Hypocaloric, high-protein nutrition therapy for critically ill patients with obesity

ESPEN practical and partially revised guideline: Clinical nutrition in the intensive care unit

Following the new ESPEN Standard Operating Procedures, the previous 2019 guideline to provide best medical nutritional therapy to critically ill patients has been shortened and partially revised. Following this update, we propose this publication as a practical guideline based on the published scientific guideline, but shortened and illustrated by flow charts. The main goal of this practical guideline is to increase understanding and allow the practitioner to implement the Nutrition in the ICU guidelines. All the items discussed in the previous guidelines are included as well as special conditions.

Parenteral Nutrition Total Energy Dosing and Risk for Central Line-Associated Bloodstream Infection: A Case-Control Study

BACKGROUND

Central line-associated bloodstream infection (CLABSI) is a complication of central venous access devices used for parenteral nutrition (PN). PN overfeeding is associated with increased adverse effects; however, whether risk for CLABSI is influenced by PN dosing is uncertain.

OBJECTIVE

The purpose of the study was to assess differences in CLABSI risk associated with recommended total energy dosing in hospitalized adult patients receiving PN.

METHODS

A case-control study was conducted in a single United States Veterans Health Administration health system to assess the potential CLABSI risk factor of weight-based PN kilocalorie dosing. Hospitalized adult patients who developed CLABSI while receiving PN were identified and compared to a control group of patients who did not develop CLABSI. The exposures evaluated were overfeeding, defined as greater than 30 kcal/kg/day, and underfeeding, defined as less than 20 kcal/kg/day.

RESULTS

Twenty-nine cases of CLABSI were identified and compared with 274 controls. Odds of CLABSI were significantly higher in patients receiving greater than 30 kcal/kg/day (OR, 3.63; 95% CI, 1.55-8.48; P < .01). No significant difference in odds was found for patients receiving less than 20 kcal/kg/day (OR, .74; 95% CI, 0.21-2.57; P = .63).

CONCLUSION

Increased risk for CLABSI in hospitalized adult patients receiving PN was found to be associated with overfeeding, but not underfeeding. These results may aid clinicians in the management of patients requiring PN and in the generation of hypothesis for future investigations.

Augmented Renal Clearance Following Traumatic Injury in Critically Ill Patients Requiring Nutrition Therapy

The intent of this study was to ascertain the prevalence of augmented renal clearance (ARC) in patients with traumatic injuries who require nutrition therapy and identify factors associated with ARC. Adult patients admitted to the trauma intensive care unit from January 2015 to September 2016 who received enteral or parenteral nutrition therapy and had a 24 h urine collection within 4 to 14 days after injury were retrospectively evaluated. Patients with a serum creatinine concentration > 1.5 mg/dL, required dialysis, or had an incomplete urine collection were excluded. ARC was defined as a measured creatinine clearance > 149 mL/min/1.73 m². Two hundred and three patients were evaluated. One hundred and two (50%) exhibited ARC. A greater proportion of patients with ARC were male (86% vs. 67%; p = 0.004), had traumatic brain injury (33% vs. 9%; p = 0.001), a higher injury severity score (30 ± 11 vs. 26 ± 12; p = 0.015), were younger (36 ± 15 vs. 54 ± 17 years; p = 0.001), had a lower serum creatinine concentration (0.7 ± 2 vs. 0.9 ± 0.2 mg/dL; p = 0.001) and were more catabolic (nitrogen balance of −10.8 ± 13.0 vs. −6.2 ± 9.2 g/d; p = 0.004). The multivariate analysis revealed African American race and protein intake were also associated with ARC. Half of critically ill patients with traumatic injuries experience ARC. Patients with multiple risk factors for ARC should be closely evaluated for dosing of renally-eliminated electrolytes, nutrients, and medications.

