Exploring Whether Ventilated ICU Patients Were in Optimal Nutritional Status Regarding Energy and Protein Requirements

Talko B. Dijkhuis; Hildegard S. Franke; Wolter Paans; Willem Dieperink; Rix Groenboom

Exploring Whether Ventilated ICU Patients Were in Optimal Nutritional Status Regarding Energy and Protein Requirements

by Talko B. Dijkhuis^1*, Hildegard S. Franke², Wolter Paans^2,3, Willem Dieperink^2,3, Rix Groenboom⁴

¹Research Group Personalised Health, Hanze University of Applied Sciences, Groningen, The Netherlands

²Department of Critical Care, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands

³Research Group Nursing Diagnostics, Hanze University of Applied Sciences, Groningen, The Netherlands

⁴Research Group Digital Transformation, Hanze University of Applied Sciences, The Netherlands

^*Corresponding author: Talko B. Dijkhuis, t.b.dijkhuis@pl.hanze.nl, Research Group Personalised Health, Hanze University of Applied Sciences, Groningen, The Netherlands

Received Date: 18 January 2025

Accepted Date: 25 January, 2025

Published Date: 29 January, 2025

Citation: Dijkhuis TB, Franke HS, Paans W, Dieperink W, Groenboom R (2025) Exploring Whether Ventilated ICU Patients Were in Optimal Nutritional Status Regarding Energy and Protein Requirements. Int J Nurs Health Care Res 8:1613. https://doi.org/10.29011/2688-9501.101613

Abstract

Purpose: Under- and overfeeding in Intensive Care Units (ICUs) are linked to prolonged hospitalisation, increased morbidity, and elevated mortality. This study investigates whether ICU patients were optimally nourished according to the European Society for Clinical Nutrition and Metabolism (ESPEN) guidelines. Methods: A cohort of 158 COVID-19 patients requiring intensive care for severe respiratory failure, necessitating a nuanced approach to nutritional support, was analysed. Nutritional status was determined regarding kilocalories and protein using the Energy Expenditure derived from ventilator-measured VCO2 and the adjusted Weir equation, and data on intake through enteral feeding was used. The study included ventilated patients hospitalised for over five days without Extra Corporeal Life Support (ECLS) and receiving enteral nutrition. Associations between mortality and (i) calorie intake and (ii) protein intake were examined using Chi-Square statistics. Results: Conforming to the ESPEN guidelines, 45% of patients were malnourished, and 21% were over-nourished in kilocalories. Additionally, 61% were malnourished, and 16% were over-nourished in protein. The distribution between the groups of survivors and deceased relative to each of the groups well nourished, malnourished, and over-nourished was not statistically different (p = 0.21). The protein distribution among survivors and deceased groups was not statistically different (p = 0.67) regarding correct, insufficient, or excessive protein intake. Conclusions: Based on ESPEN guidelines, most ICU patients were inadequately nourished in kilocalories and protein. However, no significant survival differences were observed across groups with varying nutritional adequacy. Further research is recommended to explore the implications of nutritional interventions in critically ill patients.

Keywords: Nutrition; Energy expenditure; Protein intake; Patient outcomes

Introduction

Nutrition of patients in ICU settings has been an ongoing matter of controversy for a long time. Under- and overfeeding are common and are strongly associated with prolonged hospital admission, increased morbidity, and mortality [1-4]. It is recommended by the European Society for Clinical Nutrition and Metabolism (ESPEN) guidelines to give hypocaloric nutrition in the early phase and isocaloric nutrition after 3 days of acute illness [5]. It is known that there is still progression to be made in feeding critically ill patients. Also, a combination of long hospital stays and hypermetabolism makes it challenging to estimate the right nutritional therapy. COVID-19 patients are an interesting group to study in nutrition. Patients with COVID-19 often have severe respiratory failure, among other things, and are often admitted to a long hospital-stay Intensive Care Unit (ICU). Additionally, it is known that nutritional requirements are not met in COVID-19 patients because of feeding intolerance due to COVID-19 and also often caused by the necessary prone position due to respiratory problems [6-8].

The caloric content of nutrition is determined based on the calculation of the patient’s Energy Expenditure (EE), which is estimated by measurement of macronutrient or oxygen consumption and heat production or carbon dioxide production [9]. Due to the changing conditions of critically ill patients, caused, among others, by their pathophysiological response, the EE varies frequently over time, and so do the nutritional needs of the patients [10]. Determining the EE using indirect calorimetry is the golden standard for measuring caloric needs in critically ill patients at the bedside.

Indirect calorimetry uses the Weir equation to estimate EE using measured oxygen consumption (VO2) and carbon dioxide production (VCO2) [11]. Additionally, it calculates the patient’s Respiratory Quotient (RQ). The RQ is a ratio of VCO2 and VO2 resulting from the oxidation of energy substrates. It can indicate the adequacy of measurements: careful interpretation is required when the RQ falls outside the range of 0.67 and 1.3 [12].

