Can an adequate energy intake be able to reverse the negative nitrogen balance in mechanically ventilated critically ill patients?

Clinical practice guidelines for nutritional assessment and monitoring of adult ICU patients in China

The Chinese Society of Critical Care Medicine (CSCCM) has developed clinical practice guidelines for nutrition assessment and monitoring for patients in adult intensive care units (ICUs) in China. This guideline focuses on nutrition evaluation and metabolic monitoring to achieve optimal and personalized nutrition therapy for critically ill patients. This guideline was developed by experts in critical care medicine and evidence-based medicine methodology and was developed after a thorough review of the system and a summary of relevant trials or studies published from 2000 to July 2023. A total of 18 recommendations were formed and consensus was reached through discussions and reviews by expert groups in critical care medicine, parenteral and enteral nutrition, and surgery. The recommendations are based on currently available evidence and cover several key fields, including screening and assessment, evaluation and assessment of enteral feeding intolerance, metabolic and nutritional measurement and monitoring during nutrition therapy, and organ function evaluation related to nutrition supply. Each question was analyzed according to the Population, Intervention, Comparison, and Outcome (PICO) principle. In addition, interpretations were provided for four questions that did not reach a consensus but may have potential clinical and research value. The plan is to update this nutrition assessment and monitoring guideline using the international guideline update method within 3-5 years.

Measurement and estimation of energy in the critically ill

PURPOSE OF REVIEW

Recent changes in guidelines recommendation during early phase of critical illness and use of indirect calorimetry. The aim of this review is to discuss methods of determining energy requirements in the critically ill and highlight factors impacting resting energy expenditure.

RECENT FINDING

An appraisal of recent literature discussing indirect calorimetry guided-nutrition potential benefits or pitfalls. Recent attempts to devise strategy and pilot indirect calorimetry use in the critically ill patients requiring continuous renal replacement therapy or extracorporeal membrane oxygenation are also discussed. Additionally, we briefly touched on variability between guidelines recommended energy target and measured energy expenditure for adult critically ill patients with obesity.

SUMMARY

While energy requirement in the critically ill continues to be an area of controversy, recent guidelines recommendations shift toward providing less aggressive calories during acute phase of illness in the first week of ICU.Use of indirect calorimetry may provide more accurate energy target compared to the use of predictive equations. Despite the absence of literature to support long term mortality benefits, there are many potential benefits for the use of indirect calorimetry when available.

Isocaloric nutritional support reduces ventilator duration time in major trauma patients

AIMS

Major trauma patients need adequate nutrition for recovery. This study aimed to evaluate the adequacy of nutritional supply and the correlation between nutritional supply and clinical outcome.

METHODS

A single-centre retrospective observational study was undertaken, describing the amounts of energy and proteins provided to 320 critically ill trauma patients during the first 10 days after admission. The data were collected from the electronic medical records of patients admitted to the trauma intensive care unit during the study period and descriptive statistical analyses were performed with the SPSS software.

RESULTS

The mean proportion of supplied energy to recommended energy during the first 10 days after admission was 57.5%, and the mean percentage of supplied protein to recommended protein intake was 51.3%. The patients were divided into those who received ≥70% (isocaloric nutrition group) and those who received <70% (hypocaloric nutrition group) of their estimated requirements. Both the duration of ventilator use (12.7 ± 10.5 vs. 16.0 ± 15.8 days, respectively, p = 0.009) and duration of parenteral nutrition (1.1 ± 1.4 vs. 2.0 ± 2.0 days, respectively, p = 0.001) were shorter in the isocaloric nutrition group (n = 83) than in the hypocaloric nutrition group (n = 237).

CONCLUSION

Total energy and the amount of protein supplied were insufficient compared to the recommended amount. The duration of ventilator use was shorter in the isocaloric nutrition group than in the hypocaloric nutrition group. The association between shortened ventilator use and isocaloric nutrition requires further investigation as a potential intervention to reduce the risk of complications such as ventilator-related pneumonia.

Association of nitrogen balance trajectories with clinical outcomes in critically ill COVID-19 patients: A retrospective cohort study

BACKGROUND & AIMS

The intensity and duration of the catabolic phase in COVID-19 patients can differ between survivors and non-survivors. The purpose of the study was to assess the determinants of, and association between, nitrogen balance trajectories and outcome in critically ill COVID-19 patients.

