Electrolyte disorders during the initiation of nutrition therapy in the ICU

PURPOSE OF REVIEW: To summarize recent evidence on prevalence, risk factors, significance, treatment, and prevention of electrolyte disorders in critically ill with a specific focus on disorders during the initiation of nutrition. RECENT FINDINGS: Electrolyte disturbances appear to occur often during critical illness, and most of them seem to be associated with impaired outcome. However, a recent systematic review indicated insufficient evidence to answer clinically relevant questions regarding hypophosphatemia. Similar questions (which thresholds of serum levels are clinically relevant; how serum levels should be corrected and how do different correction regimens/approaches influence outcome) are not clearly answered also for other electrolytes. The most crucial feature of electrolyte disturbances related to feeding is refeeding syndrome. Recent evidence supports that additionally to the correction of electrolyte levels, a temporary restriction of calories (reducing the magnitude of this metabolic feature, including electrolyte shifts) may help to improve outcome. SUMMARY: Diverse electrolyte disorders often occur in critically ill patients. Hypophosphatemia, hypokalemia, and hypomagnesemia that are encountered after initiation of feeding identify refeeding syndrome. Along with correction of electrolytes, reduction of caloric intake may improve the outcome of the refeeding syndrome.</p

Bioelectric impedance analysis for body composition measurement and other potential clinical applications in critical illness

PURPOSE OF REVIEW: Insight into body composition is of great value in the ICU. Bioelectric impedance analysis (BIA) is the most applicable bedside technique. However, bioimpedance has not been validated in the critically ill, and the interpretation of the measurements poses challenges. This review discusses the potential clinical applications of BIA and explores caveats and solutions to its use in the intensive care setting. RECENT FINDINGS: A correlation is repeatedly found between raw impedance parameters, fluid ratios, overhydration, and adverse outcome of critical illness. However, cut-off and reference values remain elusive. Experience with BIA-guided fluid management in the ICU is limited. BIA-derived muscle mass appears a promising biomarker for sarcopenia, correlating well with CT-analysis. Body cell mass and fat-free mass provide potential use in estimation of metabolic rate, protein requirements and pharmacokinetics. Several methods of reducing bias in BIA parameters in critical illness require validation. SUMMARY: There are currently too many uncertainties and discrepancies regarding interpretation of bioimpedance in critical illness, to justify therapeutic consequences. However, there are several promising areas of research, concerning some of the most urgent clinical problems in intensive care, emphasizing the need to evaluate further the use and interpretation of bioimpedance in the intensive care setting

Mitochondrial dysfunction in critical illness during acute metabolic stress and convalescence : consequences for nutrition therapy

PURPOSE OF REVIEW: Mitochondrial dysfunction is associated with increased morbidity and mortality during and after critical illness. The concept of adaptive mitochondrial metabolic-bio-energetic downregulation rather than bio-energetic failure during the acute phase of critical illness has gained traction. As mitochondria are not able to utilize substrate during adaptive hibernation and aggressive feeding induces further harm, this condition has consequences for nutrition therapy. RECENT FINDINGS: Meeting resting energy expenditure in early critical illness is associated with enhanced oxidative stress and attenuation of autophagy, as is hyperglycemia. The negative effect of early high protein administration remains unclear, whereas fat appears bio-energetically inert. Although antioxidant micronutrients are essential to mitochondrial function, high-dosage studies of single vitamins (C and D) failed to show benefit. Convalescence probably requires increased micronutrient and macronutrient administration to aid anabolism and restore mitochondrial function, although robust data on requirements and actual intake are lacking. SUMMARY: Optimal nutrition therapy in the early phase of critical illness should avoid overfeeding and preserve (adaptive) mitochondrial function. Micronutrient supplementation probably requires a strategic cocktail instead of a high dosage of a single nutrient. Focus on identification of distinct metabolic phases to adapt nutrition during and after critical illness is essential.</p

Poor physical recovery after critical illness: Incidence, features, risk factors, pathophysiology, and evidence-based therapies

Purpose of reviewTo summarize the incidence, features, pathogenesis, risk factors, and evidence-based therapies of prolonged intensive care unit (ICU) acquired weakness (ICU-AW). We aim to provide an updated overview on aspects of poor physical recovery following critical illness.Recent findingsNew physical problems after ICU survival, such as muscle weakness, weakened condition, and reduced exercise capacity, are the most frequently encountered limitations of patients with postintensive care syndrome. Disabilities may persist for months to years and frequently do not fully recover. Hormonal and mitochondrial disturbances, impaired muscle regeneration due to injured satellite cells and epigenetic differences may be involved in sustained ICU-AW. Although demographics and ICU treatment factors appear essential determinants for physical recovery, pre-ICU health status is also crucial. Currently, no effective treatments are available. Early mobilization in the ICU may improve physical outcomes at ICU-discharge, but there is no evidence for benefit on long-term physical recovery.SummaryImpaired physical recovery is observed frequently among ICU survivors. The pre-ICU health status, demographic, and ICU treatment factors appear to be important determinants for physical convalescence during the post-ICU phase. The pathophysiological mechanisms involved are poorly understood, thereby resulting in exiguous evidence-based treatment strategies to date

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.</p

Current insights in ICU nutrition : tailored nutrition

Purpose of reviewTo summarize recent research on critical care nutrition focusing on the optimal composition, timing, and monitoring of enteral feeding strategies for (post)-ICU patients. We provide new insights on energy and protein recommendations, feeding intolerance, and describe nutritional practices for coronavirus disease 2019 ICU patients.Recent findingsThe use of indirect calorimetry to establish individual energy requirements for ICU patients is considered the gold standard. The limited research on optimal feeding targets in the early phase of critical illness suggests avoiding overfeeding. Protein provision based upon the absolute lean body mass is rational. Therefore, body composition measurements should be considered. Body impedance analysis and muscle ultrasound seem reliable, affordable, and accessible methods to assess body composition at the bedside. There is inadequate evidence to change our practice of continuous enteral feeding into intermittent feeding. Finally, severe acute respiratory syndrome coronavirus 2 patients are prone to underfeeding due to hypermetabolism and should be closely monitored.SummaryNutritional therapy should be adapted to the patient's characteristics, diagnosis, and state of metabolism during ICU stay and convalescence. A personalized nutrition plan may prevent harmful over- or underfeeding and attenuate muscle loss. Despite novel insights, more research is warranted into tailored nutrition strategies during critical illness and convalescence