Feeding should be individualized in the critically ill patients

Advances in nutritional metabolic therapy to impede the progression of critical illness

With the advancement of medical care and the continuous improvement of organ support technologies, some critically ill patients survive the acute phase of their illness but still experience persistent organ dysfunction, necessitating long-term reliance on intensive care and organ support, known as chronic critical illness. Chronic critical illness is characterized by prolonged hospital stays, high mortality rates, and significant resource consumption. Patients with chronic critical illness often suffer from malnutrition, compromised immune function, and poor baseline health, which, combined with factors like shock or trauma, can lead to intestinal mucosal damage. Therefore, effective nutritional intervention for patients with chronic critical illness remains a key research focus. Nutritional therapy has emerged as one of the essential components of the overall treatment strategy for chronic critical illness. This paper aims to provide a comprehensive review of the latest research progress in nutritional support therapy for patients with chronic critical illness.

Parenteral nutrition in the hospital setting/short-term parenteral nutrition

PURPOSE

This article is based on presentations and discussions held at the International Safety and Quality of Parenteral Nutrition (PN) Summit concerning the acute care setting. Some European practices presented in this article do not conform with USP general chapter <797> requirements. Nevertheless, the purpose is to cover the challenges experienced in delivering high-quality PN within hospitals in the United States and Europe, in order to share best practices and experiences more widely.

SUMMARY

Core issues regarding the PN process within an acute care setting are largely the same everywhere: There are ongoing pressures for greater efficiency, optimization, and also concurrent commitments to make PN safer for patients. Within Europe, in recent years, the use of market-authorized multi-chamber bags (MCBs) has increased greatly, mainly for safety, cost-effectiveness, and efficiency purposes. However, in the US, hospitals with low PN volumes may face particular challenges, as automated compounding equipment is often unaffordable in this setting and the variety of available MCBs is limited. This can result in the need to operate several PN systems in parallel, adding to the complexity of the PN use process. Ongoing PN quality and safety initiatives from US institutions with various PN volumes are presented. In the future, the availability of a greater selection of MCBs in the US may increase, leading to a reduction in dependence on compounded PN, as has been seen in many European countries.

CONCLUSION

The examples presented may encourage improvements in the safety and quality of PN within the acute care setting worldwide.

Relationship between critical care nutrition and post-intensive care syndrome in surviving ventilated patients with COVID-19: a multicenter prospective observational study

The impact of nutrition therapy in the acute phase on post-intensive care syndrome (PICS) remains unclear. We conducted a multicenter prospective study on adult patients with COVID-19 who required mechanical ventilation for more than three days. The questionnaire was mailed after discharge. Physical PICS, defined as less than 90 points on the Barthel index (BI), was assigned as the primary outcome. We examined the types of nutrition therapy in the first week that affected PICS components. 269 eligible patients were evaluated 10 months after discharge. Supplemental parenteral nutrition (SPN) >400 kcal/day correlated with a lower occurrence of physical PICS (10% vs 21.92%, p = 0.042), whereas the amounts of energy and protein provided, early enteral nutrition, and a gradual increase in nutrition delivery did not, and none correlated with cognitive or mental PICS. A multivariable regression analysis revealed that SPN had an independent impact on physical PICS (odds ratio 0.33, 95% CI 0.12-0.92, p = 0.034), even after adjustments for age, sex, body mass index and severity. Protein provision ≥1.2 g/kg/day was associated with a lower occurrence of physical PICS (odds ratio 0.42, 95% CI 0.16-1.08, p = 0.071). In conclusion, SPN in the acute phase had a positive impact on physical PICS for ventilated patients with COVID-19.

Resting energy expenditure measured by indirect calorimetry in mechanically ventilated patients during ICU stay and post-ICU hospitalization: A prospective observational study

PURPOSE

The metabolic course during and after critical illness is unclear. We performed repeated indirect calorimetry (IC) measurements during ICU- and post-ICU hospitalization to determine resting energy expenditure (REE).

METHODS

Prospective observational design. In ventilated ICU patients, IC measurements were performed every three days until hospital discharge. Measured REE as predicted by the Harris-Benedict equation (HBE-REE) and 25 kcal/adjusted body weight/day (25-REE) were compared.

