Special Feature
Get out of Bed and Walk!
By Dean R. Hess, PhD, RRT, Respiratory Care, Massachusetts General Hospital, Department of Anesthesiology, Harvard Medical School, Boston, is Associate Editor for Critical Care Alert.
Dr. Hess receives grant/research support from Respironics and Pari; is a retained consultant for Respironics; and receives royalties from Impact.
Early in my career as a respiratory therapist, we had an unusual piece of equipment in the ICU — the Birdmobile. This distinctive piece of equipment was a souped-up walker with wheels, to which we added a Bird Mark 7 ventilator, oxygen tanks, and a seat. I wish I had a picture, but unfortunately this was long before the days of digital photography. The image remains sharp in my mind. We used this contraption to ambulate mechanically ventilated patients. The patient was removed from the Emerson, BEAR, or MA-1, attached to the Bird, and ambulated in the ICU. If the patient was strong enough, we would venture outside the ICU, and if the weather was good, we would even go outside. The seat allowed the patient to sit down if fatigued and I can remember pushing patients back to the ICU if they were exhausted. I can recall the special relationships that I developed with some of those patients and their families on these "road trips" — their faces come to mind as I write this.
That was in the 1970s. It was a simpler time to be sure. Our mechanically ventilated patients were awake by day and asleep at night. They followed commands and moved around in bed. We did not consider elevating the head of the bed to prevent ventilator-associated pneumonia because many of our patients spent much of the day out of bed in a chair. It was before the time of complicated ventilator modes and propofol. Today, most mechanically ventilated patients are confined to bed, heavily sedated, and physically restrained for their protection.
But are our current practices of bed rest and sedation for mechanically ventilated patients really protective? It has been increasingly reported that quality of life after critical illness is often sub-optimal. This is particularly true in the domain of physical function. The words "critical illness myopathy and neuropathy" were not part of our vocabulary 25 years ago. Today, survivors of ARDS have persistent physical disability for years after ICU discharge. The consequences of these acquired deficits may lead to disability, social isolation, institutionalization, and significant economic burden for society. A variety of factors are responsible for these physical deficits, including severity of illness, acute inflammation, corticosteroid administration, and use of neuromuscular blockers. But perhaps the most important risk factor is prolonged bed rest.1,2 Now, early in the 21st century, there is renewed interest in physical activity for mechanically ventilated patients.3
Mobility in the Medical ICU
Morris et al conducted a prospective cohort study of mobility in medical ICU patients with acute respiratory failure requiring mechanical ventilation on admission; 165 patients were mobilized and another 165 were not.4 An ICU mobility team initiated the protocol within 48 hours of mechanical ventilation. The team consisted of a critical care nurse, nursing assistant, and physical therapist, but unfortunately did not include a respiratory therapist. Patients who received mobility were out of bed earlier (5 days vs 11 days; P < 0.001), had physical therapy initiated more frequently in the ICU (91% vs 13%; P < 0.001), and had similarly low complication rates compared with usual care. For the patients who received early mobility, ICU length of stay was 5.5 days vs 6.9 days for usual care (P = 0.025). Also, hospital length of stay for patients receiving the mobility protocol was 11.2 days vs 14.5 days for usual care (P = 0.006). Importantly, there were no untoward events during any ICU mobility session and no cost differences. The authors concluded that a mobility team initiated earlier physical therapy and that this was feasible and safe, did not increase costs, and was associated with decreased ICU and hospital length of stay.
A methodologic weakness of this study was that ICU nursing unit assignment rather than randomization was used to allocate patients to the study groups. But perhaps a more important shortcoming was the absence of involvement by respiratory therapists. Thus, mobilization was limited to that which could be accomplished within the length of the ventilator circuit. Although patients were transferred from bed to chair and stood at the bedside, full ambulation was not feasible. Moreover, absence of a respiratory therapist precluded manipulation of the ventilator settings to compensate for any adverse effects on gas exchange (e.g., desaturation) that might occur during mobility.
Bailey et al utilized a team consisting of nurses, respiratory therapists, physical therapists, and critical care technicians to ambulate respiratory failure patients.5 This was a prospective cohort study to determine whether early activity is feasible and safe in this patient population. They enrolled all consecutive respiratory failure patients who required mechanical ventilation > 4 days who were admitted to their respiratory ICU. During the 7-month study period, they conducted 1449 activity events in 103 patients. The activity events included 233 episodes of sitting on bed, 454 episodes of sitting in a chair, and 762 episodes of ambulation. In patients with an endotracheal tube in place, there were 593 activity events, of which 42% were ambulation. The majority of survivors (69%) were able to ambulate > 100 feet at ICU discharge. Of note, there were < 1% activity-related adverse events including fall to the knees without injury, feeding tube removal, systolic blood pressure > 200 mm Hg, systolic blood pressure < 90 mm Hg, and desaturation to < 80%. It is particularly important to note that no patient was extubated during activity. The authors concluded that early activity was feasible and safe in this patient population. Although this study demonstrated that physical activity among mechanically ventilated patients in the ICU is feasible and safe, the lack of a control group precludes any conclusions related to patient outcomes.
