Glycemic Effects of a Low-Carbohydrate Enteral Formula Compared With an Enteral Formula of Standard Composition in Critically Ill Patients: An Open-Label Randomized Controlled Clinical Trial

Effects of high-fat, low-carbohydrate enteral nutrition in critically ill patients: A systematic review with meta-analysis

BACKGROUND & AIMS

High-fat, low-carbohydrate enteral nutrition has gained attention, with expectations of an improved respiratory condition, fewer complications, and lower mortality. The present study performed a systematic review and meta-analysis of randomized controlled trials to examine the effects of high-fat, low-carbohydrate enteral nutrition in critically ill adult patients.

METHODS

We searched MEDLINE via Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL), and ICHUSHI for randomized controlled trials comparing high-fat, low-carbohydrate enteral nutrition to standard enteral nutrition in critically ill adult patients who received enteral nutrition. The primary outcome was mortality. Secondary outcomes included intensive care unit (ICU) mortality, length of ICU stay, length of mechanical ventilation, and adverse events of diarrhea and gastric residual volume. We examined the risk of bias using the Cochrane risk-of-bias tool for randomized trials version 2. We assessed the overall certainty of evidence based on the Grading of Recommendations Assessment, Development, and Evaluation methodology. Synthesis results were calculated with risk ratios and 95% confidence intervals using a Mantel-Haenszel random-effects model.

RESULTS

Eight trials with 607 patients were included. The effects of high-fat, low-carbohydrate enteral nutrition on mortality did not significantly differ from those of standard enteral nutrition (62/280 [22.1%] vs. 39/207 [18.8%], risk ratios = 1.14, 95% confidence intervals 0.80 to 1.62, P = 0.47). No significant differences were observed in ICU mortality, ICU length of stay, diarrhea, or gastric residual volume between the two groups. However, high-fat, low-carbohydrate enteral nutrition was associated with a significantly shorter duration of mechanical ventilation (mean difference -1.72 days, 95% confidence intervals -2.93 to -0.50, P = 0.005).

CONCLUSION

High-fat, low-carbohydrate enteral nutrition may not affect mortality, but may decrease the duration of mechanical ventilation in critically ill adult patients. Limitations include the small number of studies and potential for bias. Further research is needed to confirm these results and investigate effects on other outcomes and in a subgroup of patients requiring mechanical ventilation.

Determination of glycaemic response to the consumption of two specialised formulas for glycaemic control

To assess the glycaemic response after ingestion of two specialised oral and enteral nutrition formulas for glycaemic control. The participants were sixteen healthy volunteers, aged 21-49 years, with normal glucose tolerance. The volunteers attended the tests fasting for 10 h, for 5 weeks, and consumed the reference food - glucose solution - for 3 weeks, and the two formulas DiamaxO and DiamaxIG in the following weeks, in amounts equivalent to 25 g of available carbohydrates. During the period of 120 min, seven blood samples were taken through capillary blood sampling to determine the glycaemic response. The glycaemic index (GI) was calculated according to the trapezoidal rule, ignoring areas below the fasting line. The glycaemic load (GL) was determined by the formula GL = ((GI(glucose = reference) × 'g' of available carbohydrate per serving]/100. The formulas showed low GI and GL. GI = 37·8 and GL = 6·6 for DiamaxO and GI = 21·5 and GL = 3·5 for DiamaxIG. The peak of the glycaemic response occurred 30 min after ingestion, with a marked difference in blood glucose between the Diamax products in relation to glucose. Differences were also significant at times 15, 45, 60 and 90 min in relation to glucose (ANOVA with post hoc Bonferroni, P < 0·005), but not between the two products. However, the AUC and the GI of DiamaxIG are significantly smaller than that of the DiamaxO second t test (P = 0·0059). The glycaemic response to the products is quite reduced, presenting a curve with a little accentuated shape, without high peak, especially in the modified product.

