Early Mobilization in the Intensive Care Unit: A Systematic Review

Abstract

Purpose

The purpose of this review is to evaluate the literature related to mobilization of the critically ill patient with an emphasis on functional outcomes and patient safety.

Methods

We searched the electronic databases of PubMed, CINAHL, Medline (Ovid), and The Cochrane Library for a period spanning 2000–2011. Articles used in this review included randomized and nonrandomized clinical trials, prospective and retrospective analyses, and case series in peer-reviewed journals. Sackett's Levels of Evidence were used to classify the current literature to evaluate the strength of the outcomes reported.

Results

Fifteen studies met inclusion criteria and were reviewed. According to Sackett's Levels of Evidence, 9 studies were level 4 evidence, one study was level 3, 4 studies were level 2, and one study was level one evidence. Ten studies pertained to patient safety/feasibility and 10 studies pertained to functional outcomes with 5 fitting into both categories.

Conclusion

A search of the scientific literature revealed a limited number of studies that examined the mobilization of critically ill patients in the intensive care unit. However, literature that does exist supports early mobilization and physical therapy as a safe and effective intervention that can have a significant impact on functional outcomes.

INTRODUCTION

The early mobilization of patients in the intensive care unit (ICU) has received considerable attention in clinical and scientific literature over the past several years.^1,2,3 A wide range of published reports has attempted to study the effects of mobilization and physical therapy on multiple factors including patient safety, ambulation capacity, muscle strength, functional outcomes such as activities of daily living, duration of mechanical ventilation, ICU length of stay, hospital length of stay, and mortality.

There are inherent complications to mobilizing critically ill patients that appear straightforward but are not well established. These apparent complications include, but are not limited to: tenuous hemodynamic status, severe weakness, multiple central catheters and life supporting monitors, artificial airways and operational factors such as variable rehabilitation work practices.^4,5,6,7

Studies have demonstrated that survivors of critical illness have impaired exercise capacity and persistent weakness, suboptimal quality of life, enduring neuropsychological impairments and high costs of health care utilization.^8,9,10,11,12 It has been hypothesized that ICU-based interventions may play a role in reducing these ongoing physical and neuropsychological impairments in ICU survivors in both the short- and long-term, highlighting the importance of studying this population.¹²

When patients require admission or readmission to the ICU, a period of enforced bed rest generally ensues. Despite knowledge of the deleterious effects of bed rest on multiple body systems,^13,14,15,16 the ICU is a complicated and difficult environment in which to mobilize the critically ill.^1,17 Multiple life-sustaining catheters and monitors, sedative medication used to calm agitation or reduce energy expenditure, impaired levels of alertness from medications, sleep disturbances, electrolyte imbalances, and tenuous hemodynamic status all are contributing factors that limit mobilization.

As critical care medicine improves and overall mortality decreases, survivors of ICU admissions are realizing greater morbidity. Severe weakness, deficits in self-care and ambulation, poor quality of life, hospital readmission, and death have all been reported in patients up to 5 years after discharge from the ICU.^12,18

Mobilizing patients in the intensive care environment is not without risk. Catheters and supportive equipment attached to patients can become dislodged and cause injury. Insertion and reinsertion of catheters can increase infection risk and cause unwanted stress and pain for patients and families already stressed by the medical acuity of the ICU. Critically ill patients with physiological derangements can have adverse hemodynamic responses to activity. Patients with limited aerobic capacity may respond to exertional stress with exaggerated heart rate and blood pressure responses or conversely may not have enough physiologic reserve to meet even the seemingly simple task of sitting on the edge of the bed.

Although the frequency of published reports related to mobilizing critically ill patients is increasing, the number of controlled, randomized trials is few. The purpose of this review was to examine the literature and characterize the clinical benefits of mobilizing critically ill patients found predominantly in the ICU, specifically related to safety and functional outcomes.

METHODS

Literature Search

The electronic databases of PubMed, CINAHL/Nursing, Medline (Ovid) and the Cochrane Library were searched as noted in Figure 1. The key search terms, “mobilization,” “exercise,” and “physical therapy” were combined with “intensive care unit” and “critical illness.” Reference lists of review articles and original publications were manually reviewed supplementing the electronic search to ensure that the database searches were comprehensive.

Figure 1.

Search algorithm.

