Efficacy of hypocaloric total parenteral nutrition in hospitalized obese patients: a prospective, double-blind randomized trial

Obesity and critical care nutrition: current practice gaps and directions for future research

Background

This review has been developed following a panel discussion with an international group of experts in the care of patients with obesity in the critical care setting and focuses on current best practices in malnutrition screening and assessment, estimation of energy needs for patients with obesity, the risks and management of sarcopenic obesity, the value of tailored nutrition recommendations, and the emerging role of immunonutrition. Patients admitted to the intensive care unit (ICU) increasingly present with overweight and obesity that require individualized nutrition considerations due to underlying comorbidities, immunological factors such as inflammation, and changes in energy expenditure and other aspects of metabolism. While research continues to accumulate, important knowledge gaps persist in recognizing and managing the complex nutritional needs in ICU patients with obesity. Available malnutrition screening and assessment tools are limited in patients with obesity due to a lack of validation and heterogeneous factors impacting nutrition status in this population. Estimations of energy and protein demands are also complex in patients with obesity and may include estimations based upon ideal, actual, or adjusted body weight. Evidence is still sparse on the role of immunonutrition in patients with obesity, but the presence of inflammation that impacts immune function may suggest a role for these nutrients in hemodynamically stable ICU patients. Educational efforts are needed for all clinicians who care for complex cases of critically ill patients with obesity, with a focus on strategies for optimal nutrition and the consideration of issues such as weight stigma and bias impacting the delivery of care.

Conclusions

Current nutritional strategies for these patients should be undertaken with a focus on individualized care that considers the whole person, including the possibility of preexisting comorbidities, altered metabolism, and chronic stigma, which may impact the provision of nutritional care. Additional research should focus on the applicability of current guidelines and evidence for nutrition therapy in populations with obesity, especially in the setting of critical illness.

Nutrition priorities in obese critically ill patients

PURPOSE OF REVIEW

During critical illness, several neuroendocrine, inflammatory, immune, adipokine, and gastrointestinal tract hormone pathways are activated; some of which are more intensified among obese compared with nonobese patients. Nutrition support may mitigate some of these effects. Nutrition priorities in obese critically ill patients include screening for nutritional risk, estimation of energy and protein requirement, and provision of macronutrients and micronutrients.

RECENT FINDINGS

Estimation of energy requirement in obese critically ill patients is challenging because of variations in body composition among obese patients and absence of reliable predictive equations for energy expenditure. Whereas hypocaloric nutrition with high protein has been advocated in obese critically ill patients, supporting data are scarce. Recent studies did not show differences in outcomes between hypocaloric and eucaloric nutrition, except for better glycemic control. Sarcopenia is common among obese patients, and the provision of increased protein intake has been suggested to mitigate catabolic changes especially after the acute phase of critical illness. However, high-quality data on high protein intake in these patients are lacking. Micronutrient deficiencies among obese critically ill patients are common but the role of their routine supplementation requires further study.

SUMMARY

An individualized approach for nutritional support may be needed for obese critically ill patients but high-quality evidence is lacking. Future studies should focus on nutrition priorities in this population, with efficient and adequately powered studies.

Diagnosis and Management of Intraabdominal Infection: Guidelines by the Chinese Society of Surgical Infection and Intensive Care and the Chinese College of Gastrointestinal Fistula Surgeons

The Chinese guidelines for IAI presented here were developed by a panel that included experts from the fields of surgery, critical care, microbiology, infection control, pharmacology, and evidence-based medicine. All questions were structured in population, intervention, comparison, and outcomes format, and evidence profiles were generated. Recommendations were generated following the principles of the Grading of Recommendations Assessment, Development, and Evaluation system or Best Practice Statement (BPS), when applicable. The final guidelines include 45 graded recommendations and 17 BPSs, including the classification of disease severity, diagnosis, source control, antimicrobial therapy, microbiologic evaluation, nutritional therapy, other supportive therapies, diagnosis and management of specific IAIs, and recognition and management of source control failure. Recommendations on fluid resuscitation and organ support therapy could not be formulated and thus were not included. Accordingly, additional high-quality clinical studies should be performed in the future to address the clinicians' concerns.

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.

Nutrition management of obese critically ill adults: A survey of critical care dietitians in Australia and New Zealand

BACKGROUND

Guideline recommendations for nutrition therapy in critically ill obese adults are inconsistent. This study aimed to describe how dietitians working in an intensive care unit (ICU) in Australia and New Zealand (ANZ) approach managing the nutritional needs of an obese, critically ill adult.

METHODS

Invitations to participate were via personal email communication. The survey was also disseminated through a research email list and a dietitian-based newsletter. The multiple-choice case-based survey consisted of 12 questions relating to nutrition prescription and were based on international nutrition guideline recommendations including (i) weight used in energy and protein predictive equations; (ii) energy and protein prescription at ICU admission and day 7, (iii) commencement of enteral nutrition, and; (iv) use of supplemental protein. Data are reported as n (%).