METHODS

This retrospective monocentric observational study involved patients admitted to the intensive care unit (ICU) of the University Hospital of Clermont Ferrand, France, from January 2020 to May 2021 for COVID-19 pneumonia. Patients were excluded if referred from another ICU, if their ICU length of stay was <72 h, or if they were treated with renal replacement therapy during the first seven days after ICU admission. Data were collected prospectively at admission and during ICU stay. Death was recorded at the end of ICU stay. Comparisons of the time course of nitrogen balance according to outcome were analyzed using two-way ANOVA. At days 3, 5, 7, 10 and 14, uni- and multivariate logistic regression analyses were performed to assess the impact of a non-negative nitrogen-balance on ICU death. To investigate the relationships between nitrogen balance, inflammatory markers and protein intake, linear and non-nonlinear models were run at days 3, 5 and 7, and the amount of protein intake necessary to reach a neutral nitrogen balance was calculated. Subgroup analyses were carried out according to BMI, age, and sex.

RESULTS

99 patients were included. At day 3, a similar negative nitrogen balance was observed in survivors and non-survivors: -16.4 g/d [-26.5, -3.3] and -17.3 g/d [-22.2, -3.8] (p = 0.54). The trajectories of nitrogen balance over time thus differed between survivors and non-survivors (p = 0.01). In survivors, nitrogen balance increased over time, but decreased from day 2 to day 6 in non-survivors, and thereafter increased slowly up to day 14. At days 5 and 7, a non-negative nitrogen-balance was protective from death. Administering higher protein amounts was associated with higher nitrogen balance.

CONCLUSION

We report a prolonged catabolic state in COVID patients that seemed more pronounced in non-survivors than in survivors. Our study underlines the need for monitoring urinary nitrogen excretion to guide the amount of protein intake required by COVID-19 patients.

Feasibility of achieving different protein targets using a hypocaloric high-protein enteral formula in critically ill patients

Background and aims

Combining energy and protein targets during the acute phase of critical illness is challenging. Energy should be provided progressively to reach targets while avoiding overfeeding and ensuring sufficient protein provision. This prospective observational study evaluated the feasibility of achieving protein targets guided by 24-h urinary nitrogen excretion while avoiding overfeeding when administering a high protein-to-energy ratio enteral nutrition (EN) formula.

Methods

Critically ill adult mechanically ventilated patients with an APACHE II score > 15, SOFA > 4 and without gastrointestinal dysfunction received EN with hypocaloric content for 7 days. Protein need was determined by 24-h urinary nitrogen excretion, up to 1.2 g/kg (Group A, N = 10) or up to 1.5 g/kg (Group B, N = 22). Variables assessed included nitrogen intake, excretion, balance; resting energy expenditure (REE); phase angle (PhA); gastrointestinal tolerance of EN.

Results

Demographic characteristics of groups were similar. Protein target was achieved using urinary nitrogen excretion measurements. Nitrogen balance worsened in Group A but improved in Group B. Daily protein and calorie intake and balance were significantly increased in Group B compared to Group A. REE was correlated to PhA measurements. Gastric tolerance of EN was good.

Conclusions

Achieving the protein target using urinary nitrogen loss up to 1.5 g/kg/day was feasible in this hypercatabolic population. Reaching a higher protein and calorie target did not induce higher nitrogen excretion and was associated with improved nitrogen balance and a better energy intake without overfeeding. PhA appears to be related to REE and may reflect metabolism level, suggestive of a new phenotype for nutritional status.

Trial registration 0795-18-RMC.