Study Selection Criteria

Articles included in this review were: prospective randomized trials, prospective cohort studies, retrospective analyses, and case series. We further limited our inclusion to articles that focused on adults that were published in English between January 1, 2000 and June 1, 2011 to capture the most recently published work. Studies were evaluated to determine fit to the inclusion criteria by review of the title, and the list of potential articles was further sorted by reviewing abstracts by the primary author (JA). Studies were excluded if they were review articles, only studied nonmobility interventions, and/or described programs or protocols designed to promote early mobilization. If relevancy was questioned, both authors then collaborated on the final decision for inclusion.

Levels of Evidence

Sackett's Levels of Evidence were used to rate the strength of the research¹⁹ process where research was ranked from strongest to weakest using a 5 point grading system as outlined in Table 1. The authors (DM and JA) collaborated equally on scoring.

Table 1.

Sackett's Levels of Evidence

1A	Systematic Review of Randomized Controlled Trials (RCTs)
1B	RCTs with Narrow Confidence Interval
1C	All or None Case Series
2A	Systematic Review Cohort Studies
2B	Cohort Study/Low Quality RCT
2C	Outcomes Research
3A	Systematic Review of Case-Controlled Studies
3B	Case-controlled Study
4	Case Series, Poor Cohort Case Controlled
5	Expert Opinion

Adapted from Levels of Evidence. Oxford Centre for Evivdence-based Medicine - Levels of Evidence (March 2009) Website. Available www.cebm.net. Accessed September 26, 2011.

RESULTS

Fifteen studies were included in this review and submitted to analysis. Many outcomes were reported in the mobilization of critically ill patients and included a wide range of data. The studies were categorized into two groups based on the outcome addressed: safety and functional outcomes. Functional outcomes were further subdivided into one of 3 areas: muscle strength; quality of life/patient symptoms, and mobility. Some studies overlapped multiple categories. Of the studies reviewed, 4 reported on muscle strength, two on quality of life, and 13 on functional mobility.

Studies included both prospective and retrospective design while randomization occurred in just 3 studies.^20,21,22 The randomization in Chiang et al's study²² occurred in a postintensive care environment. Ten studies examined cohort populations or samples of convenience. Eleven of those were prospective.^{4,20,21,22,23,24,25,26,27,28,29} Four studies were retrospective analyses.^18,30,31,32 Two of those studied patients in a postacute environment.^30,31

Safety/Adverse Events

Of all studies reviewed, 10 papers reported data concerning untoward events (eg, line removal, extubation), physiological responses [eg, heart rate (HR), blood pressure (BP), pulse oximetry] and/or need for alteration in medical plan of care (eg, sedative or vasopressor administration). The authors (JA and DM) defined these events as pertaining to patient safety. As noted in Table 2 untoward events occurred in ≤ 4% of total patient interactions. The reviewed studies used specific physiologic responses and patient complaints (see Table 3) to initiate and terminate exercise or activity sessions. Bailey et al²³ consecutively enrolled patients with respiratory failure who required mechanical ventilation for >4 days. There were 14 activity-associated untoward events during 1,449 activity sessions, none of which were deemed serious. In the study by Pohlman and colleagues³² a descriptive analysis of the intervention arm of the study by Schweickert et al,²⁰ activity associated adverse events occurred in 16% (80 of 498) of therapy sessions with patients on mechanical ventilation. The authors describe many of the events as “expected physiological changes with exercise.” Examples include a HR increase greater than 20% of baseline (21 of 498 or 4.2 %), and a respiratory rate (RR) greater than 40 breaths per minute (20 of 498 interactions or 4.0%). Activity sessions were halted due to exceeding the predetermined criteria (see Table 3).

Table 2.

