Oral Citrulline Supplementation in COPD Patients With Malnutrition

Fat Free Mass Index (in kg.m-2) measured by bioelectrical impedance analysis

Grip strength will be measured using a dynamometer with the patient in a seated position, elbow bent at 90°, shoulders relaxed and forearm in a neutral position. The dynamometer should be held in the dominant hand. The measurement should be taken twice. The highest value will be used.

The maximum voluntary force of the quadriceps of the left lower limb will be measured on a weight bench using a strain gauge to determine force during isometric contraction (at 90° knee flexion). The position of the patient will be standardized: arms crossed over the chest, no back support during the measurement and no support of the hips and contralateral leg to avoid any compensatory movement. Three reproducible measurements (+/-10%) will be taken at 1 min intervals, with the highest value selected.

The 6-min walking test (6MWT) measures the distance that a patient can walk on an indoor 30-m flat corridor for a 6-min period. Due to a familiarisation effect, two tests will be performed, with at least 15 min of intervening rest, with the greatest distance in the two tests being recorded. The 6-min walking distance (6MWD) will be expressed in metres. Other variables will be measured: minimum pulse oxygen saturation (SpO2), peak heart rate and dyspnoea and fatigue ratings at the end of test.

Actigraphy is an objective measurement of physical activity using a device that measures acceleration and movement (accelerometer). The number of steps walked daily is used to assess free daily-living activity in clinical trials. It is measured using an accelerometer worn 24 hours a day during five days. In this study, we will use the triaxial accelerometer Actigraph GT3X®. Instructions for the medical device use are provided on the website https://www.theactigraph.com.

The patient will be instructed to wear the accelerometer around the wrist 24 hours a day during 5 consecutive days including week-end and will be asked to maintain usual routine activity. The number of steps walked daily will be the average of the daily number of steps over the five days.

Flow-mediated dilatation (FMD) of the brachial artery will be calculated according to standard recommendations. Briefly, a pneumatic cuff will be placed on the right forearm distal to the elbow. The probe will be placed approximately midway between the antecubital and axillary regions and secured with a stereoscopic arm. Basal diameter and velocity will be recorded continuously for a minimum period of one minute. The cuff will then be inflated to 250 mm Hg for 5 minutes before sudden deflation to induce post-ischemic hyperemia. Fifteen minutes later, baseline measurements will be repeated to measure endothelial-independent, nitrate-induced dilatation. Nitrate-induced dilatation (NMD) will be calculated 4 min after sublingual administration of 0.3 mg trinitrin (NATISPRAY, Teofarma S.R.L. Italy). FMD and NMD will be expressed as a percentage change in basal diameter and in mm, after post-ischemic hyperemia and after administration of nitrate derivatives, respectively.

The BODE index is a multidimensional index of disease severity in COPD that incorporates four independent predictors: the body mass index (BMI), the degree of airflow obstruction assessed by the Forced Expiratory Volume in one second (FEV1), the modified Medical Research Council (mMRC) dyspnea scale, and the exercise capacity assessed by the 6-min walking distance (6MWD) test.

the COPD Assessment Test (CAT) is a patient-completed questionnaire assessing globally the impact of COPD (cough, sputum, dysnea, chest tighteness) on health status. CAT scores range from 0 to 40. Higher scores indicate a more severe impact of COPD on the patient's life. The difference between stable and exacerbating patients is five units. No target score represents the best possible outcome.

The Visual Simplified Respiratory Questionnaire (VSRQ) is designed to assess health-related quality of life (HRQoL) in patients with chronic obstructive pulmonary disease (COPD). It contains eight items: dyspnea, anxiety, depressed mood, sleep, energy, daily activities, social activities and sexual life.

the Modified Medical Research Council (mMRC) Dyspnea Scale Stratifies severity of dyspnea in respiratory diseases, particularly COPD. The higher the degree, the more severe the shortness of breath.

The DIsability RElated to COPD Tool (DIRECT) is a 10-item questionnaire that specifically assesses COPD-related disability.