Survival among patients in the ICU has improved dramatically over the past 20 years. Indeed, the observation that extremely ill patients often survive their illnesses has led to a relatively new focus of clinical investigation on patients who survive critical illness. Rehabilitation after critical illness is arduous and often frustratingly slow, particularly in elderly patients. The greatest burdens that survivors of critical illness face are related to neuromuscular dysfunction and neuropsychological maladjustment.42,43 Patients who survive respiratory failure, circulatory failure (e.g., in association with ARDS42 or sepsis10), or both seem to have these problems with the greatest frequency and intensity. Indeed, in patients who require prolonged mechanical ventilation, neuromuscular recovery is typically prolonged and incomplete. Studies show that up to 65% of such patients have functional limitations after discharge from the hospital.38,44 Neuromuscular abnormalities may last for many years in some patients.45
As mentioned earlier, in the past, routine features of general care provided in the ICU included liberal use of sedation and immobilization of the patient, which were thought to be necessary for facilitating interventions to normalize physiological function by artificial means. Recently, there has been a paradigm shift away from this approach toward a “less is more” philosophy for patients in the ICU.46
This paradigm shift is consistent with the observation that long-term physical problems in survivors of critical illness, particularly those with respiratory failure, may result from the protracted ICU stay and period of immobilization during which the patient is receiving organ support that is essential for survival. Functional disability, a natural consequence of weakness, is a frequent and long-lasting complication in survivors of critical illness.41 Herridge et al.38 followed a cohort of survivors of ARDS for 5 years after hospital discharge. Muscle weakness and functional impairment were frequently observed at 1 year, and recovery from physical dysfunction was incomplete even 5 years after discharge.42 At the 5-year assessment, the results of 6-minute walk tests were still only 70% of the predicted results. Elderly survivors of critical illness appear to fare particularly poorly. Sacanella et al.47 reported a significant reduction in functional status in elderly survivors of critical illness who had had normal functional status at ICU admission; functional status had not returned to baseline 1 year after discharge.
The focus on rehabilitation of critically ill patients should begin in the ICU and continue all the way to recovery at home. This is particularly important because the burden of illness affects not only the patient but his or her family or other caregivers as well. Accordingly, preparing both the patient and family or other caregivers for the difficult task of recovery may help lessen this burden.
Given the substantial physical dysfunction noted in survivors of critical illness, several investigators have evaluated the effect of ICU care that is focused on optimizing early physical activity in spite of the severity of illness. This strategy involves minimizing sedation and enlisting the early involvement of a diverse, multidisciplinary group of clinicians, including physical and occupational therapists, nurses, respiratory therapists, and patient care technicians, with the goal of getting patients up and out of bed. The discontinuation of deep sedation is a critical first step in optimizing patient activity and awareness. For example, studies have shown that the interruption of daily sedative use during mechanical ventilation increases the percentage of days during which patients are awake and able to follow commands.48 De Jonghe et al.49 noted that use of a sedation algorithm designed to allow patients to be more alert was associated with a 50% reduction in pressure sores, presumably because of reductions in sedative-related immobilization. In a before-and-after quality-improvement project, Needham et al.50 reported that changes in ICU care to reduce sedative use improved in-hospital activity levels in a group of patients in the medical ICU.
Currently, therapeutic interventions to prevent or attenuate ICU-acquired weakness and functional impairment after critical illness are limited to moderate glucose control, as noted above, and early mobilization. In 1975, Burns and Jones51 described a walker device designed for patients who require mechanical ventilation. Technological methods have evolved to the point that ambulation during mechanical ventilation44,52,53 and even extracorporeal membrane oxygenation therapy54 is now feasible. Protocols designed to mobilize patients in the ICU consist of sequential strategies from lesser to greater complexity of activities, depending on a patient's ability to perform these activities. Such strategies are similar to the approach used by physical therapists who care for patients outside the ICU.
Bailey and colleagues52 reported on mobilization in a large cohort of patients who required mechanical ventilation. These investigators described a “culture change,” whereby activity was encouraged as soon as the condition of patients was hemodynamically stable with modest ventilator settings (i.e., fraction of inspired oxygen ≤0.6 and positive end-expiratory pressure ≤10 cm of water). Ambulation, even during mechanical ventilation, was feasible with few adverse events (e.g., device removal or deterioration of vital signs). Burtin and colleagues55 reported the benefits of a cycling exercise session with the use of a bedside cycle ergometer attached to the foot of the bed. The ergometer could provide passive range-of-motion exercise for patients who were not sufficiently alert to participate and active resistance for those who were capable of pedaling. These investigators noted improved strength and physical function at hospital discharge in the patients who were randomly assigned to cycle ergometry.
Morris et al.53 reported the results of a prospective, nonrandomized trial of mobilization in patients who were receiving mechanical ventilation. The mobilization group was out of bed faster and had shorter hospital stays. There were no differences in the duration of mechanical ventilation or in the condition of the patient at hospital discharge. At 1 year after discharge, the mobilization group was almost half as likely to have died or been rehospitalized; this suggests a better long-term recovery profile.56 In 2009, Schweickert et al.44 performed a prospective randomized, blinded trial of physical and occupational therapy from the inception of respiratory failure. This immediate mobilization strategy led to a near doubling of functional independence at hospital discharge, despite the fact that hospital length of stay did not differ between the intervention and control groups. The patients who were randomly assigned to immediate mobilization spent fewer days receiving mechanical ventilation and had less delirium and greater maximal walking distances. In addition, more patients in the early-mobilization group were discharged to home after hospitalization. Independent predictors of functional independence at ICU discharge were younger age, absence of sepsis, and randomized assignment to early physical and occupational therapy. Despite an early, aggressive approach to mobilization in a study population that included patients with acute lung injury, morbidly obese patients, patients with shock requiring vasoactive infusions, and patients receiving ongoing renal-replacement therapy, there were very few adverse events, none of which were consequential with respect to outcome. Indeed, the most common barriers to early mobility were failure to awaken from sedation, agitation when sedation was discontinued, and scheduled diagnostic tests.57