RESULTS

In 56 patients (38% females, 71[13]years, BMI 29(27;31)kg/m2), 189 ICU IC measurements were performed. Measured REE did not differ from HBE-REE at ICU admission, but was lower than 25-REE. Measured REE was increased compared to baseline on ICU-admission-day four (29(29-30)kcal/kg/day; mean difference 3.1(1.4-4.9)kcal/kg/day, p < 0.001) and thereafter during ICU admission. During post-ICU ward stay, 44 measurements were performed in 23 patients, showing a higher mean REE than during ICU stay (33(31-35)kcal/kg/day; mean difference 2.6(1.2-3.9)kcal/kg/day, p < 0.001). The REE in the ICU and ward was >110% of HBE-REE from day four onwards.

CONCLUSIONS

Critically ill mechanically ventilated patients were shown to have a resting energy expenditure (REE) > 110% of predicted REE on ICU admission day four and thereafter. Indirect calorimetry measurements suggest that the mean energy requirements during post-ICU hospitalization are higher than those in the ICU.

Modified Nutrition Risk in the Critically ill score and mortality in critically ill patients with traumatic brain injury

BACKGROUND

Understanding the relationship between nutrition risk at admission to the intensive care unit (ICU) and the prognosis of patients with traumatic brain injury (TBI) may aid early recognition of high-risk patients.

METHODS

We extracted data from the Medical Information Mart for Intensive Care III and the electronic ICU Collaborative Research Databases. Using modified Nutrition Risk in the Critically ill score (mNUTRIC) within the first 24 h of ICU admission, 5153 patients were divided into three groups: low (≤1, n = 1765), moderate (2-4, n = 2574), and high (≥5, n = 814). The primary outcome was 28-day in-hospital mortality, and the secondary outcomes were 7-day in-hospital mortality, length of ICU stay, and duration of mechanical ventilation.

RESULTS

During the median follow-up time of 6.69 days, 647 deaths occurred in total. After adjustment for potential confounding factors, setting the low mNUTRIC group as a reference, the risk of 28-day mortality was increased in the high and moderate mNUTRIC groups (hazard ratio [HR]high vs low [95% CI]: 4.21 [2.70-6.58] and 2.84 [1.95-4.14], respectively). Similarly, high and moderate mNUTRIC scores are linked to a higher risk of 7-day mortality (PTrend  < 0.001) and a longer duration of mechanical ventilation (PTrend  < 0.001). The effect of mNUTRIC on mortality varied by serum glucose level (PInteraction  = 0.01). Lastly, those whose mNUTRIC scores deteriorated within the first 3 days have a 1.46 times greater risk of dying compared with patients with improved mNUTRIC scores.

CONCLUSIONS

Nutrition risk screening by mNUTRIC score at the time of admission to the ICU may improve mortality prediction.

Toward nutrition improving outcome of critically ill patients: How to interpret recent feeding RCTs?

Although numerous observational studies associated underfeeding with poor outcome, recent randomized controlled trials (RCTs) have shown that early full nutritional support does not benefit critically ill patients and may induce dose-dependent harm. Some researchers have suggested that the absence of benefit in RCTs may be attributed to overrepresentation of patients deemed at low nutritional risk, or to a too low amino acid versus non-protein energy dose in the nutritional formula. However, these hypotheses have not been confirmed by strong evidence. RCTs have not revealed any subgroup benefiting from early full nutritional support, nor benefit from increased amino acid doses or from indirect calorimetry-based energy dosing targeted at 100% of energy expenditure. Mechanistic studies attributed the absence of benefit of early feeding to anabolic resistance and futile catabolism of extra provided amino acids, and to feeding-induced suppression of recovery-enhancing pathways such as autophagy and ketogenesis, which opened perspectives for fasting-mimicking diets and ketone supplementation. Yet, the presence or absence of an anabolic response to feeding cannot be predicted or monitored and likely differs over time and among patients. In the absence of such monitor, the value of indirect calorimetry seems obscure, especially in the acute phase of illness. Until now, large feeding RCTs have focused on interventions that were initiated in the first week of critical illness. There are no large RCTs that investigated the impact of different feeding strategies initiated after the acute phase and continued after discharge from the intensive care unit in patients recovering from critical illness.

