Hypocaloric feeding of obese patients in the intensive care unit

Early metabolic support for critically ill trauma patients: A prospective randomized controlled trial

BACKGROUND

There is a lack of consensus regarding the optimal nutritional support for trauma patients. We hypothesize that early postinjury metabolic support focusing on adequate protein would modify the metabolic signature and alter the inflammatory environment for critically ill trauma patients.

METHODS

We conducted a prospective randomized controlled pilot trial for adult patients admitted to the surgical intensive care unit following traumatic injury. Patients were randomized to receive early metabolic support (EMS) (peripheral amino acid infusions) or standard of care (enteral nutrition as soon as feasible). Routine laboratory assessments, nitrogen balance, cytokines, and metabolomic analyses were assessed at baseline and day 5 after intervention.

RESULTS

A total of 42 trauma patients were randomized into well-balanced groups with similar age (32 years), Injury Severity Score (25), and body mass index (27.4 kg/m2). Early metabolic support provided significantly more protein (1.43 g/kg vs. 0.35 g/kg; p < 0.0001) and more calories (12.6 kcal/kg vs. 7.5 g/kg; p = 0.0012) over the first 5 days as compared with the standard of care. Early metabolic support modified protein catabolism and synthesis as demonstrated by a larger median negative nitrogen balance (-16.3 g vs. -5.3 g; p = 0.03) and a unique metabolomic profile at day 5. The biochemical profile of patients who received EMS was defined by greater declines in circulating levels of stress hormone precursors and increased levels of amino acids. The inflammatory response following EMS resulted in a greater decrease in interleukin-1B (p = 0.02) and increase in soluble interleukin-6 receptor (p = 0.01) between baseline and day 5 as compared with the standard of care. The EMS group had a decreased length of stay (15 vs. 22 days) and decreased surgical intensive care unit length of stay (8 vs. 9 days); however, this disappeared after adjustment for Injury Severity Score in this small population.

CONCLUSIONS

Early metabolic support with amino acid is safe, modifies metabolism, and may downregulate the inflammatory state associated with significant trauma, warranting a larger trial to assess for improved outcomes.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level II.

Adequacy of prescribed caloric and protein intake and reduction of mortality in critically ill patients with body mass indices <30 kg/m2

OBJECTIVE

Although the provision of nutrition helps minimize adverse outcomes in most patients in intensive care units (ICUs), little is known about the relative effect of energy and protein delivered on mortality in ICU patients with different ranges of body mass index (BMI). The aim of this study was to examine the relationships between adequacy of dietary energy and protein intakes separately and simultaneously, and short-term mortality in medical ICU patients across four BMI categories.

METHODS

We enrolled 1693 patients admitted to a medical center ICU in Taiwan during the period of 2005 to 2011, subcategorizing them by BMI levels: <18.5(n = 418), 18.5-24.9 (n = 889), 25-29.9 (n = 289), and ≥30 kg/m² (n = 97). Dietary energy and protein intake (DEI and DPI) were defined by the percent of prescribed dosages that each patient actually received: highly adequate (>80%), moderately adequate (60-80%), and inadequate (<60%), during the first 10 d in the ICU.

RESULTS

Mean DEI was 1237 kcal/d and DPI 47 g protein/d. Analyzed separately in our multiple regression models, moderately and highly adequate DEI (P_trends = 0.003-0.026) and DPI (P_trends = 0.001-0.004) were both significantly correlated with reduced mortality in patients with BMI <18.5, 18.5-24.9, and 25-29.9 kg/m² but not in those with BMI levels ≥30 kg/m². With DEI and DPI analyzed simultaneously, only APACHE II scores and DPI levels remained significantly related to reduced mortality in patients with BMI <30 kg/m².

CONCLUSION

Although the adequacy of delivery of prescribed DEI or DPI dosages appeared to be important for reduced risks for mortality in ICU patients with BMI <30 kg/m² when analyzed separately, DPI had a stronger effect on decreases in ICU mortality when the two were analyzed simultaneously. Further investigation may be needed to study the role of increased protein in improving clinical outcomes.