The role of low-carbohydrate diets in the intensive care unit

Low-carbohydrate, high-fat (LCHF) nutrition therapy is characterized by carbohydrates comprising <26% of the daily caloric intake and a higher proportion of fat. LCHF therapies reduce exogenous glucose load, improve glycemic control, decrease inflammation, and improve clinical outcomes such as respiratory function. Given the altered metabolism in critically ill patients, LCHF nutrition therapy may be especially beneficial as it enables the conservation of protein and glucose for metabolic roles beyond energy use. In critical illness, LCHF diets have the potential to reduce hyperglycemia, improve ventilation, decrease hospital length of stay and reduce hospital costs. The purpose of this commentary piece is to describe LCHF nutrition therapy, summarize its impact on health outcomes, and discuss its role in the intensive care unit (ICU). Additional research on the effects of LCHF nutrition therapy on critically ill patients is warranted, including a focus on COVID-19.

Continuous Glucose Monitoring in the Intensive Care Unit

Traditionally, the care of critically ill patients with diabetes or stress hyperglycemia in the intensive care unit (ICU) demands the use of continuous intravenous insulin (CII) therapy to achieve narrow glycemic targets. To reduce the risk of iatrogenic hypoglycemia and to achieve glycemic targets during CII, healthcare providers (HCP) rely on hourly point-of-care (POC) arterial or capillary glucose tests obtained with glucose monitors. The burden of this approach, however, was evident during the beginning of the pandemic when the immediate reduction in close contact interactions between HCP and patients with COVID-19 was necessary to avoid potentially life-threatening exposures. Taking advantage of the advancements in current diabetes technologies, including continuous glucose monitoring (CGM) devices integrated with digital health tools for remote monitoring, HCP implemented novel protocols in the ICU to care for patients with COVID-19 and hyperglycemia. We provide an overview of research conducted in the ICU setting with the use of initial CGM technology to current devices and summarize our recent experience in the ICU.

Enteral nutrition product formulations: A review of available products and indications for use

When oral nutrition is not feasible, enteral nutrition (EN) therapy is often considered the preferred route of nutrition support to meet the nutrient needs of individuals with a functional gastrointestinal tract across multiple levels of care (critical care, acute care, and home care). Enteral formulations have progressively evolved over the last 50 years from the simple blending of hospital food thin enough to run through a feeding tube, to the development of commercial standard formulas, followed by specialized formulas with immune-modulating and disease-specific qualities, to the most recent shift to food-based or blenderized EN composed of natural, whole foods with perceived health benefits. With the vast number of enteral formulations on the market, clinicians may be overwhelmed trying to determine proven vs theoretical benefits. This review is intended to explore differences in enteral formulations, identify implications for clinical practice, and review evidenced-based clinical guidelines to assist clinicians in enteral formula selection.

Glycemic Management of Hospitalized Patients Receiving Nutrition Support

Enteral nutrition (EN) and parenteral nutrition (PN) increase the risk of hyperglycemia and adverse outcomes, including mortality, in patients with and without diabetes. A blood glucose target range of 140-180 mg/dL is recommended for hospitalized patients receiving artificial nutrition. Using a diabetes-specific EN formula, lowering the dextrose content, and using a hypocaloric PN formula have all been shown to prevent hyperglycemia and associated adverse outcomes. Insulin, given either subcutaneously or as a continuous infusion, is the mainstay of treatment for hyperglycemia. However, no subcutaneous insulin regimen has been shown to be superior to others. This review summarizes the evidence on and provides recommendations for the treatment of EN- and PN-associated hyperglycemia and offers strategies for hypoglycemia prevention. The authors also highlight their institution's protocol for the safe use of insulin in the PN bag. Randomized controlled trials evaluating safety and efficacy of targeted insulin therapy synchronized with different types of EN or PN delivery are needed.

