Open Access

Intensive care unit acquired muscle weakness: when should we consider rehabilitation?

Critical Care200913:167

https://doi.org/10.1186/cc7937

Published: 20 July 2009

Abstract

Muscle weakness is highly prevalent during acute critical illness, with the poor exercise performance that occurs after critical illness being recognized as a consequence of skeletal muscles weakness. Advanced techniques to measure peripheral muscle strength are available, but they have limited use in the clinical setting. Simple volitional methods to assess strength are limited because they rely on patient motivation, which can be problematic in the critical care setting. At present, the mechanisms that underlie skeletal muscle wasting and weakness are poorly understood, but use of rehabilitation early in critical illness appears to have beneficial effects on outcome. The future direction will be to determine the underlying mechanisms as well as developing rehabilitation programmes during both the acute and the post critical illness stages.

In this month's issue of Critical Care, Truong and coworkers [1] review the data on skeletal muscle dysfunction after acute critical illness. Increasingly recognized, skeletal muscle weakness can be commonplace in the intensive care unit (ICU) setting, with a single centre study demonstrating that 25% of patients have muscle weakness [2]. In another study of 116 patients [3], reduction in limb strength was associated with respiratory muscle weakness and delayed weaning from mechanical ventilation. These and other data have directed the focus of health care in the UK onto rehabilitation after critical illness, and guidelines by the National Institute of Clinical Excellence (NICE) were recently published [4].

Identification and stratification of patients with ICU acquired weakness (AW), who could benefit from rehabilitation, is of fundamental importance. Nonvolitional assessments of muscle strength, using such techniques as magnetic stimulation of peripheral nerves, have provided detailed physiological data that demonstrate significant reductions in muscle strength [58]. However, availability of these objective tools for assessment is limited outside the research environment, and consequently they are of limited clinical utility. Other measurements have been proposed, such as hand grip strength, which are easier to perform, but such volitional tests in critically ill patients are difficult to interpret, especially if a borderline low normal result is obtained, because this could indicate weakness, poor motivation or inability to complete the task. Ali and colleagues [9] showed that that handgrip strength can be a predictor of mortality, although this could also be a reflection of critical illness severity. A novel technique to consider that is relatively simple and portable is the use of ultrasound to measure quadriceps cross-sectional area as a nonvolitional surrogate marker of quadriceps strength [10]. Although this has the potential to be a clinical useful tool, the ability of ultrasound to measure cross-sectional area sequentially in order to quantify muscle loss and predict functional outcome remains unproven.

Although these data demonstrate the occurrence of ICU-AW, there is a paucity of data that provide insight into the pathophysiological mechanisms involved. Truong and coworkers [1] identify risk factors that have been shown to be associated with muscle weakness, and provide a summary of the potential mechanisms of immobility and disuse related muscle atrophy. Although these are rational explanations, our current knowledge of the muscle atrophy/hypertrophy signalling pathways and muscle proteolysis pathways are mainly based on animal data. Human studies have revealed dissociations between actual protein turnover and alterations in signalling pathways that are purported to control protein synthesis and breakdown [11, 12]. Human studies within the ICU setting are needed before we can begin to elucidate the processes that underlie critical illness associated muscle loss. From this, muscle and other biomarkers could potentially identify those patients who are at risk for major functional limitation who would benefit the most from interventions such as rehabilitation.

Despite our limited mechanistic knowledge, skeletal muscle weakness has been shown to be an independent predictor of mortality in stable patients with chronic obstructive pulmonary disease and chronic heart failure, with rehabilitation improving outcome [1316]. Although exercise in these patients is often carried out during stable periods, Truong and coworkers [1] challenge the view that ICU patients receiving invasive mechanical ventilation should be excluded from mobilization, highlighting a low incidence of adverse events. However, we must influence the culture within critical care to promote these changes.

Recently, Schweickert and colleagues [17] demonstrated the safety and efficacy of combined sedation holds and whole body rehabilitation during the early stages of critical illness. These interventions were conducted by a multidisciplinary team in centres that did not routinely provide physical therapy at the early stages of mechanical ventilation, demonstrating better functional outcome at hospital discharge. As always within the context of a clinical trial, strict exclusion criteria preclude this study from being wholly generalizable, especially because these data pertain only to medical ICU patients. Despite significant differences in the delivery of physical therapy rehabilitation services in ICUs in different countries, these data show that critically ill patients can safely receive early rehabilitation therapy with improved outcomes. The next challenge is to unravel the pathophysiology of this acquired skeletal muscle disease and to develop further intervention strategies, including clinical trials investigating the effects of rehabilitation after critical illness.

Abbreviations

AW: 

acquired weakness

ICU: 

intensive care unit.

Declarations

Authors’ Affiliations

(1)
Department of Critical Care, Lane Fox Respiratory Unit,Guy's St Thomas' NHS Foundation Trust
(2)
Department of Critical Care, Lane Fox Respiratory Unit,NIHR Comprehensive Biomedical Research Centre,Guy's St Thomas' NHS Foundation Trust and King's College London

