Advances in medical care of critically ill patients have increased survival. However, patients who survive can be left with neuromuscular¹ and neurocognitive² impairments leading to impaired physical function^3–5 and decreased quality of life (QOL).^3,4,6,7 Recent attention has been directed toward the practice of pairing daily sedative interruption with physical activity very early in the course of medical management of patients who are mechanically ventilated and critically ill. Early mobilization has been shown to be feasible and safe,^8–10 decrease days on mechanical ventilation (MV),¹¹ decrease hospital and intensive care unit (ICU) lengths of stay,⁹ and improve cognitive and functional outcomes.¹¹ Despite the research supporting early mobilization as an intervention to consider in the management of patients with critical illness, it can be challenging to implement and unanswered questions about its use and delivery remain. The standard of care regarding early mobilization and physical therapy involvement for patients in the ICU is highly varied depending on factors such as the type of facility (ie, academic vs community hospital) and the patient’s clinical scenario (ie, cerebrovascular accident vs chronic obstructive pulmonary disease).¹² The purpose of this article is to review the current research addressing early mobilization in patients undergoing critical illness, discuss how it can be implemented into practice, and identify areas for future research.

Management of critically ill patients has traditionally involved periods of immobility and bedrest and use of analgesic and sedative medications, and can require the use of MV. The deleterious effects of bedrest and medical management of critical illness have been well described.^13–16 Effects of bedrest are both physical and cognitive, including the presence of ICU-acquired weakness (ICU-AW)^14,15 and delirium.¹⁶ Furthermore, deficits can develop rapidly. Skeletal muscle strength has been shown to decrease by 1% to 1.5% per day of bedrest.¹⁷ In patients on MV, marked atrophy of diaphragmatic myofibers has been noted after 18 to 69 hours of inactivity and MV.¹⁸ In patients who develop delirium during the first 5 days of ICU stay, nearly half (45.2%) develop delirium on the second day after ICU admission.¹⁹

Strength deficits after critical illness can be profound and impact both short- and long-term patient outcomes. The incidence of ICU-AW in patients mechanically ventilated for at least 7 days is 25% to 58%.^20,21 In patients awake enough to participate in the Medical Research Council Scale for Muscle Strength (MRC) assessment, 25% had ICU-acquired paresis.²⁰ In a study including nonresponsive patients with myopathy (established using electrophysiologic studies), the incidence of neuromuscular dysfunction was 58%.²¹ Other studies have found this number to be even higher, between 50% and 100%.^22–24 The presence of neuromuscular dysfunction can contribute to difficulty weaning from the ventilator²⁵ and may be a predictor of prolonged ventilation.^26,27 In addition, the presence of ICU-AW has been associated with increased mortality.^21,28

Studies suggest that cognitive function and physical function influence each other.²⁹ Delirium associated with critical illness (ie, ICU-acquired delirium) impacts a majority of patients who are mechanically ventilated.^2,30 It is characterized by changes in arousal and other cognitive deficits that can fluctuate and can occur early in the course of critical illness.³¹ It requires the use of standard assessment measures, such as the Confusion Assessment Method for the ICU (CAM-ICU) for accurate identification.^32,33 Recently it has been noted that even validated tools such as the CAM-ICU may be suboptimal for identifying the presence of ICU delirium,³⁴ as sensitivity can be as low as 47%.³⁵ ICU-acquired delirium is independently associated with mortality.^2,36 Risk of death at 6 months² and 1 year³⁶ has been shown to increase 10% for every day spent with delirium. The presence of ICU-acquired delirium is also associated with longer hospital stay^30,37 and increased ICU and hospital costs.³⁸

The impact of critical illness is not limited to a patient’s ICU stay. The physical and cognitive impairments can persist long after hospital discharge, having profound effects on a patient’s physical function and QOL. Survivors of acute respiratory distress syndrome (ARDS) demonstrate persistent weakness 1 year after critical illness, and only 50% of ICU survivors are able to return to work.³ Patients demonstrate ambulation distance on the 6-minute walk test³⁹ that is reduced from norms 1^3,5 and 2 years⁵ after critical illness and have reduced QOL at 12⁶ and 23 months⁷ after discharge from the hospital and ICU, respectively. These deficits persist even when pulmonary function returns to near normal.³ Herridge and colleagues⁴ found that, in ARDS survivors, exercise capacity and mean score on the physical component of the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36)⁴⁰ were below normative values even 5 years after discharge from the ICU, despite return of pulmonary function to normal.⁴ In addition, lack of early mobility in the ICU has been associated with increased hospital readmission and death.⁴¹