The Influence of Obesity on Treatment and Outcome of Severely Burned Patients

Obesity and the related medical, social, and economic impacts are relevant multifactorial and chronic conditions that also have a meaningful impact on outcomes following a severe injury, including burns. In addition to burn-specific difficulties, such as adequate hypermetabolic response, fluid resuscitation, and early wound coverage, obese patients also present with common comorbidities, such as arterial hypertension, diabetes mellitus, or nonalcoholic fatty liver disease. In addition, the pathophysiologic response to severe burns can be enhanced. Besides the increased morbidity and mortality compared to burn patients with normal weight, obese patients present a challenge in fluid resuscitation, perioperative management, and difficulties in wound healing. The present work is an in-depth review of the current understanding of the influence of obesity on the management and outcome of severe burns.

Impact of Obesity and Visceral Fat on Mortality in Hematopoietic Stem Cell Transplantation

RATIONALE

Many studies have shown the importance of body composition parameters, muscle, and fat mass, evaluated by several methods in hematopoietic stem cell transplantation (HSCT) outcomes. Ultrasound (US) is an efficient and low-cost method to evaluate body composition, even though there have not been many studies in HSCT.

OBJECTIVES

Our goal was to investigate the muscle, visceral fat (VF), and echogenicity before HSCT and after engraftment, evaluated by US and its association with outcomes.

METHODS

All adult patients with hematological malignances admitted for HSCT autologous and allogeneic were eligible to enter this prospective study. Their thigh muscle thickness, VF, and echogenicity were evaluated by US on the first day of hospitalization (baseline) and after engraftment (15-25 days post-HSCT).

RESULTS

We evaluated 50 patients; 42% were male and 58% had undergone allogeneic HSCT. Most patients were <55 years old (68%) and had normal body mass index (50%). We found a significant reduction of right and left muscle thickness (P < .001) and echogenicity (P = .002) after engraftment compared with baseline. Our elderly patients had significantly bigger right-thigh muscle thickness (P = .02) and more VF (P = .009). The following data were higher in obese patients: right and left muscle thickness (P < .001), VF (P = .003), and echogenicity (P = .04). Death in the first 100 days had a positive association with obesity (P = 0.001) and VF (P = .002). VF was the only variable independent of HSCT type and age in mortality risk.

CONCLUSION

Obesity and VF had an important impact in mortality. US could be a useful tool and strategy for evaluating body composition in HSCT patients.

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).

Nitrogen Balance During Venovenous Extracorporeal Membrane Oxygenation Support: Preliminary Results of a Prospective, Observational Study

BACKGROUND

Current literature is insufficient to support specific guidelines for estimating nutrition needs during extracorporeal membrane oxygenation (ECMO). The purpose of this single-center observational study was to investigate protein catabolism during venovenous (VV) ECMO support and assess whether current nutrition recommendations were adequate.

METHODS

All patients admitted to the Lung Rescue Unit between November 2016 and June 2017 were screened for eligibility. Patients with a documented nitrogen balance (NB) study were included in the data set. NB results were excluded for a change in blood urea nitrogen ≥10 mg/dL during the urine collection or unquantified nitrogen losses. Demographics, ECMO-specific data, NB, nutrition prescription, and infusion were recorded in a prospective, observational manner.

RESULTS

After exclusions, 25 NB results in 16 patients were included for analysis. Nonobese (body mass index [BMI] ˂ 30 kg/m² ) and obese (BMI ≥ 30 kg/m² ) patients received 85% and 84% of their prescribed protein, respectively. Nonobese patients had a mean NB of -1.7 ± 5.7, whereas obese patients had a mean NB of -11.5 ± 9.6. Obese patients displayed significantly higher urine urea nitrogen (26.7 ± 7.7 vs 13.5 ± 4.3; P = .00004).

CONCLUSIONS

These preliminary findings suggest that current guidelines for estimating protein needs in critically ill patients may be adequate for nonobese patients receiving VV ECMO. However, current protein recommendations for critically ill obese patients may not be adequate during VV ECMO support, possibly related to significantly higher rates of catabolism. Future studies with a larger cohort of patients are needed to confirm these results.