Nitrogen balance in mechanically ventilated obese patients

ABSTRACT Objective This study aimed to evaluate if the protein intake recommendations for obese critically ill requiring mechanical ventilation are sufficient to promote a positive or neutral nitrogen balance. Methods Cross-sectional study that included 25 obese, ≥18 years old, undergoing mechanical ventilation and who were target to receive high-protein enteral nutrition therapy (2.0-2.5g/kg ideal body weight). Clinical, nutritional and biochemical variables were analyzed. Nitrogen balance was performed when patient was receiving full enteral nutrition therapy and was classified: positive when intake was greater than excretion; negative when excretion was greater than intake; neutral when both were equal. Results The characteristics of patients evaluated were 64.1±9.4 years old, clinical treatment 88%, body mass index 36.5±5.1kg/m2, nitrogen balance 0.3g/day (-5.3 to 4.8g/day), protein intake 2.1g/day (2.0-2.3g/kg) ideal body weight. Of individuals analyzed, 52% showed positive or neutral nitrogen balance with median of 4.23g/day 2.41 to 6.40g/day) in comparison to negative group with median of -5.27g/day (-10.38 to -3.86g/day). Adults had higher ratio of negative nitrogen balance (57.1%) than elderly (44.4%), with protein intake of 2.0 versus 2.1g/day, respectively. No correlation was found between nitrogen balance and variables assessed. Conclusion High-protein enteral nutrition therapy contributed to positive or neutral nitrogen balance for approximately half of obese ventilated individuals. With similar protein intake, elderly showed a higher proportion of positive or neutral nitrogen balance. Nitrogen balance can be influenced by various factors, so further studies are required to identify different protein needs in obese critically.

High protein intake during the early phase of critical illness: yes or no?

The rationale for the provision of nitrogen from proteins given via the enteral route or from intravenous amino acids is to boost the synthesis of muscle proteins, and thereby to limit the severity of intensive care unit-acquired weakness by the prevention of muscle loss. However, the optimal timing for supplemental nitrogen provision is a matter of debate and controversy. Indeed, consistent data from retrospective studies support an association between high early protein intakes and better outcomes, while recent post-hoc findings from prospective studies raise safety concerns. This pro–con paper details the arguments of both sides and highlights the need for large-scale prospective studies assessing the safety and efficacy of different levels of protein intake in combination with physical activity and summarizes the currently recruiting clinical trials.

ESPEN guideline on clinical nutrition in the intensive care unit

Following the new ESPEN Standard Operating Procedures, the previous guidelines to provide best medical nutritional therapy to critically ill patients have been updated. These guidelines define who are the patients at risk, how to assess nutritional status of an ICU patient, how to define the amount of energy to provide, the route to choose and how to adapt according to various clinical conditions. When to start and how to progress in the administration of adequate provision of nutrients is also described. The best determination of amount and nature of carbohydrates, fat and protein are suggested. Special attention is given to glutamine and omega-3 fatty acids. Particular conditions frequently observed in intensive care such as patients with dysphagia, frail patients, multiple trauma patients, abdominal surgery, sepsis, and obesity are discussed to guide the practitioner toward the best evidence based therapy. Monitoring of this nutritional therapy is discussed in a separate document.

High-Protein Hypocaloric Nutrition for Non-Obese Critically Ill Patients

High-protein hypocaloric nutrition, tailored to each patient's muscle mass, protein-catabolic severity, and exogenous energy tolerance, is the most plausible nutrition therapy in protein-catabolic critical illness. Sufficient protein provision could mitigate the rapid muscle atrophy characteristic of this disease while providing urgently needed amino acids to the central protein compartment and sites of tissue injury. The protein dose may range from 1.5 to 2.5 g protein (1.8-3.0 g free amino acids)/kg dry body weight per day. Nutrition should be low in energy (≈70% of energy expenditure or ≈15 kcal/kg dry body weight per day) because efforts to match energy provision to energy expenditure are physiologically irrational, risk toxic energy overfeeding, and have repeatedly failed in large clinical trials to demonstrate clinical benefit. The American Society for Parenteral and Enteral Nutrition currently suggests high-protein hypocaloric nutrition for obese critically ill patients. Short-term high-protein hypocaloric nutrition is physiologically and clinically sensible for most protein-catabolic critically ill patients, whether obese or not.