Safety and ICU Mobilization

Study	Study Design (N = subjects)	Sackett's Levels of Evidence	Physical Therapy Interventions	Safety profile	Other notable findings
Stiller K. 200427	Prospective One-group pretest-posttest design N = 160 total patients with 31 receiving mobilization	4	Functional mobility Supine-to-sit Sitting edge of bed Standing Transfers Ambulation	69 mobilization sessions with 31 patients (MV = 7 patients (23%)): 3 events (4%) during PT treatments (2 patients on MV) desaturation (≤ 88%) responsive to increased FIO2 Overall, no serious adverse medical consequences	Study highlights the physiologic responses (HR, BP, SpO2) and patient safety associated with mobilization Paper “reintroduces” an algorithm for safe patient handling pertaining to the acute care/ICU settings Only 31 of 160 of patients (19%) were mobilized following the screening process
Zafiropoulos B. 200429	Prospective One-group pretest-posttest design N = 17	4	Patients participated in progressive mobilization from supine> sitting> standing> marching × 1 minute for each activity	Minute ventilation increased due to increases in tidal volume & respiratory rate with standing with no additional increase with marching; the breathing pattern demonstrated greater upper chest versus abdominal excursion ABG values were normal HR/BP/MAP increased with mobilization from supine> sitting Overall, no adverse medical consequences	Study emphasized the hemodynamic and respiratory responses in patients who were s/p abdominal surgery ⋄ Included measurements of chest wall and abdominal movements to characterize the breathing pattern No hemodynamic or respiratory compromise Altered breathing pattern favored upper chest breathing/ventilation Pain was not monitored No control group for comparison
Bailey P. 200723	Prospective One-group pretest-posttest design N = 103 patients	4	Twice daily PT/activity sessions Functional Mobility Supine-to-sit Sitting edge of bed Standing Transfers Ambulation FIO2 was increase 0.2 prior to sessions	1449 PT/activity sessions: 14 events (<1%) occurred during PT sessions: falls to knees (×5) desaturation < 80% (×3) SBP<90 mm(×4) SBP>200 mmHg(×1) Nasogastric tube removal (×1) Overall, no serious adverse medical consequences	Study provides systems review criteria (neurologic/circulatory/respiratory) used to screen patients prior to mobilization Of the approximate 1500 activities performed: ⋄ Sit at edge of bed (16%) ⋄ OOB (31%) ⋄ Ambulate (53%) Age & co morbidities did not influence ambulatory status
Morris PE. 200825	Prospective Cohort study (N = 330; 165 intervention/protocol; 165 “usual” care”)	2B	Mobilization program implemented 7 days/week by “mobility team” consisting of: PT Critical care RN Nursing assistant	116 of 135 patients (80%) of protocol patients received PT during hospital stay for approx. 638 total PT sessions Therapy sessions not initiated if BP/HR outside of listed inclusion criteria (£ 1.4% of total sessions) Overall, no serious adverse medical consequences	Protocol for mobilization(activity algorithm) and criteria for limiting therapy sessions are well defined Mobility sessions primarily ended due to patient c/o fatigue without significant change in vital signs
Burtin C. 200921	Prospective RCT (N = 90 enrolled; 67 completed) (36 control; 31 treatment group)	2B	5 days/week Both groups received: Upper extremity ther. ex. Lower extremity ther ex. Functional training. Treatment group: Additional cycling session × 20 minutes total, daily	425 total exercise sessions 16 sessions (<4%) terminated due to desaturation <90% or HTN; 3 subjects withdrawn: ⋄ Achillestendon rupture (×1) ⋄ cardiorespiratory instability (×2)	Achilles tendon rupture could be considered a serious adverse event injury most likely due to the addition of cycling as a treatment modality cardio-respiratory instability not well defined in paper.
SchweickertWD. 200920	Prospective RCT (N = 104; all patients completed study)	1B	7 days/week Treatment group: Progressive UE/LE ther ex.; Trunk control/balance activities Functional training including ADL's	498 PT/OT sessions: 1 desaturation <80% 1 radial artery line removed PT/OT was discontinued during 19 sessions (4%) for perceived patient-ventilator asynchrony Overall, no adverse medical consequences	Protocol for mobilization and criteria for limiting therapy sessions are well defined Study supports that early PT/OT is safe and the primary event limiting patient participation in PT/OT was patient-ventilator asynchrony
Pohlman MC. 201032	Retrospective Descriptive study/case series using data from prior study (see Schweickert above) N = 49 patients	4	As noted above	In patients receiving MV, the primary reasons for missed therapy session MV asynchrony (<4%) MAP <65 mmHg(<1%) Vasoactive medication (<1 %) Active GIB (<1%) PT/OT sessions were terminated due to Desaturation >5% (6%) HR & MV asynchrony (4%) Agitation/discomfort (2%) Device/line removal (<1%) Overall, no adverse medical consequences	Early PT/OT is feasible & safe within 24–48 hours of ICU admission/MV PT/OT occurred on 87% of eligible days (n = 498 of 570); # of missed session similar between MV and extubated patients Patients performed more aggressive mobilization as they progressed from MV to extubation PT/OT sessions proceeded even though patients had central venous access/HD catheters; arterial lines; ETT/tracheostomy tubes Following extubation, PT/OT held primarily due to patient refusal (c/o fatigue)
Zanni JM. 20104	Prospective Pilot Project One-group pretest-posttest design (N = 32 eligible; 22 completed study to hospital discharge)	4	Observational report to define patient profiles and therapy services in ICU: consult & treatment frequency mobility/ADL's ROM/strength patient safety	50 reviewed PT/OT session with 19 patients Overall, no serious adverse medical consequences	Study identified common barriers & provides helpful recommendations to implement PT/OT in ICU setting over half of patients required post-acute rehabilitation following ICU stay 81% of patients had an episode of delirium
Needham DM. 201026	Prospective Quality Improvement (QI) project Case controlled (N = 57 total (27 pre QI; 30 post QI)	3B	Functional mobility Supine-to-sit Sitting edge of bed Standing Transfers Ambulation	Pre-QI: 210 PT/OT treatment session No events QI Period: 810 PT/OT treatment sessions 4 events (rectal or feeding tube displacement) Overall, no serious adverse medical consequences	Increased number of PT/OT consults & treatment sessions incorporating more advanced mobilization activities without increased incidence of adverse events
Bourdin G. 201028	Prospective One-group repeated measurements N = 20 consecutive patients	4	Functional mobility training (chair sitting; tilting up with & without arms supported, ambulation)	424 interventions with 13 events (3%) loss of muscle tone without fall extubation; desaturation <88%, hypotension Overall, no serious adverse medical consequences	Study emphasizes the physiologic responses associated with a variety of mobilization procedures Study determined barriers to rehabilitation Study determined that early mobilization was feasible and safe ⋄ Included use of equipment to facilitate upright/assisted standing