Protein in the Hospital: Gaining Perspective and Moving Forward

Provision of adequate protein is crucial for optimizing outcomes in hospitalized patients. However, the methodologies upon which current recommendations are based have limitations, and little is known about true requirements in any clinical population. In this tutorial, we aim to give clinicians an understanding of how current protein recommendations were developed, an appreciation for the limitations of these recommendations, and an overview of more sophisticated approaches that can be applied to better define protein requirements. A broader perspective of the challenges and opportunities in determining clinical protein requirements can help clinicians think critically about the individualized nutrition care they provide to their patients with the goal of administering adequate protein to optimize outcomes.

Evaluation of factors influencing 18F-FET uptake in the brain

PET using the amino-acid O-(2-¹⁸F-fluoroethyl)-l-tyrosine (¹⁸F-FET) is gaining increasing interest for brain tumour management. Semi-quantitative analysis of tracer uptake in brain tumours is based on the standardized uptake value (SUV) and the tumour-to-brain ratio (TBR). The aim of this study was to explore physiological factors that might influence the relationship of SUV of ¹⁸F-FET uptake in various brain areas, and thus affect quantification of ¹⁸F-FET uptake in brain tumours. Negative ¹⁸F-FET PET scans of 107 subjects, showing an inconspicuous brain distribution of ¹⁸F-FET, were evaluated retrospectively. Whole-brain quantitative analysis with Statistical Parametric Mapping (SPM) using parametric SUV PET images, and volumes of interest (VOIs) analysis with fronto-parietal, temporal, occipital, and cerebellar SUV background areas were performed to study the effect of age, gender, height, weight, injected activity, body mass index (BMI), and body surface area (BSA). After multivariate analysis, female gender and high BMI were found to be two independent factors associated with increased SUV of ¹⁸F-FET uptake in the brain. In women, SUV_mean of ¹⁸F-FET uptake in the brain was 23% higher than in men (p < 0.01). SUV_mean of ¹⁸F-FET uptake in the brain was positively correlated with BMI (r = 0.29; p < 0.01). The influence of these factors on SUV of ¹⁸F-FET was similar in all brain areas. In conclusion, SUV of ¹⁸F-FET in the normal brain is influenced by gender and weakly by BMI, but changes are similar in all brain areas.

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SUV_mean of ¹⁸F-FET in the normal brain is influenced by gender.

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SUV_mean of ¹⁸F-FET in the normal brain is weekly influenced by BMI.

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The influence of these factors on SUV of ¹⁸F-FET is similar in all brain areas.

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.

Protein requirement in critical illness

How much protein do critically ill patients require? For the many decades that nutritional support has been used there was a broad consensus that critically ill patients need much more protein than required for normal health. Now, however, some clinical investigators recommend limiting all macronutrient provision during the early phase of critical illness. How did these conflicting recommendations emerge? Which of them is correct? This review explains the longstanding recommendation for generous protein provision in critical illness, analyzes the clinical trials now being claimed to refute it, and concludes with suggestions for clinical investigation and practice.

What is the best nutritional support for critically ill patients?

Optimum nutritional support in critical illness remains controversial. A recent review of nutritional interventions in the ICU concluded that few of them improved clinical outcomes. In our view, it is a serious shortcoming of these trials that they focused on calories, falling far short of current recommendations for protein provision. Well designed clinical trials that ensure sufficient protein provision are urgently needed if we are to improve the quality of nutritional support in the ICU.

Initiation of nutritional support is delayed in critically ill obese patients: a multicenter cohort study

BACKGROUND

A high catabolic rate characterizes the acute phase of critical illness. Guidelines recommend an early nutritional support, regardless of the previous nutritional status.

OBJECTIVE

We aimed to assess whether the nutritional status of patients, which was defined by the body mass index (BMI) at admission in an intensive care unit (ICU), affected the time of nutritional support initiation.

