Natalia Daniela Llobera

Micronutrient deficiencies are commonly observed in patients with obesity and may persist or worsen following bariatric and metabolic surgery. Emerging evidence suggests that micronutrients play a fundamental role in tissue repair, collagen synthesis, immune function, and inflammatory regulation processes that are critical in postoperative healing. Therefore, deficiencies in these nutrients could be pivotal in understanding and preventing postoperative complications. However, the potential link between preoperative micronutrient status and the development of postoperative complications, such as anastomotic or gastric fistula, remains underexplored. This narrative review aims to investigate the correlation between specific micronutrient deficiencies (e.g., vitamin C, zinc, selenium, vitamin A, and iron) and the incidence of fistula after bariatric surgery. We will discuss the underlying biological mechanisms, clinical evidence, and possible preventive strategies, including preoperative screening and targeted supplementation. Our aim is to highlight the often-overlooked micronutrient deficiency as a risk factor in patients undergoing bariatric surgery, both in the pre- and postoperative periods, and to propose a more comprehensive approach to patient assessment and management.

Background: Accurately estimating resting energy expenditure (REE) in critically ill obese patients remains a significant clinical challenge, as predictive equations are consistently inadequate. Metabolic heterogeneity across obesity classes and the role of substrate utilization are insufficiently characterized. Objective: To evaluate the impact of different weight-normalization methods on the interpretation of REE and to identify independent metabolic determinants of weight-adjusted energy expenditure in critically ill patients with obesity. Methods: Bicentric cross-sectional study of 148 critically ill adults with obesity undergoing indirect calorimetry. REE normalized by actual body weight (REE/kg), ideal body weight (REE/IBW), and adjusted body weight (REE/AdjBW) was calculated. Multivariable models with robust standard errors (HC3), stratified analyses by obesity class (I–III) with a Chow test, and internal validation were performed using 10-fold cross-validation and bootstrap resampling (1000 iterations). Results: Absolute REE did not differ significantly between BMI categories (p = 0.679), while REE/kg progressively decreased from normal weight (27.8 kcal/kg/day) to class III obesity (16.9 kcal/kg/day; p < 0.001). The respiratory quotient (RQ) emerged as the most robust independent correlate of adjusted REE (β = −13 to −15 kcal·kg⁻¹·day⁻¹; p < 0.001), whereas clinical severity scores (SOFA, APACHE II) and comorbidity (Charlson) did not show significant associations. Stratified analyses revealed significant structural heterogeneity between obesity classes (F = 4.545, p = 0.0001), with no significant predictors identified in class III obesity, likely reflecting limited statistical power in this subgroup. Conclusions: Normalizing REE using different weight indices fundamentally alters its metabolic interpretation. RQ surpasses traditional clinical scores as a correlate of adjusted REE, consistent with a phenotype of metabolic inflexibility. The heterogeneity between obesity classes underscores the need for individualized indirect calorimetry rather than reliance on predictive equations.

Background: Precise measurement of resting energy expenditure (REE) is essential in the intensive care unit (ICU), where metabolic requirements evolve throughout the course of critical illness. Predictive equations frequently fail to capture this variability, and limited data describe phase-dependent changes in REE using indirect calorimetry (IC). This study aimed to evaluate phase-related variation in REE and metabolic phenotypes in mechanically ventilated adults and to identify clinical and physiological correlates of both absolute REE and REE normalized by ideal body weight (REE/IBW). Methods: We conducted an observational, retrospective cross-sectional study in two ICUs at different hospitals. A total of 149 mechanically ventilated adults with a valid IC measurement were included and classified by illness phase: acute (0–3 days), intermediate (4–14 days), or chronic (>14 days). Differences in metabolic and gas-exchange variables were assessed using ANOVA or Kruskal–Wallis tests. Two multivariable linear regression models were fitted, one using absolute REE and a second using REE/IBW, incorporating metabolic phenotype categories to account for body-size heterogeneity. Results: Metabolic profiles differed across illness phases. Median REE increased from the acute (1664 kcal/day) to the intermediate (1869 kcal/day) and chronic (2074 kcal/day; p = 0.024) phases. Hypometabolic profiles were more frequent in the acute phase (64%), whereas hypermetabolic profiles were more prevalent in later phases (48%). RQ values were higher in the chronic phase compared with the acute phase (median 0.99 vs. 0.80; p < 0.001). In multivariable analyses, illness severity scores showed weak or inconsistent associations with REE after adjustment for gas-exchange variables. VCO₂ was independently associated with absolute REE (adjusted R² = 0.83). In the REE/IBW model, VCO₂, RQ, BMI, and metabolic phenotype were associated with normalized energy expenditure, with higher adjusted R² (0.87) and lower prediction error metrics. Conclusions: Resting energy expenditure and metabolic phenotypes vary across phases of critical illness. Gas-exchange variables, particularly VCO₂, were more closely associated with measured energy expenditure than severity scores. Normalization of REE by ideal body weight reduced variability and improved model performance, highlighting the analytical value of indirect calorimetry for characterizing phase-dependent metabolic patterns in critically ill adults.