Effects of enteral nutrition with different energy supplies on metabolic changes and organ damage in burned rats

BACKGROUND

Enteral nutrition (EN) is an important treatment for burn patients. However, severe gastrointestinal damage caused by major burns often leads to EN intolerance. Trophic EN solves this problem basically, but how to transition from trophic EN to standard EN smoothly is still a challenge in burn clinical nutrition. The aim of this study is to investigate the effects of EN with different energy supplies on metabolic changes, organ damage and prognosis in burned rats.

METHODS

Different feeding regimens were designed based on the continuous monitoring of resting energy expenditure in rats. Thirty-two Sprague-Dawley rats were randomly divided into a normal control group, burn +50% REE group, burn +75% REE group and burn +100% REE group. At the end of a nutritional treatment cycle (14th day), nuclear magnetic resonance spectroscopy, blood biochemistry analysis and quantification of subscab bacteria were performed to explore the differences in metabolic changes, degrees of organ damage and prognoses between the groups.

RESULTS

Sixteen metabolites involving seven metabolic pathways were identified from the different energy supply groups. After burn injury, resting energy consumption and body weight loss increased obviously. Meanwhile, weight loss was inversely related to energy supply. The greatest changes in the degree of organ damage, the level of plasma proteins, lipids and endotoxins, as well as the quantification of subscab bacteria were observed in the 50% REE group, followed by the 75 and 100% groups.

CONCLUSIONS

Achieving an early balance between energy supply and expenditure is conducive to mitigating metabolic disorders and improving prognosis after burn injury.

Dynamic metabolic changes measured by indirect calorimetry during the early phase of septic shock: a prospective observational pilot study

BACKGROUND AND AIMS

Energy metabolism (energy deficit, substrate consumption) in the early phase of septic shock is not clearly understood. The objective of this study was to describe its evolution using indirect calorimetry.

METHODS

Prospective observational pilot study including ventilated adult patients with septic shock admitted in a surgical intensive care unit (ICU). Metabolic data were collected using the COSMED Q-NRG + ® calorimeter: carbon dioxide production (VCO2), oxygen consumption (VO2), resting energy expenditure (REE), respiratory quotient (RQ) and the rate of substrate utilization (proteins, lipids, and carbohydrates). The main criterion was the evolution of the energy deficit (dE) from D1 to D6.

RESULTS

In total, 34 patients were included and 15 patients (age: 57.6 ± 12.8 years; Simplified Acute Physiology Score II: 52 ± 11) were eligible for final analysis. Time for initiation of nutritional support was 2.5 ± 1.5 days. The dE improved during the study period (slope = 2.9 [1.8; 4.2]; p < 0.001). The REE remained stable during the first week with no significant variation (slope = -0.16 [-1.49; 0.79]; p = 0.78). The RQ remained stable overall (slope = 0.01 [0.00; 0.03]; p = 0.10). The substrates utilization significantly changed at D3 in favor of protein consumption (slope = 6.50 [4.44; 8.85]; p < 0.001) with an overall significant decrease in the consumption of non-protein substrates.

CONCLUSION

Energy deficit improved while REE and RQ remained relatively stable during the first week of ICU stay. The significance of the variations of substrates consumption was unclear. These preliminary results should be further explored with larger studies.

[Critical deficiencies of energy and protein with a high provision of non-nutritional calories after one week in an intensive care unit]

INTRODUCTION

nutritional therapy is essential for the treatment of critically ill patients, although its right application fails frequently, which increases the risk for undernutrition and complications.

OBJECTIVE

to evaluate the nutritional adequacy of patients with enteral nutritional support in an intensive care unit (ICU).

METHODS

a cohort study was conducted including adults admitted to the ICU with enteral support and stay ≥ 7 days. Demographic data, severity of the disease, and clinical and nutritional scores, including IL-6 levels and body composition, were evaluated at admission. Nutritional intake was recorded daily in relation to the target intake according to international guidelines, for calculation of caloric and protein deficiencies.

