The Case

A 54-year-old woman with end-stage chronic obstructive pulmonary disease (COPD) was admitted with acute on chronic respiratory failure. She was placed on the list for a lung transplant. Due to severe hypoxemia, she was intubated, mechanically ventilated, and required extracorporeal membrane oxygenation (ECMO) support.

About six days into the hospitalization, the patient developed clotting problems, a known complication of the ECMO oxygenator. She was taken to the operating room and underwent an uneventful change of the ECMO circuit. On the way back to the intensive care unit (ICU), the team was moving the patient out of an elevator when a piece of equipment became snagged on the elevator door. The ECMO circuit alarmed, but the patient remained stable. The circuit alarms were silenced and the decision was made to continue back to the ICU and recheck the system there.

After returning to the ICU, the nurse noted that the femoral cannula site was oozing. Some clots were also noted in the new oxygenator. A perfusionist was called to reassess the ECMO circuit. Usually, a perfusionist is expected to be at bedside to monitor all aspects of the ECMO system as soon as any patient has reached the ICU. However, in this case, the perfusionist was covering multiple floors, and the patient's arrival in the ICU was delayed by the elevator issue. Therefore, it took the perfusionist almost 30 minutes to see the patient after the patient left the operating room. The perfusionist immediately realized that the oxygenator was filled with room air. The air had been transmitted to the patient's circulation, leading to an air embolism. The team immediately instituted treatment but, within a few hours, the patient became severely hypotensive and bradycardic. A “code blue” was called. Despite aggressive attempts at resuscitation, return of circulation was not achieved. The patient's family decided to stop resuscitation efforts and she was pronounced dead.

Following this event, ICU nurses were trained in basic perfusion skills, and a protocol was instituted whereby all ECMO patients would be cared for by a nurse trained in critical care, with a perfusion-trained nurse as backup. The device was later sent to the company for further investigation and was found to have a small breach in the oxygenator, which was probably caused by the mishap in the elevator.

The Commentary

By L. Mikael Broman, MD, PhD

Background and Significance

ECMO is an advanced life support technology that is used in cases of severe respiratory, cardiac, or combined cardiorespiratory failure, when conventional critical care is insufficient for continued life support.  During ECMO, blood is drained from the patient's vascular system, circulated outside the body by a mechanical pump, passing through an oxygenator which adds oxygen and removes carbon dioxide, and then reinfused into the patient. The method may also be used to bridge to lung or heart transplant, or for short-term support during advanced airway surgery. Initiating ECMO involves surgical procedures to implant cannulae in the patient’s major blood vessels. The patient’s blood is then drained from a large central vein (usually the inferior vena cava), passing through an artificial lung (i.e., oxygenator) where the blood is oxygenated and carbon dioxide is removed. The oxygenated blood is then pumped back into the patient’s circulatory system. If purely respiratory support is required, the return cannula is placed on the venous side (venovenous or VV ECMO). If both cardiac and pulmonary support are required, the return cannula is placed on the arterial side (venoarterial, VA ECMO).  

ECMO is a complex technology that requires a team of personnel with specific training and expertise. The major complications of ECMO include healthcare-associated infections, hematologic complications (bleeding and thrombosis), and mechanical complications, like the one described in this Case. Patients receiving ECMO must receive anticoagulant therapy due to a substantial risk of blood clots in the artificial circulation, even though modern ECMO equipment has lining materials for increased biocompatibility. The balance between clotting in the ECMO circuit and bleeding in the patient is delicate and requires close monitoring of coagulation. The most common complications of ECMO are bleeding from cannulation sites (15-20%) or surgical wounds (15-30%) (ELSO Registry, Extracorporeal Life Support Organization, Ann Arbor, MI. USA). Up to 21% of adult patients who undergo ECMO suffer intracranial hemorrhage with a mortality of >80%,¹ and thromboembolic events such as oxygenator clots have been reported in 11-13%, and cerebral infarction in 2-4% of adult cases.^2-4

In this Case, the patient experienced an adverse event during transport on ECMO from the operating room back to the ICU. Data on complications of intra-hospital ECMO transport are scarce. Almost a decade ago, Arkansas Children's Hospital reported seven adverse events in 57 transfers (12.3%), all of which were considered minor complications that did not result in significant clinical consequences.⁵ Our hospital has performed almost 1,300 ECMO treatments since 1987, requiring 120-180 intra-hospital ECMO transfers to locations such as operating theatres and radiology annually.  We also have performed nearly 1,000 inter-hospital ECMO transports. Our analyses of inter-hospital ECMO transports identified complication rates as high as 30%,^6-8 with patient-related complications accounting for almost two-thirds of events and equipment-related complications for approximately 15%. Given that intra-hospital transfers are much shorter than inter-hospital transfers, the latter appear to carry higher risk.⁶ However, given the paucity of published reports on ECMO complications associated with patient transports, it is reasonable to assume that there is significant underreporting of such problems.

