Our approach for out-of-center initiation of extracorporeal membrane oxygenation and subsequent interhospital transport

Referring institutions may be ICUs, emergency departments and intermediate care units; however, emergency transport companies may also request evaluation for ECMO retrieval. Contact details as well as basic information about the program are published online (https://​www.​muv.​ac.​at/​13i2). Requests are usually received by telephone. Each case is discussed individually in a conversation between the attending senior physician at ICU 13i2 and the treating physician at the referring institution. We regard the use of our adapted patient checklist based on our own evaluation sheet [17] as mandatory (see Fig. 2a, b) to meet our demands for both evaluation and documentation standards.

Candidacy for ECMO treatment and ECMO retrieval are assessed separately.

We primarily consider patients for respiratory ECMO including the subcategory of extracorporeal CO₂ removal. The evaluation of respiratory ECMO indication itself adheres to our standard in-house principles complying with the ELSO Patient Care Practice Guidelines [18‐20] and the European Society of Intensive Care Medicine (ESICM) guidelines [21] summarily shown in Table 1. We also assess patients for cardiac ECMO following the respective VA ECMO guidelines [4, 18, 19, 22]; however, except for unforeseen emergency situations, retrieval options for VA ECMO patients remain a focus for future development. For the final rule-in we always take definite decisions on an individual patient-centered basis. When the ECMO indication is borderline, the attending senior physician involves peer experts to discuss the case. In patients eligible for bridging strategies such as to organ transplantation, we involve the cardiac or thoracic surgeon on call into the decision-making process.

The paramount goal remains to assess the patient as early as possible and, if feasible, to offer a safe center admission without antecedent intervention by a mobile ECMO team. The ECMO retrieval is generally considered when the risk of a conventional transport is deemed unacceptable. The candidacy for retrieval is impacted by clinical factors, transport-related circumstances and the critical appraisal of all clinicians involved. We regard states of circulatory and/or respiratory instability, no transport option without ECMO, and rapid deterioration as rule-in criteria. Among others, this may be the case in severe gas exchange disorders, such as a Horovitz index of < 50 mm Hg despite optimal conservative management, pre-cardiac arrest situations or antecedent cardiopulmonary resuscitation (CPR) due to the underlying condition, need to reposition the patient from prone to supine position for transport although thereby provoking imminent instability, transport denial by an emergency medical physician, high vasopressor doses or hyperlactatemia. Also, we reflect the degree of pretransport hypoxemia, hypoperfusion, and acidosis on the expected duration of transport to anticipate the risk of further deterioration arising from the transport duration itself; however, the consensus of the entire teams at the referring institution, the mobile ECMO team and the ICU team remaining in-house are a sine qua non for the conduction of an ECMO retrieval.

When potentially reversible pathologies such as untreated pneumothorax are contributing to the patient’s condition, the retrieval is delayed, and the candidacy is re-evaluated after the cause has been addressed.

Currently, we do not routinely launch to patients in cardiac arrest to perform eCPR; however, when time from conventional CPR start to the expected time of our team’s arrival is below 30 min, and eCPR criteria are met, we continue our retrieval process with the aim of emergency VA cannulation. This may particularly be the case in patients already accepted for retrieval, who develop cardiac arrest during our approach. In these cases, we adhere to our in-house emergency department’s recommendations [22].

Principally, we also extend our portfolio to scenarios which may necessitate the change of an already running ECMO circuit or a modification in cannula configuration prior to the transport.

Upon acceptance for ECMO retrieval and reassurance of the available target bed, we assess our own unit’s staff resources for ECMO retrieval which includes considerations for both the outreach team and the ICU team remaining in-house. The latter must be able to meet the clinical demands even when unexpected events occur during the absence of the retrieval team. To provide retrieval availability even during peak times or personnel shortages, we expanded our capabilities for ECMO retrievals with a pool of ICU nursing staff. This initiative allows us to mostly guarantee the participation of at least one nurse capable of managing both intensive care nursing and ECMO management.

When ECMO retrieval cannot be offered due to any reason, the hazards of a primary transport to our center without antecedent ECMO implementation will be taken after careful consideration.

After a positive decision to retrieve the patient, the preparation phase ensures that 1) the mobile ECMO team is assembled and informed, 2) equipment is packed and checked, 3) transport for both team approach and ICU transfer is organized and 4) the referring institution is briefed.