RESULTS

in all, 26 from 132 admitted patients were included. Their probability of mortality was 20-25 % due to disease severity by APACHE (16.6 ± 6.02) and SOFA (8 ± 4.4). Undernutrition risk was 5.6 ± 1.09 by NRS-2002 and 4.3 ± 1.2 by angle phase. Caloric deficiency was -674 kcal/day, with 13 % proteins (28 ± 11.5 g/d) and 42 % lipids, including 17.5 % of non-nutrient calories from propofol. NUTRIC was significantly associated with percentages of the caloric prescription at days 3 and 7 (R2 = 0.21, p = 0.01).

CONCLUSION

patients had a caloric/protein deficit with critical protein deficit of -85.2 g/day, and an inadequate proportion between protein calories and non-protein calories, increasing their risk of complications.

Energy expenditure and feeding practices and tolerance during the acute and late phase of critically ill COVID-19 patients

BACKGROUND & AIMS

Different metabolic phases can be distinguished in critical illness, which influences nutritional treatment. Achieving optimal nutritional treatment during these phases in critically ill patients is challenging. COVID-19 patients seem particularly difficult to feed due to gastrointestinal problems. Our aim was to describe measured resting energy expenditure (mREE) and feeding practices and tolerance during the acute and late phases of critical illness in COVID-19 patients.

METHODS

Observational study including critically ill mechanically ventilated adult COVID-19 patients. Indirect calorimetry (Q-NRG+, Cosmed) was used to determine mREE during the acute (day 0-7) and late phase (>day 7) of critical illness. Data on nutritional intake, feeding tolerance and urinary nitrogen loss were collected simultaneously. A paired sample t-test was performed for mREE in both phases.

RESULTS

We enrolled 21 patients with a median age of 59 years [44-66], 67% male and median BMI of 31.5 kg/m2 [25.7-37.8]. Patients were predominantly fed with EN in both phases. No significant difference in mREE was observed between phases (p = 0.529). Sixty-five percent of the patients were hypermetabolic in both phases. Median delivery of energy as percentage of mREE was higher in the late phase (94%) compared to the acute phase (70%) (p = 0.001). Urinary nitrogen losses were significant higher in the late phase (p = 0.003).

CONCLUSION

In both the acute and late phase, the majority of the patients were hypermetabolic and fed enterally. In the acute phase patients were fed hypocaloric whereas in the late phase this was almost normocaloric, conform ESPEN guidelines. No significant difference in mREE was observed between phases. Hypermetabolism in both phases in conjunction with an increasing loss of urinary nitrogen may indicate that COVID-19 patients remain in a prolonged acute, catabolic phase.

Endogenous Glucose Production in Critical Illness

Regulation of endogenous glucose production (EGP) by hormonal, neuronal, and metabolic signaling pathways contributes to the maintenance of euglycemia under normal physiologic conditions. EGP is defined by the generation of glucose from substrates through glycogenolysis and gluconeogenesis, usually in fasted states, for local and systemic use. Abnormal increases in EGP are noted in patients with diabetes mellitus type 2, and elevated EGP may also impact the pathogenesis of nonalcoholic fatty liver disease and congestive heart failure. In this narrative review, we performed a literature search in PubMed to identify recently published English language articles characterizing EGP in critical illness. Evidence from preclinical and clinical studies demonstrates that critical illness can disrupt EGP through multiple mechanisms including increased systemic inflammation, counterregulatory hormone and catecholamine release, alterations in the hypothalamic-pituitary axis, insulin resistance, lactic acidosis, and iatrogenic insults such as vasopressors and glucocorticoids administered as part of clinical care. EGP contributes to hyperglycemia in critical illness when abnormally elevated and to hypoglycemia when abnormally depressed, each of which has been independently associated with increased mortality. Increased EGP may also promote protein catabolism that could worsen critical illness myopathy and impede recovery. Better understanding of the mechanisms and factors contributing to dysregulated EGP in critical illness may help in the development of therapeutic strategies that promote euglycemia, reduce intensive care unit-associated catabolism, and improve patient outcomes.