Effect of Protein-Fortified Diet on Nitrogen Balance in Critically Ill Patients: Results from the OPINiB Trial

Nitrogen balance (NB) is considered a good marker of adequate protein intake and it has been suggested to be a good predictor of patients' health outcomes. However, in literature, there is a lack of large randomized trials examining NB-guided protein intake in patients in intensive care units (ICUs). A randomized controlled trial enrolling patients admitted to ICU was done to compare changes in NB. Participants were randomized to a standard or protein-fortified diet (protein intake of 1.8 g/kg/day according to the guidelines of the Society of Critical Care Medicine and the American Society for Parenteral and Enteral Nutrition). The primary endpoint was represented by the NB on Day 1, 3, and study exit. Forty patients were enrolled in the study (19 in the protein-fortified group). The longitudinal analysis showed that, on Day 3, patients randomized to the protein-fortified diet were more likely (p < 0.001) to present better NB (at 3 days, patients in the protein-fortified diet were estimated to have a nitrate value of 5.22 g more than patients in the standard diet, 95% CI 3.86-6.58). The protein-fortified diet was found to be significantly and directly associated with changes in NB in critically ill patients admitted to ICU.

Enteral Nutrition in the Mechanically Ventilated Patient

Mechanically ventilated patients are unable to take food orally and therefore are dependent on enteral nutrition for provision of both energy and protein requirements. Enteral nutrition is supportive therapy and may impact patient outcomes in the intensive care unit. Early enteral nutrition has been shown to decrease complications and hospital length of stay and improve the prognosis at discharge. Nutrition support is unique for patients on mechanical ventilation and, as recently published literature shows, should be tailored to the individuals' underlying pathology. This review will discuss the most current literature and recommendations for enteral nutrition in patients receiving mechanical ventilation.

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.

Association of protein intake with the outcomes of critically ill patients: a post hoc analysis of the PermiT trial

Background

The optimal amount of protein intake in critically ill patients is uncertain.

Objective

In this post hoc analysis of the PermiT (Permissive Underfeeding vs. Target Enteral Feeding in Adult Critically Ill Patients) trial, we tested the hypothesis that higher total protein intake was associated with lower 90-d mortality and improved protein biomarkers in critically ill patients.

Design

In this post hoc analysis of the PermiT trial, we included patients who received enteral feeding for ≥3 consecutive days. Using the median protein intake of the cohort as a cutoff, patients were categorized into 2 groups: a higher-protein group (>0.80 g · kg-1 · d-1) and a lower-protein group (≤0.80 g · kg-1 · d-1). We developed a propensity score for receiving higher protein. Primary outcome was 90-d mortality. We also compared serial values of prealbumin, transferrin, 24-h urinary nitrogen, and 24-h nitrogen balance on days 1, 7, and 14.

Results

Among the 729 patients included in this analysis, the average protein intake was 0.8 ± 0.3 g · kg-1 · d-1 [1.0 ± 0.2 g · kg-1 · d-1 in the higher-protein group (n = 365) and 0.6 ± 0.2 g · kg-1 · d-1 in the lower-protein group (n = 364); P < 0.0001]. There was no difference in 90-d mortality between the 2 groups [88/364 (24.2%) compared with 94/363 (25.9%), propensity score-adjusted OR: 0.80; 95% CI: 0.56, 1.16; P = 0.24]. Higher protein intake was associated with an increase in 24-h urea nitrogen excretion compared with lower protein intake, but without a significant change in prealbumin, transferrin, or 24-h nitrogen balance.

Conclusions

In the PermiT trial, a moderate difference in protein intake was not associated with lower mortality. Higher protein intake was associated with increased nitrogen excretion in the urine without a corresponding change in prealbumin, transferrin, or nitrogen balance. Protein intake needs to be tested in adequately powered randomized controlled trials targeting larger differences in protein intake in high-risk populations.

High-Protein Hypocaloric Nutrition for Non-Obese Critically Ill Patients

High-protein hypocaloric nutrition, tailored to each patient's muscle mass, protein-catabolic severity, and exogenous energy tolerance, is the most plausible nutrition therapy in protein-catabolic critical illness. Sufficient protein provision could mitigate the rapid muscle atrophy characteristic of this disease while providing urgently needed amino acids to the central protein compartment and sites of tissue injury. The protein dose may range from 1.5 to 2.5 g protein (1.8-3.0 g free amino acids)/kg dry body weight per day. Nutrition should be low in energy (≈70% of energy expenditure or ≈15 kcal/kg dry body weight per day) because efforts to match energy provision to energy expenditure are physiologically irrational, risk toxic energy overfeeding, and have repeatedly failed in large clinical trials to demonstrate clinical benefit. The American Society for Parenteral and Enteral Nutrition currently suggests high-protein hypocaloric nutrition for obese critically ill patients. Short-term high-protein hypocaloric nutrition is physiologically and clinically sensible for most protein-catabolic critically ill patients, whether obese or not.

