Introduction and Background
Extracorporeal Life Support (ECLS) is an expanded scope of therapies offering heart and/or lung support. Such therapies include Ventricular Assist Devices (VAD), Impella heart pumps, Extracorporeal Carbon Dioxide Removal (ECCOR) and Extracorporeal Membrane Oxygenation (ECMO). These various therapies can assist in treating acute cardiorespiratory failure, which remains a leading cause of death, with mortality as high as 41% (1). Extracorporeal Membrane Oxygenation is the application of cardiopulmonary bypass to temporarily support cardiorespiratory function until the underlying cardiac or respiratory condition can be treated.
Extracorporeal Membrane Oxygenation is not a cure, but can provide a potentially life-saving bridge for patients with cardiorespiratory failure, when conventional therapies are ineffective (2). The principles behind ECMO are to improve gas exchange and end-organ tissue perfusion, by decreasing ventricular stretch, pulmonary arterial tension, and tissue hypoxia. In effect, ECMO offloads the heart and lungs, and allows for organ rest and recovery time (3). The intent of this paper is to introduce the reader to the principles of ECMO and describe the novel role Critical Care Paramedics (CCPs) have as an integral part of the ECMO retrieval and transport team.
Principles of Extracorporeal Oxygenation and Perfusion
Extracorporeal Membrane Oxygenation provides non-pulmonary gas exchange and can assist systemic circulation in both pediatric and adult populations. In simple terms, ECMO is a pump and membrane which effectively circulates the patient’s blood outside the body (hence ‘extracorporeal’), allowing oxygen to diffuse into the blood and carbon dioxide diffuse out via their respective concentration gradients. Extracorporeal Membrane Oxygenation can be achieved via three routes of blood flow: Aterio-venous (A-V), Veno-Arterial (V-A) and Veno-Venous (V-V), with VA and VV being the most common (4) (Figure 1).
Figure 1. Ma, M. A case study of bed 25. SlideShare. 2011 ECMO Configurations; [slide #31] Available from: https://www.slideshare.net/manaenma/a-case-study-15067601
Although ECMO is not a first line treatment, it has shown to improve patient outcomes for those presenting in cardiorespiratory failure. Evidence from a large randomized control trial demonstrated the benefits of ECMO in adults with cardiorespiratory failure, and has become common practice in the ongoing treatment of patients presenting with severe respiratory distress (5). Indications for ECMO are multifaceted and include hypoxia, hypercapnia, sepsis and cardiogenic shock refractory to conventional treatment, such as mechanical ventilation, prone positioning, and drug therapies.
There was renewed interest in ECMO during the H1N1 influenza outbreaks of 2009, where patients progressed to severe Acute Respiratory Distress Syndrome (ARDS) and could not be managed with conventional therapies. With the complications and progression of H1N1 and ARDS, ECMO was integral to managing this patient population (6).
ECMO Retrieval Team
Extracorporeal Membrane Oxygenation is typically available only in highly specialized hospitals. This means, either transporting a patient who is critical to be placed on ECMO, or having a retrieval team initiating ECMO at the sending facility and transporting the patient to definitive care.
When considering interfacility transport of the ECMO patient, the use of personnel specifically trained in patient transport, and the provision of care in the transport setting, can improve the margin of safety and help mitigate the risk associated with such an inherently unstable patient population. Therefore, a highly-specialized team with appropriate knowledge, resources, and training is needed to safely transport these patients. Teams who specialize in ECMO retrieval typically vary in size and composition, with only a few including paramedics as integral team members. While there is limited literature identifying paramedics as part of an interdisciplinary ECMO team, CCPs are well-skilled at transport of unstable patients and managing adverse events in the field (7-9, 10-11). Therefore, due to the unpredictable nature of the transport environment, having paramedics as part of a hospital-based ECMO transport team can mitigate the risks unique to this setting.
What follows is the experience of an ECMO team at a quaternary care university-affiliated teaching hospital, working with a CCP land-based ambulance service to develop an interdisciplinary, interagency ECMO transport team to include CCPs as integral team members.
Critical Care Paramedic’s Role in an Interdisciplinary ECMO Retrieval Team
Toronto Paramedic Services (TPS) is Canada’s largest municipal based paramedic service, and operates one of Canada’s busiest land-based critical care transport programs. The TPS critical care transport program, was developed in 1998 to meet the critical care interfacility transport needs in a highly-regionalized health care delivery system; serving more than seven million people in the Greater Toronto Area (GTA). The program operates 24 hours a day, seven days a week, and carries out over 1200 critical care interfacility transports annually. The severity of illness and injury of these patients is high, with over 60% being intubated and mechanically ventilated, with a comparable proportion being vasopressor-dependent. The rate of in-transit critical events is 6.5%, with no in-transit deaths between 2005 and 2010 (8). Inclusive of the expanded role and skill set of the TPS CCPs, is the transport of intra-aortic balloon pump (IABP) dependent patients. The TPS program is the only one in Canada carrying out interfacility transport of IABP dependent patients using a paramedic-only model (10,11).
In early 2013, the Toronto General Hospital (TGH) ECMO team identified the need to expand the availability of ECMO to outlying hospitals. The cavate was to identify an existing, functional, structured and safe transport system to facilitate this need. Identifying that TPS already had a very successful critical care transport program, they approached TPS to develop a formal interdisciplinary team to carry out ECMO transports. The guiding principle behind the development of an interdisciplinary team with expertise in ECMO, critical care, and patient transport logistics, was to meet the need of these complicated patients in the transport setting.
