Predicting Resting Energy Expenditure in Critically Ill Patients by Measuring Lean Body Mass by US

Study Overview
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Brief Summary
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The study aims to correlate Lean Body Mass (LBM) Evaluated by Musculoskeletal Ultrasound with Resting Energy Expenditure (REE) measured by Indirect Calorimetry and to generate a predictive equation of REE based on LBM, in addition to identifying other factors that may affect REE such as age, gender, and severity scores.

Detailed Description
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Caloric needs in critically-ill patients fluctuate significantly over the course of the disease which might expose patients to either malnutrition or overfeeding.Malnutrition is associated with deterioration of lean body mass (LBM), poor wound healing, increased risk of nosocomial infection, and weakened respiratory muscles. On the other hand overfeeding in medically compromised patients can promote lipogenesis, hyperglycemia, and exacerbation of respiratory failure. Many factors may affect the resting energy expenditure (REE) through manipulation of oxygen consumption (VO2). One of the strongest determinants of REE is the LBM. A measurement of muscle mass and changes in muscle mass could thus provide an index of LBM in critically ill patients. At present, computerized tomography, magnetic resonance imaging and dual-energy X-ray absorptiometry (DXA) are widely used as reference methods for evaluating LBM in vivo. However, these methods are impractical in critically ill patients. More practically, ultrasound scanning is a simple, portable, safe, and a low-patient burden technique. Several studies found that the use of ultrasound can be a good estimate to LBM. Indirect calorimetry remains the accepted standard for determining the REE in the critically ill. Indirect calorimetry measures oxygen consumption(VO2) and carbon dioxide excretion (VCO2 ) (both in mL/min), which are used to calculate the respiratory quotient and the resting energy expenditure. Although, the measured LBM has been shown as an important determinant of REE, there was no previous study tested the relationship between estimated LBM by ultrasound-based muscle thickness measurement and REE.

Official Title
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The Novel Use of Point of Care Ultrasound to Predict Resting Energy Expenditure in Critically Ill Patients by Measuring Lean Body Mass Using Musculo-skeletal Ultrasound

Conditions
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Resting Energy Expenditure

Intervention / Treatment
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* Diagnostic Test: US Muscle layer thickness (MLT) estimation
* Diagnostic Test: REE estimation by indirect calorimetry


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: - Patient requiring ventilatory support > 24 hours Exclusion Criteria: Patient who will require FIO2 more than 0.6. Air leak from the chest tube. Patient with body temperature > 39oC. Patients with known endocrine dysfunction. Patients on parenteral nutrition

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Study group<br>critically-ill patients who will be admitted to the surgical ICU for ventilatory support and will be expected to continue for more than one day US Muscle layer thickness (MLT) estimation will be used to estimate LBM and REE estimation by indirect calorimetry will be performed | Diagnostic Test: US Muscle layer thickness (MLT) estimation<br>* Three measurements will be made at each of three sites; mid-upper arm, forearm and thigh anteriorly and the mean value will be calculated. Measurement sites will be marked with indelible ink to ensure day-to-day consistency. Thigh: MLT of the quadriceps femoris muscle (M. Vastus intermedius and M. rectus femoris) will be assessed bilaterally Mid-upper arm: Muscle layer thickness will be measured over the biceps,midway between the tip of the acromion and the tip of the olecranon Forearm: A point midway between the antecubital skin crease and the ulnar styloid was marked and muscle thickness down to the interosseus membrane<br>Diagnostic Test: REE estimation by indirect calorimetry<br>* REE will be calculated using indirect calorimetry via metabolic module on General Electric ventilator (Engstrom Carestation and Carescape R860, GE Health care, USA) All indirect calorimetric measurements will be done using standardized technique. Gas calibration will be performed before each measurement, and the measurements will last for at least 30 minutes. Measurements will be taken with the patient lying supine and ventilator settings left unchanged for at least 60 minutes ahead of indirect calorimetry. The REE will be calculated during the first 24 hours of admission to ICU.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| correlation between LBM derived from ultrasound MLT and REE by indirect calorimetry | The correlation of the LBM derived from ultrasound MLT to the REE measured within 24 hours of ICU admission with indirect calorimetry | 24 hours of ICU admission | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Predictive equation for REE based on US measurement of MLT | generation of predictive equation of REE based on ultrasound measurement of MLT | 24 hours of ICU admission | 
| Estimation of the effect of severity scores on the REE | Estimation of the effect of severity scores on the REE | 24 hours of ICU admission | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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lean body mass, resting energy expenditure, oxygen consumption, Indirect calorimetry, carbon dioxide excretion, respiratory quotient