Exploration of muscle loss and metabolic state during prolonged critical illness: Implications for intervention?

• Published in: PloS one Vol. 14; no. 11; p. e0224565
• Main Authors: Wandrag, Liesl, Brett, Stephen J, Frost, Gary S, Bountziouka, Vasiliki, Hickson, Mary
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 14-11-2019; Public Library of Science (PLoS)
• Subjects: Adult; Aged; Amino acids; Biology and Life Sciences; Breakdowns; C-reactive protein; C-Reactive Protein - metabolism; Catabolism; Critical care; Critical Illness; Cytidine - analogs & derivatives; Cytidine - urine; Enteral nutrition; Female; Forearm; Hospital patients; Hospitals; Humans; Illnesses; Inflammation; Intensive care; Intensive care units; International standardization; International standards; Length of Stay; Male; Medical research; Medicine and Health Sciences; Metabolism; Middle Aged; Muscle, Skeletal - metabolism; Muscle, Skeletal - physiopathology; Muscles; Muscular Atrophy - blood; Muscular Atrophy - physiopathology; Muscular Atrophy - urine; Musculoskeletal system; Nitrogen; Nitrogen balance; Nutrition research; Parenteral nutrition; Patients; Physical Sciences; Proteins; Recovery; Rehabilitation; Research and Analysis Methods; Systematic review; Teachers; Thigh; Trauma; Ultrasonic imaging; Ultrasound; United Kingdom; Urea; Urea - urine; Ventilation; United Kingdom; United Kingdom > UK; England
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0224565

Muscle wasting in the critically ill is up to 2% per day and delays patient recovery and rehabilitation. It is linked to inflammation, organ failure and severity of illness. The aims of this study were to understand the relationship between muscle depth loss, and nutritional and inflammatory markers during prolonged critical illness. Secondly, to identify when during critical illness catabolism might decrease, such that targeted nutritional strategies may logically be initiated.
This study was conducted in adult intensive care units in two large teaching hospitals. Patients anticipated to be ventilated for >48 hours were included. Serum C-reactive protein (mg/L), urinary urea (mmol/24h), 3-methylhistidine (μmol/24h) and nitrogen balance (g/24h) were measured on days 1, 3, 7 and 14 of the study. Muscle depth (cm) on ultrasound were measured on the same days over the bicep (bicep and brachialis muscle), forearm (flexor compartment of muscle) and thigh (rectus femoris and vastus intermedius).
Seventy-eight critically ill patients were included with mean age of 59 years (SD: 16) and median Intensive care unit (ICU) length of stay of 10 days (IQR: 6-16). Starting muscle depth, 8.5cm (SD: 3.2) to end muscle depth, 6.8cm (SD: 2.2) were on average significantly different over 14 days, with mean difference -1.67cm (95%CI: -2.3 to -1cm), p<0.0001. Protein breakdown and inflammation continued over 14 days of the study.
Our patients demonstrated a continuous muscle depth loss and negative nitrogen balance over the 14 days of the study. Catabolism remained dominant throughout the study period. No obvious 'nutritional tipping point" to identify anabolism or recovery could be identified in our cohort. Our ICU patient cohort is one with a moderately prolonged stay. This group showed little consistency in data, reflecting the individuality of both disease and response. The data are consistent with a conclusion that a time based assumption of a tipping point does not exist.
International Standard Randomised Controlled Trial Number: ISRCTN79066838. Registration 25 July 2012.