DESIGN

We conducted a cohort study that reported a retrospective analysis of a multicenter ICU database (OUTCOMEREA) by using data prospectively entered from January 1997 to October 2012. Patients who needed orotracheal intubation within the first 72 h and >3 d were included.

RESULTS

Data from 3257 ICU stays were analyzed. The delay before feeding was different according to BMI groups (P = 0.035). The delay was longer in obese patients [BMI (in kg/m²) ≥30; n = 663] than in other patients with either low weight (BMI <20; n = 501), normal weight (BMI ≥20 and <25; n = 1135), or overweight (BMI ≥25 and <30; n = 958). The association between nutritional status and a delay in nutrition initiation was independent of potential confounding factors such as age, sex, and diabetes or other chronic diseases. In comparison with normal weight, the adjusted RR (95% CI) associated with a delayed nutrition initiation was 0.92 (0.86, 0.98) for patients with low weight, 1.00 (0.94, 1.05) for overweight patients, and 1.06 (1.00, 1.12) for obese patients (P = 0.004).

CONCLUSIONS

The initiation of nutritional support was delayed in obese ICU patients. Randomized controlled trials that address consequences of early compared with delayed beginnings of nutritional support in critically ill obese patients are needed.

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.

Current applications of metabolic monitoring in the pediatric intensive care unit

Delivery of adequate nutrients during illness to counteract the metabolic stress response and facilitate healing and tissue repair is an important goal in the care of critically ill children. With recent advances in technology, accurate minute-to-minute gas exchange and energy expenditure measurements are now available in intensive care units. The bedside availability of these devices may allow a titrated approach to energy delivery for patients, ushering in a new era of individualized nutrition therapy. Basic concepts, available monitoring devices, indications, pitfalls, and bedside application of metabolic monitoring are discussed in this article.

Why critically ill patients are protein deprived

Critical illness dramatically increases muscle proteolysis and more than doubles the dietary protein requirement. Yet surprisingly, most critically ill patients receive less than half the recommended amount of protein during their stay in a modern intensive care unit. What could explain the wide gap between the recommendations in clinical care guidelines and actual clinical practice? We suggest that an important aspect of the problem is the failure of guidelines to explain the pathophysiology of protein-energy malnutrition and the ways critical illness modifies protein metabolism. The difficulty created by the lack of a framework for reasoning about appropriate protein provision in critical illness is compounded by the many ambiguous and often contradictory ways the word malnutrition is used in the critical care literature. Failing to elucidate these matters, the recommendations for protein provision in the guidelines are incoherent, unconvincing, and easy to ignore.

Obesity and burns

The population of overweight patients presenting to burn facilities is expected to increase significantly over the next decades due to the global epidemic of obesity. Excess adiposity mediates alterations to key physiological responses and poses challenges to the optimal management of burns. The purpose of this study is to document the general epidemiological aspects of thermal injuries in the obese population, outline relevant physiological aspects associated with obesity, and draw attention to topics relating to the management, rehabilitation, and prognosis of burns in this emerging subpopulation of patients.

Pilot study of the SPRINT glycemic control protocol in a Hungarian medical intensive care unit

INTRODUCTION

Stress-induced hyperglycemia increases morbidity and mortality. Tight control can reduce mortality but has proven difficult to achieve. The SPRINT (Specialized Relative Insulin and Nutrition Tables) protocol is the only protocol that reduced both mortality and hypoglycemia by modulating both insulin and nutrition, but it has not been tested in independent hospitals.

METHODS

SPRINT was used for 12 adult intensive care unit patients (949 h) at Kálmán Pándy Hospital (Gyula, Hungary) as a clinical practice assessment. Insulin recommendations (0-6 U/h) were administered via constant infusion rather than bolus delivery. Nutrition was administered per local standard protocol, weaning parenteral to enteral nutrition, but was modulated per SPRINT recommendations. Measurement was every 1 to 2 h, per protocol. Glycemic performance is assessed by percentage of blood glucose (BG) measurements in glycemic bands for the cohort and per patient. Safety from hypoglycemia is assessed by numbers of patients with BG < 2.2 (severe) and %BG < 3.0 and < 4.0 mmol/liter (moderate and light). Clinical effort is assessed by measurements per day. Results are median (interquartile range).

