Bedside calculation of energy expenditure does not guarantee adequate caloric prescription in long-term mechanically ventilated critically ill patients: a quality control study

System for continuous metabolic monitoring of mechanically ventilated patients

In clinical settings, due largely to the cost, size and calibration complexity of existing indirect calorimetry systems, there is seldom instrumentation available to provide reliable, continuous tracking of a mechanically ventilated patient's metabolic output in support of proper nutrition. The atypical metabolisms associated with critically ill patients are difficult to predict and both underfeeding and overfeeding lead to negative impacts on both mortality and the recovery and healing processes. With these issues in mind, a novel ventilator-agnostic indirect calorimetry sensor design, prototype development, and validation were undertaken with the goal of enabling 24/7 metabolic monitoring of mechanically ventilated patients by means of a passive, rate-proportional side-stream sampling scheme and miniature mixing chamber. The miniature mixing chamber enables the use of small, low-cost gas concentration and flow sensing components to ensure the affordability of commercial design-for-manufacture implementations of the prototype sensor. In addition to continuous measurement of patient metabolism, the prototype sensor also enables autonomous monitoring and detection of calibration drift in the gas measurement sensors without disrupting the patient ventilation.

Bioenergetic Balance of Continuous Venovenous Hemofiltration, a Retrospective Analysis

(1) Background: Nutrition therapy guided by indirect calorimetry (IC) is the gold standard and is associated with lower morbidity and mortality in critically ill patients. When performing IC during continuous venovenous hemofiltration (CVVH), the measured VCO₂ should be corrected for the exchanged CO₂ to calculate the ‘true’ Resting Energy Expenditure (REE). After the determination of the true REE, the caloric prescription should be adapted to the removal and addition of non-intentional calories due to citrate, glucose, and lactate in dialysis fluids to avoid over- and underfeeding. We aimed to evaluate this bioenergetic balance during CVVH and how nutrition therapy should be adapted. (2) Methods: This post hoc analysis evaluated citrate, glucose, and lactate exchange. Bioenergetic balances were calculated based on these values during three different CVVH settings: low dose with citrate, high dose with citrate, and low dose without citrate. The caloric load of these non-intentional calories during a CVVH-run was compared to the true REE. (3) Results: We included 19 CVVH-runs. The bioenergetic balance during the low dose with citrate was 498 ± 110 kcal/day (range 339 to 681 kcal/day) or 26 ± 9% (range 14 to 42%) of the true REE. During the high dose with citrate, it was 262 ± 222 kcal/day (range 56 to 262 kcal/day) or 17 ± 11% (range 7 to 32%) of the true REE. During the low dose without citrate, the bioenergetic balance was −189 ± 77 kcal/day (range −298 to −92 kcal/day) or −13 ± 8% (range −28 to −5%) of the true REE. (4) Conclusions: Different CVVH settings resulted in different bioenergetic balances ranging from −28% up to +42% of the true REE depending on the CVVH fluids chosen. When formulating a caloric prescription during CVVH, an individual approach considering the impact of these non-intentional calories is warranted.

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.

Risks in Management of Enteral Nutrition in Intensive Care Units: A Literature Review and Narrative Synthesis

Critically ill patients in the intensive care unit (ICU) have a high risk of developing malnutrition, and this is associated with poorer clinical outcomes. In clinical practice, nutrition, including enteral nutrition (EN), is often not prioritized. Resulting from this, risks and safety issues for patients and healthcare professionals can emerge. The aim of this literature review, inspired by the Rapid Review Guidebook by Dobbins, 2017, was to identify risks and safety issues for patient safety in the management of EN in critically ill patients in the ICU. Three databases were used to identify studies between 2009 and 2020. We assessed 3495 studies for eligibility and included 62 in our narrative synthesis. Several risks and problems were identified: No use of clinical assessment or screening nutrition assessment, inadequate tube management, missing energy target, missing a nutritionist, bad hygiene and handling, wrong time management and speed, nutritional interruptions, wrong body position, gastrointestinal complication and infections, missing or not using guidelines, understaffing, and lack of education. Raising awareness of these risks is a central aspect in patient safety in ICU. Clinical experts can use a checklist with 12 identified top risks and the recommendations drawn up to carry out their own risk analysis in clinical practice.

