The First Annual BEACH (BElgian Annual eCmo Hands-on) Course

What better way to spend a rainy, cool day in Belgium than ECLS on the BEACH? A contingent of specialists took a standing-room only crowd of ECMO newbies through a crash-course in the basic tenets of mechanical support. A brief history of circulatory support brought us from the halcyon days of pulsatile roller pumps all the way to our current models, discussing the data (read: lack of) to support this life-saving technology.

 

Donker, de Somer, and Jacobs gave us the indications for both VV (Respiratory) and VA (Cardiac) support, including the new hotness, ECCO2R and ECPR. Keep it simple: VA for a failing heart, VV for failing lungs. Either way, the blood’s being oxygenated - the difference is where you give it back (VV to the right side, VA to the left). Hopefully, you can stay out of the rabbit hole, where Fabio Taccone shows you how to start making complex alternative cannulations (VV-A, VA-V, etc).

 

Speaking of cannulas, the audience found out just how essential echocardiography and fluoroscopy are for getting a patient initially supported. You’d be surprised how many nooks and crannies the cannulas can end up in (and all the tissues they can perforate when they get there).

 

Finally we found out just how difficult it can be to manage fluids, medications and coagulation while on mechanical support. Turns out, when you have a patient’s circulating blood supply interacting with an artificial surface for a while, kinetics and dynamics tend to go a little haywire. My best bit of advice is to make friends with your local pharmacist, but barring that, keep special focus on analgosedatives, antibiotics, and anticoagulants.

 

Sadly, all of ECMO can’t possibly be explained in a single blog post, so I encourage you all to check out the tremendous amount of resources available out there in the #FOAMed world.                

BEACH Course

‘Extreme disasters’ will survive on ECMO, but is it where we want to spend our money?

 

Indications and contraindications (Dirk Donker)

Notes/Discussions

VV: Oxygenation failure or CO2 removal (ECCO2R)

VA: Cardiac support; inability to wean from CPB; ECPR

 

Following publish of SHOCK II Trial, significant increase in ECMO usage in Germany

 

www.SAVE-SCORE.com  → survival prediction after VA ECMO

 

NO DATA FROM RCTs for ECMO in Cardiac failure

 

VA ECMO for refractory septic shock? Poor data

ECPR: CHEER Trial: 50% survival; Netherlands already has 45% survival rate for cardiac arrests - would ECMO add anything?

________________

VV: H1N1 CESAR Trial: initial increase in VV ECMO usage, which has now declined since 2012

Indicated in ARDS refractory to conventional therapies; diversity of usage across centers

Limitation of CESAR: not every patient was cannulated for ECMO (strictly transferred to higher level center)

 

Dual-lumen catheter/Avalon: IJ cannulation that allows for mobilization/good for bridge to lung transplantation (‘awake ECMO’)

Possible indication for trauma (lung contusion?)

 

 

ECMO principles (Dirk Donker)

Notes/Discussions

Patient interacts with the machine; drainage of central venous blood; propelled through centrifugal pump, oxygenated (artificial membrane → supplied with mixture of air/oxygen) and then returned to patient (either venous (VV) or arterial (VA) or both (VAV).

 

Oxygenator is very efficient: made up of tiny tubes with ~1 m^2 of surface area (compared to 70 m^2 in native lung)

 

Older models/pediatric circuits use roller pumps → now centrifugal/non-occlusive with magnetic levitation; electrical, non-pneumatic, non-pulsatile; speed 0-4000 RPM with flows up to 8 L/min

 

Circuit connections are risk for infection/air entrainment so should be minimized

 

Oxygen/air mixture sweeps past membrane (resin) which allows for gas exchange; faster flow rates yields increased CO2 removal (essentially minute ventilation); oxygenation is primarily determined by blood flow    

Introduction to cannulation (Dirk Donker)

Notes/Discussions

Multi-stage venous cannula

Single stage venous cannula

TEE essential for ECMO cannulation to confirm adequate placement

 

Drainage cannula in IVC: ensure guidewire is in the SVC, otherwise risk of malposition in hepatic veins/RA - case report of RA perforation

Possible for Avalon catheter to end up in RV - case report of RCA perforation  

 

Pre-procedure fluoroscopy to make educated guess about anatomy (rarely in straight line)

Need combination of TTE, TEE, and fluoroscopy for successful cannulation

 

VV: IJ/FEM, Fem-Fem, IJ; ensure adequate distance apart to prevent recirculation

Spontaneous breathing can cause recirculation!*

 