Therapeutic Properties and Use of Extra Virgin Olive Oil in Clinical Nutrition: A Narrative Review and Literature Update

Extra virgin olive oil (EVOO) is a cornerstone of the Mediterranean diet (MedD). In this narrative review, we synthesize and illustrate the various characteristics and clinical applications of EVOO and its components—such as oleic acid, hydroxytyrosol, and oleuropein—in the field of clinical nutrition and dietetics. The evidence is split into diet therapy, oleic acid-based enteral nutrition formulations and oral supplementation formulations, oleic acid-based parenteral nutrition, and nutraceutical supplementation of minor components of EVOO. EVOO has diverse beneficial health properties, and current evidence supports the use of whole EVOO in diet therapy and the supplementation of its minor components to improve cardiovascular health, lipoprotein metabolism, and diabetes mellitus in clinical nutrition. Nevertheless, more intervention studies in humans are needed to chisel specific recommendations for its therapeutic use through different formulations in other specific diseases and clinical populations.

Nutritional therapy in critically ill patients with diabetes

PURPOSE OF REVIEW

There has been a significant increase in nutrition therapy related studies within the critical care cohort in recent years. Management of patients with both diabetes and stress hyperglycaemia through targeted nutrition interventions is no exception. The aim of this review is to outline current available diabetes specific nutrition formula, its impact on gastric emptying and subsequently glycaemic control as well as explore recent literature on the efficacy of utilizing nutrition support to optimize glycaemic control in critically ill patients.

RECENT FINDINGS

Studies explored within this review were similar in terms of outcomes measures, focusing primarily on insulin use and glycaemic control. Although there were promising results in terms of the impact of diabetes-specific nutrition formula on these outcome measures, there were no significant associations with clinical outcomes.

SUMMARY

The use of diabetes-specific formulae in critically ill patients with pre-existing diabetes and stress hyperglycaemia can be considered a logical approach to minimize the risks associated with high doses of insulin. Additional research is required to address the effects of these formulae on the dysglycaemia, nursing workload, safety of glycaemic control and cost-effectiveness.

Relationship between blood glucose variability and muscle composition in ICU patients receiving nutrition support: A pilot study

BACKGROUND AND AIMS

Many critically ill patients experience increased blood glucose variability (BGV). The objective of the current pilot study was to assess the relationship between muscle composition (defined as average Hounsfield units (HU)) among ICU patients with an abdominal CT scan within seven days of intubation, and BGV (defined as coefficient of variation (CV)) calculated from blood glucose levels measured each morning while intubated.

METHODS

The first serum blood glucose measurement obtained each day during intubation was recorded, blood glucose CV ((mean/SD)∗100) was calculated. Cross-sectional muscle area (CSA; cm²) at the third lumbar region was identified using the -29 to +150 HU range; muscle composition was calculated as the average HU. BGV predictors were determined using linear regression.

RESULTS

Eighty-two patients were included (53% female), with a median age of 64 (25th, 75 percentile (IQR): 51, 70) years. The median CV was 29% (IQR: 20, 37); 40% of subjects required insulin. The median CSA was 100.4 cm² (IQR: 84.0, 120.8) and muscle composition was 20.4 HU (IQR: 12.2, 29.4). Patients received only 36% of estimated calorie requirements. Insulin administration, history of diabetes, and muscle composition were significant BGV predictors.

CONCLUSION

Among these adult intubated ICU patients, higher muscle composition was associated with lower BGV. Future research is needed to corroborate these findings, determine other factors associated with poor muscle quality, and identify methods to describe muscle composition for all ICU patients.

Glycemic targets in critically ill adults: A mini-review

Illness-induced hyperglycemia impairs neutrophil function, increases pro-inflammatory cytokines, inhibits fibrinolysis, and promotes cellular damage. In turn, these mechanisms lead to pneumonia and surgical site infections, prolonged mechanical ventilation, prolonged hospitalization, and increased mortality. For optimal glucose control, blood glucose measurements need to be done accurately, frequently, and promptly. When choosing glycemic targets, one should keep the glycemic variability < 4 mmol/L and avoid targeting a lower limit of blood glucose < 4.4 mmol/L. The upper limit of blood glucose should be set according to casemix and the quality of glucose control. A lower glycemic target range (i.e., blood glucose 4.5-7.8 mmol/L) would be favored for patients without diabetes mellitus, with traumatic brain injury, or who are at risk of surgical site infection. To avoid harm from hypoglycemia, strict adherence to glycemic control protocols and timely glucose measurements are required. In contrast, a higher glycemic target range (i.e., blood glucose 7.8-10 mmol/L) would be favored as a default choice for medical-surgical patients and patients with diabetes mellitus. These targets may be modified if technical advances for blood glucose measurement and control can be achieved.