Sarcopenia and Psychosocial Variables in Patients in Intensive Care Units: The Role of Nutrition and Rehabilitation in Prevention and Treatment

Critical illness leads to decline in muscle mass that promotes decline in physical function and psychological function and may lead to cognitive decline or dementia. Nurses are key to driving the multidisciplinary interventions that prevent protein loss and promote positive outcomes for critically ill patients.

A prospective study of energy and protein intakes in critically ill patients

BACKGROUND & AIMS

Providing adequate and appropriate food and nutrients satisfying the patients' safe nutritional need is one of the most important care practices for critically ill patients (CIPs) in ICU settings, and is strongly related to the patients' safety.

METHODS

In this prospective cross-sectional study data were collected from a 52-bed medical intensive care unit on 777 consecutive patients in six different ICUs. The patients' weights and heights were measured based on ulna length, knee height, MAC, Calf C, and Wrist C. Also, patient weight change history was asked for. All currently in-use dietary supplements and formulas in the ICU settings were checked for their ingredients. The patients' nutritional need was calculated individually for the disease state based on dietary ESPEN guidelines.

RESULTS

Mean ICU and hospital stay duration was 14.45 ± 11.81 and 15.38 ± 11.88 days respectively. Mean energy and protein requirements in the target population were 1804.61 ± 201.76 Kcal/day and 77.94 ± 12.72 gr/day, respectively. Mean actual energy and protein intakes were 1052.75 ± 561.25 Kcal/day and 35.38 ± 23.19 gr/day, respectively. Satisfaction percents for mean energy and protein requirement in the total population were 58.34% (1052.75/1804.4) and 45.41% (35.38/77.9), respectively. In 21.4% and 4.4% of the studied group, energy and protein intakes were about 75-100% of the patients' actual need, respectively. Another data analysis for patients with over 10 days of inpatient time showed that only 14.2% of patients had energy intakes, and only 3.2% of them had protein intakes in the range of 75-100% of their requirements.

CONCLUSION

Results showed that energy and protein intakes in CIPs are low, disproportionate to their requirements. Therefore, actual dietary intake records, individual dietary requirement calculation, and individual dietary planning in relation with the patients' disease and stress should be considered. Such an accurate nutritional care process can promote patient safety.

Electronic Noses for Well-Being: Breath Analysis and Energy Expenditure

The wealth of information concealed in a single human breath has been of interest for many years, promising not only disease detection, but also the monitoring of our general well-being. Recent developments in the fields of nano-sensor arrays and MEMS have enabled once bulky artificial olfactory sensor systems, or so-called "electronic noses", to become smaller, lower power and portable devices. At the same time, wearable health monitoring devices are now available, although reliable breath sensing equipment is somewhat missing from the market of physical, rather than chemical sensor gadgets. In this article, we report on the unprecedented rise in healthcare problems caused by an increasingly overweight population. We first review recently-developed electronic noses for the detection of diseases by the analysis of basic volatile organic compounds (VOCs). Then, we discuss the primary cause of obesity from over eating and the high calorific content of food. We present the need to measure our individual energy expenditure from our exhaled breath. Finally, we consider the future for handheld or wearable devices to measure energy expenditure; and the potential of these devices to revolutionize healthcare, both at home and in hospitals.

Indirect calorimetry in nutritional therapy. A position paper by the ICALIC study group

BACKGROUND & AIMS

This review aims to clarify the use of indirect calorimetry (IC) in nutritional therapy for critically ill and other patient populations. It features a comprehensive overview of the technical concepts, the practical application and current developments of IC.

METHODS

Pubmed-referenced publications were analyzed to generate an overview about the basic knowledge of IC, to describe advantages and disadvantages of the current technology, to clarify technical issues and provide pragmatic solutions for clinical practice and metabolic research. The International Multicentric Study Group for Indirect Calorimetry (ICALIC) has generated this position paper.

RESULTS

IC can be performed in in- and out-patients, including those in the intensive care unit, to measure energy expenditure (EE). Optimal nutritional therapy, defined as energy prescription based on measured EE by IC has been associated with better clinical outcome. Equations based on simple anthropometric measurements to predict EE are inaccurate when applied to individual patients. An ongoing international academic initiative to develop a new indirect calorimeter aims at providing innovative and affordable technical solutions for many of the current limitations of IC.

CONCLUSION

Indirect calorimetry is a tool of paramount importance, necessary to optimize the nutrition therapy of patients with various pathologies and conditions. Recent technical developments allow broader use of IC for in- and out-patients.

