRV management without increasing the risk for potential complications.

Bench-to-bedside review: mobilizing patients in the intensive care unit--from pathophysiology to clinical trials

As the mortality from critical illness has improved in recent years, there has been increasing focus on patient outcomes after hospital discharge. Neuromuscular weakness acquired in the intensive care unit (ICU) is common, persistent, and often severe. Immobility due to prolonged bed rest in the ICU may play an important role in the development of ICU-acquired weakness. Studies in other patient populations have demonstrated that moderate exercise is beneficial in altering the inflammatory milieu associated with immobility, and in improving muscle strength and physical function. Recent studies have demonstrated that early mobility in the ICU is safe and feasible, with a potential reduction in short-term physical impairment. However, early mobility requires a significant change in ICU practice, with reductions in heavy sedation and bed rest. Further research is required to determine whether early mobility in the ICU can improve patients' short-term and long-term outcomes.

Impact of energy deficit calculated by a predictive method on outcome in medical patients requiring prolonged acute mechanical ventilation

To assess energy balance in very sick medical patients requiring prolonged acute mechanical ventilation and its possible impact on outcome, we conducted an observational study of the first 14 d of intensive care unit (ICU) stay in thirty-eight consecutive adult patients intubated at least 7 d. Exclusive enteral nutrition (EN) was started within 24 h of ICU admission and progressively increased, in absence of gastrointestinal intolerance, to the recommended energy of 125.5 kJ/kg per d. Calculated energy balance was defined as energy delivered - resting energy expenditure estimated by a predictive method based on static and dynamic biometric parameters. Mean energy balance was - 5439 (sem 222) kJ per d. EN was interrupted 23 % of the time and situations limiting feeding administration reached 64 % of survey time. ICU mortality was 72 %. Non-survivors had higher mean energy deficit than ICU survivors (P = 0.004). Multivariate analysis identified mean energy deficit as independently associated with ICU death (P = 0.02). Higher ICU mortality was observed with higher energy deficit (P = 0.003 comparing quartiles). Using receiver operating characteristic curve analysis, the best deficit threshold for predicting ICU mortality was 5021 kJ per d. Kaplan-Meier analysis showed that patients with mean energy deficit > or =5021 kJ per d had a higher ICU mortality rate than patients with lower mean energy deficit after the 14th ICU day (P = 0.01). The study suggests that large negative energy balance seems to be an independent determinant of ICU mortality in a very sick medical population requiring prolonged acute mechanical ventilation, especially when energy deficit exceeds 5021 kJ per d.

Nutritional considerations for animals with pulmonary disease

Recent publications in the human and veterinary literature have indicated that patients with pulmonary disease require specific nutritional consideration to ensure that optimal benefit is derived with nutrition support. Although additional research is needed in this area, preliminary recommendations can be made using information from the scant studies performed thus far in veterinary medicine and from information extrapolated from the human literature. These recommendations are likely to provide significant clinical benefit to patients with pulmonary disease. This article aims to provide the reader with a summary of the available information and links to other relevant sources.

Nutrition support and the chronic critical illness syndrome

Critical illness can be viewed as consisting of 4 distinct stages: (1) acute critical illness (ACI), (2) prolonged acute critical illness, (3) chronic critical illness, and (4) recovery. ACI represents the evolutionarily programmed response to a stressor. In ACI, substrate is shunted away from anabolism and toward vital organ support and inflammatory proteins. Nutrition support in this stage is unproven and may ultimately prove detrimental. As critical illness progresses, there is no evolutionary precedent, and man owes his life to modern critical care medicine. It is at this point that nutrition and metabolic support become integral to the care of the patient. This paper (1) delineates and develops the 4 stages of critical illness using current evidence, clinical experience, and new hypotheses; (2) defines the chronic critical illness syndrome (CCIS); and (3) details an approach to the metabolic and nutrition support of the chronically critically ill patient using the metabolic model of critical illness as a guide. It is our hope that this clinical model can generate testable hypotheses that can improve the outcome of this unique population of patients.

