Critical Transport Issues

      You are working as part of a ground-based specialty care transport unit (SCTU) staffed with one EMT, one paramedic and a transport specialty RN when you receive a bizarre call from dispatch. The dispatcher says that one of your company's contracted facilities is inquiring about immediate transfer of a patient on extracorporeal membrane oxygenation (ECMO). After explaining to the dispatcher that ECMO is not a Sesame Street character, you frantically try to remember the last ECMO patient you transported. After several minutes, you realize you have never transported an ECMO patient and are not completely sure of what may be involved.

   Interfacility transport of a patient requiring extracorporeal membrane oxygenation (ECMO) is a rare occurrence in EMS, and there are few articles referencing the clinical, logistical or safety considerations during these types of transfers. This article will provide an overview of ECMO apparatus, as well as the complexities that may be associated with a specialty transport of this type.

WHAT IS ECMO?

   ECMO is a therapy in which non-oxygenated blood is removed from the venous system, oxygenated and then returned to the body through either the venous or arterial system to provide temporary cardiac and pulmonary support.¹ ECMO differs from cardiac bypass in two essential areas: 1) non-thoracic vessels (such as femoral or cervical) are cannulated, and 2) it may be utilized for as long as several weeks. Where the goal of cardiac bypass is support during surgery, ECMO gives the cardiopulmonary system an opportunity to recover from some adverse event. It is often used in the neonatal ICU for newborn infants with congenital heart defects or severe respiratory distress. Survival is reported at 70%-80% for these patients.² Typically, neonatal ECMO is only done for up to 30 days; however, there are reports of patients being successfully treated for much longer--one for more than three months. ECMO use in adult patients is generally for severe cardiac dysfunction that is not responding to other supportive measures such as intra-aortic balloon pump (IABP) and ventilatory support. In those cases, ECMO serves as a bridge to placement of a ventricular assist device (VAD) or heart transplant. Limited evidence also points to successful use in cardiac arrest patients in the emergency department.³

   Typical applications for ECMO involve cannulation of a vein and an artery (VA, or veno-arterial) and cannulation of a vein (VV, or veno-venous). A common method of VA access is to place a cannula in the right jugular vein and advance it to the right atrium. A second catheter is then placed into the right carotid artery and advanced to the aorta to allow for return of blood from the ECMO device. VA ECMO bypasses the pulmonary circulation. In VV access, a double-lumen catheter is placed into the right jugular vein and advanced to the right atrium. When blood is returned to the patient, it is directed to the pulmonary system via the tricuspid valve. VV ECMO maintains pulmonary blood flow.

   The use of ECMO has many possible complications for patients. Bleeding is one of the most severe, as all patients on ECMO require systemic heparinization to prevent clotting and subsequent embolization. Gastrointestinal hemorrhage and intracranial bleeds can have grave consequences. Other complications include thromboembolism, air embolism, limb ischemia, acute renal failure and oxygenator failure.⁴

ECMO APPARATUS

   ECMO apparatus consists of a blood pump, venous reservoir, membrane oxygenator and heat exchanger. The pump may be either a simple roller or centrifugal unit, depending on the application. The reservoir or bladder, maintained below heart level, stores the blood in preparation for entering the membrane oxygenator. The bladder is essential to prevent pressure changes and subsequent damage where the cannula(s) enters the blood vessel(s). The membrane oxygenator is made of a thin silicon sheath that is very efficient for the exchange of both oxygen and carbon dioxide. Since heat is lost as the blood passes through the ECMO apparatus, the heat exchanger maintains the blood at body temperature before it is reintroduced to the patient's circulation.¹

   Key safety features of the ECMO apparatus are air bubble detectors; filters; and pressure, oxygenation and temperature monitors. The air bubble detectors identify micro-bubbles and, if found, turn off the pump. The filters screen for air or thrombi to prevent embolization. The monitors maintain against dangerous changes or spikes in the pressure of blood in the apparatus, and also monitor oxygen saturation and temperature of the blood before it returns to the patient.

CHALLENGES IN ECMO TRANSPORT

   There are several challenges facing the interfacility transport service contemplating transportation of a patient on ECMO. Factors that must be considered include: likelihood of successful transportation with positive patient outcome, team composition and safety considerations for transport.

   Most institutions that initiate ECMO are more than capable of fully caring for patients in their current settings. Reasons for transport include: suboptimal cardiothoracic physician staffing, centers that are not capable of initiating VAD therapies in the patient who has failed to wean, and institutions that do not have cardiac transplant capabilities. One must quickly realize that this cardiac patient is extremely ill and may not survive an interfacility transport. The agency providing transportation will have limited input into patient stability for transport, since the patient has been stabilized to the highest extent possible and usually requires therapies above those of the referring institution.

