Acute muscle wasting in critical illness is a major cause of disability amongst intensive care survivors. There are limited data detailing sequential loss of muscle mass and less data characterising histological muscle changes. We hypothesised that loss of Rectus Femoris Cross-Sectional Area (RFCSA) would be determined by the severity of acute critical illness and paralled by a reduction in myofibre cross-sectional area determined from analysis of muscle biopsy samples. Critically ill patients were recruited from two hospitals within the first 24 hours of admission. Inclusion criteria were: likely to (i) remain intubated ≥ 48 hours and (ii) remain in critical care ≥ 7 days. Patients were excluded if they i) were pregnant ii) had disseminated malignancy or iii) suffered from a primary neuromuscular disease. Serial RFCSA measurements were taken using B-mode ultrasound, on days 1, 3, 7 and 10 of admission. Bedside physiological data was collected, for stratification of illness severity by numbers of failed organ systems, defined by the Sequential Organ Failure Assessment score. Patients were retrospectively excluded if they failed to maintain inclusion/exclusion criteria for the length of the study. Serial vastus lateralis muscle biopsies were performed in 50% of patients. 91 patients were recruited, of which 63 were included for final analysis. 1 patient could not undergo RFCSA due to morbid obesity (BMI 67kg/m2). The greatest RFCSA reduction was observed in patients with ≥ 2 organ failure; 21.5±10.5% in ≥ 2 organ failure vs.7.2± 9.7% in 1 organ failure; p <0.0001 (Fig.1). Greater loss of RFCSA was observed at day 3 in patients with multi-organ failure compared with single organ failure patients (8.7±16.3% in ≥ 2 organ Failure vs. 1.8± 9.6% in 1 organ failure; p<0.01). Significant differences were observed between those with 2-3 organ failure compared with ≥ 4 organ failure by days 7 and 10 (19.5±9.4% vs. 26.3± 12.0%; p<0.01). Histological analysis showed a reduction in type 1 fibre cross sectional area (4.3±3.1% loss per day in single organ failure and 2.9±3.3% loss per day in multi-organ failure; p =0.24). The change in type 2 fibres was more variable. The data show that changes in rectus femoris cross-sectional area can be detected early in critical illness by ultrasound. Using this apprach, it was possible to discriminate between patients with single organ and multi-organ failure in regard to muscle loss using this technique. It was not possible to discriminate between patient groups on the basis of fibre size changes anlaysed from biopsy samples.
The Biomedical Basis of Elite Performance (London) (2012) Proc Physiol Soc 26, PC76
Poster Communications: The musculoskeletal ultrasound in critical care: longitudinal evaluation (UK-MUSCLE) study: severity of acute critical illness determines the degree of muscle wasting
Z. A. Puthucheary1,3, J. Rawal1, B. Connolly2,3, M. McPhail3,4, G. Ratnayake2, P. Sidhu3, D. Shrikrishna6, P. Hopkins3, O. Foot5, M. Kalakoutis5, C. James5, H. Ogilvie5, N. Hopkinson6, M. Polkey6, M. Rennie7, A. Rowlerson5, J. Moxham3, S. Harridge5, N. Hart2, H. Montgomery1
1. Institute of Health and Human Performance, University College London, London, United Kingdom. 2. Guy's & St Thomas' and King's College London, NIHR Comprehensive Biomedical Research Centre, London, United Kingdom. 3. Kings College Hospital NHS Trust, London, United Kingdom. 4. Imperial College London Hammersmith Hospital NHS Trust, London, United Kingdom. 5. Centre of Human & Aerospace Physiological Sciences, Kings College London, London, United Kingdom. 6. NIHR Respiratory Biomedical Research Unit at Royal Brompton and Harefield NHS Foundation Trust and Imperial College, London, London, United Kingdom. 7. University of Nottingham, Nottingham, United Kingdom.
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Where applicable, experiments conform with Society ethical requirements.