RESULTS

There were 742 measurements over 1088 h of control (16.4 measurements/day), which is similar to clinical SPRINT results (16.2/day). Per-patient hours of control were 65 (50-95) h. Initial per-patient BG was 10.5 (7.9-11.2) mmol/liter. All patients (100%) reached 6.1 mmol/liter. Cohort BG was 6.3 (5.5-7.5) mmol/liter, with 42.2%, 65.1% and 77.6% of BG in the 4.0-6.1, 4.0-7.0, and 4.0-8.0 mmol/liter bands. Per-patient, median percentage time in these bands was 40.2 (26.7-51.5)%, 62.5 (46.0-75.7)%, and 74.7 (61.6.8-87.8)%, respectively. No patients had BG < 2.2 mmol/liter, and the %BG < 4.0 mmol/liter was 1.9%. These results were achieved using 3.0 (3.0-5.0) U/h of insulin with 7.4 (4.4-10.2) g/h of dextrose administration (all sources) for the cohort. Per-patient median insulin administration was 3.0 (3.0-3.0) U/h and 7.1 (3.4-9.6) g/h dextrose. Higher carbohydrate nutrition formulas than were used in SPRINT are offset by slightly higher insulin administration in this study.

CONCLUSIONS

The glycemic performance shows that using the SPRINT protocol to guide insulin infusions and nutrition administration provided very good glycemic control in initial pilot testing, with no severe hypoglycemia. The overall design of the protocol was able to be generalized with good compliance and outcomes across geographically distinct clinical units, patients, and clinical practice.

Appropriate protein provision in critical illness: a systematic and narrative review

BACKGROUND

Widely varying recommendations have been published with regard to the appropriate amount of protein or amino acids to provide in critical illness.

OBJECTIVE

We carried out a systematic review of clinical trials that compared the metabolic or clinical effects of different protein intakes in adult critical illness and comprehensively reviewed all of the available evidence pertinent to the safe upper limit of protein provision in this setting.

DESIGN

MEDLINE was searched for clinical trials published in English between 1948 and 2012 that provided original data comparing the effects of different levels of protein intake on clinically relevant outcomes and evidence pertinent to the safe upper limit of protein provision to critically ill adults.

RESULTS

The limited amount and poor quality of the evidence preclude conclusions or clinical recommendations but strongly suggest that 2.0-2.5 g protein substrate · kg normal body weight⁻¹ · d⁻¹ is safe and could be optimum for most critically ill patients. At the present time, most critically ill adults receive less than half of the most common current recommendation, 1.5 g protein · kg⁻¹ · d⁻¹, for the first week or longer of their stay in an intensive care unit.

CONCLUSION

There is an urgent need for well-designed clinical trials to identify the appropriate level of protein provision in critical illness.

[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.

Nutrition delivery for obese ICU patients: delivery issues, lack of guidelines, and missed opportunities

The most appropriate enteral formula for the severely obese population has yet to be determined. The obese patient in the intensive care unit (ICU) creates numerous difficulties for managing care, one being the ability to deliver appropriate and timely nutrition. Access for nutrition therapy, either enteral or parenteral, can also create a challenge. Currently, no specific guidelines are available on a national or international scale to address the issues of how and when to feed the obese patient in the ICU. A bias against feeding these patients exists, secondary to the perception that an enormous quantity of calories is stored in adipose tissue. Making a specialty enteral formula for obesity from existing commercial formulas and other modular nutrient components is not practical, secondary to difficulty with solubility issues, dilution of the formula, and safety concerns. Using today's concepts and current metabolic data, a formula could be produced that would address many of the specific metabolic derangements noted in obesity. This formula should have a high-protein, low-carbohydrate content with at least a portion of the lipid source coming from fish oil. Specific nutrients that may be beneficial in obesity include arginine, glutamine, leucine, L-carnitine, lipoic acid, S-adenosylmethionine, and betaine. Certain trace minerals such as magnesium, zinc, and selenium may also be of value in the obese population. The concept of a specific bariatric formulation for the ICU setting is theoretically sound, is scientifically based, and could be delivered to patients safely.

