CHAPTER 24: Physical Therapy

KEY POINTS

• Survivorship from critical illness may include substantial neuromuscular weakness that can persist for many years following the index hospitalization.

• Immobility can commonly accompany supportive care. Understanding the effects of bed rest and immobility on muscle, heart, and nervous system is necessary to balance the risks and benefits of early mobilization.

• Early physical therapy can be performed safely despite ongoing critical illness.

• Alternative strategies for mobilization include cycle ergometry and neuromuscular stimulation.

• Successful early mobility programs include criteria for safe mobilization, which focus on the neurologic, cardiovascular, and pulmonary criteria.

INTRODUCTION—SURVIVORSHIP

In the last quarter century, research developments have led to improvements in diagnosis and resuscitation of critically ill patients, particularly those undergoing mechanical ventilation (MV).^1-4 With these improvements, survival for many populations of critically ill patients has increased.^4-7 Accordingly, intensive care unit (ICU) outcomes research has expanded, documenting substantial morbidity in survivors. ICU-acquired weakness is a common problem following critical illness and is associated with prolonged hospitalization, delayed weaning, and increased mortality.^8-10 Up to 25% of patients requiring MV for greater than 7 days develop ICUAW,¹¹ and a systematic review of 24 studies including patients with sepsis, multiorgan failure, or prolonged MV identified neuromuscular dysfunction in 46% of patients.⁹ Furthermore, long-term follow-up studies of survivors of critical illness have demonstrated significantly impaired health-related quality of life and physical functioning up to 5 years after ICU discharge, with weakness being the most commonly reported physical limitation.^12,13

Factors such as systemic inflammation, medications (particularly corticosteroids), electrolyte disturbances, and immobility have been implicated in the pathogenesis of ICU-AW.^14,15 Although no one has systematically measured immobility during ICU care, clinicians acknowledge its presence during the earliest days of critical illness, particularly during deep sedation or neuromuscular blockade, specific MV strategies (eg, prone ventilation), and other advanced support (eg, continuous hemodialysis).

BED REST AND IMMOBILITY

Rest is necessary for the natural repair of weakened or damaged tissue and remodeling of muscle. Bed rest is most often accompanied by sleep, a process necessary for normal neurologic, immune, and endocrine function. The average person rests for 6 to 9 hours per day during sleep and shorter periods of rest may occur at other times. When people are ill, they often sleep and rest for longer periods.¹⁶

Prolonging rest has the potential for several benefits during general illness. For the injured body part, rest may avoid pain. By avoiding unnecessary exertion, metabolic resources may be maximally utilized for healing. During critical illness, reducing oxygen consumption by muscles may help preferentially deliver oxygen to injured or hypoxic organ systems. Similarly, in patients with respiratory failure, oxygen requirements and minute ventilation needs may be reduced. For hypertensive patients, rest may lower blood pressure, potentially preventing myocardial ischemia and dysrhythmias. Finally—and perhaps the most common reason for ...