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Original Studies

Safety With Mobilization and Ambulation During Physical Therapy Sessions for Patients on Mechanical Circulatory Support 50 Days or Greater

Decker, Lauren M.; Mumper, Valerie A.; Russell, Scott P.; Smith, Beth A.

Author Information
Journal of Acute Care Physical Therapy: July 2019 - Volume 10 - Issue 3 - p 85-92
doi: 10.1097/JAT.0000000000000097
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The benefits of early mobility for critically ill patients are well known and have been shown to safely mitigate the negative sequelae of bed rest through the reduction of delirium and neuromuscular weakness and by promoting physical, psychiatric, and cognitive upregulation.1,2 Studies have also supported positive affective outcomes for hospitalized patients who are provided the opportunity to view and experience outdoor environments.3 Allowing these types of early mobility experiences appears especially important for patients who require prolonged intensive care unit (ICU) stays, as these patients are at an even greater risk of developing mood changes such as depression, anxiety, and post–intensive care syndrome that may influence their overall health outcome.4–7

Despite the benefits of early mobilization, patients in the ICU may remain on bed rest for extended periods due to numerous modifiable perceived barriers, including patient-related safety concerns, lack of equipment and staffing, attitude/culture, and process-related barriers.8 While inherent risks exist regarding potential disruption of standard ICU lines and equipment, the risks are potentiated for patients requiring mechanical circulatory support (MCS).

Mechanical circulatory support is designed to be used as a short-term support device for less than 30 days. It is indicated for patients with cardiogenic shock or acute respiratory failure whose conditions are potentially reversible. It may be used for recovery, as a bridge to durable ventricular assist device implantation, or as a bridge to heart/lung transplant.9 Given the extracorporeal nature of the inflow and outflow cannulas, the possibility exists for cannula movement and/or dislodgement. The sequelae from cannula movement and/or dislodgement pose the risk for suction events, rapid hemodynamic collapse, and exsanguination.10,11 Anecdotal evidence suggests that staff concerns regarding mobility-related line disruption, cannula dislodgement, or medical decompensation may further influence a culture of resistance to mobilization out of bed and ambulation of patients on MCS.12,13

Although manufacturers do not provide guidelines for MCS greater than 30 days or for use of the Centrimag pump with an extracorporeal life support oxygenator system, patients at many centers do remain on MCS for longer periods while awaiting recovery or transplant.9 Present manufacturer guidelines encourage bed-level range of motion and discourage out of bed mobilization; however, growing evidence supports safe patient mobilization and ambulation on MCS.9

Literature suggests that mobilization may be safe and feasible for patients on short-term MCS, but much of the preliminary evidence is limited due to small sample sizes, case report study designs, and restrictions to low-level activities within the bed and/or patient's room.14–16 Ko et al17 reported “no clinically significant adverse event in patients” during 31 physical therapy (PT) sessions with patients supported by extracorporeal membrane oxygenation (ECMO) who participated in mobility, though PT was stopped in 5% of sessions because of tachypnea or tachycardia. In a retrospective analysis of 100 patients receiving ECMO by Abrams et al,18 35 patients safely participated in PT without PT-related complications. In a recent retrospective cohort study by Wells et al,19 early mobilization while on extracorporeal life support was reported to be both feasible and safe, and those patients who mobilized with PT while on MCS achieved higher-mobility scores postcannulation, which resulted in higher rates of patients able to discharge directly home with family. Boling et al12 reported that patients with venovenous extracorporeal membrane oxygenation included in their nurse-driven mobility program were able to safely ambulate both within the ICU and in the hallways adjacent to the ICU, suggesting that leaving the ICU may be feasible.

Studies introduce the feasibility and safety of mobilizing patients on MCS greater than 30 days. Takayama et al20 described the safe ambulation of 14 patients receiving bilateral ventricular assist device support without adverse events during PT sessions, including 1 patient on MCS for 144 days, and Wells et al19 recently reported findings that included a patient on MCS for 114 days.

At our academic medical center, physical therapists have had the opportunity to help patients remain mobile as they await organ transplant for as long as 242 days on MCS, progressing ambulation out of the room and even off the unit with interdisciplinary collaboration. The growing incidence of this unique patient population at our center and the inherent risk factors of extended MCS utilization prompted the clinical question and purpose of this study: for critically ill patients on MCS greater than 50 days, can patients safely participate in mobility both inside and outside of the ICU as part of PT treatment interventions?