MV = mechanical ventilation, PT = physical therapy, OT = occupational therapy, FiO2 = fraction of inspired oxygen, HR = heart rate, HTN = hypertension

BP = blood pressure, SBP = systolic blood pressure, MAP = mean arterial pressure, SPo2 = saturation of peripheral oxygen, ICU = intensive care unit

ABG = arterial blood gas, OOB = out of bed, RN = nurse, s/p = status post, c/o = complains of, RCT = randomized controlled trial, Ther ex. = therapeutic exercise, ROM = range of motion, UE/LE = upper/lower extremity, ADL = activity of daily living, GIB = gastrointestinal bleed, HD = hemodialysis, ETT = endotracheal tube

Table 3.

Criteria for Terminating a PT/OT Mobilization Session as Summarized from the Literature

Heart Rate: >70% APMHR > 20% decrease in resting HR < 40 beats/minute; > 130 beats/minute New onset dysrhythmia New anti-arrhythmia medication New MI by ECG or cardiac enzymes	Pulse Oximetry/SpO2: > 4% decrease < 88%- 90%
Blood Pressure: SBP >180 mmHg > 20% decrease in SPB/DBP; orthostatic hypotension MAP < 65 mmHg; >110 mmHg Presences of vasopressor medication; new vasopressor or escalating dose of vasopressor medication	Mechanical Ventilation: FIO2 ≥ 0.60 PEEP ≥ 10 Patient-ventilator asynchrony MV mode change to assist-control Tenuous airway
Respiratory Rate: < 5 breaths/minute; > 40 breaths/minute	Alertness/Agitation and Patient symptoms: Patient sedation or coma – RASS ≤ −3 Patient agitation requiring addition or escalation of sedative medication; RASS >2 Patient c/o intolerable DOE Patient refusal

PT = physical therapy, OT = occupational therapy, HR = heart rate, RR = respiratory rate

SPo2 = saturation of peripheral oxygen, MI = myocardial infarction, ECG = electrocardiogram

BP = blood pressure, SBP/DBP = systolic/diastolic blood pressure, MAP = mean arterial blood pressure

FiO2 = fraction of inspired oxygen, Peep= positive end expiratory pressure, MV = mechanical ventilation

APMHR = age predicted maximum heart rate, RASS = Richmond Agitation Sedation Scale, DOE = dyspnea on exertion

Overall, the most commonly cited adverse event was oxygen desaturation. These episodes were of short duration lasting less than 3 minutes. In studies that reported on adverse events, accidental removal of patient support equipment happened rarely (<1%) further highlighting the safety of patient mobilization. Burtin et al²¹ reported one Achilles tendon rupture in their intervention group that used in-bed cycle ergometry. There were no serious adverse events that required life saving measures or alterations in the patient's medical care.