Energy expenditure and indirect calorimetry in critical illness and convalescence: current evidence and practical considerations

The use of indirect calorimetry is strongly recommended to guide nutrition therapy in critically ill patients, preventing the detrimental effects of under- and overfeeding. However, the course of energy expenditure is complex, and clinical studies on indirect calorimetry during critical illness and convalescence are scarce. Energy expenditure is influenced by many individual and iatrogenic factors and different metabolic phases of critical illness and convalescence. In the first days, energy production from endogenous sources appears to be increased due to a catabolic state and is likely near-sufficient to meet energy requirements. Full nutrition support in this phase may lead to overfeeding as exogenous nutrition cannot abolish this endogenous energy production, and mitochondria are unable to process the excess substrate. However, energy expenditure is reported to increase hereafter and is still shown to be elevated 3 weeks after ICU admission, when endogenous energy production is reduced, and exogenous nutrition support is indispensable. Indirect calorimetry is the gold standard for bedside calculation of energy expenditure. However, the superiority of IC-guided nutritional therapy has not yet been unequivocally proven in clinical trials and many practical aspects and pitfalls should be taken into account when measuring energy expenditure in critically ill patients. Furthermore, the contribution of endogenously produced energy cannot be measured. Nevertheless, routine use of indirect calorimetry to aid personalized nutrition has strong potential to improve nutritional status and consequently, the long-term outcome of critically ill patients.

Nutrition During Critical Care: An Audit on Actual Energy and Protein Intakes

INTRODUCTION

Oral nutrition is delivered frequently in intensive care units (ICUs) but rarely studied. The primary objective of this study was to quantify nutrition intakes in patients exclusively orally fed (OF) and in those receiving medical nutrition solutions or both.

METHODS

Adults who stayed in a mixed ICU for ≥3 days were studied. Nutrition deficits were calculated as the difference between estimated energy or protein targets (determined by weight-based formulas) and actual intakes (recorded on a daily basis by nurses). Total volumes of enteral or parenteral nutrition solutions, propofol, and glucose infused over 24 hours were collected and energy and protein amounts were calculated. In OF patients, food intake at each meal (breakfast, lunch, and dinner) was estimated using the "one-quarter portion" method.

RESULTS

Among the 289 included patients aged 67 (57-75.5) years, 253 were fed and received, on average, 14.3 (7.8-19) kcal/kg/d and 0.53 (0.27-0.8) g/kg/d protein. In OF patients (n = 126), intakes were 9.7 (5.8-19) kcal/kg/d and 0.35 (0.17-0.57) g/kg/d protein. In the subset of OF patients with ICU stay ≥ 7 days (n = 37), respectively, 51% and 94% never received ≥80% of their energy and protein targets.

CONCLUSION

Nutrition intakes were lower by oral feeding compared with other exclusive or combined medical nutrition. Compared with the prescribed amounts, the deficit was larger for proteins than for energy.

How to choose the best route of feeding during critical illness

Increased and specific nutritional requirements occurring during critical illness need to be covered by appropriate administration of energy, nitrogen and micronutrients, especially in case of pre-existing malnutrition, chronic insufficient oral intakes or expected delay before recovery of eating. The use of artificial nutrition (enteral or parenteral) is recommended whenever the oral intakes are insufficient, in order to avoid the detrimental consequences of malnutrition and promote the best possible outcome of severely ill patients. This paper aims to provide an overview and practical recommendations of artificial nutrition therapy in the ICU setting.

Nutrition in Sepsis: A Bench-to-Bedside Review

Nutrition therapy in sepsis is challenging and differs from the standard feeding approach in critically ill patients. The dysregulated host response caused by infection induces progressive physiologic alterations, which may limit metabolic capacity by impairing mitochondrial function. Hence, early artificial nutrition should be ramped-up and emphasis laid on the post-acute phase of critical illness. Caloric dosing is ideally guided by indirect calorimetry, and endogenous energy production should be considered. Proteins should initially be delivered at low volume and progressively increased to 1.3 g/kg/day following shock symptoms wane. Both the enteral and parenteral route can be (simultaneously) used to cover caloric and protein targets. Regarding pharmaconutrition, a low dose glutamine seems appropriate in patients receiving parenteral nutrition. Supplementing arginine or selenium is not recommended. High-dose vitamin C administration may offer substantial benefit, but actual evidence is too limited for advocating its routine use in sepsis. Omega-3 polyunsaturated fatty acids to modulate metabolic processes can be safely used, but non-inferiority to other intravenous lipid emulsions remains unproven in septic patients. Nutrition stewardship, defined as the whole of interventions to optimize nutritional approach and treatment, should be pursued in all septic patients but may be difficult to accomplish within a context of profoundly altered cellular metabolic processes and organ dysfunction caused by time-bound excessive inflammation and/or immune suppression. This review aims to provide an overview and practical recommendations of all aspects of nutritional therapy in the setting of sepsis.