RESULTS

Sixty-three dietitians participated in the survey. Most commonly, adjusted body weight calculated as 'weight at BMI 25 kg/m² + 25% excess weight' was used in equations to guide energy (44 respondents, 70%) and protein (39 respondents, 62%) prescription. At day 1, energy and protein prescription was most commonly based on the European Society of Parenteral and Enteral Nutrition (ESPEN) guideline recommendation of 20-25 kcal/kg (39 respondents, 62%) and 1.3 g protein/kg adjusted body weight (36 respondents, 57%). Thirteen (21%) respondents had an indirect calorimetry device in their ICU to measure energy expenditure. On day 7, the ESPEN recommendations were again the most common method used for prescribing energy (30 respondents, 48%) and protein (23 respondents. 48%) needs. Thirty-eight dietitians (60%) reported they would use early supplemental protein to meet protein requirements.

CONCLUSIONS

ICU dietitians in ANZ who responded to the survey most commonly report using the ESPEN ICU guideline recommendations (20-25 kcal/kg and 1.3 g protein/kg adjusted body weight) to guide nutrition prescription in an obese critically ill adult. Prospective studies are required to confirm these findings.

Protein Requirements during Hypocaloric Nutrition for the Older Patient With Critical Illness and Obesity: An Approach to Clinical Practice

Current guidelines recommend a hypocaloric, high protein nutrition regimen for patients with obesity and critical illness. The impact of advancing age presents with unique challenges in which a greater protein intake is required to overcome the anabolic resistance associated with aging in the face of presumed decreased renal function. The primary objective of this review is to provide an overview of the impact of obesity and advancing age on protein requirements for patients with critical illness and review the scientific evidence supporting the rationale for hypocaloric, high protein nutrition for this subpopulation, as well as provide some practical suggestions for their clinical management.

Hypoenergetic feeding does not improve outcomes in critically ill patients with premorbid obesity: a post hoc analysis of a randomized controlled trial

Optimal energy goals for adult, obese critically ill surgical patients are unclear. To date, there has been little data comparing feeding regimens for obese and non-obese critically ill surgical patients and the effect on outcomes. The objective was to compare the effect of hypoenergetic and euenergetic feeding goals in critically ill obese patients on outcomes, including infection, intensive care unit length of stay, and mortality. We hypothesized that hypoenergetic feeding of patients with premorbid obesity (body mass index ≥ 30 kg•m^-2) during critical illness does not affect clinical outcomes. Post hoc analyses were performed on critically ill surgical patients enrolled in a randomized controlled trial. Patients were randomized to receive 25-30 kcal•kg^-1•d^-1 (105-126 kJ.kg^-1•d^-1, euenergetic) or 12.5-15 kcal•kg^-1•d^-1 (52-63 kJ.kg^-1 •d^-1, hypoenergetic), with equal protein allocation (1.5 g•kg^-1•d^-1). The effect of feeding regimen on outcomes in obese and nonobese patients were assessed. Of the 83 patients, 30 (36.1%) were obese (body mass index ≥ 30 kg•m^-2). Average energy intake differed based on feeding regimen (hypoenergetic: 982±61 vs euenergetic: 1338±92 kcal•d^-1, P = .02). Comparing obese and nonobese patients, there was no difference in the percentage acquiring an infection (66.7% [20/30] vs 77.4% [41/53], P = .29), intensive care unit length of stay (16.4±3.7 vs 14.3±0.9 days, P = .39), or mortality (10% [3/30] vs 7.6% [4/53], P = .7). Within the subset of obese patients, the percentage acquiring an infection (hypoenergetic: 78.9% [15/19] vs euenergetic: 45.5% [5/11], P = .11) was not affected by the feeding regimen. Within the subset of nonobese patients, there was a trend toward more infections in the euenergetic group (hypoenergetic: 63.6% [14/22] vs euenergetic: 87.1% [27/31], P = .05). Hypoenergetic feeding does not appear to affect clinical outcomes positively or negatively in critically ill patients with premorbid obesity.

Clinical Nutrition in Critical Care Medicine - Guideline of the German Society for Nutritional Medicine (DGEM)

PURPOSE

Enteral and parenteral nutrition of adult critically ill patients varies in terms of the route of nutrient delivery, the amount and composition of macro- and micronutrients, and the choice of specific, immune-modulating substrates. Variations of clinical nutrition may affect clinical outcomes. The present guideline provides clinicians with updated consensus-based recommendations for clinical nutrition in adult critically ill patients who suffer from at least one acute organ dysfunction requiring specific drug therapy and/or a mechanical support device (e.g., mechanical ventilation) to maintain organ function.