Data Collection

The University of Southern California institutional review board determined that the project (HS-17-00647) was exempt, as risks to subjects were minimized, the selection of subjects was equitable, and data were appropriately monitored and protected to maintain subject privacy. Retrospective data collection was completed at a single medical center using information from PT documentation in the electronic medical record. Data were collected on consecutive patients from 2012 through 2016 who received either venovenous extracorporeal membrane oxygenation via a double-lumen internal jugular catheter (Avalon cannula) or Centrimag bilateral ventricular assist device support. At the time of data collection, patients with femoral or central cannulation or venoarterial extracorporeal membrane oxygenation were not mobilized and were thus excluded from this study. Figure 1 depicts selection criteria.

Selection Criteria for Study Inclusion. BIVAD indicates bilateral ventricular assist device; MCS, mechanical circulatory support; PT, physical therapy; VV ECMO, venovenous extracorporeal membrane oxygenation.

This study focuses on the 13 patients who participated in PT while on prolonged MCS for greater than 50 days. The average length of support time was 103 days (standard deviation, 63; range: 50-242 days). Study data were collected and managed using REDCap electronic data capture tools hosted at University of Southern California. REDCap (Research Electronic Data Capture) is a secure, Web-based application designed to support data capture for research studies, providing (1) an intuitive interface for validated data entry; (2) audit trails for tracking data manipulation and export procedures; (3) automated export procedures for seamless data downloads to common statistical packages; and (4) procedures for importing data from external sources.21

Data collected were age, gender, number of PT sessions completed by each patient, mobility level achieved during each session, the occurrence of adverse events, duration of MCS, and indication for MCS.

Mobility Levels

Mobility levels were defined as follows: level 1 = no mobilization or passive range of motion of extremities, level 2 = turning in bed (including active-assisted range of motion of extremities, level 3 = sitting in bed with the head of bed elevated, level 4 = sitting on the edge of the bed with feet on floor, level 5 = sitting in a chair, level 6 = standing, level 7 = marching in place, and level 8 = ambulation. Each mobility level is further defined in Table 1. This mobilization scale was the adapted version of a validated ICU mobility scale as used by Abrams et al.18,22

TABLE 1. - Mobility Levelsa
Mobility Level Level of Activity Definition
1 No mobilization Passively rolled or passive ROM of extremities
2 Turning in bed (including active-assisted ROM of extremities) Actively assists with rolling and/or active-assisted ROM of extremities
3 Sitting in bed with the head of bed elevated Sitting with the head of bed elevated or in cardiac chair position in bed
4 Sitting on the edge of the bed with feet on floor May be assisted by staff but involves actively sitting over the side of the bed with some trunk control
5 Sitting in a chair Passively moved to chair from the edge of the bed (via mechanical lift equipment or a squat pivot transfer where patient is unable to advance either lower extremity including shuffling or stepping)
6 Standing Weight bearing through the feet in a standing position, with or without assistance
7 Marching in place Able to walk on spot by lifting alternate feet, with or without assistance
8 Ambulation Able to walk away from bed or in front of the bedside with or without assistance, including shuffling steps between bed and chair or commode
ROM, range of motion.
aAdapted from Abrams et al18 with permission from Biomed Central.18

Adverse Events

To address the research question of whether it was safe for patients to participate in mobility, data were collected on adverse events. Adverse events related to mobility were defined prior to data collection as either major or minor events. Major adverse events included: ground-level fall, dislodgement of cannulas or other invasive lines, bleeding from the cannula insertion site requiring interventions such as transfusions or additional suturing, decrease in mean arterial pressure by greater than 20 mm Hg, conversion to an unstable dysrhythmia that required intervention, or decrease in peripheral capillary hemoglobin oxygen saturation (Spo2) to less than 80%.12 Minor adverse events included oozing from lines that requires a noninvasive intervention such as a dressing change or transient decrease in Centrimag flows.


Patient Demographics

Patient demographics are shown in Table 2.

TABLE 2. - Demographics of Patients on Prolonged MCS for Greater Than 50 Days
Characteristic Mean (SD) or n (%)
Age 43 (17)
Female, n (%) 6 (46.2%)
Type of MCS, n (%)
VV ECMO 6 (46.2%)
BIVAD 7 (53.8%)
Indication for MCS, n (%)
CM 4 (57.1%)
Cardiogenic shock 3 (43.9%)
ARDS 2 (33.3%)
CF 2 (33.3%)
IPF 1 (33.3%)
Respiratory failure 1 (16.6%)
Days on MCS 103.23 (63.14)
ARDS, acute respiratory distress syndrome; BIVAD, biventricular assistive device; CF, cystic fibrosis; CM, cardiomyopathy; IPF, idiopathic pulmonary fibrosis; MCS, mechanical circulatory support; VV ECMO, venovenous extracorporeal membrane oxygenation.

Physical Therapy Sessions

Patients participated in a total of 454 PT sessions. Of this total, 199 (43.8%) occurred during the first 50 days on MCS support; 12 of 13 patients participated in these sessions. An additional 255 (56.2%) PT visits occurred after 50 days on MCS; 10 patients participated in these sessions, 1 of whom did not receive therapy prior to 50 days.