Caloric Adequacy in the First Week of Mechanically Ventilated Patients has No Impact on Long-term Daily Life Activities

Aim and objective

The aim and objective of this study is to test the effect of an optimized caloric supply in the first week of intensive care unit (ICU) stay in mechanically ventilated patients on the ability to perform their activities of daily living (ADL) in the long-term.

Materials and methods

A prospective observational study comparing patients who achieved an adequate caloric target (≥80%) vs those whose target was inadequate (<80%). The primary outcome under study is the instrumental ADL (IADL) scale after 6 months of discharge.

Results

Ninety-two patients were evaluated in the ICU and 50 were alive at 6 months. Follow-up was lost for 3 patients and 47 patients were evaluated at ICU and after 6 months. Thirty-four patients reached the energetic target and 13 did not reach it. There was no significant variation in IADL.

Conclusion

The energy adequacy in the first week of hospitalization was achieved by most survivors; however, this conduct does not seem to have influenced the ability to perform ADL after 6 months of discharge.

How to cite this article

Dariano AP, Couto CFL, Rubin BA, Viana MV, Friedman G. Caloric Adequacy in the First Week of Mechanically Ventilated Patients has No Impact on Long-term Daily Life Activities. Indian J Crit Care Med 2020;24(12):1206–1212.

Indirect Calorimetry in Clinical Practice

Indirect calorimetry (IC) is considered as the gold standard to determine energy expenditure, by measuring pulmonary gas exchanges. It is a non-invasive technique that allows clinicians to personalize the prescription of nutrition support to the metabolic needs and promote a better clinical outcome. Recent technical developments allow accurate and easy IC measurements in spontaneously breathing patients as well as in those on mechanical ventilation. The implementation of IC in clinical routine should be promoted in order to optimize the cost–benefit balance of nutrition therapy. This review aims at summarizing the latest innovations of IC as well as the clinical indications, benefits, and limitations.

Metabolic and Nutritional Characteristics of Long-Stay Critically Ill Patients

Background: insufficient feeding is frequent in the intensive care unit (ICU), which results in poor outcomes. Little is known about the nutrition pattern of patients requiring prolonged ICU stays. The aims of our study are to describe the demographic, metabolic, and nutritional specificities of chronically critically ill (CCI) patients defined by an ICU stay >2 weeks, and to identify an early risk factor. Methods: analysis of consecutive patients prospectively admitted to the CCI program, with the following variables: demographic characteristics, Nutrition Risk Screening (NRS-2002) score, total daily energy from nutritional and non-nutritional sources, protein and glucose intakes, all arterial blood glucose values, length of ICU and hospital stay, and outcome (ICU and 90-day survival). Two phases were considered for the analysis: the first 10 days, and the next 20 days of the ICU stay. Statistics: parametric and non-parametric tests. Results: 150 patients, aged 60 ± 15 years were prospectively included. Median (Q1, Q3) length of ICU stay was 31 (26, 46) days. The mortality was 18% at ICU discharge and 35.3% at 90 days. Non-survivors were older (p = 0.024), tended to have a higher SAPSII score (p = 0.072), with a significantly higher NRS score (p = 0.033). Enteral nutrition predominated, while combined feeding was minimally used. All patients received energy and protein below the ICU’s protocol recommendation. The proportion of days with fasting was 10.8%, being significantly higher in non-survivors (2 versus 3 days; p = 0.038). Higher protein delivery was associated with an increase in prealbumin over time (r² = 0.19, p = 0.027). Conclusions: High NRS scores may identify patients at highest risk of poor outcome when exposed to underfeeding. Further studies are required to evaluate a nutrition strategy for patients with high NRS, addressing combined parenteral nutrition and protein delivery.