ECMO Initiation

Patient reception

Focuses on optimal transition from pre-hospital to in-hospital care. Immediate patient transfer onto the trauma trolley, correct positioning of the automated compression device (often moves away from the center of the chest) and exposure of the patient. A succinct handover is provided by the ambulance to the team leader and the decision making intensive care clinician.

Handover should include

• Ambulance call time or time of arrest if with ambulance
• Witnessed or unwitnessed arrest
• Initial rhythm
• Bystander CPR
• Any salient information about the patient past history

Following the ECMO support essential further detail is communicated in a usual standard handover.

Decision making

It is important to separate the decision-making process from the procedural proceedings and the preparedness to cannulate. Preparation and set up is, whenever possible, done before the arrival of the patient to focus on this crucial period of patient reception and hand over. Brief considerations follow and the decision of whether ECMO is indicated or not should be clearly announced to the room and conveyed by the team leader.

If staffing allows, separation of proceduralist and decision-maker is preferred. E.g. during day time to separate the proceduralists (cannulator 1 and 2) from the decision-maker e.g. the senior ECMO consultant.

Cannulation phase

The cannulation phase commences with the skin prep (Betadine solution) at which point the ACLS modifications apply and should be pronounced by the cannulator. Concurrently the following processes need to occur:

External cardiac massage

A consistent rhythm and depth is provided by using an automated mechanical compression device such as the LUCAS/Corpuls. There should however be preparedness to switch to manual compressions in the event of a technical failure. Usage of an automated device improves space around the patient. Positioning of the LUCAS/Corpuls over the central sternum in the mid-mamillary line is essential and needs to be rechecked throughout its application; migration towards the upper abdomen is commonly observed.

Cannula choice

Generally, a 17Fr arterial and 19 or 21Fr multi-stage venous cannula suffice to provide satisfactory blood flow and are faster to insert. In small adults or if difficult, a smaller 15Fr arterial cannula and 19Fr multi-state venous cannula are also acceptable. They are capable of providing adequate organ support with flows of 3-4 L/minute blood flow during temperature controlled post-arrest care.

Percutaneous cannulation

This follows standard techniques as described, using smaller cannulae to minimise the time to VA ECMO support and connection to a pre-primed ECMO circuit. For a detailed description of the cannulation technique see the procedure guide.

Key points in ECPR cannulation are

• The femoral vessels must be imaged with ultrasound
• Compressions may be paused for needling the vessels for a maximum of 60 seconds. The team leader will monitor interruptions and prompt for compressions to be restarted after 60 seconds if not already restarted.
• Note the arterial guidewire provided with the cannula (red tip) is shorter than the venous wire so can NOT be used for venous cannula insertion
• The venous guidewire must be imaged in the IVC and the arterial guidewire must be ascertained as either NOT being in the IVC (only the venous wire) or imaged in the abdominal aorta (in long or short axis) to avoid inadvertent VV or AA flow.

There is no strong preference regarding the femoral side (left or right) for access and return cannulae, however, in a larger person, the RA/SVC junction may only be reached from the right femoral vessel. Therefore venous cannulation on the right side is preferred. One cannula on each side is preferred to reduce the risk of leg hyper-perfusion syndrome. In case of any difficulty, unilateral cannulation is acceptable. Time to support takes precedence over these considerations. Femoral artery distal perfusion cannula is NOT required for initial deployment and can be sited thereafter.

ACLS modification

Standard ACLS therapies should be applied until the cannulation procedure commences. At this stage no further attempts should be made to defibrillate the patient until the patient is established on VA ECMO support.

The team leader needs to explicitly inform the resuscitation team “ECMO cannulation commencing – NO FURTHER DEFIBRILLATION ATTEMPTS” once the cannulator starts with the skin prep.

Brief rhythm checks should still occur during cannulation, as ROSC may allow the cannulation team to slow down.

During needling of the vessel, it may be necessary to pause compressions until the guidewire is inserted. Compression pauses must be kept to an absolute minimum and shall not exceed 60 seconds. The resuscitation team leader should monitor and advise the cannulation team if time has been exceeded.

When VA ECMO support is imminent, i.e. as the circuit is being connected to the cannulae, adrenaline boluses should be discontinued as there is a risk of significant hypertension on establishment of a circulation with ECMO blood flow.

ECMO Console start up

For detailed initiation and console procedures for HLS and PLS circuits see here.

A reminder video is shown here or see the direct instructions below.

Running the Rotaflow

The PLS system blood flow signal is obtained prior to patient connection via generous application of ultrasonic paste to flow sensor at the pump head

• Turn console on, confirm clamp and silence alarm
• Turn RPM knob up and down to zero
• If no flow signal or numerics appears and the display has three ‘dashes’ return RPM to zero and apply more ultrasonic paste
• If time allows remove the pump head and check for air bubbles
• Unscrew yellow cap from oxygenator
• Release all clamps and run at 2000 RPM (look for light agitation in priming reservoir bag) and confirm final de-airing of the circuit and oxygenator
• Re-apply yellow cap
• Place a ECMO clamp on the ECMO circuit (immediately post oxygenator), return RPM knob to zero and silence alarms. This is the final clamp to be removed after patient connection and ECMO pump initiation
• Clamp both blue and red tubing from the reservoir bag with blue clamps to hand over. This prevents circuit prime spilling from the reservoir during patient connection.
• Await handing over circuit for connection

Circuit Connection

The flushed access and return cannulae are connected to the access and return limbs of the primed circuit. Single flush acceptable.

PLS circuit

Sterilise the end portion of the circuit with Betadine soaked gauze (this can be done by a Cannultor 3 if available), apply clamp and cut one hand-width above. Bring the two ends into the sterile field.

Be certain about matching the access cannula to access tubing (entering pump first, blue mark on tubing) and the return cannula to return tubing (coming from oxygenator, red mark on tubing).

FINAL CHECKS

Mandatory checks by cannulator before connection – assistant to remind them

• Check for obvious air – tubing, oxygenator, pumphead
• Clamp on the circuit
• Oxygen connected and turned on

Perform underwater seal connection

• Check connection for air bubbles
• Cannulators: CLAMPS OFF
• Set 1500 RPM and Console operator: CLAMP OFF
• Steadily increase ECMO support (3000-4000 RPM) to achieve desired blood flow

Confirmation

• Visualise direction of blood flow from the access cannula to pump head
• Colour change across the oxygenator confirms gas delivery and function

Once VA ECMO flow is established, mechanical compression can be discontinued and the time on support is documented.

Strongly consider a CXR or further ultrasound imaging whilst still sterile to possibly optimise the position of the access cannula.