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.

Nutrition support for the acute lung injury/adult respiratory distress syndrome patient: a review

Support for Acute Lung Injury (ALI) and Adult Respiratory Distress Syndrome (ARDS) in many ways represents the summation of all intensive care unit nutrition modalities. Basic tenets of management are based on those established for the general population of mechanically ventilated patients. As a marker of critical illness however, patients with ALI/ARDS suffer from other organ dysfunctions that require advanced support. Specific issues to be considered in this population include carbon dioxide production, prevention of aspiration, and modulation of the inflammatory response. These particular areas, with special attention paid to the role of lipids in ALI/ARDS, will be reviewed.

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.

Providing nutrition to critically ill obese adults: use of the nursing process

Caring for obese critically ill patients is not always the same as caring for critically ill patients who are not obese. Fortunately, nurses have many resources available to them to guide them in this process. However, research that specifically addresses the needs of obese critically ill patients is still lacking in many areas and should be considered as potential areas to develop evidence-based practices.

Metabolic support of the obese intensive care unit patient: a current perspective

PURPOSE OF REVIEW

Obesity is a widespread condition associated with a variety of mechanical, metabolic, and physiologic changes that affect both health outcomes and delivery of care. Nutrition support is a key element of management during critical illness known to improve outcomes favorably, but is likewise complicated in the presence of obesity. This review serves to discuss the challenges unique to management of critically ill obese patients and an evidence-based approach to nutrition support in this patient population.

RECENT FINDINGS

High-protein, hypocaloric feeding has emerged as a nutrition support strategy capable of reducing hyperglycemia and protein catabolism, while promoting favorable changes in body composition and fluid mobilization. Recent data have shown a protective effect of mild-moderate obesity (BMI 30-39.9 kg/m2), with improved morbidity and mortality outcomes in this subgroup. Therefore, it is unclear whether hypocaloric feeding represents an inferior approach in this subgroup in which weight maintenance may be preferable.

SUMMARY

There are many obstacles that limit provision of nutrition support in the obese ICU patient. Calculating energy needs accurately is extremely problematic due to a lack of reliable prediction equations and a wide variability in body composition among the obese patients. Further research is needed to determine a better approach to estimating energy needs in this population, in addition to validating hypocaloric feeding as the standard approach to nutrition support in the obese patients.

Toward protein-energy goal-oriented therapy?

Protein calorie malnutrition is a concern in critically ill patients. Prospective studies to define the ideal calorie/protein intake to administer not only to meet requirements but also to change outcome are lacking. Strack van Schijndel and colleagues have observed an improvement in survival when patients reach the calorie target according to indirect calorimetry and a protein intake of greater than 1.2 g/kg per day. Their prospective observational study sheds new light on this field.

Management of sepsis in patients with liver failure

PURPOSE OF REVIEW

Sepsis constitutes the most common cause of death in the ICU. Liver dysfunction is manifested among previously normal subjects with sepsis but even more so in populations with preexisting liver disease. Managing these patients is more challenging. We will review recent literature in sepsis and liver disease, and their bedside application.

RECENT FINDINGS

At the cellular-chemical level, studies showed that platelet aggregation and neutrophil activation occur before and are independent of microcirculatory changes which are apparent in all animal septic models. At the clinical level, early goal-directed therapy, euglycemia, low tidal volume ventilation, and early and appropriately dosed renal replacement therapy among others are all tools to improve sepsis survival. Acknowledgement of liver disease as an immunocompromised host, and identification and treatment of complications can positively change the outcome of sepsis in liver disease.

SUMMARY

Much has been advanced in the field of sepsis management. Understanding the pathophysiology of liver dysfunction and decompensation of a diseased liver incites questions for future research. Early goal-directed therapy, lactate clearance, glycemic control, low volume ventilation strategies, nutrition, adrenal insufficiency, renal dysfunction, hepatorenal syndrome prevention and treatment are some of the issues in the management of sepsis, with or without liver disease, that are relevant in this review.