Feeding the critically ill obese patient: a systematic review protocol

REVIEW QUESTION/OBJECTIVE

The objective of this review is to identify effective enteral nutritional regimens targeting protein and calorie delivery for the critically ill obese patient on morbidity and mortality.More specifically, the review question is:In the critically ill obese patient, what is the optimal enteral protein and calorie target that improves mortality and morbidity?

BACKGROUND

The World Health Organization (WHO) defines obesity as abnormal or excessive fat accumulation that may impair health, or, empirically, as a body mass index (BMI) ≥ 30 kg/m. Twenty-eight percent of the Australian population is obese with the prevalence rising to 44% in rural areas, and there is evidence that rates of obesity are increasing. The prevalence of obese patients in intensive care largely mirrors that of the general population. There is concern, however, that this may also be rising. A recently published multi-center nutritional study of critically ill patients reported a mean BMI of 29 in their sample, suggesting that just under 50% of their intensive care population is obese. It is inevitable, therefore, that the intensivist will care for the critically ill obese patient.Managing the critically ill obese patient is challenging, not least due to the co-morbid diseases frequently associated with obesity, including diabetes mellitus, cardiovascular disease, dyslipidaemia, sleep disordered breathing and respiratory insufficiency, hepatic steatohepatitis, chronic kidney disease and hypertension. There is also evidence that metabolic processes differ in the obese patient, particularly those with underlying insulin resistance, itself a marker of the metabolic syndrome, which may predispose to futile cycling, altered fuel utilization and protein catabolism. These issues are compounded by altered drug pharmacokinetics, and the additional logistical issues associated with prophylactic, therapeutic and diagnostic interventions.It is entirely plausible that the altered metabolic processes observed in the obese intensify and compound the metabolic changes that occur during critical illness. The early phases of critical illness are characterized by an increase in energy expenditure, resulting in a catabolic state driven by the stress response. Activation of the stress response involves up-regulation of the sympathetic nervous system and the release of pituitary hormones resulting in altered cortisol metabolism and elevated levels of endogenous catecholamines. These produce a range of metabolic disturbances including stress hyperglycemia, arising from both peripheral resistance to the effects of anabolic factors (predominantly insulin) and increased hepatic gluconeogenesis. Proteolysis is accelerated, releasing amino acids that are thought to be important in supporting tissue repair, immune defense and the synthesis of acute phase reactants. There is also altered mobilization of fuel stores, futile cycling, and evidence of altered lipoprotein metabolism. In the short term this is likely to be an adaptive response, but with time and ongoing inflammation this becomes maladaptive with a concomitant risk of protein-calorie malnutrition, immunosuppression and wasting of functional muscle tissue resulting from protein catabolism, and this is further compounded by disuse atrophy. Muscle atrophy and intensive care unit (ICU) acquired weakness is complex and poorly understood, but it is postulated that the provision of calories and sufficient protein to avoid a negative nitrogen balance mitigates this process. Avoiding lean muscle mass loss in the obese intuitively has substantial implications, given the larger mass that is required to be mobilized during their rehabilitation phase.There is, in addition, evolving evidence that hormones derived from both the gut and adipose tissue are also involved in the response to stress and critical illness, and that adipose tissue in particular is not a benign tissue bed, but rather should be considered an endocrine organ. Some of these hormones are thought to be pro-inflammatory and some anti-inflammatory; however both the net result and clinical significance of these are yet to be fully elucidated.The provision of adequate nutrition has become an integral component of supportive ICU care, but is complex. There is ongoing debate within critical care literature regarding the optimal route of delivery, the target dose, and the macronutrient components (proportion of protein and non-protein calories) of nutritional support. A number of studies have associated caloric deficit with morbidity and mortality, with the resultant assumption that prescribing sufficient calories to match energy expenditure will reduce morbidity and