Influence of different dialysis modalities in the measurement of resting energy expenditure in patients with acute kidney injury in ICU

ESPEN practical guideline on clinical nutrition in hospitalized patients with acute or chronic kidney disease

BACKGROUND AND AIMS

Hospitalized patients often have acute kidney disease (AKD) or chronic kidney disease (CKD), with important metabolic and nutritional consequences. Moreover, in case kidney replacement therapy (KRT) is started, the possible impact on nutritional requirements cannot be neglected. On this regard, the present guideline aims to provide evidence-based recommendations for clinical nutrition in hospitalized patients with KD.

METHODS

The standard operating procedure for ESPEN guidelines was used. Clinical questions were defined in both the PICO format, and organized in subtopics when needed, and in non-PICO questions for the more general topics. The literature search was from January 1st, 1999 until January 1st, 2020. Each question led to one or more recommendation/statement and related commentaries. Existing evidence was graded, as well as recommendations and statements were developed and agreed upon in a multistage consensus process.

RESULTS

The present guideline provides 32 evidence-based recommendations and 8 statements, defining how to assess nutritional status, how to define patients at risk, how to choose the route of feeding, and how to integrate nutrition with KRT. In the final online voting, a strong consensus was reached in 84% at least of recommendations and 100% of statements.

CONCLUSION

The presence of KD in hospitalized patients identifies a highly heterogeneous group of subjects with widely varying nutrient needs and intakes. Considering the high nutritional risk related with this clinical condition, an individualized approach consisting of nutritional status evaluation and monitoring, frequent evaluation of nutritional requirements, and careful integration with KRT should be planned to avoid both underfeeding and overfeeding. Practical recommendations and statements were developed, aiming at defining suggestions for everyday clinical practice in the individualization of nutritional support in this patient setting. Literature areas with scarce or without evidence were also identified, thus requiring further basic or clinical research.

Two-hour indirect calorimetry measurement as a predictor of 24-hour energy expenditure in critically ill surgical patients: A longitudinal study

BACKGROUND

Measuring energy expenditure (EE) by indirect calorimetry (IC) has become the gold standard tool for critically ill patients to define energy targets and tailor nutrition. Debate remains as to the optimal duration of measurements or the optimal time of day in which to perform IC.

METHODS

In this retrospective longitudinal study, we analyzed results of daily continuous IC in 270 mechanically ventilated, critically ill patients admitted to the surgical intensive care unit in a tertiary medical center and compared measurements performed at different hours of the day.

RESULTS

A total of 51,448 IC hours was recorded, with an average 24-h EE of 1523 ± 443 kcal/day. Night shift (00:00-8:00) was found to have significantly lower EE measurements (mean, 1499 ± 439 kcal/day) than afternoon (16:00-00:00; mean, 1526 ± 435 kcal/day) and morning (8:00-16:00; mean, 1539 ± 462 kcal/day) measurements (P < 0.001 for all). The bi-hourly time frame that most closely resembled the daily mean was 18:00-19:59, with a mean of 1521 ± 433 kcal/day. Daily EE measurements of the continuous IC at days 3-7 of admission showed a trend toward a daily increase in 24-h EE, but the difference was not statistically significant (P = 0.081).

CONCLUSIONS

Periodic measurements of EE can differ slightly when performed at various hours of the day, but the error range is small and may not necessarily have a clinical impact. When continuous IC is not available, a 2-h EE measurement between 18:00 and 19:59 can serve as a reasonable alternative.

Metabolic and nutritional aspects in continuous renal replacement therapy

Nutrition is one of the foundations for supporting and treating critically ill patients. Nutritional support provides calories, protein, electrolytes, vitamins, and trace elements via the enteral or parenteral route. Acute kidney injury (AKI) is a common and devastating problem in critically ill patients and has significant metabolic and nutritional consequences. Moreover, renal replacement therapy (RRT), whatever the modality used, also profoundly impacts metabolism. RRT and of the extracorporeal circuit impede 'effect the evaluation of a patient's energy requirements by clinicians. Substrates added and removed within the extracorporeal treatment are not always taken into consideration, making treatment even more challenging. Furthermore, evidence on nutritional support during continuous renal replacement therapy (CRRT) is scarce, and there are no clinical guidelines for nutrition adaptations during CRRT in critically ill patients. Most recommendations are based on expert opinions. This review discusses the complex interaction between nutritional support and CRRT and presents some milestones for nutritional support in critically ill patients on CRRT.