Intestinal failure

PURPOSE OF REVIEW

The gastrointestinal tract plays a major role in critical illness. We will review four common problem areas pertaining to the gut and abdominal compartment that intensivists managing critically ill patients must deal with on an everyday basis.

RECENT FINDINGS

In the area of enteral nutrition, there have been concerns that early feeding in hemodynamically unstable patients might cause bowel infarction by increasing the gut oxygen consumption beyond splanchnic oxygen delivery. The most recent data suggest that early enteral feeding, even when patients are receiving vasopressors, is safe and may actually protect the gut by increasing gut perfusion. Although there are no new treatments for ileus, in most critically ill patients ileus primarily affects the stomach and large intestine, and most patients who are diagnosed with ileus may still be fed enterally as long as they are fed distal to the stomach. Diarrhea is a common occurrence in the intensive care unit, particularly in patients who are being fed enterally. Of most import is the realization that Clostridium difficile infection is ubiquitous and must be considered in virtually every case of diarrhea. Abdominal compartment syndrome is usually a result of shock, and its resuscitation with increased intra-abdominal pressure results in many untoward hemodynamic and respiratory events. Early recognition and treatment seem to be associated with improved outcome.

SUMMARY

Continued progress in the areas of optimal nutritional support, understanding the implications of alterations in immune function of the gut, and the avoidance of such morbid complications as abdominal compartment syndrome are expected.

Nutrition of the critically ill patient and effects of implementing a nutritional support algorithm in ICU

AIM

To test whether a feeding algorithm could improve the nutritional support of intensive care patients.

BACKGROUND

Numerous factors may impede delivery of both enteral and parenteral nutrition to patients in the intensive care unit. Often there is a discrepancy between what is prescribed and actual delivery of nutrients. The purpose of this study was to test the effect of a nutritional support algorithm in an intensive care unit mainly by using the enteral route and if necessary by combining enteral and parenteral nutrition.

METHODS

In this prospective study, nutritional data were collected from routinely fed critically ill patients (controls, n=21) during the first three days following admission to the intensive care unit. A nutritional support algorithm was then implemented and nutritional data were collected from critically ill patients who participated in this intervention (intervention group, n=21). Data collected included the total amount of calories prescribed vs. received, onset of delivery of enteral nutrition, enteral vs. parenteral nutrition, and the use and size of enteral feeding tubes.

RESULTS

Patients in the intervention group were both prescribed and actually received significantly larger amounts of nutrients than patients in the control group. They also received a larger proportion of their nutrients in the form of enteral nutrition. In addition, the nutritional support algorithm led to greater consistency in nursing practices with respect to aspiration of gastric content and rate of increment in enteral feeding.

CONCLUSION

The study confirms that a nutritional support algorithm improved the delivery of nutrients to critically ill patients. The algorithm was most effective with respect to the delivery of enteral nutrition. The effect was primarily because of early and more rapid increment in the delivery of enteral nutrition administered by nurses based on improved physician orders. The combination of enteral and parenteral nutrition may contribute to meeting adequate nutritional requirements.

RELEVANCE TO CLINICAL PRACTICE

By using a nutritional algorithm focused on enteral nutrition, but including parenteral nutrition as a supplement, it is possible to improve the delivery of clinical nutrition in the intensive care unit patients.

Enteral feeding in the critically ill: are nursing practices contributing to hypocaloric feeding?

INTRODUCTION

Enteral feeding is the preferred method of nutritional support for the critically ill; however, a significant number of these patients are under-fed. It is possible that common nursing practices associated with the delivery of enteral feeding may contribute to under-feeding although there is little data available describing nursing practice in this area.

METHOD

A descriptive survey-based design was used to explore the enteral feeding practices of 376 critical care nurses (response rate 50.5%). Participants completed a 57-item survey that focused on general enteral feeding practice and the management of feeding intolerance and complications.