Association of specialized enteral nutrition with glycemic control and clinical outcomes in critically ill patients: A meta-analysis of randomized controlled trials

OBJECTIVE

To evaluate the association of glycemic-control formulae (GCF) with measurements of glycemic control and clinical outcomes compared to standard enteral formulae (SF) in critically ill patients.

DATA SOURCES

MEDLINE, EMBASE, Scopus and the Cochrane Central Register of Controlled Trials were searched from inception up to January, 2021.

STUDY SELECTION

RCTs that assessed the effects of GCF relative to SF in adult critically ill patients.

DATA EXTRACTION

Measurements of glycemic control were the primary outcomes. Secondary outcomes included insulin requirements, mechanical ventilation (MV), length of intensive care unit (ICU) stay and mortality. Two authors independently extracted data and assessed risk of bias using the Cochrane's RoB 2 tool and the GRADE approach was used to assess the quality of evidence.

DATA SYNTHESIS

Ten studies (12 reports, 685 patients) were included. The use of GCFs was associated with lower blood glucose (WMD, -16.06 mg/dL; 95% CI -23.48 to -8.63; I² = 47%) and lower daily administered insulin (WMD, -7.20 IU; 95% CI -13.92 to -0.48; I² = 53%). Glycemic variability, measured by the coefficient of variation, was also associated with the use of GCFs (WMD, -6.84%; 95% CI, -13.57 to -0.11; I² = 95%). In contrast, analyses for length of ICU stay (WMD, -0.12, 95% CI -1.77 to 1.52; I² = 0%), duration of MV (WMD, -0.34 days; 95% CI, -1.72 to 1.04; I² = 0%) and mortality (RR, 1.13; 95% CI 0.82 to 1.56; I² = 0%) were not statistically significant. Quality of evidence ranged from low to very low, and only one study was judged as at low risk of bias.

CONCLUSIONS

In this meta-analysis, GCFs were significantly associated with lower insulin requirements and improved glycemic control. Although results for clinical outcomes were not statistically significant, there is insufficient evidence to confirm or exclude important differences due to serious imprecision in the effect estimates and overall low quality of evidence. The effects of GCFs on clinical outcomes require confirmation in larger randomized trials.

Low-carbohydrate, high-fat enteral formulas for managing glycemic control in patients who are critically ill: A review of the evidence

Hyperglycemia is associated with increased morbidity and mortality. Low-carbohydrate, high-fat (LCHF) enteral formulas are marketed to improve glycemic control; however, given the multifactorial mechanisms contributing to hyperglycemia in patients who are critically ill, the effect that LCHF formulas may have on improving glycemic control in this patient population is unclear. Current guidelines for the use of LCHF formulas among patients who are critically ill are limited by a lack of evidence. This review explores recent research published in the past 7 years to determine whether LCHF enteral formulas improve glycemic control compared with standard enteral formulas in patients who are critically ill. Four randomized controlled trials met the inclusion criteria for this review. Their results suggest that LCHF formulas may improve glycemic control in patients who are critically ill with diabetes mellitus and/or who are hyperglycemic. Further large-scale randomized controlled trials are warranted to validate these findings among different subgroups of patients with critical illness. The potential benefits of LCHF formulas need to be weighed against specific limitations, including that LCHF formulas typically do not contain sufficient protein to meet the recommended needs of patients who are critically ill.

