Special Feature

What Benefits Do Physical Therapy Confer on Critically Ill Patients?

By Leslie A. Hoffman, PhD, RN, Department of Acute/Tertiary Care, School of Nursing, University of Pittsburgh, is Associate Editor for Critical Care Alert.

Examination of patient outcomes beyond survival has become an important focus of critical care research in the last decade. A substantial body of literature supports the conclusion that patients who experience critical illness face a lengthy recovery, especially if the need for mechanical ventilation is prolonged.1 There are also adverse psychosocial outcomes, including depression, post traumatic stress syndrome, and increased caregiver burden.2 If patients are to recover to their prior functional status, they are likely to require an extended period of rehabilitation. This essay will discuss the barriers and benefits to instituting a mobility therapy protocol early in the recovery phase of critical illness.

Risk Factors

The best rehabilitative approach involves minimizing factors that predispose to muscle weakness and deconditioning and limiting the duration of mechanical ventilation. Several strategies for accomplishing this goal are shown in Figure 1 (below).3

Among these strategies, attempts to minimize weakness or deconditioning using mobility therapy have received the least attention.4 An increasing body of evidence suggests that attention to such techniques can have substantial benefits in patients who require ICU admission.

Who Can Be Mobilized?

Critically ill patients are commonly viewed as "too sick" to tolerate any activity, and therefore best managed by sedation and rest. In a study designed to evaluate the safety and feasibility of early mobilization, Bailey, et al5 began an activity protocol "early" in critical illness and continued this protocol until ICU discharge. Three criteria were used to define patient readiness to begin the protocol: neurologic, respiratory and circulatory. Neurologic criteria required that the patient respond to verbal stimuli (purposeful response). Respiratory criteria required an inspired oxygen fraction of less than 0.6 and positive end-expiratory pressure less than 10 cm H2O. Circulatory criteria required absence of orthostatic hypotension and catecholamine drips.

Over one year, 103 patients participated in 1,449 activity events, defined a priori as sitting on edge of bed without back support (n = 233), sitting in a chair after transfer (n = 454), and ambulation with or without assistance (n = 762). Of these patients, the majority (89%) were on mechanical ventilation. Nine patients experienced an adverse event, all minor, such as falling to the knees without injury, a drop in blood pressure to < 90mm Hg, or a fall in oxyhemoglobin saturation to < 80%. Of importance in today's cost-conscious healthcare environment, the intervention was carried out in a budget-neutral manner by a team consisting of existing ICU staff (nurses, respiratory therapists, physical therapists and critical care technicians). Similar success in safely achieving early mobility has been reported by several other centers,6-8 suggesting that, when patients meet criteria for stability, mobilization can be safely begun early in recovery.

Passive activity also seems to have benefits. Griffiths et al9 enrolled 5 critically ill patients who required neuromuscular blockade in a protocol wherein one leg of each patient was treated with continuous passive motion for three 3-hour periods daily for 7 days and the other leg received routine nursing care for 7 days. Continuous passive motion prevented atrophy and there was an 11% gain in fiber area compared with a 35% decrease in controls. Zanotti et al10 compared the effects of active limb mobilization with or without electrical stimulation on muscle strength in 24 patients with COPD who remained bed-bound and ventilator dependent after 50 days in the ICU. Elective stimulation plus active limb mobilization improved muscle strength (p = .02) and shortened the time required to perform a bed-to-chair transfer (10.8 ± 2.4 vs. 14.3. ± 2.5 days; p =.001).

What are the Benefits and Risks of Early Mobility?

Potential benefits of mobility therapy include a decreased hospital and ICU length of stay,6 higher level of functional ability at ICU discharge,5 decreased time to wean on transfer to a long-term acute care setting,11 and greater likelihood of discharge to home.12 Morris et al,6 from a study in which an ICU mobility team (RN, Nursing Assistant, Physical Therapist) rotated among 7 ICUs, reported that protocol patients (n = 150) experienced a shorter ICU length of stay (9.3 vs 10.3 days; p = .04) and hospital length of stay (14.4 vs 16.3 days; p =.008), compared to non-protocol patients. Bailey et al5 reported that patients who began a mobility protocol in the ICU progressed faster in regaining functional ability after transfer to a rehabilitation unit.