Risk factors for the debilitating deficits associated with critical illness are many. Factors contributing to ICU-AW include systemic inflammation, seen as a response to sepsis and multisystem organ dysfunction. In addition, the use of medications such as corticosteroids and neuromuscular blocking agents, abnormal blood glucose levels, and immobility can contribute to ICU-AW.¹ Hypoglycemia and immobility can also contribute to neurocognitive changes, along with hypotension, hypoxemia, and sedation.⁴² Research aimed at controlling the multiple medical factors that may contribute to weakness and delirium is ongoing. Addressing immobility has been a recent “hot topic” toward which many groups are focusing in an effort to improve overall patient outcomes.

Immobility in the ICU is related to a number of factors. One is the use of sedative and analgesic drugs for critically ill patients undergoing MV. Drugs such as benzodiazapines, propofol, haloperidol, and opiates are often initiated to manage agitation and anxiety and facilitate medical care.⁴³ Addressing the effect of sedative use on patient outcomes, Kress and colleagues⁴⁴ described findings from a trial in which daily sedative interruption was performed, allowing patients to be awake and able to follow commands. This intervention was shown to be feasible and safe and resulted in a reduction in duration on MV and a reduction in ICU length of stay (LOS).⁴⁴

To build upon this intervention, a controlled trial paired periods of sedation interruption with physical therapy (PT) and occupational therapy (OT) very early in the patient’s hospital course.¹¹ PT and OT sessions were coordinated with daily interruption of sedation. Therapy sessions consisted of assisting the patient to sit at the edge of the bed, stand, ambulate, and perform activities of daily living such as dressing and grooming, even in the presence of MV and an endotracheal tube. Patients in the intervention group received PT and OT on average 1.5 days after intubation.¹¹ The majority of sessions (68%) were conducted while subjects were intubated and on MV.⁸ Patients who received early PT and OT demonstrated significant return to independent functional status (59% vs 35% of patients, P = .02) as measured by the Functional Independence Measure (FIM),⁴⁵ increased ambulation distance (33.4 vs 0 m, P = .004) at time of hospital discharge, more ventilator-free days (23.5 vs 21.1, P = .05), and 50% fewer days of delirium (2 vs 4, P = .02) at time of hospital discharge. Those in the control group received PT and OT 7.4 days after intubation.

Other studies have shown that mobilizing patients who are mechanically ventilated via an endotracheal tube is feasible and safe^46,47 and that patients mobilized early in their ICU stay have decreased ICU and hospital LOS.⁹ In addition to the practice of facilitating out of bed activity (eg, sitting, standing, and walking), use of cycle ergometry, in which the legs are cycled actively or passively as the patient remains in bed,⁴⁸ and electrical muscle stimulation^49,50 have shown promising results. Finally, protocols and algorithms have been described to help with decision making regarding initiation and progression of early mobilization and exercise.^9,51,52

As with many medical practices, there are questions regarding early mobilization that warrant further exploration. However, there are some relative certainties. To implement an early mobilization program, one must first have practitioners in a variety of disciplines who support the effort to mobilize patients early. Second, the coordination of care among a variety of critical care specialists must be addressed. Finally, there must be processes in place to facilitate the creation of an individualized plan for each patient to ensure timely and successful early mobilization.

It is clear that the approach to implementing early mobilization involves the entire care team. Gaining support from team members can be difficult, as there may be a perception that changing practice in the ICU may add a great deal of time and effort⁵³ to an already busy workload. The culture of an ICU may or may not endorse mobilizing patients who have traditionally been kept on bedrest. Reasons for this include insufficient knowledge of clinical outcomes, tendency to resist change, and the fact that ICU practitioners are often removed from the difficulties patients can face at the time of hospital discharge.⁵³ However, a number of groups have addressed the issue of culture as a hindrance to change.^10,54