METHODS

The former guidelines of the German Society for Nutritional Medicine (DGEM) were updated according to the current instructions of the Association of the Scientific Medical Societies in Germany (AWMF) valid for a S2k-guideline. According to the S2k-guideline classification, no systematic review of the available evidence was required to make recommendations, which, therefore, do not state evidence- or recommendation grades. Nevertheless, we considered and commented the evidence from randomized-controlled trials, meta-analyses and observational studies with adequate sample size and high methodological quality (until May 2018) as well as from currently valid guidelines of other societies. The liability of each recommendation was described linguistically. Each recommendation was finally validated and consented through a Delphi process.

RESULTS

In the introduction the guideline describes a) the pathophysiological consequences of critical illness possibly affecting metabolism and nutrition of critically ill patients, b) potential definitions for different disease phases during the course of illness, and c) methodological shortcomings of clinical trials on nutrition. Then, we make 69 consented recommendations for essential, practice-relevant elements of clinical nutrition in critically ill patients. Among others, recommendations include the assessment of nutrition status, the indication for clinical nutrition, the timing and route of nutrient delivery, and the amount and composition of substrates (macro- and micronutrients); furthermore, we discuss distinctive aspects of nutrition therapy in obese critically ill patients and those treated with extracorporeal support devices.

CONCLUSION

The current guideline provides clinicians with up-to-date recommendations for enteral and parenteral nutrition of adult critically ill patients who suffer from at least one acute organ dysfunction requiring specific drug therapy and/or a mechanical support device (e.g., mechanical ventilation) to maintain organ function. The period of validity of the guideline is approximately fixed at five years (2018-2023).

Metabolic support challenges with obesity during critical illness

Adiposity-based chronic disease, critical illness, and nutrition therapy increase the risk for overfeeding and worsened nutritional and clinical outcomes. Hypocaloric, high-protein nutrition therapy provides critically ill obese patients the opportunity to achieve net protein anabolism with a reduced risk for overfeeding-related complications. The intent of this review is to discuss the impact of obesity on clinical outcomes, describe the consequences of obesity that increase complications associated with nutrition therapy, provide the framework to develop a hypocaloric, high-protein regimen, review the scientific evidence to support this mode of therapy, and discuss its limitations. Practical suggestions for patient monitoring are also provided.

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.

Will We Ever Agree on Protein Requirements in the Intensive Care Unit?

The precise value of the normal adult protein requirement has long been debated. For many reasons-one of them being the difficulty of carrying out long-term nutrition experiments in free-living people-uncertainty is likely to persist indefinitely. By contrast, the controlled environment of the intensive care unit and relatively short trajectory of many critical illnesses make it feasible to use hard clinical outcome trials to determine protein requirements for critically ill patients in well-defined clinical situations. This article suggests how the physiological principles that underlie our understanding of normal protein requirements can be incorporated into the design of such clinical trials. The main focus is on 3 principles: (1) the rate of body nitrogen loss roughly predicts an individual's minimum protein requirement and is thus essential to measure to identify individual patients and clinical situations in which the minimum protein requirement is importantly increased, (2) existing muscle mass sets an upper limit on the rate at which amino acids can be mobilized from muscle for transfer to central proteins and sites of injury and is thus important to monitor to identify patients who are at greatest risk of protein deficiency-related adverse outcomes, and (3) negative energy balance increases the dietary protein requirement, so calorie-deprived patients-whether obese or not-should be enrolled in hard clinical outcome trials that compare the current practice of "permissive underfeeding" (underprovision of all nutrients, including protein) with hypocaloric nutrition supplemented by a suitably generous amount of protein.

Protein and Calorie Requirements Associated With the Presence of Obesity

Obesity compounds the metabolic response to critical illness and increases the risk for overfeeding complications due to its comorbidities. Hypocaloric, high-protein nutrition therapy affords the hospitalized patient with obesity the opportunity to achieve net protein anabolism with a reduced risk of overfeeding complications. The intent of this review is to provide the theoretical framework for development of a hypocaloric high-protein regimen, scientific evidence to support this mode of therapy, and unique considerations for its use in specialized subpopulations. Macronutrient goals and practical suggestions for patient monitoring are given.

The Critical Care Obesity Paradox and Implications for Nutrition Support

Obesity is a leading cause of preventable death worldwide. The prevalence of obesity has been increasing and is associated with an increased risk for other co-morbidities. In the critical care setting, nearly one third of patients are obese. Obese critically ill patients pose significant physical and on-physical challenges to providers, including optimization of nutrition therapy. Intuitively, obese patients would have worse critical care-related outcome. On the contrary, emerging data suggests that critically ill obese patients have improved outcomes, and this phenomenon has been coined "the obesity paradox." The purposes of this review will be to outline the historical views and pathophysiology of obesity and epidemiology of obesity, describe the challenges associated with obesity in the intensive care unit setting, review critical care outcomes in the obese, define the obesity-critical care paradox, and identify the challenges and role of nutrition support in the critically ill obese patient.