Resting energy expenditure in critically ill patients: Evaluation methods and clinical applications

Patients on intensive care present systemic, metabolic, and hormonal alterations that may adversely affect their nutritional condition and lead to fast and important depletion of lean mass and malnutrition. Several factors and medical conditions can influence the energy expenditure (EE) of critically ill patients, such as age, gender, surgery, serious infections, medications, ventilation modality, and organ dysfunction. Clinical conditions that can present with EE change include acute kidney injury, a complex disorder commonly seen in critically ill patients with manifestations that can range from minimum elevations in serum creatinine to renal failure requiring dialysis. The nutritional needs of this population are therefore complex, and determining the resting energy expenditure is essential to adjust the nutritional supply and to plan a proper diet, ensuring that energy requirements are met and avoiding complications associated with overfeeding and underfeeding. Several evaluation methods of EE in this population have been described, but all of them have limitations. Such methods include direct calorimetry, doubly labeled water, indirect calorimetry (IC), various predictive equations, and, more recently, the rule of thumb (kcal/kg of body weight). Currently, IC is considered the gold standard.

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

BACKGROUND

Currently, the execution of indirect calorimetry, which is considered the gold standard for measuring energy expenditure, is not indicate during dialysis, and it may interfere on nutritional therapy of these patients. This study aimed to evaluate the resting energy expenditure (REE) in patients with severe acute kidney injury treated by different modalities of dialysis and to identify whether dialysis influences on REE.

METHODS

This was a prospective cohort study that evaluated patients admitted in intensive care units with diagnosis of acute kidney injury AKIN-3, mechanically ventilated, and submitted to conventional hemodialysis (CHD), extended hemodialysis (EHD) or high volume peritoneal dialysis (HVPD). Indirect calorimetry was performed at pre dialysis time and during the dialysis procedure. Parameters that could change REE were also evaluated.

RESULTS

One-hundred patients undergoing 290 dialysis sessions were evaluated, with mean age 60.3 ± 17 years, 69% were male and 74% have died. There was no significant difference between REE of predialysis time and during dialysis time (2156 ± 659 kcal vs. 2100 ± 634 kcal, respectively, p = 0.15). No difference was observed in the REE before and during dialysis of different modalities. There were no differences between parameters pre and during dialysis of each modality. There was only a difference in norepinephrine dose, which was higher in pre dialysis time in HVPD and EHD modalities, compared with CHD modality. Moreover, during dialysis time, EHD modality had significantly higher VAD compared to other dialysis modalities.

CONCLUSION

The three evaluated modalities did not change REE. Indirect calorimetry can be performed during dialysis procedures and there was no difference between ventilation parameters, sedatives use, body temperature and VAD in both moments.

Effect of early enteral nutrition on patients with digestive tract surgery: A meta-analysis of randomized controlled trials

Postoperative early enteral nutrition (EEN) is useful for the effective recovery of patients that have undergone surgery. However, the feasibility and efficacy of EEN in patients with digestive tract surgery remain inconclusive. In the present meta-analysis, the PubMed, EMBASE, Web of Science, The Cochrane Library, China National Knowledge Infrastructure and VIP databases were searched to identify controlled trials of patients with and without EEN following digestive tract surgery between October, 1966 and December, 2014. Methodological quality assessment was carried out for each of the included studies. For estimation of the analysis indexes, relative risk (RR) was used as the effect size of the the categorical variable, while the weighted mean difference (MD) was used as the effect size of the continuous variable. The meta-analysis was conducted using RevMan 5.2 software. Eleven randomized controlled trials involving 1,095 patients were included in the meta-analysis. The results revealed that, EEN in patients with digestive tract surgery was more effective in decreasing the incidence of infectious [RR=0.50, 95% confidence interval (CI): 0.38, 0.67; P<0.01] and non-infectious complications (RR=0.72, 95% CI: 0.43, 1.22; P<0.05) and shortening the length of first bowel action (MD=−4.10, 95% CI: −5.38, −2.82; P<0.05). It also had a significant influence on increasing the serum albumin (MD=2.87, 95% CI: 1.03, 4.71; P<0.05) and serum prealbumin (MD=0.04, 95% CI: 0.02, 0.05; P<0.05) levels. In conclusion, the results of the study have shown that EEN in patients with digestive tract surgery improved the nutritional status, reduced the risk of postoperative complications, shortened the length of hospital stay and promoted the functional recovery of the digestive system.

