Bridging the Gap to Recovery with Physical Therapy on ECMO

Shea Sparks, MD, MS
PGY 2 - Emory Emergency Medicine

We’ve all seen the viral videos of patients connected to dozens of machines by an array of precisely positioned tubes flocked by a team of people while they walk down a hallway or even ride a bike outside. They capture the world’s attention for many reasons, but when you consider what’s happening in those videos and what it means for the patient, they become even more significant. One of the most complex examples of physical therapy and occupational therapy (PT/OT) for critically ill patients involves ambulating those on extracorporeal membrane oxygenation, or ECMO.

ECMO is an advanced form of life support used in severe cases of cardiac or respiratory failure that have failed to respond to conventional medical therapies as a temporary “bridge” to definitive treatment or recovery. While there are several different configurations, the two major types of ECMO include venoarterial (VA) for primary cardiac failure and venovenous (VV) for primary respiratory failure. ECMO functions as an external circuit consisting of a blood pump, a membrane lung, and conduit tubing, and involves cannulating the large vessels of the neck or the groin.¹

Traditionally, patients receiving ECMO support are also mechanically ventilated. However, in recent years, the concept of “awake” ECMO in non-intubated patients has been gaining traction, as it has the potential to avoid the additional complications inherent to mechanical ventilation and sedation.² There are 800 ECMO centers across the globe,³ but of those, only a small portion regularly participate in “awake” ECMO, and an even smaller portion make PT and early mobilization a routine part of the treatment plan.

While the advent and advancement of support devices like ECMO continue to improve survival rates of critically ill patients, the incidence and prevalence of complication rates in these patients continues to rise, as well. Notably, the inactivity and immobility often required during the acute phase of critical illness is known to have deleterious physiological effects on a variety of organ systems.⁴ For example, critical illness myopathy (CIM) involves a primary myopathy in critically ill patients resulting in weakness and profound muscle atrophy ultimately progressing to flaccid paresis or plegia and can include the respiratory muscles. This often presents as difficulty weaning ventilation or a failure to thrive but is also characterized by profound histologic changes on a microscopic level.⁵ While barriers to understanding its incidence and etiology remain, the prevalence of CIM has been estimated at 40%.⁶ CIM often results in prolonged ICU stays, increased morbidity and mortality, and an increased need for intensive rehabilitation at discharge.⁷ Other risks of prolonged immobility include increased risk for pneumonia, pressure ulcers, deep vein thromboses, delirium, and overall deconditioning.

Patients requiring mechanical circulatory support (MCS), including ECMO, are vulnerable to developing CIM. Many MCS devices are placed via the groin, limiting a patient’s ability to sit upright, and all MCS devices come with the risk of life-threatening device complications or bleeding if moved or dislodged during activity. This results in many MCS and ECMO patients remaining intubated for prolonged periods of time or, if extubated, being placed on strict bed rest precautions.⁸ As such, the opportunity to improve early mobility in these vulnerable patients could have a significant influence on the clinical trajectory and overall recovery. Outside of the physical benefits, the mental and emotional toll on MCS patients requiring prolonged bed rest and intensive care unit (ICU) admissions is substantial.^9,10 The potential benefits of physical therapy in critically ill patients is vast, and includes improved clearance of secretions, pulmonary recovery with decreased ventilator days and improved respiratory function, improved functionality, and maintenance of muscle mass.^11,12

The integration of PT/OT into the ICU care of ECMO patients is key but remains variable, based on the specific center, hospital culture, available resources, and the comfort levels and experience of the involved team members.⁴ Despite the significant potential benefits of early rehabilitation, there are a number of both modifiable and nonmodifiable factors that change the likelihood of early PT and mobilization as demonstrated by Tonna et al.¹³ Modifiable factors associated with an increased likelihood of early mobilization include center experience/higher patient volume, use of a dual lumen cannula (generally not applicable in VA ECMO), and bridge to transplant as the indication for MCS. Nonmodifiable factors include patient gender, patient weight, ethnicity, and number of chronic comorbidities. Deciding whether a patient would benefit from PT while on MCS requires consideration of a number of variables. Many patients on MCS, to include ECMO, have a variety of concomitant medical conditions that may require heavy sedation or immobility. However, best practices for all ICU patients –including those on ECMO – involve minimizing or eliminating continuous sedation whenever possible. While the ability to ambulate is valuable, PT can also be done in a patient’s bed with range of motion exercises and a gradual increase in mobility. Additionally, it is important to note that patients do not need to be extubated to participate in physical therapy nor to ambulate in the ICU. 

There are no standard guidelines for mobilizing ECMO patients from the international ECMO society ELSO (Extracorporeal Life Support Organization), but some non-ECMO organizations, such as the UK Physiotherapy Network, have developed some basic risk versus benefit guidelines¹⁴ and outlines for appropriate patient selection. As demonstrated by Abrams et al., there are some centers that have developed institutional guidelines and protocols for the initiation of PT with ECMO, which can have significant influence on the center’s ability to provide these services.¹⁵ Within this institutional framework, using ECMO as a bridge to transplant, the use of VV ECMO, and higher Charlson comorbidity index were identified as being predictive of an increased likelihood of mobilization while on ECMO. Alternatively, the use of mechanical ventilation, femoral cannulation, earlier year of cannulation, and use of ECMO as a bridge to recovery were associated with a decreased likelihood of earlier mobilization. While femoral cannulas were associated with a lower likelihood of mobilization, they have been used as an initial cannulation strategy in certain centers, due to ease of placement. There is evidence to support the safety and feasibility of PT in ECMO patients with femoral cannulas, but the data is limited and fear of catastrophic complications of this approach still limits its routine use.¹⁶ Aside from patient selection criteria, the importance of a cohesive team to support this endeavor is essential in maintaining safety. It takes a minimum of three team members, but often more, to adequately mobilize patients without complications while on MCS, including a qualified physical or occupational therapist, ECMO trained registered nurse, respiratory therapist for airway monitoring as applicable, perfusionist or ECMO specialist, additional nursing support, and involvement of the physician team.

In large ECMO centers across the US and internationally, there exists anecdotal and case evidence supporting the feasibility and safety of these rehabilitation practices.¹⁷ While catastrophic complications such as cannula dislodgement or fracture are possible, systematic reviews have demonstrated a relatively low risk profile.^11,18 Adverse events, such as decreased oxygen saturation, tachycardia, tachypnea, leg swelling, and vertigo, have been reported.^4,7 More serious side effects, such as cerebrovascular accidents and cardiac arrest related to a pulmonary embolism, have also been reported.¹⁵ As the optimal patient population for these interventions has yet to be defined, the risks vs benefits of early mobilization in patients who are on ECMO as a bridge to recovery should be considered, as these patients tend to be cannulated for shorter periods of time.

The next time one of these videos makes its rounds on social media, take a moment to imagine what this mobilization means to the healthcare team, the patient, and eventually the patient’s recovery.

References

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