You, et al11 reported that patients who were able to perform rudimentary movements, such as rolling, scooting, or going from supine to sitting in bed, at admission to a long-term acute care facility were more likely to wean from mechanical ventilation (p < .04) compared to those without this level of functional ability. In 80 patients on PMV (≥ 7 days) we12 identified three variables that predicted ability to return home at 6 months after ICU discharge; these were the Acute Physiology Score at ICU admission, functional ability at ICU discharge, and comorbidity.

There are also barriers to initiating early mobility. 4,13,14 ICU clinicians have concerns that early mobility might dislodge a vascular access device or the endotracheal tube. There is the potential that any additional movement, even passive exercise, will compromise oxygenation of hemodynamic parameters. The goal of maintaining the patient in a calm, pain-free and sedated state competes with the goal of early mobility. There are also concerns about the ability to justify the additional workload and costs, given the limited number of studies to date that provide evidence for benefit. A review of the limited evidence to date suggests that these concerns should not be viewed as obstacles, if appropriate patient selection, monitoring and timing are used.4,13,14

What can be Accomplished after Transfer from the ICU?

Mobility therapy is an important component of rehabilitation in long-term acute care and rehabilitation settings.15-17 Martin et al16 instituted a rehabilitation program for patients transferred to a ventilator weaning unit that included 30-60 minute sessions by a physical therapist 5 days a week; the sessions were provided during weaning trials if the patient could breathe for > 4 hours without ventilatory support. The initial phase of the program concentrated on posture and trunk control, following by standing and ambulation. Inspiratory muscle training was included if the patient could breathe independently for > 2 hours. Of interest, patients who weaned in 7 or fewer days had higher upper limb motor strength scores compared to those who required > 7 days to wean. Three variables were found to be significant in terms of weaning time: upper motor strength, exposure to neuromuscular blocking agents, and systemic steroids. Using regression analysis, an increment of 1 point in the upper extremity motor strength scale led to a reduction of ~ 7 days in weaning time.16

Several additional strategies are being tested to determine their ability to improve muscle function and, hence, ability to wean from mechanical ventilation. Patients who required prolonged mechanical ventilation (~ 50 days) and received inspiratory muscle training improved weaning success compared to patients who received a sham treatment (72% vs 40%, respectively).18 Inspiratory muscle training consisted of 4 sets of 6-10 breaths through a threshold inspiratory muscle trainer at the highest setting tolerated 5 days a week until weaned or for 28 days.

Unanswered Questions

Despite these promising results, there continue to be many unanswered questions that create barriers to implementation of mobility therapy. Clearly, the primary concern is safety. More studies are needed to allay this concern. There is a deficit of information on the nature of muscle injury and muscle recovery following critical illness.14 Consequently, it is difficult to develop protocols to reverse these deficits. Safety parameters need to be defined, as do optimal program components, duration and timing of therapy, and training to accomplish goals.

Summary

The concept that mobility therapy can hasten recovery is intrinsically appealing. However, there have been many ICU therapies that have had the same initial "box office appeal" but have failed to confer promised outcomes. More studies are necessary to better define the potential of this intuitively appealing means to improve long-term outcomes in chronically, critically ill patients.

References

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  4. Morris PE. Moving our critically ill patients: Mobility barriers and benefits. Critical Care Clinics. 2007;23:1-20.
  5. Bailey P, et al. Early activity is feasible and safe in respiratory failure patients. Crit Care Med. 2007; 35:139-145.
  6. Morris PE, et al. A mobility protocol for acute respiratory failure patients delivered by an ICU mobility team shortens hospital stay (abstract). Crit Care Med. 2006;34:A20.
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  9. Griffiths RD, et al. Effect of passive stretching on the wasting of muscle in the critically ill. Nutrition. 1995; 11:428-432.
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  11. You D, et al Does early mobility influence outcome of patients being weaned from prolonged mechanical ventilation? (abstract). Proceedings of the American Thoracic Society. 2006; 3:A41
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