Basics in clinical nutrition: Metabolic response to injury and sepsis

Substrate utilization of carbohydrates, fat, and protein in the late acute phase of critically ill surgical patients: A retrospective longitudinal study

BACKGROUND AND AIMS

Tailoring nutrition to measured energy expenditure (EE) and provision of adequate protein amounts, is considered gold standard for critically ill patients. There are currently no recommendations to measure specific substrate utilization or to adapt nutrition accordingly.

METHODS

In this retrospective longitudinal study, we analyzed results of 316 simultaneous measurements of indirect calorimetry (IC) and urinary urea nitrogen (UUN) in 191 mechanically ventilated, critically ill patients, admitted to the surgical intensive care unit (SICU) in a tertiary medical center. We calculated substrate utilization, compared it to administered nutrition, investigated factors that may influence it and tested the added value of routine UUN measurements over IC alone.

RESULTS

The mean total EE, measured using the indirect calorimetry module, was 1600 ± 451 kcal/day The mean daily fat, carbohydrates and protein oxidation were 118.3 ± 63.9 g, 53.3 ± 114.1 g and 64.7 ± 36.0 g, respectively, accounting for 68.8 % ± 31.4 %, 14.2 % ± 29.6 % and 17.0 % ± 8.6 % of the total EE. Fasting and noradrenaline administration were the only factors that influenced substrate utilization, resulting in higher fat and lower carbohydrate utilization (p < 0.045 for all). There were significant differences between percentage of substrate utilization and supply, with average differences of +28.5 % for fat, -38 % for carbohydrates and +1.9 % for protein (p < 0.006 for all).

CONCLUSIONS

SICU patients demonstrated very high fat utilization and lower than expected carbohydrate utilization, that differed significantly from amounts supplied. Further prospective studies are needed to elucidate the clinical impact of these findings.

Nutritional Strategies for the Treatment and Prevention of Sepsis Outside the Intensive Care Unit

BACKGROUND/OBJECTIVES

Sepsis is a life-threatening condition characterized by an imbalanced immune response to infection, posing a significant challenge in hospital settings due to its high morbidity and mortality rates. While much attention has been given to patients in the ICU, uncertainties remain regarding the nutritional management of septic patients in non-intensive wards. This narrative review aims to address these gaps by exploring key aspects of nutritional care in sepsis patients admitted to non-intensive wards.

METHODS

We examine the pathophysiological mechanisms driving metabolic alterations in sepsis, methods for effective nutritional assessment, and supplementation strategies, including the potential role of specific nutrients. Additionally, we discuss the preventive role of nutrition, with a focus on gut microbiota modulation.

CONCLUSIONS

By synthesizing the available literature, this review provides evidence-based insights to guide nutritional strategies for managing sepsis in patients hospitalized in non-intensive wards and highlights critical areas for future research.

Alterations in Blood Plasma Metabolome of Patients with Lesniowski-Crohn's Disease Shortly after Surgical Treatment-Pilot Study

Lesniowski-Crohn’s disease (CD) is a type of chronic inflammatory bowel disease (IBD) of uncertain etiology. Initially, pharmacological management is undertaken; however, surgical intervention is necessary to improve life quality and relieve symptoms in most cases. Here changes are reported in blood metabolome that occurred three days after the ileo-colic region resection in the case of seven patients. Alterations are observed in levels of metabolites associated with multiple mitochondrial pathways, based on the Metabolite Set Enrichment Analysis, reflecting a high energy demand in the post-operative period. As most of these metabolites are also essential nutrients supplied from foods, we believe that our results might contribute to the discussion on perioperative nutrition’s role in enhanced recovery.

How much underfeeding can the critically ill adult patient tolerate?

Critical illness leads to significant metabolic alterations that should be considered when providing nutritional support. Findings from key randomized controlled trials (RCTs) indicate that underfeeding (<70% of energy expenditure [EE]) during the acute phase of critical illness (first 7 days of intensive care unit [ICU] admission) may not be harmful and could instead promote autophagy and prevent overfeeding in light of endogenous energy production. However, the optimal energy target during this period is unclear and full starvation is unlikely to be beneficial. There are limited data regarding the effects of prolonged underfeeding on clinical outcomes in critically ill patients, but recent studies show that oral food intake is suboptimal both in the ICU and following discharge to the acute care setting. It is hypothesized that provision of full nutrition (70-100% of EE) may be important in the recovery phase of critical illness (>7 days of ICU admission) for promoting recovery and rehabilitation; however, studies on nutritional intervention delivered from ICU admission through hospital discharge are needed. The aim of this review is to provide a narrative synthesis of the existing literature on metabolic alterations experienced during critical illness and the impact of underfeeding on clinical outcomes in the critically ill adult patient.