If indirect calorimetry is unavailable, the VCO2 derived from the mechanical ventilator is recommended to determine the EE [12]. This method measures only exhaled gas volume and CO2 concentrations and does not measure O2 consumption. Therefore, a fixed RQ value of 0.86 is often assumed [14], and the calculation is then based on an adjusted version of the Weir equation [11].

The research question was: Were adult ICU patients at UMCG in optimal nutritional status regarding protein and energy requirements?

Materials and Methods

The data consisted of measurements on 158 patients from the ICU wards. Some of the IC-EE measurements were inaccurate or absent, resulting in a final population of 124 patients, 92 males. A total of 1502 measurements were obtained, as multiple measurements were done on the same patients over multiple days.

The patient’s baseline characteristics, energy expenditure data, and related clinical data for this study were extracted from the Patient Data Management System (PDMS) of ventilated patients in the ICU of the University Medical Center Groningen, the Netherlands, from January 6, 2020, to November 6, 2021.

The nutritional status in kilocalories and protein was determined using the Energy Expenditure (EE); only the VCO2 of the ventilator was available; therefore, the adjusted version of the Weir equation [11] was used to determine the EE using data of the intake through enteral nutrition. Ventilated patients who had been hospitalised for over five days without Extra Corporeal Life Support (ECLS) and had been fed by enteral nutrition were included in the study. Kruskal-Wallis and Dunn’s post-hoc tests were used to test whether there was a difference in enteral nutrition given in the ICU.

For calculations of the nutritional needs, actual body weight (ABW) was used for non-obese (BMI < 30), and both actual and adjusted body weight (AdjBW) [5] were utilised for obese subjects (BMI >=30). To determine how optimally the patients were fed, the number of kilocalories and proteins consumed by the patients was calculated. Subsequently, the calorie intake in kilocalories was compared with the EE. The protein intake was compared to the protein requirement. The extent to which a patient is optimally fed is expressed in percentages.

The association between mortality and the factors (i) calorie and (ii) protein intake was examined using Chi-Square statistics. The data were statistically analysed using Python 3.8.8; the packages statsmodels 0.13.5, and lifelines 0.27.4.

Results

Table 1 presents the patient characteristics per dataset of this study. Figures 1 and Figure 2 visualise calorie and protein intake.

(a) Baseline characteristics (n =124)
Age (mean, range)	63.4 (37-82)
Male sex (n, %)	92 (74.2)
Weight (mean, range)	95,4 (58-159)
BMI (mean, range)	30.8 (18.7-48.5)
BMI > 30 (%)	52
Ventilator days (21-day study period only) (mean, range)	8.9 (3-21)
Mortality (21-day study period only) (n, %)	42, 39.6
Mortality (hospital mortality) (n, %)	48, 38.7
(b) Energy expenditure/data	D0-2	D3–7	D8–14	D15-21	p-value
Measured EE in absolute kCal/ day (all patients) (median, IQR)	1289 (719-1708)	2035 (1769-2328)	2240 (1955-2604)	2309 (2054-2604)	<0.05
Measured EE kCal/kg actual BW (non-obese, BMI < 30) (median, IQR)	22.35 (19.58-26.16)	25.55 (22.44-28.82)	25.31 (22.42-30.71)	25.80 (22.64-29.59)	<0.05
Measured EE kCal/kg actual BW (obese, BMI >= 30) (median, IQR)	18.08 (15.87-21.6)	21.26 (18.63-24.34)	22.85 (19.52-25.87)	22.72 (20.72-24.24)	<0.05
Measured EE kCal/kg adjusted BW [5] (obese, BMI >= 30) (median, IQR)	22.45 (19.73-26.28)	25.92 (23.19-29.59)	28.02 (24.43-31.09)	27.79 (25.89-32.20)	<0.05
Measured EE kCal/kg actual BW (all patients) (median, IQR)	20.54 (17.11-24.09)	23.28 (20.07-26.66)	24.09 (21.26-27.91)	24.00 (21.85-28.76)	<0.05
Protein (median, IQR)	62.64 (35.39-83.52)	91.97 (67.71-96.46)	95.09 (71.69-105.65)	94.93 (75.61-108.86)	<0.05
Calories (median, IQR)	1289.34 (719.661708.98)	1914.88 (1384.71979.15)	1929.98 (1460.232144.11)	1935.36 (1662.752205.82)	<0.05
(c) Clinical data	D0-2	D3–7	D8–14	D15-21	p-value
Use of prone positioning (%) (mean, sd)		20.3 (4.0)	20.5 (4.0)	14.8 (3.51)	0.79
(a) patient characteristics; (b) nutrition data for the first three weeks post-intubation; (c) clinical care; BMI: Body Mass Index, BW: Body Weight in kilogram, EE kCal/kg: Energy Expenditure kilocalories per kilogram; obese BMI>=30, non-obese BMI<30; sd: standard deviation. p values are for the Kruskal-Wallis test.