Validation Study of Energy Requirements in Critically Ill, Obese Cancer Patients

BACKGROUND

Current guidelines from the American Society for Parenteral and Enteral Nutrition and the Society of Critical Care Medicine (ASPEN/SCCM) regarding caloric requirements and the provision of nutrition support in critically ill, obese adults may not be suitable for similar patients with cancer. We sought to determine whether the current guidelines accurately estimate the energy requirements, as measured by indirect calorimetry (IC), of critically ill, obese cancer patients.

MATERIALS AND METHODS

This was a retrospective validation study of critically ill, obese cancer patients from March 1, 2007, to July 31, 2010. All patients ≥18 years of age with a body mass index (BMI) ≥30 kg/m(2) who underwent IC were included. We compared the measured energy expenditure (MEE) against the upper limit of the recommended guideline (25 kcal/kg of ideal body weight [IBW]) and MEE between medical and surgical patients in the intensive care unit.

RESULTS

Thirty-three patients were included in this study. Mean MEE (28.7 ± 5.2 kcal/kg IBW) was significantly higher than 25 kcal/kg IBW (P < .001), and 78% of patients had nutrition requirements greater than the current guideline recommendations. No significant differences in MEE between medical and surgical patients in the ICU were observed.

CONCLUSIONS

Critically ill, obese cancer patients require more calories than the current guidelines recommend, likely due to malignancy-associated metabolic variations. Our results demonstrate the need for IC studies to determine the energy requirements in these patients and for reassessment of the current recommendations.

Enteral nutrition formula selection: current evidence and implications for practice

Many new enteral nutrition (EN) formulas have been created over the past several decades with a variety of intended uses. Although each is intended to promote improved outcomes, research is often unclear and, in many cases, conflicting. It is important to note that EN products are considered medical foods by the U.S. Food and Drug Administration and therefore do not have to complete premarket review or approval and are not regulated to the same extent as pharmaceuticals. While standard EN formulas are designed to meet the basic macro- and micronutrient requirements of individuals who cannot meet nutrition needs orally, specialty EN products have been developed to exhibit pharmacologic properties, such as immune-enhancing formulas containing arginine, glutamine, nucleotides, and ω-3 fatty acids. With the vast number of products available, rising costs of healthcare, and the drive toward evidence-based practice, it is imperative that clinicians carefully consider research regarding use of specialty formulas, paying close attention to the quality, patient population, clinical end points, and cost to patient and/or facility.

Nutrition and metabolic support recommendations for the bariatric patient

Managing the metabolic needs of the patient with obesity is a challenge unto itself without the added demands of accounting for an altered gastrointestinal tract. Nevertheless, with about 200,000 bariatric procedures being performed annually in the United States, clinicians must be prepared to manage the critically ill bariatric surgery patient. This article reviews the recent literature relating to nutrient needs and metabolic support for the bariatric patient. Bariatric patients are at risk for several micronutrient deficiencies, including vitamins D and B₁₂, calcium, and iron; some bariatric procedures affect macronutrient needs as well. Literature on nutrition support guidelines for the bariatric population is limited. However, with an understanding of the anatomical and physiological effects of bariatric surgery, recent guidelines for critically ill patients with obesity can be applied to the bariatric surgery population. The unique needs of the bariatric population, such as susceptibility to micronutrient deficiencies and specialized access routes, must be considered to provide safe and efficacious nutrition support. Further research is necessary to develop specific nutrition support recommendations for the bariatric population.

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

We published the first article that addressed hypocaloric, high-protein enteral nutrition therapy for critically ill patients with obesity more than 10 years ago. This study demonstrated that it was possible to successfully achieve this mode of therapy with a commercially available high-protein enteral formula and concurrent use of protein supplements. This study was also the first to demonstrate improved clinical outcomes with the use of hypocaloric, high-protein nutrition therapy. The results of this study, its unique findings, and shortcomings are discussed. Subsequent studies have added clarity to the effective use of this therapy, including its use in home parenteral nutrition patients, patients with class III obesity, and older patients with obesity.

Relationship Between Triglyceride Tolerance, Body Mass Index, and Fat Depots in Hospitalized Patients Receiving Parenteral Nutrition

BACKGROUND

Hypertriglyceridemia has been associated with adverse outcomes in patients receiving intravenous fat emulsions (IVFEs), but little is known about its prevalence and causes.

MATERIALS AND METHODS

The study investigated whether a relationship exists between body mass index (BMI) and triglyceride tolerance in parenterally fed patients. We conducted a retrospective analysis of 287 adults receiving parenteral nutrition to determine whether patients with very low BMI (VLBMI, <16 kg/m(2)) tolerate IVFEs better than do patients with low BMI (LBMI, 16-18.4 kg/m(2)), normal-weight patients (NBMI, 18.5-24.9 kg/m(2)), and overweight/obese patients (HBMI, ≥25 kg/m(2)).