Supplemental Parenteral Nutrition Is the Key to Prevent Energy Deficits in Critically Ill Patients

This review emphasizes the role of a timely supplemental parenteral nutrition (PN) for critically ill patients. It contradicts the recommendations of current guidelines to avoid the use of PN, as it is associated with risk. Critical illness results in severe metabolic stress. During the early phase, inflammatory cytokines and mediators induce catabolism to meet the increased body energy demands by endogenous sources. This response is not suppressed by exogenous energy administration, and the early use of PN to reach the energy target leads to overfeeding. On the other hand, early and progressive enteral nutrition (EN) is less likely to cause overfeeding because of variable gastrointestinal tolerance, a factor frequently associated with significant energy deficit. Recent studies demonstrate that adequate feeding is beneficial during and after the intensive care unit (ICU) stay. Supplemental PN allows for timely adequate feeding, if sufficient precautions are taken to avoid overfeeding. Indirect calorimetry can precisely define the adequate energy prescription. Our pragmatic approach is to start early EN to progressively test the gut tolerance and add supplemental PN on day 3 or 4 after ICU admission, only if EN does not meet the measured energy target. We believe that supplemental PN plays a pivotal role in the achievement of adequate feeding in critically ill patients with intolerance to EN and does not cause harm if overfeeding is avoided by careful prescription, ideally based on energy expenditure measured by indirect calorimetry.

Prevalence of Underprescription or Overprescription of Energy Needs in Critically Ill Mechanically Ventilated Adults as Determined by Indirect Calorimetry: A Systematic Literature Review

BACKGROUND

Underfeeding and overfeeding has been associated with adverse patient outcomes. Resting energy expenditure can be measured using indirect calorimetry. In its absence, predictive equations are used. A systematic literature review was conducted to determine the prevalence of underprescription and overprescription of energy needs in adult mechanically ventilated critically ill patients by comparing predictive equations to indirect calorimetry measurements.

METHODS

Ovid MEDLINE, CINAHL Plus, Scopus, and EMBASE databases were searched in May 2013 to identify studies that used both predictive equations and indirect calorimetry to determine energy expenditure. Reference lists of included publications were also searched. The number of predictive equations that underestimated or overestimated energy expenditure by ±10% when compared to indirect calorimetry measurements were noted at both an individual and group level.

RESULTS

In total, 2349 publications were retrieved, with 18 studies included. Of the 160 variations of 13 predictive equations reviewed at a group level, 38% underestimated and 12% overestimated energy expenditure by more than 10%. The remaining 50% of equations estimated energy expenditure to within ±10 of indirect calorimetry measurements. On an individual patient level, predictive equations underestimated and overestimated energy expenditure in 13-90% and 0-88% of patients, respectively. Differences of up to 43% below and 66% above indirect calorimetry values were observed.

CONCLUSIONS

Large discrepancies exist between predictive equation estimates and indirect calorimetry measurements in individuals and groups. Further research is needed to determine the influence of indirect calorimetry and predictive equation limitations in contributing to these observed differences.

Metabolic implications of peritoneal dialysis in patients with acute kidney injury

BACKGROUND

Peritoneal dialysis (PD) is a treatment for selected acute kidney injury patients (AKI), but little is known about its metabolic implications. The aim of the present study was to evaluate the metabolic implications of glucose absorption, sodium removal, protein loss into the dialysate, and catabolism in AKI patients undergoing high-volume PD and to identify risk factors associated with those metabolic effects.

METHODS

A prospective cohort study over 18 consecutive months evaluated 208 sessions of high-volume PD performed in 31 AKI patients. One session of high-volume PD lasted 24 hours. Repeated-measures analysis was performed, and correlations were calculated using the Spearman test for continuous variables and generalized linear models for categorical variables.