RESULTS

The enteral feeding practice of critical care nurses varied widely and included some practices that could contribute to under-feeding in the critically ill. Practices associated with the measurement of gastric residual volumes (GRV) were identified as the most significant potential contributor to under-feeding. GRV measurements were commonly used to assess feeding tolerance (n = 338; 89.9%) and identified as a reason to delay feeding (n = 246; 65.4%). Delayed gastric emptying was frequently managed by prokinetic agents (n = 237; 63%) and decreasing the rate of feeding (n = 247; 65.7%) while nursing measures, such as changing patient position (n = 81; 21.5%) or checking tube placement (n = 94; 25%) were less frequently reported.

CONCLUSION

The findings of this survey support the contention that nursing practices associated with the delivery of enteral feeds may contribute to under-feeding in the critically ill patient population.

Myopathies in critical illness: characterization and nutritional aspects

Myopathies related to critical illness have received increasing recognition over the past decade and are common in patients even after a brief period in the intensive care unit. Recent studies have revealed that myopathies in the critically ill may in fact be more prevalent than neuropathies and that morbidity and mortality may be greater. Protein catabolism, an increase in urinary nitrogen loss, and muscle wasting are observed in critical illness myopathy. Muscle biopsies in critically ill patients demonstrate low glutamine levels, low protein/DNA levels, and high concentrations of extracellular water. The increased flux of glutamine in muscle in these patients is thought to be insufficient to meet the body's requirement for glutamine, and thus in critical illness this amino acid may be classified as "conditionally essential." Three subtypes of critical illness myopathy have been described that are often grouped together as acute quadriplegic myopathy: thick-filament myopathy, critical illness myopathy, and necrotizing myopathy. These can be differentiated based on clinical features and muscle biopsy. Treatments for critical illness myopathies range from primary prevention, i.e., avoiding myopathy-inducing drugs, to novel nutritional therapies, such as glutamine and glutathione supplementation. One should be particularly vigilant for the development of myopathies in critically ill alcoholic patients, who may have a chronic alcoholic myopathy at baseline. In the past decade, advances have been made in characterizing and identifying patients with myopathies due to critical illness. However, additional studies must be performed in order to develop appropriate therapies for this potentially devastating disorder.

Short-term protein intake and stimulation of protein synthesis in stunted children with cystic fibrosis

BACKGROUND

Stunted children with cystic fibrosis (CF) have less net protein anabolism than do children without CF, and the result is retarded growth in the CF patients. It is not known whether protein intake above that recommended by the Cystic Fibrosis Foundation would further stimulate whole-body protein synthesis.

OBJECTIVE

We studied the effects of 3 amounts of protein intake on whole-body protein synthesis and breakdown by using isotopic infusion of [1-(13)C]valine and [(15)N(2)]urea in children with stable CF who required tube feeding.

DESIGN

In 8 pediatric CF patients, we administered 3 randomly allocated isocaloric diets with normal (NP), intermediate (IP), and high (HP) amounts of protein (1.5, 3, and 5 g . kg(-1) . d(-1), respectively) by continuous drip feeding during a 4-d period at 6-wk intervals. Each patient acted as his or her own control. On the fourth day of feeding, whole-body protein synthesis and breakdown were measured.

RESULTS

Protein synthesis was significantly higher in the HP group (x +/- SEM: 1.78 +/- 0.07 micromol . kg(-1) . min(-1)) than in the IP (1.57 +/- 0.08 micromol . kg(-1) . min(-1); P=0.001) and NP (1.37 +/- 0.07 micromol . kg(-1) . min(-1); P < 0.001) groups. There were no significant differences in protein breakdown. Net retention of nitrogen was significantly higher in the HP group (12.93 +/- 1.42 micromol . kg(-1) . min(-1)) than in the IP (7.61 +/- 1.40 micromol . kg(-1) . min(-1); P=0.01) and HP (2.48 +/- 0.20 micromol . kg(-1) . min(-1); P < 0.001) groups.