Protein requirement in critical illness

How much protein do critically ill patients require? For the many decades that nutritional support has been used there was a broad consensus that critically ill patients need much more protein than required for normal health. Now, however, some clinical investigators recommend limiting all macronutrient provision during the early phase of critical illness. How did these conflicting recommendations emerge? Which of them is correct? This review explains the longstanding recommendation for generous protein provision in critical illness, analyzes the clinical trials now being claimed to refute it, and concludes with suggestions for clinical investigation and practice.

Comparison of Energy Expenditure and Oxygen Consumption of Spontaneous Breathing Trial Conducted With and Without Automatic Tube Compensation

Background

Weaning from mechanical ventilation is defined as the process of release of ventilatory support and how the evaluation of this phase is conducted in the spontaneous breathing trial (SBT). One of the most used modes of SBT is the continuous positive airway pressure (CPAP), which applies a continuous positive pressure in both inspiration and expiration. However, together with the mechanical ventilation modes, the automatic tube compensation (ATC) can be used, which compensates the resistance imposed by the endotracheal tube. The objective of this study was to compare oxygen consumption (VO₂) and energy expenditure (EE) during SBT conducted with and without ATC.

Methods

The study was prospective, randomized and crossover. Forty mechanically ventilated patients were admitted to an intensive care unit of a university tertiary hospital. The participants were randomly allocated in group 1, in which SBT was initiated with CPAP and ATC, followed by CPAP without ATC or in group 2, in which SBT was initiated with CPAP without ATC, followed by CPAP with ATC. Indirect calorimetry helped to measure VO₂ and EE during SBT.

Results

The differences between VO₂ and EE obtained during SBT with ATC and without ATC were -1.6 mL/kg/min (95% CI: -4.36 - 1.07) and 5.4 kcal/day (95% CI: -21.67 - 10.79), respectively.

Conclusions

We concluded that VO₂ and EE obtained during SBT with and without ATC were not different.

What is the best nutritional support for critically ill patients?

Optimum nutritional support in critical illness remains controversial. A recent review of nutritional interventions in the ICU concluded that few of them improved clinical outcomes. In our view, it is a serious shortcoming of these trials that they focused on calories, falling far short of current recommendations for protein provision. Well designed clinical trials that ensure sufficient protein provision are urgently needed if we are to improve the quality of nutritional support in the ICU.

Why critically ill patients are protein deprived

Critical illness dramatically increases muscle proteolysis and more than doubles the dietary protein requirement. Yet surprisingly, most critically ill patients receive less than half the recommended amount of protein during their stay in a modern intensive care unit. What could explain the wide gap between the recommendations in clinical care guidelines and actual clinical practice? We suggest that an important aspect of the problem is the failure of guidelines to explain the pathophysiology of protein-energy malnutrition and the ways critical illness modifies protein metabolism. The difficulty created by the lack of a framework for reasoning about appropriate protein provision in critical illness is compounded by the many ambiguous and often contradictory ways the word malnutrition is used in the critical care literature. Failing to elucidate these matters, the recommendations for protein provision in the guidelines are incoherent, unconvincing, and easy to ignore.

Moderate glucose control results in less negative nitrogen balances in medical intensive care unit patients: a randomized, controlled study

Introduction

Hyperglycemia and protein loss are common in critically ill patients. Insulin can be used to lower blood glucose and inhibit proteolysis. The impact of moderate insulin therapy on protein metabolism in critically ill patients has not been evaluated. We compared urinary nitrogen excretion, nitrogen balance, serum albumin concentrations, prealbumin concentrations, and clinical outcomes between patients receiving moderate insulin therapy (MIT) and conventional insulin therapy (CIT) in a medical ICU.