RESULTS

The median triglyceride concentration during IVFE was significantly lower in VLBMI patients at 107 mg/dL compared with 124 mg/dL in non-VLBMI patients (P = .016), despite higher lipid infusion rates in the VLBMI group. There was a significant association between triglycerides and BMI in the aggregate cohort (R = 0.2375, P < .0001), with the highest frequency of hypertriglyceridemia occurring in HBMI patients despite relatively lower lipid and energy supply. In a subset of VLBMI patients (n = 36) who had an abdominal computed tomography scan, there was 25- to 100-fold variability in the size of the abdominal adipose tissue depots. In this subgroup, triglyceride concentrations correlated with visceral fat but not subcutaneous abdominal fat.

CONCLUSIONS

In summary, patients with VLBMI have lower triglyceride concentrations during IVFEs than do other individuals, but there is considerable variability in triglycerides and body fat in this group. Caution should be employed with the use of IVFEs, especially in HBMI patients.

Nutritional care of the obese adult burn patient: a U.K. Survey and literature review

Obesity is an emerging healthcare problem and affects an increasing number of burn patients worldwide. An email survey questionnaire was constructed and distributed among the 16 U.K. burn services providing adult inpatient facilities to investigate nutritional practices in obese thermally injured patients. Responses received from all dieticians invited to participate in the study were analyzed, and a relevant literature review of key aspects of nutritional care is presented. The majority of services believe that obese patients warrant a different nutritional approach with specific emphasis to avoid overfeeding. The most common algebraic formulae used to calculate calorific requirements include the Schofield, Henry, and modified Penn State equations. Indirect calorimetry despite being considered the "criterion standard" tool to calculate energy requirements is not currently used by any of the U.K. burn services. Gastric/enteral nutrition is initiated within 24 hours of admission in the services surveyed, and a variety of different practices were noted in terms of fasting protocols before procedures requiring general anesthesia/sedation. Hypocaloric regimens for obese patients are not supported by the majority of U.K. facilities, given the limited evidence base supporting their use. The results of this survey outline the wide diversity of dietetic practices adopted in the care of obese burn patients and reveal the need for further study to determine optimal nutritional strategies.

[Guidelines for specialized nutritional and metabolic support in the critically ill-patient. Update. Consensus of the Spanish Society of Intensive Care Medicine and Coronary Units-Spanish Society of Parenteral and Enteral Nutrition (SEMICYUC-SENPE): obese patient]

As a response to metabolic stress, obese critically-ill patients have the same risk of nutritional deficiency as the non-obese and can develop protein-energy malnutrition with accelerated loss of muscle mass. The primary aim of nutritional support in these patients should be to minimize loss of lean mass and accurately evaluate energy expenditure. However, routinely-used formulae can overestimate calorie requirements if the patient's actual weight is used. Consequently, the use of adjusted or ideal weight is recommended with these formulae, although indirect calorimetry is the method of choice. Controversy surrounds the question of whether a strict nutritional support criterion, adjusted to the patient's requirements, should be applied or whether a certain degree of hyponutrition should be allowed. Current evidence suggested that hypocaloric nutrition can improve results, partly due to a lower rate of infectious complications and better control of hyperglycemia. Therefore, hypocaloric and hyperproteic nutrition, whether enteral or parenteral, should be standard practice in the nutritional support of critically-ill obese patients when not contraindicated. Widely accepted recommendations consist of no more than 60-70% of requirements or administration of 11-14 kcal/kg current body weight/day or 22-25 kcal/kg ideal weight/day, with 2-2.5 g/kg ideal weight/day of proteins. In a broad sense, hypocaloric-hyperprotein regimens can be considered specific to obese critically-ill patients, although the complications related to comorbidities in these patients may require other therapeutic possibilities to be considered, with specific nutrients for hyperglycemia, acute respiratory distress syndrome (ARDS) and sepsis. However, there are no prospective randomized trials with this type of nutrition in this specific population subgroup and the available data are drawn from the general population of critically-ill patients. Consequently, caution should be exercised when interpreting these data.

Hypocaloric home parenteral nutrition and nutrition parameters in patients following bariatric surgery

BACKGROUND

Surgical intervention is considered an acceptable treatment for morbid obesity. Complications following bariatric surgery procedures (BSPs) may necessitate home parenteral nutrition (HPN). No studies have been published on patients receiving HPN following BSP complications. The study aim was to determine if hypocaloric HPN has an effect on body mass index (BMI), albumin, and HPN complications.

METHODS

A historic cohort of patients was identified from a clinical database. Obese patients (BMI ≥35 kg/m(2)) who underwent BSP and received HPN for an anastomotic leak/fistula or bowel obstruction were included. Comparisons for start and end of therapy were made for calorie and protein intake, BMI, white blood cell count, and serum albumin level. Readmissions and metabolic and infectious complications were recorded. Obese patients received hypocaloric feeds to promote weight loss and protein for wound healing.