CONCLUSION

In stunted children with CF requiring tube feeding, the highest stimulation of whole-body protein synthesis was achieved with a short-term dietary protein intake of 5 g . kg(-1) . d(-1).

Effects of undernutrition on respiratory mechanics and lung parenchyma remodeling

Undernutrition thwarts lung structure and function, but there are disagreements about the behavior of lung mechanics in malnourished animals. To clarify this issue, lung and chest wall mechanical properties were subdivided into their resistive, elastic, and viscoelastic properties in nutritionally deprived (ND) rats and correlated with the data gathered from histology (light and electron microscopy and elastic fiber content), and bronchoalveolar lavage fluid analysis (lipid and protein content). Twenty-four Wistar rats were assigned into two groups. In the control (Ctrl) group the animals received food ad libitum. In the ND group, rats received one-third of their usual daily food consumption until they lost 40% of their initial body weight. Lung static elastance, viscoelastic and resistive pressures (normalized by functional residual capacity), and chest wall pressures were higher in the ND group than in the Ctrl group. The ND group exhibited patchy atelectasis, areas of emphysema, interstitial edema, and reduced elastic fiber content. The amount of lipid and protein in bronchoalveolar lavage fluid was significantly reduced in the ND group. Electron microscopy showed 1) type II pneumocytes with a reduction in lamellar body content, multilamellated structures, membrane vesicles, granular debris, and structurally aberrant mitochondria; and 2) diaphragm and intercostals with atrophy, disarrangement of the myofibrils, and deposition of collagen type I fibers. In conclusion, undernutrition led to lung and chest wall mechanical changes that were the result from a balance among the following modifications: 1) distorted structure of diaphragm and intercostals, 2) surfactant content reduction, and 3) decrease in elastic fiber content.

Influence of nutritional status on alcoholic myopathy

BACKGROUND

Muscle weakness and structural changes in striated skeletal muscle are common in persons with chronic alcoholism.

OBJECTIVE

The objective of the study was to assess the role of malnutrition in the development of chronic alcoholic myopathy.

DESIGN

We prospectively evaluated 146 men who reported an intake >/=100 g ethanol/d for the previous 5 y and 73 well-nourished control subjects. Alcohol consumption, energy and protein nutritional status, and deltoid muscle strength were determined. Deltoid muscle tissue specimens were taken from alcoholics and from 14 control subjects for histochemical studies and morphometric measurements of the fibers.

RESULTS

Deltoid muscle strength was less in alcoholics than in control subjects (P < 0.001). Muscle strength correlated with lifetime consumption of ethanol (r = -0.56, P < 0.001), and a decrease in muscle strength was significantly greater in the presence of energy malnutrition. Using logistic regression analysis, we observed that alcoholics with muscle strength < 18 kg had the independent risk factors of an arm muscle area < 50 cm(2) (odds ratio: 5.4; 95% CI: 2.3, 12.3), consumption of > 1600 kg ethanol throughout their lives (odds ratio: 4.5; 95% CI: 2.0, 10.1), and protein malnutrition (odds ratio: 4.2; 95% CI: 1.4, 12.7). Protein malnutrition was also associated with muscle inefficiency (P < 0.001). Histologic myopathy was present in 58% of alcoholics, was related to lifetime ethanol consumption (P = 0.001), and was more severe in the presence of protein malnutrition (P = 0.01).

CONCLUSION

Malnutrition is an additional developmental factor in the functional and structural muscle damage induced by chronic ethanol consumption.

Nutrition in critical care

Many hospitalized patients with cancer are malnourished. Some become critically ill and experience delayed wound healing, loss of muscle strength, and reduced infection fighting ability as a consequence of the loss of nutritional reserves. Complications of critical illness may cause interruption in normal gastrointestinal function and result in shock, sepsis, hypochlorhydria, systemic inflammatory response syndrome, and other disorders. As a result, critically ill patients may require nutritional support.