Methods

Patients were randomly divided into groups and treated with MIT (glucose target 120 to 140 mg/dl) or CIT (glucose target 180 to 200 mg/dl). Calories and protein intake were recorded each day. On days 3, 7 and 14, the 24-hour urinary nitrogen excretion, nitrogen balance, and serum albumin and prealbumin concentrations were measured. Clinical outcomes data were collected.

Results

A total of 112 medical ICU patients were included, with 55 patients randomized to the MIT group and 57 patients randomized to the CIT group. Patients treated with MIT showed a trend towards increased nitrogen balance (P = 0.070), significantly lower urinary nitrogen excretion (P = 0.027), and higher serum albumin (P = 0.047) and prealbumin (P = 0.001) concentrations than patients treated with CIT. The differences between the two groups were most significant on day 3, when all factors showed significant differences (P < 0.05).

Conclusions

Moderate glucose control results in less negative nitrogen balances in medical ICU patients. Differences are more significant in the early stages compared with the late stages of critical illness.

Trial registration

ClinicalTrial.Gov NCT 01227148

Terapia nutricional enteral em politraumatizados sob ventilação mecânica e oferta energética

OBJETIVO: O objetivo deste estudo foi avaliar a adequação energética dos pacientes politraumatizados em suporte ventilatório internados na unidade de terapia intensiva de um hospital público de Porto Alegre (RS), por meio da comparação entre as calorias prescritas e as efetivamente administradas, assim como entre as calorias estimadas pela equação de Harris-Benedict e a prescrição energética de cada paciente. MÉTODOS: Estudo de coorte prospectivo de pacientes politraumatizados, simultaneamente sob ventilação mecânica e terapia nutricional enteral. Verificou-se o tempo de permanência sob ventilação mecânica e a oferta energética durante o período de terapia nutricional enteral. A associação entre as variáveis quantitativas foi avaliada através do teste de correlação de Spearman devido à assimetria das variáveis. RESULTADOS: Foram acompanhados 60 pacientes, na faixa etária de 18 a 78 anos, sendo 81,7% do sexo masculino. Os tempos medianos de internação hospitalar, permanência na unidade de terapia intensiva e ventilação mecânica foram de 29, 14 e 6 dias, respectivamente. A média do percentual de dieta administrada foi de 68,6% (DP=18,3%). Da amostra total, 16 (26,7%) pacientes receberam no mínimo 80% de suas necessidades diárias. Não houve associação estatisticamente significativa entre o valor energético total administrado e os tempos de ventilação mecânica (r s=0,130; p=0,321), de unidade de terapia intensiva (r s=-0,117; p=0,372) e de internação hospitalar (r s=-0,152; p=0,246). CONCLUSÃO: Os pacientes incluídos neste estudo não receberam com precisão o aporte energético prescrito, ficando expostos aos riscos da desnutrição e seus desfechos clínicos desfavoráveis.

The ratio of energy expenditure to nitrogen loss in diverse patient groups--a systematic review

BACKGROUND & AIMS

The ratio of energy expenditure to nitrogen loss respectively of energy to nitrogen provision (E/N) is considered a valuable tool in the creation of an enteral or parenteral formulation. Specific E/N ratios for parenteral nutrition (PN) have not yet been clearly defined. To determine the range of energy expenditure, nitrogen (protein) losses, and E/N ratios for various patient groups, we performed a systematic review of the literature.

METHODS

Medline 1950-2011 was searched for all studies on patients or healthy controls reporting energy expenditure and nitrogen loss at the same time.

RESULTS

We identified 53 studies with 91 cohorts which comprised 1107 subjects. Mean TEE ± standard deviation (SD) was 31.2 ± 7.2 kcal/kg BW/day in patients (n = 881) and 35.6 ± 4.3 kcal/kg BW/day in healthy controls (n = 266). Mean total protein loss (TPL) was 1.50 ± 0.57 g/kg BW/day in patients and 0.94 ± 0.24 g/kg BW/day in healthy controls. A non-linear significant correlation was found between TPL and the E/N ratio.

CONCLUSION

The E/N ratio is not a constant value but decreases continuously with increasing protein loss. These variations should be considered in the nutritional support of patients.