Study protocol

News!! In June 2022, the Ethical Committe approved an amendment.

Why an amendment? The ambulance regions Amsterdam, Kennermerland, Noord Holland Noord were not yet agreeing cooperating to the study by means of activating the HEMS for patients with an OHCA with an age of 50 or younger. Although they plan to agree in October 2022, this caused 1) a significant delay of study inclusions as these areas are large areas and 2) in special cases, HEMS teams are activated for OHCA of young persons. Our statistician decided that due to the stepped wedged design, the study period should be prolonged after the seecond LifeLiner performing ECPR to ensure enough inclusions of control patients. Secondly, the patient inclusion of area’s of ambulance regions AMsterdam, Kennermerland and Noord-Holland Noord are subjected to selection bias. This selection bias would only be present in the control group, as these ambulance regions are served by LifeLiner 1. Therefore the statistician recommended that all patients dispatched from ambulance regions who do not cooperate with the study, should be excluded. These suggestions were copied and accepted by the Ethical board.

Study Objective

Patients with refractory out-of hospital cardiac arrest die at scene or are transported to hospital where patients might be eligible for Extracorporeal CardioPulmonary Resuscitation (ECPR) if available. However, transportation times to a hospital providing ECPR are (too) long in a situation where the adagio “Time is Brain” applies. The Helicopter Emergency Medical Services are quickly on-scene and can initiate ECPR. This intervention will be compared with HEMS dispatch without ExtraCorporeal Membrane Oxygenation (ECMO) on-board. 

Primary objective: 

To compare the effect of HEMS with ECPR versus HEMS without ECPR on survival to hospital discharge in patients between 18 and 50 years old, who sustained a witnessed out-of hospital cardiac arrest.

Secondary objectives:

1.      To study the health care costs per OCHA patient, costs per Quality Adjusted Life Year (QALY), quality of life 6 and 12 months after OHCA and total costs per life gained in the intervention group and in the control group.

2.      To study the effect of the “HEMS dispatch without ECMO on-board” compared to the current practice of not dispatching HEMS (with a retrospective control group) on survival to hospital discharge.

Study Design

Stepped-wedge trial, comparing deployment of HEMS not equipped with ECPR with HEMS equipped with ECPR in patients with a witnessed out-of-hospital cardiac arrest between the age of 18 and 50 years old. All HEMS stations will start being dispatched to OHCA of young adults, without having ECMO on board. After training, HEMS stations will switch to prehospital ECPR, thus having ECMO on-board.

Patient population

Patients with a witnessed out-of-hospital cardiac arrest between the age 18 and 50 years old are considered eligible patients. If the patients are eligible, HEMS teams are activated by the dispatcher in the incident room, during the initial 112 call. The dispatcher in the incident room is guided by a computer aided system to assess whether the patient is eligible (comparable with the lay-men SMS texting service). 390 patients will be included in an estimated 2 year time window.

Inclusion criteria

In order to be eligible to participate in this study, a subject must meet all of the following criteria:

–       Age between 18 and 50 years, known or as estimated at inclusion by the HEMS physician. 

–       Witnessed arrest (last seen well <5 min), OR signs of life (gasping, movement)

–       Initial rhythm is VT/VF OR Suspected of having a pulmonary embolism

–       Refractory cardiac arrest lasting longer than 20 minutes and shorter than 45 min

If age is not exactly known at inclusion and is estimated by the HEMS physician between 18 and 50 years but finally the patient appears to be younger or older, the patient will not be excluded.

      Exclusion criteria

A potential subject who meets any of the following criteria will be excluded from participation in this study:

–       CO2 et<1.2 kPa (10 mmHg) during CPR

–       No clear echographic visualisation of either the femoral artery or the femoral vein.

–       Expected time from collapse to arrival at an ECPR center with a direct available ECPR team is less than 30 min.

The following patients will be withdrawn after initial inclusion as soon as the following information becomes available:

–       Known malignancy

–       Known intracranial haemorrhage/ischemia <6 weeks

–       Care dependent for daily activities before arrest

–       Patients with a “do not resuscitate” order, which was not known at time of the arrest.

–       Refusal of deferred consent by the next of kin or by the patient himself to use the data. Deferred consent will not be asked to relatives of patients who die in scene, but are included in the study.