Debilidad Muscular En Uci

Intensive-Care-Unit-Acquired Muscle Weakness
Steven Deem MD

Introduction Definitions Incidence Pathology of ICU-Acquired Weakness Risk Factors and Pathogenesis Clinical Presentation and Outcomes Diagnosis Prevention and Therapy Summary and the Future

Neuromuscular abnormalities culminating in skeletal-muscle weakness occur very commonly in critically ill patients. Intensive-care-unit (ICU)acquired neuromuscular abnormalities are typically divided into 2 discrete classes: polyneuropathy and myopathy. However, it is likely that these 2 entities commonly coexist, with myopathy being the most common cause of weakness. Major risk factors for ICU-acquired neuromuscular abnormalities include sepsis, corticosteroid administration, and hyperglycemia, with other associated factors includingneuromuscular blockade and increasing severity of illness. The pathogenesis of these disorders is not well defined, but probably involves inflammatory injury of nerve and/or muscle that is potentiated by functional denervation and corticosteroids. ICU-acquired neuromuscular abnormalities are associated with multiple adverse outcomes, including higher mortality, prolonged duration of mechanicalventilation, and increased length of stay. The only intervention proven to reduce the incidence of ICU-acquired neuromuscular abnormalities is intensive insulin therapy. Additional research is necessary to better delineate the causes and pathogenesis of these disorders and to identify potential preventive and therapeutic strategies. In addition, consensus guidelines for its classification anddiagnosis are needed. Key words: neuromuscular, weakness, polyneuropathy, myopathy, polyneuromyopathy, intensive care, inflammation, mechanical ventilation, insulin, critical illness. [Respir Care 2006;51(9):1042–1052. © 2006 Daedalus Enterprises]

Introduction Weakness that is acquired during hospitalization for critical illness is increasingly recognized as a common and

Steven Deem MD isaffiliated with the Departments of Anesthesiology and Medicine, Harborview Medical Center, University of Washington, Seattle, Washington. Steven Deem MD presented a version of this paper at the 37th RESPIRATORY CARE Journal Conference, “Neuromuscular Disease in Respiratory and Critical Care Medicine,” held March 17–19, 2006, in Ixtapa, Mexico.

important clinical problem. Weakness acquired in theintensive care unit (ICU) and related acquired neuromuscular dysfunction occur in a large percentage of critically ill patients1–3 and are associated with increased morbidity and mortality.4,5 In addition, it is estimated that the development of ICU-acquired paresis may result in an average of $66,000 per patient in excess hospital charges (1996

Correspondence: Steven Deem MD, AnesthesiologyDepartment, Harborview Medical Center, Box 359724, 325 Ninth Avenue, Seattle WA 98104. E-mail: sdeem@u.washington.edu.

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RESPIRATORY CARE • SEPTEMBER 2006 VOL 51 NO 9

INTENSIVE-CARE-UNIT-ACQUIRED MUSCLE WEAKNESS
United States dollars).6 This review will discuss the incidence, causes, importance, pathogenesis, diagnosis, and prevention of ICU-acquired paresis and associated ICUacquiredneuromuscular disorders. Definitions Because weakness in critically ill patients has been described in a variety of clinical situations and ascribed to more than one etiology, several descriptive terms have been coined to attempt to define and differentiate weakness syndromes. These include critical-illness polyneuropathy, critical-illness myopathy, and acute quadriplegic myopathy. Unfortunately, theseterms may be too restrictive in that they imply a single and distinct cause of weakness for each patient or group of patients, when in fact the pathology appears to be more complex, with considerable overlap between the “syndromes.” For example, myopathy appears to be present in the majority of cases that might once have been classified as polyneuropathy (discussed in detail later).7,8 In...