mortality, although the evidence base underpinning this assumption is limited to observational studies and small, randomized trials.There is research available that suggests hyper-caloric feeding or hyper-alimentation, particularly of carbohydrates, may result in increased morbidity including hyperglycemia, liver steatosis, respiratory insufficiency with prolonged duration of mechanical ventilation, re-feeding syndrome and immune suppression. But the results from studies of hypo-caloric and eucaloric feeding regimens in critically ill patients are conflicting, independent of the added metabolic complexities observed in the critically ill obese patient.Notwithstanding the debate regarding the dose and components of nutritional therapy, there is consensus that nutrition should be provided, preferably via the enteral route, and preferably initiated early in the ICU admission. The enteral route is preferred for a variety of reasons, not the least of which is cost. In addition there is evidence to suggest the enteral route is associated with the maintenance of gut integrity, a reduction in bacterial translocation and infection rates, a reduction in the incidence of stress ulceration, attenuation of oxidative stress, release of incretins and other entero-hormones, and modulation of systemic immune responses. Yet there is evidence that the initiation of enteral nutritional support for the obese critically ill patient is delayed, and that when delivered is at sub-optimal levels. The reasons for this remain obscure, but may be associated with the false assumption that every obese patient has nutritional reserves due to their adipose tissues, and can therefore withstand longer periods with no, or reduced nutritional support. In fact obesity does not necessarily protect from malnutrition, particularly protein and micronutrient malnutrition. It has been suggested by some authors that the malnutrition status of critically ill patients is a stronger predictor of mortality than BMI, and that once malnutrition status is controlled for, the apparent protective effects of obesity observed in several epidemiological studies dissipate. This would be consistent with the large body of evidence that associates malnutrition (BMI < 20 kg/m) with increased mortality, and has led some authors to postulate that the weight-mortality relationship is U-shaped. This has proven difficult to demonstrate, however, due to recognized confounding influences such as chronic co-morbidities, baseline nutritional status and the nature of the presenting critical illness.This has led to interest in nutritional regimens targeting alternative calorie and protein goals to protect the obese critically ill patient from complications arising from critical illness, and particularly protein catabolism. However, of the three major nutritional organizations, the American Society of Parenteral and Enteral Nutrition (ASPEN) is the only professional organization to make specific recommendations about providing enteral nutritional support to the critically ill obese patient, recommending a regimen targeting a hypo-caloric, high-protein goal. It is thought that this regimen, in which 60-70% of caloric requirements are provided promotes steady weight loss, while providing sufficient protein to achieve a neutral, or slightly positive, nitrogen balance, mitigating lean muscle mass loss, and allowing for wound healing. Targeting weight loss is proposed to improve insulin sensitivity, improve nursing care and reduce the risk of co-morbidities, although how this occurs and whether it can occur over the relatively short time frame of an intensive care admission (days to weeks) remains unclear. Despite these recommendations observational data of international nutritional practice suggest that ICU patients are fed uniformly low levels of calories and protein across BMI groups.Supporting the critically ill obese patient will become an increasingly important skill in the intensivist's armamentarium, and enteral nutritional therapy forms a cornerstone of this support. Yet, neither the optimal total caloric goal nor the macronutrient components of a feeding regimen for the critically ill obese patient is evident. Although the suggestion that altering the macronutrient goals for this vulnerable group of patients appears to have a sound physiological basis, the level of evidence supporting this remains unclear, and there are no systematic reviews on this topic. The aim of this systematic review is to evaluate existing literature to determine the best available evidence describing a nutritional strategy that targets energy and protein delivery to reduce morbidity and mortality for the obese patient who is critically ill.

How Much and What Type of Protein Should a Critically Ill Patient Receive?