RESULTS

Twenty-three patients were included for an average study length of 1.5 months. Patients received an average of 1.2 g of protein and a median of 13.6 kcal per kg actual body weight (ABW) per day. BMI decreased by 7.1% ± 5.2%, from a median of 39.8 to 37.1, and serum albumin increased by 12.5%, from 2.8 ± 0.5 to 3.2 ± 0.6 g/dL. Readmissions occurred in 52.2% of patients with 40.0% of complications related to HPN.

CONCLUSIONS

Hypocaloric HPN is efficacious in maintaining adequate nutrition while allowing for weight loss in morbidly obese patients following complications of bariatric surgery. Frequency of HPN complications was comparable to those reported in the literature.

The ratio of energy expenditure to nitrogen loss in diverse patient groups--a systematic review

BACKGROUND & AIMS

The ratio of energy expenditure to nitrogen loss respectively of energy to nitrogen provision (E/N) is considered a valuable tool in the creation of an enteral or parenteral formulation. Specific E/N ratios for parenteral nutrition (PN) have not yet been clearly defined. To determine the range of energy expenditure, nitrogen (protein) losses, and E/N ratios for various patient groups, we performed a systematic review of the literature.

METHODS

Medline 1950-2011 was searched for all studies on patients or healthy controls reporting energy expenditure and nitrogen loss at the same time.

RESULTS

We identified 53 studies with 91 cohorts which comprised 1107 subjects. Mean TEE ± standard deviation (SD) was 31.2 ± 7.2 kcal/kg BW/day in patients (n = 881) and 35.6 ± 4.3 kcal/kg BW/day in healthy controls (n = 266). Mean total protein loss (TPL) was 1.50 ± 0.57 g/kg BW/day in patients and 0.94 ± 0.24 g/kg BW/day in healthy controls. A non-linear significant correlation was found between TPL and the E/N ratio.

CONCLUSION

The E/N ratio is not a constant value but decreases continuously with increasing protein loss. These variations should be considered in the nutritional support of patients.

Nutritional support of the obese and critically ill obese patient

With the dramatic increase in the prevalence of obesity worldwide and in the United States, it is virtually certain that clinicians will be caring for bariatric and obese nonbariatric patients in increasing numbers. This patient population presents several difficulties from the medical and surgical management perspectives. In particular, nutrition of the bariatric patient and critically ill obese patient is challenging. A clear understanding of the nutritional assessment and unique management strategies available for the bariatric and the critically ill obese patient is essential to provide them with the safest and most effective care.

Current strategies of critical care assessment and therapy of the obese patient (hypocaloric feeding): what are we doing and what do we need to do?

Two of the most challenging issues in the clinical management of the obese patient are assessing energy requirements and whether hypocaloric (permissive) underfeeding should be employed. Multiple predictive equations have been used in the literature to estimate resting metabolic rate, although no consensus has emerged regarding which prediction equation is most accurate and precise in the obese population. Hypocaloric, or permissive underfeeding, specifically refers to the intentional administration of calories that are less than predicted energy expenditure. Thus far, very few studies performed have been performed to assess the efficacy of hypocaloric feeding in the obese hospitalized patient. It is concluded that the optimal caloric intake of obese patients in the intensive care unit remains unclear given the limitation of the existing data.

Optimal caloric intake for critically ill patients: first, do no harm

Despite considerable efforts to define energy requirements for critically ill patients, no single method has been found to be precise and unbiased for all patients. As a result, clinicians have used various methods that may overestimate energy requirements for some patients. Provision of target caloric intake without regard to the complications of overfeeding, such as hyperglycemia, hypercapnia, or gastric feeding intolerance, could result in overall detrimental clinical outcome. Inadequate nutrition support is also associated with adverse clinical outcomes that necessitate optimization of delivery and tolerance of the nutrition regimen. A pivotal paper by Krishnan and colleagues published in 2003 brought these issues to the forefront of clinical practice. Key papers that support or refute the practice of "permissive underfeeding" are reviewed. Further research is necessary to determine the minimum amount of nutrition required to achieve a therapeutic benefit as well as to ascertain at what amount of additional nutrition intake offers no further improvement in clinical outcome.

Efficacy of hypocaloric parenteral nutrition for surgical patients: a systematic review and meta-analysis

BACKGROUND AND AIMS

Hypocaloric parenteral nutrition is an underfeeding strategy that lowers energy intake to around 20 kcal/kg/d. It is believed to achieve benefits by modulating metabolic responses and alleviating hyperglycemia. This study aims to systematically review the clinical efficacy of hypocaloric parenteral nutrition on surgical patients.

METHODS

Medline, SCI, Embase, Cochrane Library, Chinese Biomedicine Database (CBM) and China Knowledge Resource Integrated Database (CNKI) were searched for studies published before July 1, 2010. Randomized control trials (RCTs) that compared hypocaloric PN with standard or higher energy PN in surgical patients were identified and included. Methodological quality assessment was based on Cochrane Reviewers' Handbook and modified Jadad's Score Scale. Statistical software RevMan 5.0 was used for meta-analysis.