Background: Sarcopenia, characterized by a reduction in skeletal muscle mass and function, is a prevalent complication in the Intensive Care Unit (ICU) and is related to increased mortality. This study aims to determine whether muscle and fat mass measurements at the T12 and L1 vertebrae using chest tomography can predict mortality among critically ill COVID-19 patients requiring invasive mechanical ventilation (MV). Methods: Fifty-one critically ill COVID-19 patients on MV underwent chest tomography within 72 h of ICU admission. Muscle mass was measured using the Core Slicer program. Results: After adjustment for potential confounding factors related to background and clinical parameters, a 1-unit increase in muscle mass, subcutaneous, and intra-abdominal fat mass at the L1 level was associated with approximately 1–2% lower odds of negative outcomes and in-hospital mortality. No significant association was found between muscle mass at the T12 level and patient outcomes. Furthermore, no significant results were observed when considering a 1-standard deviation increase as the exposure variable. Conclusion: Measuring muscle mass using chest tomography at the T12 level does not effectively predict outcomes for ICU patients. However, muscle and fat mass at the L1 level may be associated with a lower risk of negative outcomes. Additional studies should explore other potential markers or methods to improve prognostic accuracy in this critically ill population.

Obesity is associated with multiple comorbidities that contribute to increased mortality among affected individuals. There are multiple treatments for this condition, including nutritional interventions, pharmacological therapies, and surgical procedures. Within these, bariatric surgery is an effective treatment option that requires a multidisciplinary approach, both before and after surgery. Nutritional management prior to surgery aims to achieve metabolic control and reduce comorbidities associated with the procedure. Postoperative nutritional management focuses on preventing complications, ensuring adequate nourishment, and providing necessary supplementation for optimal recovery and long-term success. This narrative review examines all these critical aspects of nutritional management in bariatric surgery, including preoperative nutrition, postoperative nutrition and physical activity recommendation, different nutritional aspects according to the type of bariatric surgery, and future directions for investigation.

Purpose of Review: This review aims to critically examine how VLCKD affects plasma lipoprotein, lipid and cholesterol metabolism. Cardiovascular disease is a worldwide health problem affecting millions of people and leading to high rates of mortality and morbidity. There is a well-established association between cardiovascular disease and circulating cholesterol. Various dietary recommendations are currently available for the management of dyslipidemia. Recent Findings: The very low-calorie ketogenic diet (VLCKD) is becoming increasingly popular as a treatment option for several pathological conditions, including dyslipidemia. In addition to being low in calories, the VLCKD's main feature is its unique calorie distribution, emphasizing a reduction in carbohydrate consumption in favor of fat as the primary calorie source. Lowering calorie intake through a VLCKD can reduce the endogenous production of cholesterol. However, if the foods consumed are from animal sources, dietary cholesterol intake may increase due to the higher fat content of animal products. When combined, these dietary practices may have opposing effects on plasma cholesterol levels. Summary: Studies investigating the impact of VLCKD on plasma cholesterol and low-density lipoprotein cholesterol levels report contradictory findings. While some studies found an increase in low-density lipoprotein cholesterol levels, others showed a decrease in total cholesterol and low-density lipoprotein cholesterol, along with an increase in high-density lipoprotein cholesterol.

Sarcopenia in critically ill patients is a highly prevalent comorbidity. It is associated with a higher mortality rate, length of mechanical ventilation, and probability of being sent to a nursing home after the Intensive Care Unit (ICU). Despite the number of calories and proteins delivered, there is a complex network of signals of hormones and cytokines that affect muscle metabolism and its protein synthesis and breakdown in critically ill and chronic patients. To date, it is known that a higher number of proteins decreases mortality, but the exact amount needs to be clarified. This complex network of signals affects protein synthesis and breakdown. Some hormones regulate metabolism, such as insulin, insulin growth factor glucocorticoids, and growth hormone, whose secretion is affected by feeding states and inflammation. In addition, cytokines are involved, such as TNF-alpha and HIF-1. These hormones and cytokines have common pathways that activate muscle breakdown effectors, such as the ubiquitin–proteasome system, calpain, and caspase-3. These effectors are responsible for protein breakdown in muscles. Many trials have been conducted with hormones with different results but not with nutritional outcomes. This review examines the effect of hormones and cytokines on muscles. Knowing all the signals and pathways that affect protein synthesis and breakdown can be considered for future therapeutics.

Introducción: La diarrea es una complicación frecuente en los pacientes críticos. Su origen es multifactorial. El objetivo de este trabajo es analizar la relación entre 5 fórmulas listas para usar y el desarrollo de diarrea en pacientes críticos. Métodos: Estudio retrospectivo donde se evaluó el volumen de las deposiciones de 315 pacientes y la presencia de diarrea definida con un punto de corte con un volumen de 250 ml/día. Resultados: 35.34% de los pacientes presentaron diarrea con dicho punto de corte. El volumen medio de deposiciones fue de 269.20 ml (IC 95%: 255.05-283.06). Se observó que todas las fórmulas analizadas tenían una correlación leve con la prueba de spearman entre el volumen aportado y el volumen de las deposiciones, siendo: Nutricia Nutrison ® (R: 0.159; P: 0.053), Nutricia Multifibra ® (R: 0.296; Conclusión: Por lo tanto, la fórmula y el volumen aportado son factores que podrían influenciar en que los pacientes tengan diarrea. Entendiendo estas posibles influencias de una manera mas profunda, permitirá elegir las formulas enterales con mas seguridad para un paciente con diarrea.