During 393 (86.5%) sessions, patients achieved at least mobilization to the edge of the bed. Patients achieved standing at the bedside in 319 (70%) of treatments, and 238 (52%) of total patient sessions progressed from standing at the bedside to pregait or ambulation (classified as achieving mobility levels 7 or 8). Table 3 shows the peak mobility level achieved during each PT encounter. Although data were collected for patients whose highest level of mobility achieved was sitting in a chair through passive assistance (level 5), data were not collected for patients who sat in a chair after reaching higher levels of mobility, such as those who sat in a chair for meals after therapy sessions focused on ambulation. The individual data for each of the 13 patients included in this review are represented in Table 4.

TABLE 3. - Peak Mobility Level Achieved During Physical Therapy Sessions
Peak Mobility Level Achieved Total Sessions (n = 454)
1 20 (4.4%)
2 27 (5.9%)
3 14 (3.1%)
4 66 (14.5%)
5 8 (1.8%)
6 81 (17.8%)
7 74 (16.3%)
8 164 (36.1%)
Gait outside of room 108 (23.8%)

TABLE 4. - Individualized Peak Mobility Levels Achieved, MCS Pathway, Survivorship, and Discharge Destination
Patient Type of MCS Days on MCS Total PT Sessions Peak Mobility Level (Number of Sessions) Pathway Survivorship D/C Disposition
1 2 3 4 5 6 7 8 (Total) 8 (Outside Room) Avg. Gait Distance (ft)
1 BIVAD 242 113 3 2 1 6 0 12 40 49 37 399 BTT* Y OPPT
2 BIVAD 226 73 1 5 2 7 3 24 1 30 7 31 BTT N
3 BIVAD 130 50 0 2 0 3 0 7 11 27 21 180 BTT* Y IRF
4 BIVAD 107 65 0 0 1 10 3 19 1 31 29 695 BTT* Y IRF
5 BIVAD 100 21 0 2 5 10 0 4 0 0 - - BTR N
6 ECMO 92 23 3 5 1 0 0 1 5 8 5 196 BTT N
7 ECMO 92 3 1 2 0 0 0 0 0 0 - - BTT N
8 BIVAD 81 21 0 1 0 11 0 2 2 5 0 3 BTR N
9 ECMO 62 27 1 1 2 10 2 6 3 2 0 5 BTR Y LTAC
10 ECMO 57 30 2 4 2 9 0 6 7 0 - - BTR Y IRF
11 ECMO 52 5 5 0 0 0 0 0 0 0 - - BTR N
12 ECMO 51 6 4 2 0 0 0 0 0 0 - - BTT N
13 BIVAD 50 17 0 1 0 0 0 0 4 12 10 123 BTT* Y OPPT
MCS, mechanical circulatory support; BTR, bridge to recovery; BTT, bridge to transplant; BTT*, transplant received; Y, survived hospitalization; N, expired during hospitalization; D/C, discharge; OPPT, home with outpatient physical therapy; IRF, inpatient rehab facility; LTAC, long-term acute care


Eight patients achieved level 8 ambulation during 164 (36.1%) sessions, and 66% of those sessions were completed outside of the patient's room and/or the ICU. Figure 2 illustrates the collaborative effort involved in a PT session conducted outside of the ICU. Gait distance ranged from 2 ft to 1800 ft, mean (SD) = 300.5 ft (372.3 ft). Interdisciplinary collaboration occurred during all sessions outside of patients' rooms to promote patient safety. At the study center, the interdisciplinary team typically involves a physical therapist, occupational therapist, respiratory therapist, nurse, physician, and, at times, a rehabilitation aide.

Mobilization of a Patient on Venovenous Extracorporeal Membrane Oxygenation.

Adverse Events

Adverse events occurred during 16 (3.5%) of 454 total sessions and are described in Table 5. Minor adverse events occurred in 14 (3%) of sessions and major events in 2 (0.5%) of sessions. Two major adverse events included (1) automatic implanted cardioverter defibrillator firing with conversion to a stable rate and rhythm requiring no further intervention, and (2) bleeding from cannula site noted at end of session that required surgical exploration; however, the patient was found to have no disruption of cannulas. Fourteen minor adverse events included (1) 11 transient drops in Centrimag flow with resolution upon repositioning the patient, and (2) 2 instances of oozing from dialysis catheter sites addressed with dressing changes. One equipment malfunction occurred during ambulation in the ICU hallway; the patient's pump failed. Because ambulation of patients on MCS requires interdisciplinary collaboration, a backup pump was present with the accompanying nurse, and emergent replacement took place immediately with no decompensation in the patient's medical status.