FUNCTIONAL OUTCOMES

Muscle Strength

Extremity muscle strength was measured by hand-held dynamometry or manual muscle testing [eg, Medical Research Council (MRC) scoring] in 4 studies as noted in Table 4 and defined in Table 5. Medical Research Council scores, handgrip, and extremity strength did not differ at time of discharge from the ICU^20,21 but Burtin et al²¹ showed increased quadriceps muscle force at time of hospital discharge. In postacute settings where patients were mechanically ventilated for a minimum of 14 days prior to transfer, strength gains were observed. In one study,³⁰ subjects were mechanically ventilated for a median duration of 46 to 52 days (22.8 ± 80.8 days) and demonstrated upper extremity/lower extremity (UE/LE) strength gains measured by dynamometry. In another study³⁰ patients were mechanically ventilated for 18.1 ± 7 days and also demonstrated UE/LE strength gains by manual muscle testing (MMT). Both studies found increases in respiratory muscle strength.

Table 4.

Outcomes of ICU Mobilization

Study	Study Design (N = subjects)	Levels of Evidence (Sackett)	Physical Therapy Interventions	Functional Outcomes			Other notable findings
				Strength/ROM	QOL	Mobility
Martin UJ. 200530	Retrospective One-group pretest- posttest design N = 49 enrolled; 49 completed study)	4	Treatment group underwent UE/LE ther ex., trunk control tasks; cycle ergometry, inspiratory muscle training and functional training × 5 days/week	Increased UE/LE strength as measured on 5 point scale; increased inspiratory muscle force (maximal NIF)	N/A	All patients bedridden initially; Following rehab program, patients demonstrated higher scores on FIM for supine <> sit and sit <> stand but no differences for ambulation/stairs	setting is a post intensive care unit (vent rehab unit; MV > 14 days) negative correlation between UE strength at admission and weaning duration no control group
Chiang LL. 200622	Prospective RCT (N = 39 enrolled; 32 completed study) (15 control; 17 treatment group)	2B	Treatment group underwent UE/LE ther ex., breathing retraining ex., and functional training × 5 days/week × 6 weeks	Increased UE/LE strength (hand-held dynamometry) and respiratory muscle force (PImax & PEmax)	N/A	Treatment group had higher scores on FIM and Barthel Index following 3 and 6 weeks of PT intervention	setting is a post-ICU ⋄ median MV days≥ 46 ⋄ may not be applicable to acute care/ICU increased vent free time in treatment group moderate correlation b/w limb strength and ADL performance and mobility impaired cognitive status at a baseline improved throughout intervention period small sample size
Bailey P. 200723	Prospective One-group pretest- posttest design (N = 103 patients)	4	Twice daily PT/activity session	N/A	N/A	Median distance ambulated by survivors was 64.6 meters	Study provides criteria (neurologic/circulatory/respiratory) for initiating mobility Study verifies that early mobilization of ICU patients can be achieved Increased number of co morbid conditions did not influence ambulatory status Ambulation distance at ICU discharge may predict post-acute d.c. destination No control group for comparison
Morris PE. 200825	Prospective Cohort study (N = 330; 165 intervention; 165 “usual” care”)	2B	Mobilization program implemented 7 days/week by “mobility team” consisting of PT, critical care RN and nursing assistant	N/A	N/A	Intervention group reached mobilization milestones sooner (eg: day to first OOB)	Protocol for mobilization is well defined Intervention group had shorter hospital & ICU lengths of stay potentially leading to cost savings Intervention group had increased PT frequency throughout hospital length of stay On average, protocol patients initiated OOB 7 days earlier compared to usual care No differences in MV duration or d.c. destinations Nonrandomized
Thomsen GE. 200824	Prospective One-group pretest- posttest design [N = 104 patients (91 Survivors)]	4	Functional mobility training (ROM; sitting at edge of bed and OOB; ambulation)	N/A	N/A	More advanced mobilization activities (OOB transfers & sitting; ambulation) increased within 24 hours of transfer to the unit where mobilization is emphasized	Mean distance of ambulation at d.c. was ≥ 200 feet Sedatives, even intermittent sedation administration decreased likelihood of ambulation female gender and reduced illness severity (ie, APACHE score) associated with greater ambulation