The key aspects of ensuring safety during the transport of patients on ECMO include:

• A dedicated ECMO transport team that includes ECMO specialists as well as critical care support staff
• Specific training for both dedicated ECMO staff and general critical care staff on managing ECMO-related emergencies
• A structured checklist (“ECMO A-B-C”) to assess the functioning of the ECMO circuit, which is used both for routine assessment and in emergencies

Intra-hospital/in-hospital ECMO transport team

Critical ECMO transport team members would typically include physicians, surgeons, specialist nurses, respiratory therapists, and sometimes nurses’ aides. All staff taking part in transports of patients on life support should know their role on the team and the equipment used. These roles can be divided into specialized ECMO support (e.g., an ECMO physician, perfusionist or ECMO specialist nurse, surgeon, etc.) and general critical care support (e.g., the ECMO specialist nurse caring for patient too, intensivist, anesthetist, critical care nurse, nurse’s aide, etc.). The individual competences may overlap, and team staffing may vary across centers.⁹ In perfusionist-driven programs, that professional may not always be available in-hospital or, as in the current case, may be occupied elsewhere. In programs where the ECMO specialist nurse plays the central role, that competence is present at the bedside managing both the patient and ECMO at all times, 24 hours and 7 days a week. At our institution, the program is based on ECMO specialist nurses (adult/pediatric critical care nurses), ECMO specialist physicians (anesthetist intensivists), and ECMO nurse aides – all with at least a basic ECMO specialist education that adheres to Extracorporeal Life Support Organization (ELSO, Ann Arbor MI, USA) standards. Daily exposure time per staff is high since the unit is a dedicated ECMO ICU, only treating ECMO patients of all ages.

Transfer should be commenced after a timeout, which includes a short introduction of the patient and the current situation, explanation of the purpose of ECMO, and a clear description to the whole group of "red flags," such as known circuit clots or an earlier bleeding site. A Situation-Background-Assessment-Recommendation (SBAR) format is advisable for such briefings.^10,11

Checklists are recommended to ensure availability of rescue equipment that should always be at "arm's length reach" from the patient. Rescue equipment for both ventilation and ECMO should be available, including a spare ECMO console and drive-unit, a rescue kit (dry oxygenator and centrifugal pump connected with tubing ready for priming with saline), Fogarty catheters (for dealing with clots in cannula), and blood products. The timeout and checklist should be utilized before leaving any location, e.g. ward, computed tomography (CT) or operating room.^12,13

Staff training and education

Guidelines for education are published and updated by the ELSO, and available on-line at www.elso.org/Resources/guidelines.aspx. Regular training should be organized for all team members, preferably employing simulated situations. Simulated sessions using an actual ECMO circuit are essential to familiarize staff with the equipment and common equipment-related problems. These sessions can be performed in situ or in a dedicated simulation lab.

Full simulator (high-fidelity) training requires more resources since it takes the team off site, and supervisors have to be experienced in ECMO and educated in simulation pedagogy. A commercial mannequin customized for ECMO is costly. In simulations in situ, all team members work in their daily roles with real-life emergency scenarios involving whole patient and ECMO care, ventilation, and circulation (e.g., CPR if needed). Such realistic sessions are extremely valuable to all team members. Communication is key for success and is an important part of training. One to two simulation days per staff per year at high-volume centers and more often in low-volume ECMO centers (<5-10 treatments per year) are adequate for training and education.^14-17

Use of a dedicated ECMO checklist

Use of a uniform checklist applicable to any ECMO-related emergency minimizes the risk of missing any equipment-related complication. In our program, we have implemented the ECMO A-B-C checklist which is a specialized device-patient interface checklist (see below and Appendix).¹⁸ It is used every time a patient is moved from one bed to another, or from ambulance to aircraft, when equipment is changed (emergency or not), when a patient is “unplugged” to rely on batteries and gas bottles (before leaving ward), when a patient arrives for “plug-in” at new location, and to quickly diagnose any alarm or event out of the ordinary. It is feasible for use at bedside, with ambulating patients, and for mobile ECMO. The ECMO A-B-C checklist is also used as part of the patient survey the ECMO specialist nurse performs when beginning every shift.