ESPEN guideline on clinical nutrition in hospitalized patients with acute or chronic kidney disease

Acute kidney disease (AKD) - which includes acute kidney injury (AKI) - and chronic kidney disease (CKD) are highly prevalent among hospitalized patients, including those in nephrology and medicine wards, surgical wards, and intensive care units (ICU), and they have important metabolic and nutritional consequences. Moreover, in case kidney replacement therapy (KRT) is started, whatever is the modality used, the possible impact on nutritional profiles, substrate balance, and nutritional treatment processes cannot be neglected. The present guideline is aimed at providing evidence-based recommendations for clinical nutrition in hospitalized patients with AKD and CKD. Due to the significant heterogeneity of this patient population as well as the paucity of high-quality evidence data, the present guideline is to be intended as a basic framework of both evidence and - in most cases - expert opinions, aggregated in a structured consensus process, in order to update the two previous ESPEN Guidelines on Enteral (2006) and Parenteral (2009) Nutrition in Adult Renal Failure. Nutritional care for patients with stable CKD (i.e., controlled protein content diets/low protein diets with or without amino acid/ketoanalogue integration in outpatients up to CKD stages four and five), nutrition in kidney transplantation, and pediatric kidney disease will not be addressed in the present guideline.

Energy expenditure and caloric targets during continuous renal replacement therapy under regional citrate anticoagulation. A viewpoint

BACKGROUND

Indirect calorimetry (IC) is the gold standard for measuring energy expenditure in critically ill patients However, continuous renal replacement therapy (CRRT) is a formal contraindication for IC use.

AIMS

To discuss specific issues that hamper or preclude an IC-based assessment of energy expenditure and correct caloric prescription in CRRT-treated patients.

METHODS

Narrative review of current literature.

RESULTS

Several relevant pitfalls for validation of IC during CRRT were identified. First, IC measures CO₂ production (VCO₂) and O₂ consumption to calculate resting energy expenditure (REE) with the Weir equation. VCO₂ measurements are influenced by CRRT because CO₂ is exchanged during the blood purification process. CO₂ exchange also depends on type of pre- and/or postdilution fluid(s). CO₂ dissolves in different forms with dynamic but unpredictable impact on VCO₂. Second, the effect of immunologic activation and heat loss on REE caused by extracorporeal circulation during CRRT is poorly documented. Third, caloric prescription should be adapted to CRRT-induced in- and efflux of different nutrients. Finally, citrate, which is the preferred anticoagulant for CRRT, is a caloric source that may influence IC measurements and REE.

CONCLUSION

Better understanding of CRRT-related processes is needed to assess REE and provide individualized nutritional therapy in this condition.

Indirect calorimetry as point of care testing

Determining energy requirement is a fundamental of nutrition support. Indirect calorimetry (IC) has been long recognized as the gold standard for assessing basal or resting energy expenditure (REE). The measurement of REE is recommended particularly in the situation where adjustment of energy provision is critical. The result of the IC measurement can lead to changes in treatment and since the change can be carried out immediately at the bedside, this may be considered as point-of-care testing. Beyond the nutritional aspects, studies of energy expenditure with IC have brought out more understanding of the metabolic changes during the natural course of diseases or conditions as well as those related to the intervention. The literature in various disease states has shown that changes in energy expenditure may reveal hidden metabolic information that might be translated into clinical information and have the potential of being both prognostic indicators and/or treatment targets.

Modification of Nutrition Therapy During Continuous Renal Replacement Therapy in Critically Ill Pediatric Patients: A Narrative Review and Recommendations

Introduction

Nutrition is an important part of treatment in critically ill children. Clinical guidelines for nutrition adaptations during continuous renal replacement therapy (CRRT) are lacking. We collected and evaluated current knowledge on this topic and provide recommendations.

Methods

Questions were produced to guide the literature search in the PubMed database.

Results

Evidence is scarce and extrapolation from adult data was often required. CRRT has a direct and substantial impact on metabolism. Indirect calorimetry is the preferred method to assess resting energy expenditure (REE). Moderate underestimation of REE is common but not clinically relevant. Formula‐based calculation of REE is inaccurate and not validated in critically ill children on CRRT. The nutrition impact of nonintentional calories delivered as citrate, lactate, and glucose during CRRT must be considered. Quantifying nitrogen balance is not feasible during CRRT. Protein delivery should be increased by 25% to compensate for losses in the effluent. Fats are not removed by CRRT and should not be adapted during CRRT. Electrolyte disturbances are frequently present and should be treated accordingly. Vitamins B1, B6, B9, and C are lost in the effluent and should be adapted to the effluent dose. Trace elements, with the exception of selenium, are not cleared in relevant quantities. Manganese accumulation is of concern because of potential neurotoxicity.

Conclusion

Current recommendations regarding nutrition support in pediatric CRRT must be extrapolated from adult studies. Recommendations are provided, based on the weak level of evidence. Additional research on this topic is warranted.