Schweickert WD. 200920	Prospective RCT (N = 104; all patients completed study)	1B	Treatment group underwent progressive UE/LE ther ex., trunk control/balance activities and functional training including ADL's × 7 days/week	No difference in UE/LE strength as measured by MRC or hand grip	N/A	Increased % of intervention group returned to functional baseline as defined by FIM and Barthel Index and had greater unassisted walking distance at hospital d.c.	Early mobilization associated with reduced incidence of delirium and ventilator free days MV did not preclude acquisition of mobility milestones Study included performance of ADL's 87% of therapy sessions completed No differences in ICU or hospital length of stay No differencein ICU-acquired weakness
Burtin C. 200921	Prospective RCT (N = 90 enrolled; 67 completed) (36 control; 31 treatment group)	2B	Both groups received UE/LE ther ex and functional training × 5 days/week treatment group had additional cycling session × 20 minutes total duration × 5 days/week	Hand held dynamometry: no difference in quadriceps muscle force at ICU d.c. but increased quadriceps muscle force noted at hospital d.c; No difference in hand grip strength at either time point	Improved QOL (SF-36 PF) at time of hospital d.c.	No differences at time of discharge from ICU. Treatment group had increased 6 MWT distance and at time of hospital discharge	moderate correlation between quadriceps strength and 6 MWT and SF-36 trends noted for proportion of patients who were ambulatory and/or discharged home (study not adequately powered) no differences in ability to transfer from sit <> stand or ambulate independently between groups no differences in weaning time, length of ICU or hospital stay
Needham DM 201026	Prospective QI project Case controlled (N = 57 total (27 pre QI; N = 30 post QI)	3B	Functional mobility training (supine to sit; sitting at edge of bed; OOB transfers; ambulation)	N/A	N/A	Greater percentage of patients engaged in more advanced mobilization (i.e.: OOB activities)	Additional QOL goals accomplished: increase number of PT/OT consults & interventions; reduction in missed PT/OT sessions reduced use of sedative drugs increased alertness with reduced delirium reduced ICU and hospital LOS
Morris PE 201118	Retrospective cohort analysis of survivors from prior study*** (see Morris 2008) N = 258 of 280 survivors of acute respiratory failure	2B	Mobilization program implemented 7 days/week by “mobility team” consisting of PT, critical care RN and nursing assistant	N/A	N/A	Patient participation in an ICU mobilization program was associated with reduced hospital readmission or death in the year following hospitalization	Study determined additional variables associated with hospital readmission including female gender, co-morbidties, and tracheostomy >50% of survivors will have a readmission or die in the year following hospitalization
Montagnani G 201131	Retrospective Non-equivalent Pretest-Posttest Control Group Design (N = 56 weaning program (WP); N = 63 pulmonary rehab (PR))	4	WP patients performed UE/LE ther. ex including UE/LE cycling and mobilization 6 days/week PR subjects exercise on treadmill/UE/LE ergometer and low intensity PRE's daily × 15–21 days	N/A	Dyspnea scores declined in both groups	Both groups demonstrated improvement in FIM scores	Setting was post-acute/long-term weaning center Included objective measurement of dyspnea FIM may be useful outcome tool in this novel setting for patients who require prolonged MV ⋄ Patients who are deemed “difficult to wean” Not randomized with small sample size

PT = physical therapy, OT = occupational therapy, MV = mechanical ventilation, NIF = negative inspiratory force, QOL = quality of life, N/A = not applicable

FIM = functional independence measure, PImax= peak inspiratory pressure, PEmax= peak expiratory pressure, HR = heart rate, ICU = intensive care unit

D.C.= discharge, c/o = complains of, s/p = status post, OOB = out of bed, RN = nurse, RCT = randomized controlled trial, LOS = length of stay

APACHE = acute physiology and health evaluation score, 6MWT = six minute walk test, MRC = Medical research council SF-36 = short form health survey

Table 5.

Medical Research Council (MRC) Scoring System for Muscle Strength^*

Score	Description
0	No visible contraction	Movements Assessed
1	Visible muscle contraction, but no limb movement	Upper Extremity:	Lower Extremity:
2	Active movement, but not against gravity	Shoulder abduction	Hip flexion
3	Active movement against gravity	Elbow flexion	Knee Extension
4	Active movement against gravity and resistance	Wrist extension	Dorsiflexion
5	Active movement against full resistance

Maximum score: 60 (4 limbs; 3 movements per extremity with maximum score of 15 points per limb)

Minimum score: 0 (quadriplegia)

^*Adapted from Schweickert and Hall. ICU-Acquired Weakness. Chest 2007;31:1541−1549.