TABLE 5. - Occurrence of Adverse Events During Physical Therapy Sessions
Number of Sessions, n (%), n = 454
Minor events 14 (3.1)
Transient drop in Centrimag flow 11 (2.4)
Oozing from (non-MCS) catheter sites 2 (0.44)
Equipment malfunction 1 (0.22)
Major events 2 (0.4)
AICD firing 1 (0.22)
Bleeding from ECMO cannula site 1 (0.22)
AICD, automated implantable cardioverter defibrillator; ECMO, extracorporeal membranous oxygenation; MCS, mechanical circulatory support.

Adverse events occurred during PT sessions both before and after patients' 50th day on MCS. Eleven adverse events were experienced by 3 patients prior to 50 days; 10 events were minor and 1 was major. Five additional adverse events were experienced by 4 patients on prolonged MCS greater than 50 days, of which 4 were minor and 1 was major. Five patients account for all 16 events, 2 of whom experienced events both before and after their 50-day mark.


Table 4 exhibits the individual survivorship of patients on prolonged MCS included in this study. The majority of patients (61.5%) on prolonged MCS were awaiting heart or lung transplantation, and 50% of those patients survived to receive a donor organ. All patients who received a transplanted organ survived to discharge but required ongoing PT in either an inpatient rehabilitation facility or an outpatient setting. Fewer than half of the patients on prolonged MCS as a bridge to recovery survived to discharge. All of these surviving patients required continued PT in either inpatient rehabilitation facility or long-term acute care settings following their hospitalizations.


Evidence has long endorsed the benefits of PT's role within early mobility for critically ill patients, including those on short-term MCS support.14,16–20,23 The results of this study suggest that patients on prolonged (≥50 days) MCS support were able to safely participate in skilled PT visits outside of the room, outside of the ICU where, in our facility, patients are offered a view of the outdoors, or, for some, even the outdoors.

Although the occurrence of major and/or minor adverse events was low in this study (<4%), mobilization is not without risk. Interestingly, adverse events were more prevalent within the first 50 days on MCS despite a greater number of PT sessions completed after 50 days. The results suggest that adverse events may occur at any point during a patient's MCS course. Use of a multidisciplinary team is encouraged to optimize safety when mobilizing outside of patients' rooms. In this study, each team member's role contributed to the prompt management of all adverse events, allowing all patients to continue participation in skilled PT without negatively impacting their medical courses. Based on experience, we recommend that the following team members be present: physical therapist, registered nurse, and respiratory therapist if applicable for the management of supplemental oxygen. For some patients, the presence of a rehabilitation aide, occupational therapist, and/or family member is also beneficial.

As the prevalence of MCS systems increases and biomedical technology advances, ongoing studies establishing the efficacy and safety of different types of PT-driven mobility both inside and outside of patients' rooms for those requiring prolonged MCS need to be evaluated to support development of early mobility programs. Although this study reports a low risk of adverse events and no negative outcomes for 8 patients performing ambulation in 164 PT sessions, a risk/benefit ratio for this intervention could not be determined. The study design did not allow for testing the efficacy of the intervention itself, which should be assessed in future studies to determine the risk/benefit ratio. The lack of a control group limits further statistical analysis and impacts the generalization of results. Regardless of the study's limitations, this preliminary observational design may provide value to other centers with PT-driven early mobility programs. In future research aimed at addressing the safety of mobilizing this specific patient population, the authors recommend using a prospective approach with a larger sample size that compares with a control group.

This study has several additional limitations. Although data were collected for 75 patients, the inclusion criteria of PT consults and MCS duration for 50 or more days reduced the sample size to 13 patients. Additional loss to follow up occurred after patients expired or were weaned to decannulation from MCS, at which point data were no longer collected. As well, data were collected from a single medical center and excluded patients with femoral or centrally cannulated venovenous extracorporeal membrane oxygenation and all patients on venoarterial extracorporeal membrane oxygenation. Data collection in this study was dependent on documentation; therefore, some minor adverse events may not have been documented.

Because this study used an adapted version of the ICU mobility levels, direct comparisons cannot be made to previous articles that used the original or an adaptation of this tool.18 For this study, mobility levels 5 and 8 (bed to chair transfer and ambulation, respectively) were redefined, as seen in Table 1, to effectively capture data for patients who ambulated short distances, including bed to chair.


Patients who are critically ill and require prolonged MCS support can safely participate in PT. With a collaborative multidisciplinary team, safe ambulation both inside and outside of the ICU is possible for such patients. Opportunities for future research include the effect of PT on survivorship, postdischarge functional mobility, quality of life, and return to previous work, family, and life roles of those surviving prolonged MCS support.


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