RESULTS

Five trials met all inclusion criteria and were included in the final meta-analysis. There were significant reductions in infectious complications (RR, 0.60; 95%CI 0.39-0.91, P = 0.02; I(2) = 38%) and length of hospitalization (LOS) associated with receiving hypocaloric PN (MD-2.49 days, 95%CI -3.88 to -1.11, P = 0.0004; I² = 48%). Stratified analysis of the smaller trials (<60) and larger trials demonstrated that the heterogeneity between trials was mainly associated with sample size. When smaller trials were excluded, hypocaloric PN was associated with reduction in infectious complications (RR, 0.21, 95%CI 0.06-0.72, P = 0.01, I2 = 0%) and shortening of LOS (MD, -2.32 days, 95%CI -3.72 to -0.93, P = 0.001, I² = 0%).

CONCLUSION

Hypocaloric parenteral nutrition may reduce infectious complications and the length of hospitalization in post-operative patients. However, this conclusion is tentative due to patient type and sample size. Furthermore, in terms of hypocaloric PN, the actual energy amount still varies a great deal (from 15 kcal/kg/d to 20 kcal/kg/d). This suggests that further research, including larger randomized clinical trials is required.

Nutrition in critically ill obese patients

Critically ill obese patients require timely nutrition in the intensive care unit. Hypocaloric, high protein nutritional feeding might have a role in critically ill obese patients. Although critically ill obese patients need special medical and nutritional care as do nonobese patients in the ICU, there are some differences in the literature about the initiation, routes, and nature of nutritional support. This article reviews the norms of nutritional care among critically ill obese patients and the differences between these patients and those with a normal BMI.

An Update on Nutrition Support in the Critically Ill

Nutrition support in the critically ill patient has shifted from adjunctive toward fundamental therapy with the publication of high-grade evidence. Early enteral nutrition (EN) is recommended because it is associated with decreased infectious complications and use of EN is associated with decreased mortality and infections compared with parenteral nutrition (PN). EN is not without risks, such as diarrhea or aspiration, but use of prokinetic agents, head of bed elevation, and use of feeding protocols can maximize benefits and minimize risks. Although recently high-grade evidence on nutrition support in the critically ill population has been published, many controversies still exist. In obese patients, use of hypocaloric feedings with increased protein has been demonstrated to promote weight loss and improved glucose management. In nonobese patients, small studies have demonstrated that providing more than 70% or less than 30% of goal caloric intake may be associated with worse outcomes, but more studies are needed. Additional research is also needed to conclude whether withholding intravenous fat emulsions for the first 7 to 10 days of PN reduces infectious complications. Finally, more high-quality studies are needed to define the role of immune-enhancing nutrients such as arginine, glutamine, omega-3 fatty acids, zinc, and selenium.

Review article: permissive underfeeding in short-term nutritional support

BACKGROUND

The importance of adequate nutritional support in selected patient groups is well established. Traditionally, the amounts of macronutrients provided have been based on a perceived need to achieve, if not exceed, energy and protein balance. In recent years, there has been increasing interest in the concept of 'permissive underfeeding'.

AIM

To determine whether or not there is evidence of benefit for permissive underfeeding in selected groups.

METHODS

Studies were identified from MEDLINE, Embase and PubMed databases and the Cochrane collaboration. The search was limited from January 1950 to January 2010. Further searches were made from the references of original articles. The literature search revealed 591 abstracts of relevant studies. All abstracts were initially reviewed by the primary author (AO) and those that did not fulfil the inclusion criteria were discarded. The remaining articles were requested and were reviewed independently by two authors (AO, JM).

RESULTS

Twelve studies were included in the final analysis. Eight of these were randomized interventional trials. Three were prospective cohort studies and one was a retrospective analysis.

CONCLUSION

This review suggests that permissive underfeeding may be associated with improved outcomes and reduced morbidity in patients requiring short-term nutritional support.

Provision of nutritional support to those experiencing complications following bariatric surgery

This review details the practicalities of providing nutrition support to obese patients who experience complications following bariatric surgery and highlights some of the nutritional challenges encountered by this group of patients. Bariatric surgery to treat morbid obesity has significantly increased internationally over the past decade with hospital admissions rising annually. The gastric bypass is currently the most commonly performed procedure. The complication rate can be up to 16%, with a considerable proportion having nutritional implications. The treatment can involve avoidance of oral diet and nutrition support, i.e. enteral or parenteral nutrition. Opposition to nutrition support can be encountered. It is useful to clarify the aims of nutrition support, these being: the avoidance of overfeeding and its consequences, preservation of lean body mass and promotion of healing. Evidence suggests that hypoenergic nutrition is not harmful and may actually be beneficial. There is a lack of consensus regarding the optimum method to predict the nutritional requirements in the obese acutely unwell patient. The literature suggests that the predicted equations are fairly accurate compared to measured energy expenditure in free living obese patients before and after bariatric surgery. However, these findings cannot be directly applied to those obese patients experiencing complications of bariatric surgery, who will be acutely unwell exhibiting inflammatory response. It is therefore necessary to refer to the literature on energy expenditure in hospitalized obese patients, to help guide practice. More research examining the energy and protein requirements of obese patients needing nutrition support following bariatric surgery is urgently required.