Functional Mobility: The most frequently described functional outcomes assessed were: time to mobility milestones [eg, time to first out of bed (OOB), standing]; ambulation distance,²⁴ the Barthel Index,³³ the Functional Independence Measure (FIM)³⁴ or select parts of the FIM [Functional Status Score in the ICU (FSS-ICU)].⁴ The FSS-ICU, similar to the FIM, rates functional activities between 1 (total assist) and 7 (complete independence). A score of 0 is assigned if a patient is unable to perform a task. Only 5 of the items from the FIM are included: (1) rolling, (2) transfer from supine to sit, (3) sitting at the edge of bed, (4) transfer from sit to stand, and (5) ambulation are combined in the cumulative FSS-ICU score.⁴

Mobility milestones were accomplished earlier in the intervention groups than the comparison groups in 4 studies.^20,24,25,26 Compared to controls, ambulation frequency was greater in the study by Thomsen et al²⁴ and ambulation distance was greater at time of hospital discharge in the studies by Schweickert et al²⁰ and Burtin et al.²¹

Objective measures such as the FIM & Barthel Index improved in the intervention groups at time of hospital discharge but without significant differences at time of ICU discharge in the study by Schweickert et al.²⁰ In the postacute care setting, bed mobility and transfers were improved in 3 studies^22,30,31 but ambulation/locomotion were only improved in the studies by Chiang et al²² and Montagnani et al.³¹

Quality of Life & Patient Symptoms: Burtin et al²¹ noted improvements in the physical functioning (PF) subscore of the SF-36 at time of hospital discharge but quality of life (QOL) was not reported for the transition from ICU to ward. Dyspnea was measured in the postacute care setting in the study by Montagnani et al.³¹ These patients were hospitalized for approximately 40 days prior to postacute admission, had tracheostomies, and required prolonged mechanical ventilation. The symptom of dyspnea was reduced following the rehabilitation period.

DISCUSSION

The focus of critical care medicine in the ICU is restoration of physiological or hemodynamic stability and prevention of death. The historical approach to achieve these goals has included long periods of immobility and bedrest. The impact of life-sustaining ICU technology on patients that have required sedation, long-term mechanical ventilation, and bedrest has been profound with respect to severe muscle weakness, functional impairments, and loss of quality of life.¹⁵ By understanding the negative sequella of ICU-induced bed rest, investigators are attempting to correct these derangements by reducing the dosage and frequency of sedative medication and mobilizing critically ill patients once hemodynamic stability has been achieved. We have reviewed published reports that have studied this clinical approach.

Safety: Studies included in this review persuasively conclude that the mobilization of critically ill but stable patients in the ICU and immediate postacute environment, who have required a period of mechanical ventilation, can be done safely with minimal risk to the patient. Although most studies included patients receiving 4 or more days of mechanical ventilation, Pohlman et al²⁰ demonstrated the safety of physical therapy intervention occurring within two days of intubation. The most common untoward event was transient oxygen desaturation that was attenuated by rest and increasing the FiO₂ delivered to the patient. Line dislodgment and/or accidental extubation, frequently mentioned dangers of mobilization, happened rarely, further highlighting the safety profile of patient mobilization.

In all studies, hemodynamic, respiratory, and cognitive criteria were established a priori to ensure patient safety (Table 3). These criteria guided the clinicians to determine patient eligibility for mobilization and, it is presumed, limited untoward events by providing the treating physical therapist and/or occupational therapist parameters to guide the intensity of the mobilization sessions. Mobilization was loosely described in most studies citing therapist discretion for advancing activities based on patient tolerance and stability. However, Stiller et al²⁷ provided an algorithm for initiating and terminating therapy sessions based on physiologic and laboratory data while Morris et al²⁵ provided an algorithm for mobility progression based on patient's physical capabilities.

Overall activity-induced increases in HR, BP, respiratory rate (RR), tidal volume, and minute ventilation were within acceptable ranges, challenging the perception that patients in the ICU are “too sick” to participate in mobilization activities.^4,27,28 As noted multiple studies have reported on safety and feasibility but the lack of reported negative events could reflect a bias of nonreporting of adverse incidents.