The assembly of the retrieval team is done by the ECMO team leader in collaboration with either the 13i2 head of nursing, if present, or with the most experienced ECMO nurse in charge.

The team composition is flexible depending on personnel resources and transport factors. It allows four different versions when a ground-based approach is conducted (see Fig. 3). For an air-bound transport, team compilation is adapted to the air ambulance operator’s individual specifications. The option with one physician only necessitates the availability of medical capacities at the referring institution (at least one physician or nurse for sterile guided assistance during cannulation), which is ascertained during the telephone conversation. The same requirement applies when no ECMO nurse is available for transport.

Self-protection by means of personal protective equipment according to our institution’s hygiene standards and reflective vests for the interhospital period is provided.

Our transport equipment is mainly prepacked and located in the ICU. The remaining items are individually added. The ECMO-specific sterile goods are enclosed in duplicate. We include a versatile handheld ultrasound device as a back-up. For retrieval purposes, Cardiohelp® (Maquet, Getinge Group, Rastatt, Germany) consoles are used comprising sensors for real-time pressure and blood measurements. Alternatively, we use Xenios (Xenios AG, Heilbronn, Germany) devices. We prefer the transport of ready primed ECMO circuits to the patient to keep preparation time at the referring institution as short as possible. Depending on the travelling distance, patient-related factors and weather conditions, an ECMO heat exchange device is added.

When a ground-based approach is performed, equipment and ECMO team are transported to the referring hospital by a designated emergency team transport vehicle of the Johanniter. It is exclusively available for medical and equipment transfers on a 24/7 basis. Each vehicle provides seats for five team members plus driver and a 220 V power supply. The Johanniter emergency coordination center uses a specified transport code for ECMO retrieval purposes ensuring correct dispatch of one of the dedicated vehicles regardless of the person answering the request. The air-bound approach is individually organized to meet all aeronautical and medical demands.

Before the mobile ECMO team launches, intensive care transport availability for the subsequent patient transfer is checked. For this purpose, we use a prioritized list including 10 organizations offering intensive care transfer capabilities (6 of which are land-based and 4 are air-bound). This list also includes the respective information about individual response time, place of departure, oxygen and air supply, 220 V power supply, solution for ECMO fixation and other specifics, such as seats available in the case of full attendance. Before the mobile team launches, the selected organization is prealerted and confirmation of transfer capacity is obtained. Ultimate alerting is done by the referring hospital subsequently to ECMO implantation.

During the telephone conversation with the referring institution, information about the upcoming ECMO retrieval is provided. Subsequently, a 1-page preparation sheet is sent to the institution (Fig. 4). It serves as an information source containing key points about the upcoming retrieval and including specific preparation recommendations, such as ordering packed red blood cells at call or preparation of the ultrasound machine.

After completion of the preparation process delineated above, a final team and equipment check is done together using the “Let’s-go” checklist shown in Table 2. Then, the mobile ECMO team launches.

As soon as the emergency team transport vehicle is heading for the referring hospital, information about the expected time of arrival is provided to the referring institution by telephone. This conversation is also used to exchange updates about the patient’s condition. All members of the mobile ECMO team are updated about the current situation and the patient’s condition including the most probable strategies for ECMO configuration, cannula implantation and alternative solutions for an unexpected deterioration as well as potential back-up capacities (e.g., local cardiac catheterization laboratory for additional guidewires).

Upon arrival and introduction, the team splits: the ECMO team leader reviews the diagnostic findings together with the attending doctor of the referring institution to confirm the ECMO indications. Simultaneously, the ECMO assistant physician performs a preliminary echocardiography assessment to estimate cardiac function, volume status and valve function. This protocol also includes exploratory sonography of both pleural spaces and abdomen. Then, bilateral vascular sonography is performed of both groin and neck veins and arteries including diameter measurements. Also, simultaneously the ECMO circuit as well as the console are checked by the ECMO nurse and preparation of the cannulation is started. When the indications for ECMO and ECMO retrieval remain unchanged, all parties involved are informed and briefed. These steps may be shortened or partly omitted when the patient’s condition does not allow any time delay.