In a recently reported study, Schweickert et al randomly assigned 104 patients to early exercise and mobilization (physical and occupational therapy) during periods of daily interruption of sedation (intervention; n = 49) or to daily interruption of sedation with therapy as ordered by the primary care team (control; n = 55).6 Every morning, unresponsive patients in the intervention group underwent passive range-of-motion exercises for all limbs. Physical therapy and occupational therapy were then coordinated with interruption of sedation. Sessions began with range-of-motion exercises in the supine position. If this was tolerated, treatment was advanced to bed mobility activities including transfer to upright sitting. Sitting balance activities were followed by activities of daily living and exercises that encouraged increased independence with functional tasks. The session progressed to repetition of sit-to-stand transfers from bed to chair, or bed to commode, and then to pre-gait exercises and walking. Return to independent functional status at hospital discharge occurred in 59% of patients in the intervention group compared with 35% of patients in the control group (P = 0.02). Patients in the intervention group had shorter duration of delirium (median 2.0 days vs 4.0 days; P = 0.02), and more ventilator-free days during the 28-day follow-up period than did controls (23.5 days vs 21.1 days; P = 0.05). There was only one serious adverse event in the 498 therapy sessions (desaturation to < 80%). Discontinuation of therapy as a result of patient instability occurred in only 4% of all sessions, most commonly for patient-ventilator asynchrony.
Conclusion
So what have we learned about early physical activity of mechanically ventilated patients? First of all, it appears to be safe. However, its safety with widespread application is not assured. Institutional protocols should be implemented to assure adequate monitoring and supervision during physical activity of these patients. Greatest benefit is likely the result of a multidisciplinary approach including intensivists, critical care nurses, respiratory therapists, physical therapists, occupational therapists, and critical care technicians. Each of these disciplines brings specialized expertise to maximize the safety and benefit of physical activity and ambulation. The optimal timing of initiation of physical activity in mechanically ventilated patients is unclear. Undoubtedly, patients should be hemodynamically stable before physical activity is started. It also seems prudent to forego physical activity if the patient requires high levels of ventilator support. Of course, the patient needs to be awake and cooperative, which depends in large part on the amount of pharmacologic sedation administered to the patient. For ambulation, a portable ventilator and monitoring equipment (heart rate and rhythm, blood pressure, pulse oximetry) should be used. At minimum, the patient should receive the same level of ventilatory support when physical activity is initiated and minute ventilation and oxygen levels should be increased as necessary as physical activity and ambulation progress.
Over the past 15 years, we have learned that daily spontaneous breathing trials lead to fewer ventilator days.7 We then learned that daily awakening also leads to fewer ventilator days.8 This has led to the practice of daily "wake-up-and-breathe" sessions, in which sedation is stopped and a spontaneous breathing trial is conducted. Such a protocol has been reported to shorten the duration of mechanical ventilation and afford a survival benefit.9 With the accumulating evidence supporting early physical activity for mechanically ventilated patients, perhaps the new paradigm should be, "wake up, breathe, get out of bed, and walk."
References
- Milbrandt EB. Use it or lose it! Crit Care Med 2008;36:2444-2445.
- Milbrandt EB. One small step for man … . Crit Care Med 2007;35:311-312.
- Needham DM. Mobilizing patients in the intensive care unit: Improving neuromuscular weakness and physical function. JAMA 2008;300:1685-1690.
- Morris PE, et al. Early intensive care unit mobility therapy in the treatment of acute respiratory failure. Crit Care Med 2008;36:2238-2243.
- Bailey P, et al. Early activity is feasible and safe in respiratory failure patients. Crit Care Med 2007;35:139-145.
- Schweickert WD, et al. Early physical and occupational therapy in mechanically ventilated, critically ill patients: A randomised controlled trial. Lancet 2009;373:1874-1882.
- Ely EW, et al. Effect on the duration of mechanical ventilation of identifying patients capable of breathing spontaneously. N Engl J Med 1996;335:1864-1869.
- Kress JP, et al. Daily interruption of sedative infusions in critically ill patients undergoing mechanical ventilation. N Engl J Med 2000;342:1471-1477.
- Girard TD, et al. Efficacy and safety of a paired sedation and ventilator weaning protocol for mechanically ventilated patients in intensive care (Awakening and Breathing Controlled trial): A randomised controlled trial. Lancet 2008;371:126-134.
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