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.

Permissive underfeeding: its appropriateness in patients with obesity, patients on parenteral nutrition, and non-obese patients receiving enteral nutrition

The concept of permissive underfeeding is based on the rationale that higher nutrient intake is detrimental from a metabolic and functional perspective. Animal studies have demonstrated improved morbidity and mortality with energy restriction. Studies with obese patients have demonstrated that a hypocaloric feeding regimen can promote nitrogen equilibrium and minimize negative nitrogen balance without causing weight loss. In critically ill patients, permissive underfeeding with parenteral nutrition has not been well studied, although some benefit is apparent. In enterally fed patients, more research exists but the data are not generated from prospective controlled trials. Studies of enterally supported patients demonstrate an association between higher caloric intake and decreased morbidity and mortality. Despite limited research, provision of reduced energy intake in critically ill patients and obese patients may result in improved metabolic control, reduce the detrimental effects of overfeeding, and promote improved patient outcomes.

Feeding Practices of Severely Ill Intensive Care Unit Patients: An Evaluation of Energy Sources and Clinical Outcomes

OBJECTIVE

The quantity of nutrition that is provided to intensive care unit (ICU) patients has recently come under more scrutiny in relation to clinical outcomes. The primary objective of this study was to assess energy intake in severely ill ICU patients and to evaluate the relationship of energy intake with clinical outcomes.

DESIGN

Prospective cohort study.

SUBJECTS/SETTINGS

Seventy-seven adult surgery and medical ICU patients with length of ICU stay of at least 5 days.

STATISTICAL ANALYSES PERFORMED

Student's t test and chi2 tests were used to examine ICU populations. To determine the relationship of patient variables to hospital length of stay and ICU, length of stay regression trees were calculated.

RESULTS

Both groups were underfed with 50% of goal met in surgical ICU and 56% of goal met in medical ICU. Medical ICU patients received less propofol and significantly less dextrose-containing intravenous fluids when compared to surgical ICU patients (P=0.013). From regression analysis, approaching full nutrient requirements during ICU stay was associated with greater hospital length of stay and ICU length of stay. For combined groups, if % goal was > or =82%, the estimated average value for ICU length of stay was 24 days; whereas, if the % goal was <82%, the average ICU length of stay was 12 days. This relationship held true for hospital length of stay.

CONCLUSIONS

Medical and surgical ICU patients were insufficiently fed during their ICU stay when compared with registered dietitian recommendations. Medical ICU patients received earlier nutrition support, on average more enteral nutrition, with fewer kilocalories supplied from lipid-based sedatives and intravenous fluid relative to surgical ICU patients. Based upon length of stay, the data suggest that the most severely ill patient may not benefit from delivery of full nutrient needs in the ICU.

Overview of glycemic control in critical care: relating performance and clinical results

BACKGROUND

Hyperglycemia is prevalent in critical care and tight control can save lives. Current ad-hoc clinical protocols require significant clinical effort and produce highly variable results. Model-based methods can provide tight, patient specific control, while addressing practical clinical difficulties and dynamic patient evolution. However, tight control remains elusive as there is not enough understanding of the relationship between control performance and clinical outcome.

METHODS

The general problem and performance criteria are defined. The clinical studies performed to date using both ad-hoctitration and model-based methods are reviewed. Studies reporting mortality outcome are analysed in terms of standardized mortality ratio (SMR) and a 95(th) percentile (+/-2sigma) standard error (SE(95%)) to enable better comparison across cohorts.

RESULTS

Model-based control trials lower blood glucose into a 72-110 mg/dL band within 10 hours, have target accuracy over 90%, produce fewer hypoglycemic episodes, and require no additional clinical intervention. Plotting SMR versus SE(95%) shows potentially high correlation (r=0.84) between ICU mortality and tightness of control.