Cystine and Theanine as Stress-Reducing Amino Acids-Perioperative Use for Early Recovery after Surgical Stress

Perioperative nutritional therapy requires the consideration of metabolic changes, and it is desirable to reduce stress aiming at early metabolic normalization. Glutathione (GSH) is a tripeptide composed of glutamic acid, cysteine, and glycine. It is one of the strongest antioxidants in the body and important for adjusting immune function. Cystine and theanine (γ-glutamylethylamide) provide substrates of GSH, cysteine and glutamic acid, promoting the synthesis of GSH. It has been reported that the ingestion of cystine (700 mg) and theanine (280 mg) exhibits inhibitory effects against excess inflammation after strong exercise loads in athletes, based on which its application for invasive surgery has been tried. In patients undergoing gastrectomy, ingestion of cystine (700 mg) and theanine (280 mg) for 10 days from 5 days before surgery inhibited a postoperative increase in resting energy expenditure, promoted recovery from changes in interleukin-6, C-reactive protein, lymphocyte ratio, and granulocyte ratio and inhibited an increase in body temperature. In a mouse small intestine manipulation model, preoperative 5-day administration of cystine/theanine inhibited a postoperative decrease in GSH in the small intestine and promoted recovery from a decrease in behavior quantity. Based on the above, cystine/theanine reduces surgical stress, being useful for perioperative management as stress-reducing amino acids.

Metabolic Alterations in Sepsis

Sepsis is defined as “life-threatening organ dysfunction caused by a dysregulated host response to infection”. Contrary to the older definitions, the current one not only focuses on inflammation, but points to systemic disturbances in homeostasis, including metabolism. Sepsis leads to sepsis-induced dysfunction and mitochondrial damage, which is suggested as a major cause of cell metabolism disorders in these patients. The changes affect the metabolism of all macronutrients. The metabolism of all macronutrients is altered. A characteristic change in carbohydrate metabolism is the intensification of glycolysis, which in combination with the failure of entering pyruvate to the tricarboxylic acid cycle increases the formation of lactate. Sepsis also affects lipid metabolism—lipolysis in adipose tissue is upregulated, which leads to an increase in the level of fatty acids and triglycerides in the blood. At the same time, their use is disturbed, which may result in the accumulation of lipids and their toxic metabolites. Changes in the metabolism of ketone bodies and amino acids have also been described. Metabolic disorders in sepsis are an important area of research, both for their potential role as a target for future therapies (metabolic resuscitation) and for optimizing the current treatment, such as clinical nutrition.

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.

The GLIM criteria for adult malnutrition and its relation with adverse outcomes, a prospective observational study

BACKGROUND & AIMS

Malnutrition is considered a risk factor for many complications and mortality among hospitalized patients. Until 2016 there was a wide variety of clinical definitions for malnutrition, until the GLIM criteria proposed a consensual definition. The main goal of this study is to assess the performance of the GLIM criteria at acute care admission to detect those patients with adverse clinical outcomes such as mortality and the need to be transferred to critical care areas (CCA).

METHODS

This was a prospective observational study including every adult patient admitted to the regular ward of the Hospital San Ángel Inn Universidad. Every nutrition and demographic variable evaluated by the nutrition team at hospital admission was captured. The malnutrition definition according to the GLIM and separate criteria were tested for their performance to detect patients at high risk for adverse outcomes (mortality and the need to be transferred to CCA), using odd ratios (OR), their confidence interval of 95% (CI95%) and binary logistic regression accordingly.

RESULTS

A total of 1015 patients were included in the final analysis, with a prevalence of 18.9% of malnutrition (according to the GLIM definition) at hospital admission. Malnutrition was associated with mortality (OR of 59.69,CI95% 7.76-459.28) and unplanned transfer to CCA (OR of 9.453, CI95%4.35-20.56). However, despite being sensitive, the GLIM definition of malnutrition, displayed low positive predictive value, and was therefore associated with many false positives. There was a trend for higher risks for adverse outcomes with higher severity of malnutrition. Muscle wasting, chronic and acute inflammation were independent predictors for mortality and for unplanned transfer to CCA.

CONCLUSIONS

Malnutrition according to the GLIM criteria is strongly associated with mortality and transfer to CCA. Muscle wasting and inflammation (acute and chronic) were independently associated with these outcomes.