   The transport agency does have a say in the manner and nature in which the transport team is configured. It would not be prudent to transport a patient using only the SCTU model described at the beginning of this article. Because of the clinical instability of the patient and the complexity of the ECMO apparatus, it is appropriate to augment the transport team with additional staff to ensure the highest likelihood of a safe transport with positive patient outcome. Additional staff may include:

• Cardiothoracic surgical MD or physician assistant (PA). Due to the inherent risk of exsanguination in the event of an inadvertent decannulation, it is appropriate for a cardiothoracic surgical MD or PA to accompany the patient on the transport.
• Certified clinical perfusionist (CCP). The "perfusionist" is responsible for the safe operation and troubleshooting of the ECMO apparatus. Regardless of the transport nurse's comfort level with ECMO, a CCP should always be part of an ECMO transport team.
• Anesthesiologist or certified registered nurse anesthetist (CRNA). Anesthesia professionals are extremely familiar with the unique airway, oxygenation and ventilation needs of the ECMO patient. The anesthesiologist and/or CRNA are also very involved in circulatory support of the patient.
• Additional lifting assistance. If available, an additional ambulance crew should be detailed to assist in physical movement of the patient and equipment, as this task can be cumbersome for clinical staff alone.

   In addition to team composition, the transporting agency has the ultimate say and responsibility for safely transporting the patient from the referring facility to the receiving facility. Agencies that are already prepared for or accustomed to transporting isolettes, IABPs and VADs may have an easier time at initially transporting the ECMO patient without advanced warning or preparation. In general, these agencies are used to working with non-transport clinicians and have a general understanding of safe transport of such devices. The transporting agency must remember that the ECMO apparatus is generally larger than a transport VAD, but may be as large as a full-size non-transport VAD console. The physical size and weight of the ECMO apparatus may be its only limiting factor for safe transport. Vehicles equipped with hydraulic lifts and floor-mounted attachment points, commonly referred to as Bucher mounts, are preferred, as these features assist in safely lifting and securing the ECMO apparatus. It is critical that all devices introduced into the rear of the ambulance be strapped in place to prevent inadvertent movement during transport. This will provide a safer environment for both the patient and medical staff in the ambulance. Additionally, all team members must have the ability to sit and be seat-belted while the vehicle is in motion.

   Once the decision has been made to transport an ECMO patient, and the vehicle and team have been identified, the task at hand becomes safely preparing the patient for transport. As noted earlier, these patients are extremely ill and may require multiple vasopressor agents and blood products to maintain adequate hemodynamics. IV infusions should be triaged, and those deemed non-essential for transport or that can be converted to IV push should be discontinued for the sake of space. Depending on the transport time, remaining IV infusions may either be left on the current infusion pumps, if they can be safely secured, or switched to smaller transport infusion pumps. All IV lines and sites should be labeled and secured. Appropriate monitoring includes arterial and central venous pressures, continuous end-tidal CO2 and cardiac rhythm monitoring, non-invasive blood pressure and continuous core temperature. Confirm that all ECMO venous and arterial return lines are secure by suture or other method. Evaluate surgical and arterial sites for bleeding regularly and after each move. The perfusionist should remove all non-essential components of the ECMO console to reduce the size and weight. Once completely prepared for movement, the patient should be moved to the EMS stretcher with as much staff assistance as possible and secured with a minimum of three stretcher straps. All required surgical instruments and suture material should be acquired by and accompany the cardiothoracic surgical MD or PA, as inadvertent decannulation will be disastrous.

CONCLUSION

   The patient on ECMO is one of the most complex and unstable patients EMS will encounter while performing critical care transport. Although requests for ECMO transports are rare, services must still preplan for these cases. As most requests are unscheduled, transport teams should work closely with referral centers to identify what is needed to complete a transfer in a timely manner. Services and referral centers should also participate in "dry run" exercises and perform after-action critiques with a focus on safety. SCTU services should predetermine vehicles that meet the requirements to complete such a transfer and train their staff to properly secure the ECMO apparatus in these vehicles.

References

1. Townsend. Sabiston Textbook of Surgery, 18th ed., Chapter 71. W. B. Saunders, 2007.

2. Kliegman. Nelson Textbook of Pediatrics, 18th ed., Chapter 101. W.B. Saunders.

3. Marx. Rosen's Emergency Medicine: Concepts and Clinical Practice, 6th ed., Chapter 8. Mosby, Inc., 2006.

4. Libby. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 8th ed., Chapter 28. W. B. Saunders, 2007.

   Fred Ellinger, Jr., NREMT-P, is the owner/operator of SafeTec Training Services, a Pennsylvania Bureau of EMS-approved CE sponsor and trainer for many healthcare agencies and corporations in the tri-state area. He also serves as a flight paramedic for MidAtlantic MedEvac, Hahnemann University Hospital, Philadelphia, PA, and is a medical specialist with Pennsylvania Urban Search and Rescue Response System's PA Company 2 and the Bucks County Technical Rescue Task Force. He is also a Regional Course Director for The Difficult Airway Course: EMS^TM and a contributor to Airway World^TM, a unique online airway management knowledge center. Airway World is a powerful new resource that closes important gaps in airway management and resuscitation education and information for the medical community. Fred can be reached at fred.ellinger@difficultairway.net.

   Gerald Wydro, MD, is clinical associate professor of emergency medicine at Temple University School of Medicine in Philadelphia, PA, and works in the emergency department at Temple University Hospital. Dr. Wydro also serves as the regional medical director for Bucks County, PA, and is the ALS service medical director for several 9-1-1/Interfacility transport services in the region. He is also a member of EMS Magazine's editorial advisory board.