According to our idea of an optimal retrieval, the procedure for ECMO implantation itself should deviate as little as possible from the familiar protocols followed in-house; however, when placing ECMO in an unfamiliar environment with possible back-up limitations for complications, we aim for a maximum margin of safety (also see “Risk mitigation” section).

Once arrangements are completed, role allocation and chronological order of the steps are fixed and communicated. Cannulation is done using Seldinger’s technique under real-time sterile ultrasound guidance. We do not routinely provide surgical techniques such as cut down for cannulation under vision. Typically, we serially place the guidewires after ultrasound-guided puncture, followed by sonographic reassurance of the correct wire position. When the patient’s coagulation is within normal limits, heparin is given as a bolus of 50 IU/kg bodyweight at the earliest when both cannulas are in place. Further reassurance of the correct cannula positions may be obtained by means of blood gas analysis at any time point or after circuit connection by opening all clamps prior to blood flow application to detect unexpected backflow due to cannula displacement; however, as mentioned previously, the detailed methods of operation are subject to the personal experience of the cannulation providers and should follow their habitual style as close as possible.

We routinely start ECMO with an initial blood flow of 1 lpm and a sweep gas flow of 1 Lpm for the first minute, unless the patient’s condition requires an instant increase of blood flow. We determine optimal settings primarily using monitoring of the vital parameters, arterial and venous blood gas analysis (BGA), end-tidal CO₂ (etCO₂), echocardiography as well as clinical judgement.

The preparation for departure begins with ECMO start. The first section of the “back-to-base” checklist ensures that all necessary actions are taken immediately after ECMO start (Table 3).

The interhospital transfer vehicle is alerted according to the previously arranged workflow.

During another telephone call with the destination ICU, the expected time of arrival is announced and both the necessity and possibility of a diagnostic stopover such as for a contrast-enhanced computed tomography (CT) are discussed and arranged when appropriate.

Once the patient is on the stretcher and prepared for departure, the second section of our “back-to-base” checklist (Table 3) ensures that our transport prerequisites are met. Usually, the ECMO team leader and the ECMO nurse accompany the patient inside the interhospital transfer vehicle together with at least one paramedic. The emergency team transport vehicle transports the remaining team members and the equipment not in use. It follows in convoy or travels individually when air-bound transfer is conducted.

After arrival and handover procedure, the retrieval is finalized with the completion of the documentation and a team debriefing. Equipment is restocked and prepared for the next transport. Short-term and long-term feedback possibilities are offered for all parties involved.

During the evaluation process, we aim for early identification of patients with higher risks of vascular complications such as prior surgeries, vascular abnormalities, or difficult anatomical access (Fig. 2b). Additionally, thorough ultrasound assessment before, during, and after cannulation evaluates vascular integrity and identifies potential challenges for cannula placement at all possible access sites. When high risk of complications prior to cannulation advises against out-of-center ECMO initiation, the hazards for a conventional transport can be taken upon individual decision.

Among other features, our protocol emphasizes safety by integrating checkpoints through the use of mandatory checklists, such as immediately after cannulation (Table 3), enabling the early identification of complications.

Disinfection and aseptic exposure are routinely carried out for all four entry sites (i.e., neck and groin bilaterally) to avoid any time delay when cannula placement turns out to be futile at one site. Patient blood management includes the advance ordering of cross-matched packed red blood cells on call (Fig. 4). When the hemoglobin concentration is ≤ 7 g/dl after ECMO initiation with an expected transport duration of less than 30 min, or ≤ 8 g/dl for transport durations of 30 min or more, or if active bleeding is present, packed red blood cells may be requested from the referring institution for transfusion during transport. As a prophylactic measure, we administer systemic anticoagulation at the earliest when the correct cannula position is confirmed via ultrasound. When bleeding complications with an imminent threat arise during the retrieval process, individualized management enables either expedited transfer to the center or the involvement of surgical assistance at the referring hospital. As previously mentioned, our advanced simulation training is provided for all team members including scenarios for handling complications during cannulation.

Despite all our endeavours to minimize risks, however, peri-interventional complications can never be entirely excluded. Therefore, our decisions regarding ECMO and ECMO retrieval will continue to be primarily guided by an individualized risk-benefit assessment.

Future developments of our program may include a stronger focus on cardiac ECMO retrieval, along with on-call agreements with the collaborating departments.