Hopkins and colleagues⁵⁴ described the creation of an ICU, dedicated to improving outcomes for patients who were physiologically stable but still required MV. Mobilization was made a key priority and the article comprehensively describes the steps taken (Table 1) to ensure cooperation from all staff members. Among other initiatives, outcome data were collected and shared with the staff on a regular basis to reinforce the culture of early mobility. Positive outcomes included increased ambulation distance, with 69% of patients having ambulated more than 100 feet on the last day of treatment in the ICU and decreased ICU and hospital LOS by 3 days and 4 days respectively.⁴⁷ In another project, a full-time PTs and OTs were dedicated to the ICU as part of a larger quality improvement project designed to increase the utilization of therapy services. Needham and colleagues¹⁰ describes a 4-month quality improvement project in which processes were implemented to create an environment conducive to early mobilization. Changes included the modification of standard activity orders on medical ICU (MICU) admission to read “as tolerated” and a change in sedation practices that encouraged the use of “as needed” bolus doses rather than continuous intravenous infusions. Guidelines for seeking consultation with a PT or OT were developed; a PT, OT, and rehabilitation assistant were added to the MICU staff, and referrals to physiatry and neurology increased. In addition, significant education on complications of critical illness, benefits of early activity, sedation practice, and training related to rehabilitation of patients on MV was provided to all involved practitioners. Compared to the period of time before the initiation of the new processes, more patients received PT and/or OT while in the MICU (70% vs 93%, P = .04), patients received more rehabilitation sessions per patient (1 vs 7, P<.001) and demonstrated improved outcomes including improved sedation and delirium status (MICU days alert [30% vs 67%, P<.001] and not delirious [21% vs 53%, P = .003]).¹⁰

Table 1 Care process model

Mobilization in the ICU requires coordination of care. For example, to successfully mobilize a patient who is mechanically ventilated, sedation must be withheld, the patient must be assessed for level of arousal and presence or absence of delirium, ventilatory needs must be assessed (with ventilator settings altered as needed), and coordination with therapists must occur for the patient to be seen during periods of sedation interruption. Completing these steps traditionally would require bedside nurses and physicians who are responsible for assessing level of arousal and presence or absence of delirium, managing sedation, and, with the addition of respiratory therapists, implementing spontaneous breathing trials. Each step traditionally requires a designated health care professional to recognize when his or her contribution is required and to intervene accordingly.

Rather than maintain the practice whereby each practitioner focuses only on his or her typical responsibilities, a setting in which there is collaboration and overlap of duties (within their scope of practice) can better promote practices that improve patient outcomes. An example of this was outlined by Hopkins and colleagues when describing the creation of their specialty ICU. They describe a culture in which the roles of the members of the ICU team overlap and that additional training is provided so, for example, a nurse can initiate a respiratory treatment if the respiratory therapist is busy ambulating a patient.⁵⁴

Once the team has been established, creating a standardized series of objectives may be of benefit. A suggested example of this was developed by Vasilevskis and colleagues.²⁹ The authors describe an approach to managing the patient undergoing MV by which evidence-based therapies are “bundled” together in an effort to improve outcomes. Their “bundle,” abbreviated ABCDE, acknowledges that the optimal management of the intubated patient does not consist of early mobility alone but of multiple factors that need to be addressed. Along with mobilization, patients undergo sedative interruption, spontaneous breathing trials, and monitoring of delirium and level of sedation. It is a potentially useful outline of the steps needed to optimize the care of the patient who is critically ill and undergoing MV. The components of the bundle and an associated interdisciplinary model for its execution are outlined in Table 2, suggesting that the initiation of each of the components may become the responsibility of all professional disciplines, even requiring a change in the unit’s traditional scope of practice.

Table 2 Components of ABCDE bundle and suggested facilitators of each component

Admittedly, the suggestions in Table 2 and the example of a dedicated mobility unit⁵⁴ require individuals motivated to champion the implementation of a new process, an adequate number of staff and those proficient in treating patients undergoing critical illness, and, often, support from hospital administration. In some institutions, creating a formalized program in which support is given from all those who impact the hospital culture (administration, physicians, nurses, therapists, etc.) can be daunting and prevent the initiation of any implementation of early mobilization if “buy in” is not achieved at all levels. In these instances, it may be more feasible to approach a change in practice one patient at a time, working toward the aforementioned culture change in a gradual fashion, rather than trying to make global system changes at one time.