Here follows an example structure for a Treatment A-B-C that may be adjusted and adapted for care of any patient receiving mechanical support, e.g. ventilator, intraaortic balloon pump (IABP), or ECMO. When executing the A-B-C, it is important for the whole team to listen to the staff member performing the check, allowing everybody to receive the same timely information.

A ‘Treatment A-B-C’ may include the following items:

1. Device
       i. Power/electricity on
       ii. Device operating at proper settings (example: ventilator pressures, pump rpm)
       iii. Device output reaches targeted settings (example: pressure provides tidal volume, rpm creates pressure)
       iv. Device effective output is within targeted goal (example: pump pressure provides the adequate blood flow)
2. Device supply (examples: oxygen and air to the ventilator, gas and electrocardiogram for IABP)
       i. Flow to device correctly adjusted accordingly, if applicable
       ii. Pressure – pressure in tube/line appropriate (indicates integrity of line and no leakage)
3. Auxiliary (example: heater on in ECMO and renal replacement therapy)
4. Connection of device to patient
       i. Inspect: look, feel and listen. For example, orotracheal cuff balloon inflated, tube that should be tempered is warm, color adequate, fixations adequate, no strange sounds.
       ii. Look during transport: in bad light conditions (or when noisy), a flashlight may be handy for inspection.
5. Check that device supply/supplies are connected to the most secure source/s, i.e. in hospital plugs for gas and electricity plugged into wall, on transport plugs connected to ambulance gas supply and power, or to adequately filled gas bottle/s and charged batteries.

Any alarm must be seriously evaluated and the "Treatment A-B-C" may be the best tool for a structured evaluation in a stressful situation. It is also important to recognize that no algorithm is static. The A-B-C is under constant evolution during use; new items may be recognized and added to the A-B-C, improving patient safety and team efficiency. Each revision should be announced to staff before it is implemented.

Safety Issues Related to this Case

Two safety issues arose in the Case described herein. First, it appears that the transport staff may have been falsely reassured by the fact that the patient remained stable after the initial event. The fact that the patient appeared unaffected after the event does not exclude the possibility that the patient or equipment needed immediate intervention; for example, if air was slowly entering the system (as may have been the case), the patient may have initially appeared unaffected. The instinct to silence alarms is understandable in ICU personnel who are vulnerable to “alert fatigue,” but given the complexity of ECMO technology and the fact that all patients receiving ECMO are critically ill, ECMO alarms should never be simply silenced without conducting an immediate, thorough assessment of potential reasons for the alarm. The decision to return the patient to the ICU for reassessment was reasonable; however, a transport team member should have communicated the concern to the ICU team and to the team that performed the circuit change to ensure prompt reassessment.

Second, it appears that only the perfusionist had the knowledge necessary to diagnose the issue, leading to clinical deterioration when she/he was delayed. Delays like this expose vulnerability in programs in which personnel from only one profession manage a complex treatment of this type. Such key professionals, like the perfusionist in this case, may be called on to care for several patients simultaneously. If any of the other bedside staff in this Case had been trained in recognizing and managing ECMO emergencies, they could have taken the proper action sooner. The hospital appears to have responded well by ensuring that a broader range of personnel receive basic perfusion training and by ensuring redundancy in the skill sets of transport personnel.

Take-Home Points

• Intra- and inter-hospital ECMO transports should be performed by trained staff experienced in these transfers.
• Any transport should be preceded by a time-out and follow a checklist.
• An A-B-C algorithm/checklist should be used for conducting structured assessments and the entire team should listen to all the information being communicated as the check is being performed.
• Rescue equipment should always accompany the patient during transport.
• In response to an alarm, the team should stop and seek out the cause. Corrective measures should be taken accordingly, including calling for additional resources if needed.

L. Mikael Broman, MD, PhD
Sr Consultant ECMO Specialist, Intensivist and Anesthetist Physician
ECMO Centre Karolinska
Department of Pediatric Perioperative Medicine and Intensive Care
Karolinska University Hospital
Stockholm, Sweden

References

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