Protein loss, manifested as loss of muscle mass, is observed universally in all critically ill patients. Depletion of muscle mass is associated with impaired function and poor outcomes. In extreme cases, protein malnutrition is manifested by respiratory failure, lack of wound healing, and immune dysfunction. Protecting muscle loss focused initially on meeting energy requirements. The assumption was that protein was being used (through oxidation) as an energy source. In healthy individuals, small amounts of glucose (approximately 400 calories) protect muscle loss and decrease amino acid oxidation (protein-sparing effect of glucose). Despite expectations of the benefits, the high provision of energy (above basal energy requirements) through the delivery of nonprotein calories has failed to demonstrate a clear benefit at curtailing protein loss. The protein-sparing effect of glucose is not clearly observed during illness. Increasing protein delivery beyond the normal nutrition requirements (0.8 g/k/d) has been investigated as an alternative solution. Over a dozen observational studies in critically ill patients suggest that higher protein delivery is beneficial at protecting muscle mass and associated with improved outcomes (decrease in mortality). Not surprisingly, new Society of Critical Care Medicine/American Society for Parenteral and Enteral Nutrition guidelines and expert recommendations suggest higher protein delivery (>1.2 g/kg/d) for critically ill patients. This article provides an introduction to the concepts that delineate the basic principles of modern medical nutrition therapy as it relates to the goal of achieving an optimal management of protein metabolism during critical care illness, highlighting successes achieved so far but also placing significant challenges limiting our success in perspective.

Parenteral Nutrition Basics for the Clinician Caring for the Adult Patient

Parenteral nutrition (PN) is a life-sustaining therapy providing nutrients to individuals with impaired intestinal tract function and enteral access challenges. It is one of the most complex prescriptions written routinely in the hospital and home care settings. This article is to aid the nutrition support clinician in the safe provision of PN, including selecting appropriate patients for PN, vascular access, development of a PN admixture, appropriate therapy monitoring, recognition of preparation options, and awareness of preparation and stability concerns.

Obesity in the intensive care unit: risks and complications

The steady growing prevalence of critically ill obese patients is posing diagnostic and management challenges across medical and surgical intensive care units. The impact of obesity in the critically ill patients may vary by type of critical illness, obesity severity (obesity distribution) and obesity-associated co-morbidities. Based on pathophysiological changes associated with obesity, predominately in pulmonary reserve and cardiac function, critically ill obese patients may be at higher risk for acute cardiovascular, pulmonary and renal complications in comparison to non-obese patients. Obesity also represents a dilemma in the management of other critical care areas such as invasive mechanical ventilation, mechanical ventilation liberation, hemodynamic monitoring and pharmacokinetics dose adjustments. However, despite higher morbidity associated with obesity in the intensive care unit (ICU), a paradoxical lower ICU mortality ("obesity paradox") is demonstrated in comparison to non-obese ICU patients. This review article will focus on the unique pathophysiology, challenges in management, and outcomes associated with obesity in the ICU.

Nutrition and metabolic support for critically ill patients

PURPOSE OF REVIEW

Acute critical illness increases the risk of malnutrition, are more obese, and have multiple comorbidities and frequent pre-existing nutritional deficits. There is a vast amount of research and literature being written on nutritional practices in the critically ill. We review and discuss herein the important nutrition literature over the past 12 months.

RECENT FINDINGS

Sarcopenia, defined as loss of skeletal mass and strength, is associated with increased mortality and morbidity, particularly in elderly patients with trauma. Ultrasound is emerging as a noninvasive and promising method of measuring muscularity. Measuring gastric residuals and postpyloric feeding may not decrease rates of pneumonia in critically ill patients. Trophic and full feeding lead to similar long-term functional and cognitive outcomes in patients with acute respiratory distress syndrome.

SUMMARY

Nutrition and metabolic support of critically ill patients is a complex and diverse topic. Nutritional measurements, requirements, and modes and routes of delivery are currently being studied to determine the best way to treat these complicated patients. We present just a few of the current controversial topics in this fascinating arena.

Peri-operative management of the obese surgical patient 2015: Association of Anaesthetists of Great Britain and Ireland Society for Obesity and Bariatric Anaesthesia

Guidelines are presented for the organisational and clinical peri-operative management of anaesthesia and surgery for patients who are obese, along with a summary of the problems that obesity may cause peri-operatively. The advice presented is based on previously published advice, clinical studies and expert opinion.