What is stopping us from early mobility in the intensive care unit ?

Over recent decades, decreasing mortality from critical illness has led to an increasing number of intensive care unit (ICU) survivors (1, 2). Understanding the post-ICU morbidity experienced by these survivors has become increasingly important. In particular, neuromuscular weakness during critical illness is common, and although the etiology is multifactorial, disuse atrophy from prolonged immobility likely plays an important role (3). In survivors of severe critical illness, this ICUacquired weakness may be substantial and persistent, resulting in important decrements in physical function and quality of life (4, 5). A relatively new therapeutic option for prevention and treatment of ICUacquired weakness is mobilization of patients in the ICU (6). Having critically ill patients alert and engaged in mobilization, despite the use of life support therapies, may reduce muscle atrophy and lead to improved strength and physical function. Recent studies have demonstrated that mobilization, including ambulation, of mechanically ventilated patients is safe and feasible (6 –11). In this issue of Critical Care Medicine, Pohlman et al examined the feasibility of delivering physical and occupational therapy (PT/OT), coupled with daily sedative interruption, to critically ill patients in a medical ICU (12). In mechanically ventilated patients, therapy occurred on the majority of eligible study days (90%) representing a spectrum of activities that progressed from upper and lower extremity range-ofmotion exercises (85%) to sitting at the edge of the bed (69%), activities of daily living (for example, grooming, 64%), transfers (for example, moving from bed to chair, 33%), and to ambulation in a minority of sessions (15%). Adverse events (for example, desaturation, agitation/discomfort) were uncommon with therapy discontinued prematurely in only 4% of all sessions, most commonly due to patient-ventilator asynchrony or agitation. Patients generally improved over time, being able to perform a greater number of activities with less assistance, as they moved from the ICU to the medical ward. Arguably, the most important finding of this study was how early PT/OT was initiated, a median (interquartile range) of 1.5 days (1.0 –2.1) after intubation. Previous studies demonstrating the feasibility and safety of mobilizing critically ill patients have typically occurred after approximately 4 –10 days in the ICU (8, 9, 11). A single-center, nonrandomized trial of a dedicated multidisciplinary mobility team enrolled patients early ( 48 hrs after intubation), but the mean (95% confidence interval) time to the patient first getting out of bed was 8.5 days (6.6 –10.5) days (8). Muscle atrophy can occur rapidly in patients on bed rest with an interaction between immobility and critical illness leading to potentially greater muscle loss than either condition alone (6). Thus, initiating therapy as soon as possible after ICU admission may mitigate the development of significant muscle atrophy in these patients. Furthermore, mobilization and exercise may decrease oxidative stress and inflammation and prevent insulin resistance and microvascular dysfunction, which may further help to ameliorate ICU-acquired weakness (6). A common barrier to early PT/OT in critically ill patients is the use of heavy sedation, because a necessary prerequisite for the successful initiation of therapy is sedative interruption to allow for wakefulness and patient interaction. Thus, coupling protocols for daily sedative interruption with the institution of PT/OT in the present study may have synergistic effects and likely represents an important step in increasing the likelihood for being eligible for PT/OT on any given day. Sedative infusions were stopped before the majority of therapy sessions (83%) in this study. Interestingly, patients who received intermittent sedation boluses were already awake and able to follow commands, but this occurred in 10% of sessions. Recent studies in critically ill patients evaluating novel sedative agents (for example, dexmedetomidine) (13), the use of intermittent sedation (14), or no sedation at all (15) support the use of more aggressive protocols designed to limit heavy sedation, thus increasing the number of, and rapidity at which, patients in the ICU may become eligible for this beneficial therapy. However, the use of any sedation, even given intermittently, has been associated with a nearly twofold decrease in ambulation (8). Importantly, other perceived barriers (for example, vasopressors, obesity) were common but did not preclude therapy in many instances. For example, the majority of patients had at least one central venous catheter (75%) and/or acute lung injury (58%) during the therapy session, whereas a smaller proportion of patients were on two or more vasopressors (14%) and/or continuous renal replacement therapy (9%). Interestingly, delirium, present in 53% of sessions, was not a barrier to therapy per se but may have limited patients from performing higher-level activities (for example, ambulation) that they may have otherwise tolerated physically. Finally, despite being infrequent, patient intolerance of sessions may have been improved by anticipatory changes in ventilator settings (for *See also p. 2089.