Randomized Controlled Study of Glycerol Versus Dextrose in Postoperative Hypocaloric Peripheral Parenteral Nutrition

The aim of this study was to use glycerol and dextrose in hypocaloric peripheral parenteral nutrition (HPNN) and investigate their effects on postoperative metabolic and nutritional responses. Thirty patients who had undergone major gastrointestinal surgery were examined in a prospective randomized study. The study period extended from the day before operation to postoperative day 7. Fifteen patients (intervention group) received 1.2 g amino acids, 1.2 g glycerol, and 0.5 g fat emulsion/kg/day (approximately 15 kcal/kg/day). The other 15 patients (control group) received 1.2 g amino acids, 1.5 g dextrose, and 0.5 g fat emulsion/kg/day (approximately 15 kcal/kg/day). After 7 days of study, both groups were found to have a decrease in body weight, mid-arm circumference, triceps skin fold, serum albumin, and transferrin and prealbumin levels, but an increase in serum cholesterol and triglyceride levels. However, the differences between them were not significant. Improvements in nitrogen balance were observed in the intervention group (p = .035). These data suggest that advantages favoring the administration of glycerol instead of dextrose in hypocaloric parenteral nutrition could hardly be found in our investigation, except that better nitrogen equilibrium is maintained. Nonetheless, the peripheral intravenously administered ProcalAmine with fat emulsion has been well tolerated and safe for these patients, as well as more convenient for clinical use.

The risk for bloodstream infections is associated with increased parenteral caloric intake in patients receiving parenteral nutrition

Background

Patients receiving total parenteral nutrition (TPN) are at high risk for bloodstream infections (BSI). The notion that intravenous calories and glucose lead to hyperglycemia, which in turn contributes to BSI risk, is widely held but is unproven. We therefore sought to determine the role that hyperglycemia and parenteral calories play in the development of BSI in hospitalized patients receiving TPN.

Methods

Two hundred consecutive patients initiated on TPN between June 2004 and August 2005 were prospectively studied. Information was collected on patient age, sex, admission diagnosis, baseline laboratory values, intensive care unit (ICU) status and indication for TPN. Patients in the ICU were managed with strict glycemic control, whereas control on the general ward was more liberal. The maximum blood glucose level over each 8-hour period was recorded, as were parenteral daily intake, enteral daily intake and total daily caloric intake. The primary outcome measure was the incidence of BSI. Additional endpoints were ICU length of stay, hospital length of stay and mortality.

Results

A total of 78 patients (39%) developed at least one BSI, which were more common in ICU patients than in other hospitalized patients (60/122 patients versus 18/78 patients; P < 0.001). Maximum daily blood glucose concentrations were similar in patients with BSI and in patients without BSI (197 mg/dl versus 196 mg/dl, respectively). Patients with BSI received more calories parenterally than patients without BSI (36 kcal/kg/day versus 31 kcal/kg/day, P = 0.003). Increased maximum parenteral calories, increased average parenteral calories, and treatment in the ICU were strong risk factors for developing BSI. There was no difference in mortality between patients with and without BSI.

Conclusion

Increased parenteral caloric intake is an independent risk factor for BSI in patients receiving TPN. This association appears unrelated to hyperglycemia. Based upon our observations, we suggest that parenteral caloric intake be prescribed and adjusted judiciously with care taken to account for all intravenous caloric sources and to avoid even short periods of increased intake.

Obesity, inflammation, and the potential application of pharmaconutrition

Obesity is an emerging problem worldwide. Hospitalized obese patients often have a worse outcome than patients of normal weight, particularly in the setting of trauma and critical care. Obesity creates a low-grade systemic inflammatory response syndrome (SIRS) that is similar (but on a much smaller scale) to gram-negative sepsis. This process involves up-regulation of systemic immunity, is characterized clinically by insulin resistance and the metabolic syndrome, and puts the patient at increased risk for organ failure, infectious morbidity, and mortality. Through lipotoxicity and cytokine dysregulation, obesity may act to prime the immune system, predisposing to an exaggerated subsequent immune response when a second clinical insult occurs (such as trauma, burns, or myocardial infarction). Specialized nutrition therapy for such patients currently consists of a hypocaloric, high-protein diet. However, this approach does not address the putative pathophysiologic mechanisms of inflammation and altered metabolism associated with obesity. A number of dietary agents such as arginine, fish oil, and carnitine may correct these problems at the molecular level. Pharmaconutrition formulas may provide exciting innovations for the nutrition therapy of the obese patient.