The effect of a low carbohydrate formula on glycaemia in critically ill enterally-fed adult patients with hyperglycaemia: A blinded randomised feasibility trial

BACKGROUND

Enteral nutrition is a source of carbohydrate that may exacerbate hyperglycaemia. Its treatment, insulin, potentially exacerbates glycaemic variability.

METHODS

This was a prospective, parallel group, blinded, randomised feasibility trial. Patients were eligible if 18 years or over when admitted to the intensive care unit and receiving enteral nutrition (EN) exclusively with two consecutive blood glucose > 10 mmol/L. A standardized glucose management protocol determined administration of insulin. Key outcome measures were insulin administered and glycaemic variability (coefficient of variation) over the first 48 h.

RESULTS

41 patients were randomized to either standard EN (14.1 g/100 mL carbohydrate; n = 20) or intervention EN (7.4 g/100 mL carbohydrate; n = 21). Overall 59% were male, mean (±SD) age of 62.3 years ± 10.4, APACHE II score of 16.5 ± 7.8 and a median (IQR) Body Mass Index 29.0 kg/m² (25.2-35.5). Most patients (73%) were mechanically ventilated. Approximately half (51%) were identified as having diabetes prior to ICU admission. Patients in the intervention arm received less insulin over the 48 h study period than those in the control group (mean insulin units over study period (95% CI) 45.0 (24.4-68.7) vs. 107 (56.1-157.9) units; p = 0.02) and had lower mean glycaemic variability (12.6 vs. 15.9%, p = 0.01). There was a small difference in the mean percentage of energy requirements met (intervention: 72.9 vs. control: 79.1%; p = 0.4) or protein delivered (78.2 vs. 85.4%; p = 0.3).

CONCLUSIONS

A low carbohydrate formula was associated with reduced insulin use and glycaemic variability in enterally-fed critically ill patients with hyperglycaemia. Further large trials are required to determine the impact of this formula on clinical outcomes. Registered under Australian and New Zealand Clinical Trials Registry, ANZCTR number: 12614000166673.

Practice Guidelines for Enteral Nutrition Management in Dysglycemic Critically Ill Patients: A Relook for Indian Scenario

Background and aim

Intensive-care practices and settings differ for India in comparison to other countries. While guidelines are available to direct the use of enteral nutrition (EN), there are no recommendations specific to nutritional management of EN in dysglycemic patients, specific to patients in Indian critical care settings. Advisory board meetings were arranged to develop the practice guidelines specific to the Indian context, for the use of EN in dysglycemic critically ill patients and to overcome challenges in this field.

Materials and methods

Two advisory board meetings were organized to review various existing guidelines, meta-analyses, randomized controlled trials (RCTs), controlled trials and review articles, for their contextual relevance and strength. Three rounds of Delphi voting were done to arrive at consensus on certain recommendations. A systematic grading of practice guidelines by the advisory board was done based on strength of the consensus voting and reviewed supporting evidences.

Results

Based on the literature review, the recommendations for developing the practice guidelines were made as per the grading criteria agreed upon by the advisory board. The recommendations were to address challenges regarding prediction and assessment of dysglycemia (DG), acceptable glycemic targets in such settings, general nutritional aspects pertaining to DG nutrition, and nutrition in various superspecialty cases in critical care settings, where DG is commonly encountered.

Conclusion

This paper summarizes the optimum EN practices for managing DG in critically ill patients. The practical solutions to overcome the challenges in this field are presented as practice guidelines at the end of each section. These guidelines are expected to provide guidance for EN management in dysglycemic critically ill patients. These guidelines also outline the model glycemic control task force and its roles in nutrition care as well as an intensive care unit DG nutrition protocol.

How to cite this article

Mehta Y, Mithal A, Kulkarni A, Reddy BR, Sharma J, Dixit S, et al. Practice Guidelines for Enteral Nutrition Management in Dysglycemic Critically Ill Patients: A Relook for Indian Scenario. Indian J Crit Care Med 2019;23(12):594–603.