While there is no standard ECMO transport team configuration, a team typically includes an intensivist, a surgeon, a perfusionist, one or more critical care nurses, and a respiratory therapist. Apart from initiating and managing ECMO itself, the skillset required to provide ongoing care and safe transport are well within the CCP’s scope of practice. The CCP is likely the most skilled at patient management in the transport setting, as hospital-based providers are typically not familiar with providing critical care outside the hospital setting.
What makes the TGH-TPS ECMO transport team model unique is the inclusion of CCPs in a shared care model with hospital-based providers. The standard team configuration consists of a thoracic surgeon, an intensivist (ECMO physician), a perfusionist, and two CCPs. The roles and responsibilities of the five-member team are well defined and practiced through use of simulation and live-vehicle scenarios. The surgeon provides vascular access, the perfusionist initiates ECMO, and the intensivist oversees overall patient management. The CCPs’ roles include mechanical ventilation, management of medication infusions and boluses, blood product administration, management of invasive lines (central venous, arterial, and pulmonary artery), transvenous pacing, IABP and preparing the patient for interfacility transport. The CCPs are also responsible to manage transport logistics and communications between the ECMO team, the transport agency dispatch center, and the receiving facility. The CCPs provide care under a delegated acts model, using an ECMO-specific medical directive (Table 1). They also have access to a dedicated Transport Medicine Physician (TMP) who provides oversight and delegation to the paramedics.
Table 1. ECMO Auxiliary Medical Directive
- Requires VV or VA ECMO.
- ECMO Team and ECMP physician
- If certified the CCP may provide treatment in this auxiliary directive
- Patients are greater than 16 years of age
- Successful cannula placement and ECMO initiation
- Not applicable
- Mechanical Ventilation: Pressure control 10 cmH20, Respiratory Rate 10, PEEP 10 FiO2 0.3, I:E of 1:1 to 1:2 while on ECMO. May titrate FiO2 up to 1.0 and PEEP to 20 if requested by attending EMCO Physician (Or to an initial maximum of 20-20-20 PC-RR-PEEP, as requested by the ECMO Physician)
- Circulation support: Norephedrine (Levophed), Vasopressin, Epinephrine, Phenylephrine
Fluids support: Bolus 20 mL/kg RL (Maintenance infusion RL or NS at 0-150 cc/hr, may substitute sodium bicarbonate instead of NS/RL as bolus fluid 20 ml/kg for metabolic acidosis. (May switch to sodium bicarbonate infusion)
Packed Red Blood Cells (PRBC): Transfuse PRBC at request of ECMO physician or if active bleeding.
- For Sedation: Singular or combination infusions of Fentanyl (Sublimaze), Propofol (Diprivan), Midazolam (Versed), Ketamine (Ketalar) as required.
- For Paralysis: Cisatracurium or Rocuronium (Zemuron).
- Additional infusions as required: Unfractionated Heparin, Furosemide (Lasix), Tranexamic Acid (TXA) and Pantoloc (Pantoprazole)
- The CCP must patch with the TMP if medications are required beyond those provided for in these medical directives; if medication doses are required beyond those provided for in these medical directives; or in the case of ECMO failure requiring use of emergency medical directives, the CCP may provide all additional care covered by routine CCP level medical directives.
Adult Medical Directives: Extracorporeal Membrane Oxygenation Auxiliary Medical Directive. Ornge Base Hospital, Medical Advisory Committee: Mississauga, Ontario Canada: 2019; p. 96-101.
In the program’s infancy, ECMO transports were carried out using a multi-patient ambulance bus (Figure 2). The bus provided ample room for large equipment and many
Figure 2. Toronto Paramedic Service Emergency Support Unit: (Personal collection of F. (Kelly) Sheppard,)
personnel, which at times, exceeded 10 when the hospital’s ECMO program began. The bus option became impracticable because it was required to be dedicated to the transport of ECMO patients for long periods of time. As more compact transport-capable equipment became available (Figure 3), and the hospital’s ECMO service recognized the CCPs scope of practice, the five-member team, with the use of the commander style ambulance, (Figure 4) was determined to be ideal; as it minimized transport team size, and decreased reliance on hospital staff.
Figure 3. ECMO Unit used by the TGH ECMO Team. (Personal collection of F. (Kelly) Sheppard)
Figure 4 Toronto Paramedic Service Critical Care Transport Unit, Commander Style Ambulance (Personal collection of F. (Kelly) Sheppard)
Extracorporeal membrane oxygenation is potentially beneficial in patients with severe cardiopulmonary failure, when conventional therapies have failed (12). Transport of ECMO-dependent patients is complex, but is increasingly common due to changes in indications, equipment, and transport team capabilities. The CCP provides a welcome addition to the team dynamic by coordinating logistics, patient movement, equipment oversight, along with team and patient safety (13). Since its inception in 2013 this novel collaboration between TGH and TPS has successfully retrieved over 170 ECMO-dependent patients. The CCPs bring a culture and unique scope of practice that has a supporting role to a seamless decision-making process. This interdisciplinary team approach has shown the use of CCPs can help to mitigate risk and make a difference in patient care and outcomes.
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