ICU-Acquired Weakness and Recovery from Critical Illness

Abstract

eakness acquired in the intensive care unit (ICU) is caused by many different pathophysiological mechanisms that are not mutually exclusive. This is not surprising, given the diverse diseases that precipitate critical illness, the drugs used during its management, and the consequences of protracted immobility. Nonetheless, conceptualization of this entity is valuable, since weakness in survivors of critical illness is common and is associated with longstanding consequences that dramatically affect recovery. Moreover, as survival rates among patients in the ICU increase, ICU-acquired weakness will have increasing relevance for care providers outside the ICU. This article provides an overview of the condition and its effect on recovery after critical illness. Early descriptions of weakness in critical illness include reports by Osler 1 of neuromuscular dysfunction in patients with sepsis and reports by Olsen 2 of peripheral neuropathy complicating protracted coma. In 1977, myopathy was described in a patient with status asthmaticus 3 who received high doses of hydrocortisone and simultaneous neuromuscular blockade. These descriptions were followed by a landmark study by Bolton and colleagues 4 of polyneuropathy in patients in the ICU. This condition, termed critical illness polyneuropathy, is characterized by a primary axonal degeneration, without demyelination, that typically affects motor nerves more than sensory nerves. The predominant spinal cord finding is loss of anterior horn cells due to axonal degeneration. 5 Electrophysiological studies show that nerve conduction velocity is preserved, but there are reductions in the amplitudes of compound muscle action potentials (CMAPs) and sensory-nerve action potentials. Over the past two decades, improvements in survival after discharge from the ICU probably have led to increased awareness of ICU-acquired weakness. The magnitude of neuromuscular impairment in the increasing population of patients undergoing post-ICU rehabilitation has come to the attention of health care providers, patients, and families. Fe at ur es of ICU-Acquir ed W e a k ness Critical illness polyneuropathy affects the limbs (particularly the lower extremities) in a symmetric pattern. Weakness is most notable in proximal neuromuscular areas (e.g., the shoulders and hip girdle). In addition, involvement of the respiratory muscles can occur and can impede weaning from mechanical ventilation. 6 Facial and ocular muscles are rarely involved. Creatine kinase levels are not elevated in patients with critical illness polyneuropathy. The condition is distinct from the Guillain-Barré syndrome because demyelination is not seen. As distinct from a secondary myopathy resulting from muscle denervation, critical illness myopathy is a primary myopathy. 7 It is often difficult to distinguish this myopathy from critical illness polyneuropathy by means of a simple bedside

A Randomized Trial of an Intensive Physical Therapy Program for Patients with Acute Respiratory Failure

“…Therefore, improving long-term outcomes for these patients has become more clinically relevant. One of the most common and debilitating limitations for survivors of acute respiratory failure is exercise limitation and decreased physical quality of life that can persist up to 5 years after hospital discharge (3)(4)(5)(6)(7)(8). These patients have difficulty lifting and carrying groceries, climbing stairs, bending, kneeling, walking moderate distances, and performing other routine activities of daily living (3,4).…”

“…Until recently, the management of critically ill patients, including those with acute respiratory failure, consisted of inactivity and bed rest for extended periods of time (5). Such prolonged immobility can result in significant muscle wasting (5).…”

“…Such prolonged immobility can result in significant muscle wasting (5). For patients with a variety of neuromuscular disorders, physical therapy (PT) programs can be effective in reducing neuromuscular dysfunction and weakness (9)(10)(11)(12)(13).…”

The Process of Weaning from Mechanical Ventilation

“…The weakness and muscle paresis acquired in the ICU is caused by different pathophysiological mechanisms 29 . Multiple organ system failure 30 with the use of neuromuscular blocking agents, associated or not with corticosteroids, may precipitate respiratory muscle weakness 31,32 .…”

Validez y confiabilidad de las escalas de evaluación funcional en pacientes críticamente enfermos. Revisión sistemática

“…Este cuadro clínico se define como un síndrome de debilidad generalizada de las extremidades, para el cual no existe una explicación alternativa que no sea la propia enfermedad crítica del paciente 2 . Los principales factores de riesgo para el desarrollo de la DAUCI son el reposo prolongado en cama, la hiperglicemia, la sepsis, el uso de corticoesteroides y bloqueadores neuromusculares 1, [3][4][5][6][7][8][9][10][11][12] . Fisiopatológicamente, estos factores se asocian con un desbalance entre la síntesis y degradación de proteínas musculares, asociado a necrosis de las miofibrillas, produciéndose una disminución rápida y significativa de la masa muscular que puede llegar a 15% los primeros 7 días de la enfermedad crítica, además de una disminución de la densidad mineral ósea 13,14 .…”