SUMMARY

Model-based methods provide tighter, more adaptable one method fits all solutions, using methods that enable patient-specific modeling and control. Correlation between tightness of control and clinical outcome suggests that performance metrics, such as time in a relevant glycemic band, may provide better guidelines. Overall, compared to the current one size fits all sliding scale and ad-hoc regimens, patient-specific pharmacodynamic and pharmacokinetic model-based, or one method fits all control, utilizing computational and emerging sensor technologies, offers improved treatment and better potential outcomes when treating hyperglycemia in the highly dynamic critically ill patient.

A pilot study of the SPRINT protocol for tight glycemic control in critically Ill patients

BACKGROUND

Stress-induced hyperglycemia is prevalent in critical care, even in patients with no history of diabetes. Increased counter-regulatory hormone response increases gluconeogenesis and effective insulin resistance, which can be exacerbated by drug therapy. Control of blood glucose levels to the 4.0-6.1 mmol/L range has been shown to reduce mortality and improve clinical outcomes. The Specialized Relative Insulin and Nutrition Tables (SPRINT) protocol is a simple alternative intensive care unit protocol for modulating insulin and nutritional input to gain tight blood glucose control in the 4.0-6.1 mmol/L target band. The look-up tables, implemented in a wheel-based format, are used by nurses to determine glycemic control actions based on hourly or 2-hourly blood glucose measurements and nutrition and insulin administration rates.

METHODS

An 11 patient pilot study was conducted comprising 2,152 hours of blood glucose level control using the SPRINT protocol. The patient cohort average Acute Physiology and Chronic Health Evaluation II score was 22, which was higher than previous intensive insulin clinical studies.

RESULTS

Overall, 64% of measurements were in the 4.0-6.1 mmol/L band, 89% in the 4.0-7.0 mmol/L band, and 96% of all measurements in the 4.0-7.75 mmol/L band. The average value was 5.8 +/- 0.9 mmol/L. Only 1.4% of all measurements were below 4 mmol/L, with a minimum of 3.2 mmol/L. The maximum value recorded was 11.8 mmol/L.

CONCLUSIONS

Control of blood glucose level was achieved using a protocol implemented by the nursing staff without the need for physician intervention or interpretation, where control is defined as maximizing time within a desired band. The results led to a high level of support for the SPRINT protocol among clinical staff and acceptance of the frequent measurement requirement for effective control. The ease-of-use of the protocol resulted in minimal noncompliance by clinical staff.

A novel, model-based insulin and nutrition delivery controller for glycemic regulation in critically ill patients

BACKGROUND

Critically ill patients are often hyperglycemic and insulin resistant, as well as highly dynamic. Tight glucose control has been shown to significantly reduce mortality in critical care. A physiological model of the glucose-insulin regulatory system is improved and used to develop an adaptive control protocol utilizing both nutritional and insulin inputs to control hyperglycemia. The approach is clinically verified in a critical care patient cohort.

METHODS

A simple two-compartment model for glucose rate of appearance in plasma due to stepwise enteral glucose fluxes is developed and incorporated into a previously validated system model. A control protocol modulating intravenous insulin infusion and bolus, with an enteral feed rate, is developed, enabling tight and predictive glycemic regulation to preset targets. The control protocol is adaptive to patient time-variant effective insulin resistance. The model and protocol are verified in seven 10-h and one 24-h proof-of-concept clinical trials. Ethics approval was granted by the Canterbury Ethics Committee.

RESULTS

Insulin requirements varied widely following acute changes in patient physiology. The algorithm developed successfully adapted to patient metabolic status and insulin sensitivity, achieving an average target acquisition error of 9.3% with 90.7% of all targets achieved within +/-20%. Prediction errors may not be distinguishable from sensor measurement errors. Large errors (>20%) are attributable to highly dynamic and unpredictable changes in patient condition.

CONCLUSIONS

Tight, targeted stepwise regulation was exhibited in all trials. Overall, tight glycemic regulation is achieved in a broad critical care cohort with optimized insulin and nutrition delivery, effectively managing glycemia even with high effective insulin resistance.