Table 1: Baseline characteristics.

Figure 1: Protein per day

Figure 2: Calories per day.

Figure 3: Nutrition in ICU

Figure 4: ESPEN-related distribution of the calories.

According to Recommendation 8, to avoid overfeeding, early full Enteral Nutrition (EN) and Parenteral Nutrition (PN) shall not be used in critically ill patients; they shall be prescribed within three to seven days (5). Using Kruskal-Wallis and Dunn’s post-hoc tests, we found that the mean of the calories and protein given to a patient during the first two days differed from the remaining days in the ICU (p<0.01).

a patient takes in compared to the requirement of that day is expressed in percentages, Figure 4. This shows that 45% are malnourished and 21% are over-nourished in kilocalories, conforming to recommendation 18 (5). This means that 66%% of ESPEN margins were not fed in kilocalories. The percentage in which the ventilated patients received protein is shown in Figure 5. This shows that 61% are malnourished and 16% are overfed with protein (conforming to recommendation 22 [5]), which means that 77% have not received the prescribed protein and are therefore not optimally fed.

Figure 4: ESPEN-related distribution of the calories.

Statistics on Mortality and Calorie Intake

We applied the Chi-Square test to determine whether calorie intake influenced survival. The distribution between the groups of survivors and deceased relative to each of the three Calorie groups is not statistically different (p = 0.21) Table 2.

	Survivors %	Deceased %
Calorie < 80%	41.35	47.44
Calorie >=80% and <=100%	30.83	35.14
Calorie> 100%	27.82	17.41
Total	100	100

Table 2: Mortality versus calorie intake.

	Survivors %	Deceased %
Protein < 90%	60.15	61.02
Protein >=90% and <=100%	25.81	21.41
Protein > 100%	14.04	17.57
Total	100	100

Table 3: Mortality versus protein intake.

Figure 5: ESPEN-related distribution of the protein.

Statistics on mortality and protein intake

We applied the Chi-Square test to determine whether protein intake influenced mortality. The distribution between the groups of survivors and deceased relative to each of the three protein groups is not statistically different (p = 0.67) Table 3.

Discussion

The results show that nutrient requirements in ventilated COVID-19 patients are lowest in the first week, then increase in the second and third week.

This pattern can be explained from the literature by the metabolic phases of a critically ill patient. The first part of this is the acute phase. This means that only the processes in the body that are essential at that moment require energy. A lower energy requirement characterises this phase. This is followed by the postacute phase, during which an increase in the need can be seen. This phase is called the recovery phase. The ongoing picture of hypermetabolism is reflected in the results [14]. However, little reliable literature has described the metabolism of COVID-19.

The results also show that the nutritional intake does not equal the nutritional requirement in our patient group. However, the protein intake shows an upward trend in weeks 1, 2 and 3. Gastric retention in ml/24h was subtracted from the total nutritional intake consumed regardless of the concentration of gastric retention.

An optimal nutritional status of both kilocalories and protein is important for a good recovery during and after a stay in the ICU [15]. Nutritional status can be related to how well patients are fed, expressed in percentages. The ventilated patients in the ICU are 33% well-fed with kcal/24h and 21% well-fed with protein. This large difference is mainly due to the ESPEN guidelines that consider a patient to be well-fed if he/she is fed between 80 and 100%. Only if the result falls outside this range is the patient considered malnourished. This works differently for protein; the patient is not considered well-fed until the patient is fed between 90% and 100% [5]. However, the ESPEN guideline is the gold standard for ICU power supply. The corresponding formulas are, therefore, also applied in this study.

A limitation of this study is a negative intake on some days due to gastric retention in ventilated patients with a gastric tube. The measured gastric retention was so high that it contained more kcal/24h than the intake. Gastric retention in these patients cannot consist of tube feeding alone. However, the concentration of the tube feeding cannot be traced back to gastric retention. This can affect the results to an extent that cannot be traced.

On the day of discharge, the study nurses did not register intake for most patients. These data for the kcal/24h intake and protein/24h are missing. Therefore, the study does not include the discharge day of ventilated patients. Excluding the discharge day does not influence the reliability of the results, but it does affect the number of hospital days for these patients.

Conclusion

This study shows that the majority of COVID-19 patients are not very well-nourished in kilocalories and are poor in protein, according to the ESPEN guideline.

However, there is no significant difference in survival whether patients were betterfed calories or protein. Based on this conclusion, further research is recommended.

Ethical Guidelines

The study was approved by the institutional review board of the University Medical Center Groningen (UMCG, METc M23.321896) and conducted in accordance with the principles of the Declaration of Helsinki (version 64, October 2013) and the European Union General Data Protection Regulation (EU GDPR), the Dutch code of conduct for science practice, and hospital regulations and acts.

Exploring Whether Ventilated ICU Patients Were in Optimal Nutritional Status Regarding Energy and Protein Requirements