References

  1. Truong AD, Fan E, Brower RG, Needham DM: Mobilizing patients in the intensive care unit: from pathophysiology to clinical trials. Crit Care 2009, 13: 216. 10.1186/cc7885PubMed CentralView ArticlePubMedGoogle Scholar
  2. De Jonghe B, Sharshar T, Lefaucheur JP, Authier FJ, Durand-Zaleski I, Boussarsar M, Cerf C, Renaud E, Mesrati F, Carlet J, Raphaël JC, Outin H, Bastuji-Garin S, Groupe de Réflexion et d'Etude des Neuromyopathies en Réanimation: Paresis acquired in the intensive care unit: a prospective multicenter study. JAMA 2002, 288: 2859-2867. 10.1001/jama.288.22.2859View ArticlePubMedGoogle Scholar
  3. De Jonghe B, Bastuji-Garin S, Durand MC, Malissin I, Rodrigues P, Cerf C, Outin H, Sharshar T, Groupe de Réflexion et d'Etude des Neuromyopathies en Réanimation: Respiratory weakness is associated with limb weakness and delayed weaning in critical illness. Crit Care Med 2007, 35: 2007-2015. 10.1097/01.ccm.0000281450.01881.d8View ArticlePubMedGoogle Scholar
  4. NICE: CG83 Critical illness rehabilitation.2009. [http://guidance.nice.org.uk/CG83/PublicInfo/doc/English]Google Scholar
  5. Harris ML, Moxham J, Measuring respiratory and limb muscle strength using magnetic stimulation: Measuring respiratory and limb muscle strength using magnetic stimulation. Br J Intensive Care 1998, 8: 21-28.Google Scholar
  6. Harris ML, Luo YM, Watson AC, Rafferty GF, Polkey MI, Green M, Moxham J: Adductor pollicis twitch tension assessed by magnetic stimulation of the ulnar nerve. Am J Respir Crit Care Med 2000, 162: 240-245.View ArticlePubMedGoogle Scholar
  7. Mills GH, Ponte J, Hamnegard CH, Kyroussis D, Polkey MI, Moxham J, Green M: Tracheal tube pressure change during magnetic stimulation of the phrenic nerves as an indicator of diaphragm strength on the intensive care unit. Br J Anaesth 2001, 87: 876-884. 10.1093/bja/87.6.876View ArticlePubMedGoogle Scholar
  8. Watson AC, Hughes PD, Louise Harris M, Hart N, Ware RJ, Wendon J, Green M, Moxham J: Measurement of twitch transdiaphragmatic, esophageal, and endotracheal tube pressure with bilateral anterolateral magnetic phrenic nerve stimulation in patients in the intensive care unit. Crit Care Med 2001, 29: 1325-1331. 10.1097/00003246-200107000-00005View ArticlePubMedGoogle Scholar
  9. Ali NA, O'Brien JM Jr, Hoffmann SP, Phillips G, Garland A, Finley JC, Almoosa K, Hejal R, Wolf KM, Lemeshow S, Connors AF Jr, Marsh CB, Midwest Critical Care Consortium: Acquired weakness, handgrip strength and mortality in critically ill patients. Am J Respir Crit Care Med 2008, 178: 261-268. 10.1164/rccm.200712-1829OCView ArticlePubMedGoogle Scholar
  10. Seymour JM, Ward K, Sidhu P, Puthucheary Z, Steier J, Jolley C, Rafferty G, Polkey MI, Moxham J: Ultrasound measurement of rectus femoris cross-sectional area and the relationship to quadriceps strength in chronic obstructive pulmonary disease. Thorax 2009, 64: 418. 10.1136/thx.2008.103986View ArticlePubMedGoogle Scholar
  11. Greenhaff PL, Karagounis LG, Peirce N, Simpson EJ, Hazell M, Layfield R, Wackerhage H, Smith K, Atherton P, Selby A, Rennie MJ: Disassociation between the effects of amino acids and insulin on signaling, ubiquitin ligases, and protein turnover in human muscle. Am J Physiol Endocrinol Metab 2008, 295: E595-E604. 10.1152/ajpendo.90411.2008PubMed CentralView ArticlePubMedGoogle Scholar
  12. Murton AJ, Constantin D, Greenhaff PL: The involvement of the ubiquitin proteasome system in human skeletal muscle remodelling and atrophy. Biochim Biophys Acta 2008, 1782: 730-743.View ArticlePubMedGoogle Scholar
  13. Troosters T, Gosselink R, Decramer M: Short- and long-term effects of outpatient rehabilitation in patients with chronic obstructive pulmonary disease: a randomized trial. Am J Med 2000, 109: 207. 10.1016/S0002-9343(00)00472-1View ArticlePubMedGoogle Scholar
  14. Williams MA, Ades PA, Hamm LF, Keteyian SJ, LaFontaine TP, Roitman JL, Squires RW: Clinical evidence for a health benefit from cardiac rehabilitation: an update. Am Heart J 2006, 152: 835. 10.1016/j.ahj.2006.05.015View ArticlePubMedGoogle Scholar
  15. Troosters T, Gosselink R, Decramer M: Chronic obstructive pulmonary disease and chronic heart failure: two muscle diseases? J Cardiopulm Rehabil 2004, 24: 137-145. 10.1097/00008483-200405000-00001View ArticlePubMedGoogle Scholar
  16. Swallow EB, Reyes D, Hopkinson NS, Man WD, Porcher R, Cetti EJ, Moore AJ, Moxham J, Polkey MI: Quadriceps strength predicts mortality in patients with moderate to severe chronic obstructive pulmonary disease. Thorax 2007, 62: 115-120. 10.1136/thx.2006.062026PubMed CentralView ArticlePubMedGoogle Scholar
  17. Schweickert WD, Pohlman MC, Pohlman AS, Nigos C, Pawlik AJ, Esbrook CL, Spears L, Miller M, Franczyk M, Deprizio D, Schmidt GA, Bowman A, Barr R, McCallister KE, Hall JB, Kress JP: Early physical and occupational therapy in mechanically ventilated, critically ill patients: a randomised controlled trial. Lancet 2009, 373: 1874-1882. 10.1016/S0140-6736(09)60658-9View ArticlePubMedGoogle Scholar

Copyright

© BioMed Central Ltd 2009

Advertisement