RESULTS

Glucose absorption remained at approximately 35.3% ± 10.5% per session. Protein loss measured 4.2 ± 6.1 g daily, with higher values initially, which declined significantly after 2 sessions. Nitrogen balance (NB) was initially negative, but stabilized at approximately zero after 3 sessions. Glucose uptake was positively correlated with the Acute Tubular Necrosis Individual Severity Score [ATNISS (r = 0.21, p = 0.0036)], C-reactive protein (r = 0.26, p = 0.0167), protein loss (r = 0.36, p < 0.0001), and sodium removal (r = 0.24, p = 0.002). Protein loss was positively correlated with sodium removal (r = 0.22, p = 0.0085) and gastrointestinal disease (p = 0.0004). Sodium removal was positively correlated with serum sodium (r = 0.21, p = 0.0064), ATNISS (r = 0.15, p = 0.0411), urea nitrogen appearance [UNA (r = 0.24, p = 0.0019)], and fluid overload as an indication for dialysis (p < 0.0001). Urea nitrogen appearance was positively correlated with the indication for dialysis (electrolyte disturbances: p = 0.0287) and negatively correlated with nephrotoxic AKI (p < 0.0001). Nitrogen balance was negatively correlated with UNA (r = -0.389, p < 0.0001) and ischemic AKI (p = 0.0047).

CONCLUSIONS

High-volume PD did not increase hypercatabolism in AKI patients, and protein loss and glucose uptake remained constant during treatment. Those parameters were influenced by the clinical condition of the patients, including the cause of AKI, inflammation, and comorbidities-factors that should be known before the prescription of dialysis and nutrition, thus avoiding metabolic complications such as hyperglycemia, hypernatremia, and worsening catabolism.

Nutrition in the chronically ill critical care patient

Chronic critical illness is a problem in the critical care environment. The ultimate goal in managing care for the chronically critically ill is liberation from mechanical ventilation, leading to improved survival and enhanced quality of life. Clinical practice guidelines are presented as a framework in providing care for this distinct patient population. Research studies supplement the recommendations to ensure best care guides critical care decisions using the best evidence in the context of patient values and clinical expertise.

Introducing a new generation indirect calorimeter for estimating energy requirements in adult intensive care unit patients: feasibility, practical considerations, and comparison with a mathematical equation

PURPOSE

Indirect calorimetry (IC) is increasingly advocated for individualizing nutritional therapy in critically ill adult patients, but questions remain regarding its practical implementation.

MATERIALS AND METHODS

During 12 weeks, we prospectively assessed utility and practical aspects of IC use. Adult medico-surgical intensive care unit (ICU) patients were daily screened for malnutrition. Indirect calorimetry was planned in subjects considered unable to meet energy requirements on day 3 after admission. Measured energy expenditure (MEE) was compared with calculated (resting/total) energy expenditure.

RESULTS

A total of 940 evaluations were performed in 266 patients (age, 63±16 years; 59% males; Acute Physiology and Chronic Health Evaluation II score, 14±8). A total of 230 patients (86.5%) were at risk for malnutrition, and in 118 of them, IC was indicated. Practical considerations precluded measurements in 72 cases (61%). Forty-six calorimetric evaluations revealed an MEE of 1649±544 kcal per 24 hours that poorly correlated with calculated resting energy expenditure (r2=0.19) and calculated total energy expenditure (r2=0.20). Indirect calorimetry measurements were not time-consuming.

CONCLUSIONS

Indirect calorimetry was indicated in half but effectively performed in only 20% of a representative intensive care unit population at risk for malnutrition. Correlation between MEE and CEE was poor.

CLINICAL RELEVANCY STATEMENT

Indirect calorimetry is increasingly advocated for individualizing nutritional therapy in critically ill adult patients. Practical feasibility is tested in this study. Large differences between measured and calculated energy expenditure are observed. Together with patients' characteristics, feasibility results can guide clinicians or institutes in using IC in their daily clinical practice.

Nutrition support in the critically ill

PURPOSE OF REVIEW

To highlight the recent developments in nutritional support for critically ill patients.

RECENT FINDINGS

Increasing data support the benefits of early initiation of enteral nutrition, with improvements in small intestinal absorption and clinical outcomes. In contrast to the previous belief, recent data suggest caloric administration of greater than 65-70% of daily requirement is associated with poorer clinical outcomes, especially when supplemental parenteral nutrition is used to increase the amount of caloric delivery. The role of supplementary micronutrients and anti-inflammatory lipids has been further evaluated but remains inconclusive, and is not currently recommended.

SUMMARY

Together, current findings indicate that intragastric enteral nutrition should be initiated within 24 h of admission to ICU and supplementary parenteral nutrition should be avoided. Future research should aim to clarify the optimal energy delivery for best clinical outcomes, and the role of small intestinal function and its flora in nutritional care and clinical outcomes.