Muscle Strength: Although it is generally accepted that patients in critical care settings for prolonged periods of time are often “bed ridden,” deconditioned, and weak, muscle strength was infrequently reported as an outcome measure in the reviewed studies. In studies that did address muscle force production, strength was not significantly improved in the ICU^20,21 but did improve by the time of discharge from the hospital.²¹ Interestingly, strength was consistently improved in the postacute care setting.^22,30

Functional Mobility: The literature reviewed supports improvements in functional mobility following early and progressive physical therapy/occupational therapy (PT/ OT) in the ICU but the measurement of this outcome was not uniform across the literature. For example, as mentioned in the results section, variability of outcome measurements included acquisition of mobility milestones,^{18,20,21,23,24,26}

FIM,^20,22,30,31 FSS-ICU,⁴ and the Barthel Index.³³ Time to mobility milestones was reduced and patient participation in advanced mobilization activities occurred more frequently in ICUs where mobilization and PT/ OT were emphasized.^20,24,25,26 Within the ICU setting, objective measures such as the FIM & Barthel Index were used infrequently although two of the cited studies used these tools.^4,20

The FIM and Barthel Index scores improved in the intervention group in the study by Schweickert et al²⁰ with over 59% of patients achieving functional independence (FIM ≥ 5) compared to 35% of the control group at time of hospital discharge. The FIM scores also improved following rehabilitation in the postacute setting.^22,30,31 Use of the FIM, or the related FSS-ICU⁴ to measure patient disability and to compare functional outcomes is attractive since the tool is well known to rehabilitation professionals. However, the validity and reliability of this tool has not been established in the ICU setting.

Quality of Life & Patient Symptoms: Quality of life and patient symptoms were seldom measured within the ICU. One study²¹ measured QOL and one study measured patient's symptoms.³¹ Burtin et al²¹ demonstrated improvements in the physical functioning domain of the SF-36 at hospital discharge while Montagnani et al³¹ reported reduced patient dyspnea. As noted in the introduction, quality of life and neuropsychological impairments such as depression, anxiety, and posttraumatic stress disorder are negatively impacted by prolonged mechanical ventilation and ICU duration. Rehabilitation in the ICU and its influence on these factors should be an area of future research.

The physiology and complications of bed rest are well understood. Intensive care unit-acquired weakness and functional dependency are recognized as unfortunate consequences of prolonged duration in ICUs and mechanical ventilation. Although sedative medications are used to reduce metabolic energy demand for patients in respiratory failure they inhibit participation in exercise and functional activity and often cause disturbances in levels of arousal. Despite the inherently complex environment and challenges that face critical care teams, including the human resources required to safely mobilize patients, feasibility and safety has been demonstrated as noted in Table 2. Critically ill patients can exercise, sit up, transfer to bedside chairs, and ambulate in the hallways; however, few published papers have randomized and controlled this intervention. The work of Schweickert et al,²⁰ Burtin et al,²¹ and Chiang et al²² have found that participation in monitored programs of physical activity can lead to statistically significant improvements in ambulation independence, reduced duration of mechanical ventilation, better ability to perform self care activities, and improved respiratory function.

CONCLUSION/IMPLICATIONS FOR FUTURE RESEARCH

In summary, the body of evidence that has studied the mobilization of critically ill patients is small. The few randomized controlled trials include a total of only 171 patients limiting the strength of evidence. Based on the studies reviewed, early physical therapy and ICU mobilization is feasible and safe. Acquisition of mobility milestones is enhanced in ICUs that promote early rehabilitation. Improvements in quality of life and muscle strength cannot be determined at this time.

In reviewing the literature, there are several questions that must be addressed. These questions include, but are not limited to: (1) How do published papers reflect current practice as mobilization has been reported in a small percentage of ICUs? (2) What is the appropriate level of clinical expertise or experience required to safely work in a critical care environment? (3) What intensity, frequency, and dose of physical activity will lead to optimal patient outcomes? (4) What generalization to other patient populations can be made since the majority of patients studied are found in medical ICUs? (5) Should all patients who require mechanical ventilation or ICU admission be referred to physical therapy? And (6) Are there optimal patient populations who would benefit most from early mobilization, as well as populations for whom physical therapy is clearly contraindicated? The answer to these questions will provide an evidence-based approach to optimize patient outcomes for the critically ill patient.