VA: Risk of aortic valve non-opening due to counterflow → LV thrombus, pulmonary edema

Summary/Key points

Different modes VA VV VAV (Fabio Taccone)

Notes/Discussions

Cardiac ECLS: VA, V-PA, ECPR

Respiratory ECLS: VV, V-PA, AV-ECCO2R, VV-ECCO2R

 

VA: RECOVERY, DURABLE DEVICE, TRANSPLANT, DECISION

• Indications: Refractory cardiogenic shock, AMI complications, post-cardiotomy syndrome, massive PE, decompensated end-stage dilated cardiomyopathy, acute myocarditis/intoxications
• Limb ischemia, increased afterload, regional hypoxemia syndrome (peripheral cannulation)
• Central cannulation: best flow, LV offloaded, virtually zero pulmonary edema  

 

ECPR can be used for organ procurement in certain areas

 

VV: Maintain gas exchange, allow protective ventilation, allow rest & recovery, gain time for lung transplant (optimize for transplant)

 

ECCO2R: Low-flow for CO2 removal

 

“Hybrid ECLS”

VV-A: Venous insufficiency/drainage problem (multiple drainage, one return cannulae)

VA-V: Regional hypoxemia (one drainage, multiple return cannulae - one to venous system)

Perc Support: IABP, Impella, TandemHeart (used to decompress while on VA ECMO)

How to deal with antibiotics, fluids and sedation (Fabio Taccone)

Notes/Discussions

Sedation major issue on ECMO - likely contributing to oversedation, psychosis, delirium, etc

 

Ex-vivo: nearly 100% of Fentanyl/Midazolam absorbed by circuit

In-vivo: doses of Morphine, Fentanyl, Midazolam increased substantially following ECMO initiation

• Initial high sedation requirements, then needs to be decreased to prevent oversedation; BIS monitoring may be helpful for adequate sedation monitoring
• Adjunctive therapies may be helpful (Dexmedetomidine, Ketamine)

 

Fluids, increased CI/RBF, increased capillary leakage/volume of distribution may alter blood concentrations; needs higher doses of antibiotics

 

Lipophilic medications may be sequestered in the circuit; hydrophilic meds may be absorbed  

 

**ECMO did not significantly affect concentrations of hydrophilic antibiotics**  - in general should be given in higher doses - be wary of neurologic side effects with higher doses of B-lactams

 

Fluids: Salvage, Optimize, Stabilize, De-escalation (positive fluid balances associated with poor outcomes)

• Chugging/chattering cannulae may be evidence of intravascular depletion

Anticoagulation (Enno Wildschut)

Notes/Discussions

aXa does not give any information about Factor II

aPTT/PT tested against plasma - no interaction with cells (fine if patient is not sick)

Cell-based model of coagulations: TF-bearing cells can cause massive platelet activation

PT/PTT only report initial generation of thrombin - if allowed to continue would likely drop down again (information is out of date)

 

Weak thrombin activation will give appropriate aXa activity but *no* II activity → thrombogenic

Post-cardiotomy can lose up to 60% of ATIII - will lead to Heparin resistance

ASA may help to reduce Heparin dose/hyperactive platelets

 

Hemolysis actually increases thrombogenicity by exposing phospholipid from RBCs - requires higher doses of Heparin

 

Alternative anticoagulation strategies:

• Bivalrudin
• FVIIa Inhibitory Antibody (experimental)  

ECCO2R (Rita Jacobs)

Notes/Discussions

CO2 carried by dissolved bicarbonate with no saturation point; 1 L of blood can carry 500 mL of CO2

 

In theory, 500 mL/min blood flow should be sufficient to remove all produced CO2

 

iLA (interventional lung assist): uses patient’s own blood pressure to drive flow into gas exchanger; no pump needed, less blood trauma; require arterial cannulation (risk of limb ischemia, vascular injury)

• Needs U/S prior to ensure it will take < 70% of vascular circumference

 

VVCO2R (veno-venous): percutaneous placement (13-17 Fr)

• Pump-Assisted Lung Protection (PALP): can be upgraded to ECMO
• iLA Active: Novalung + diagonal pump
• Hemolung: pump + membrane
• Decap: Membrane lung + dialysis filter

Article: 3 cc/kg + ECCO2R: 6 cc/kg ARDS

• Significant increase with 60-day ventilator days

Article: AV or VV ECCO2R; no demonstrable mortality benefit

 

SUPERNOVA Trial: ECCO2R in new mod-sev ARDS

 

COPD

• Study ECCO2R vs. Invasive Ventilation (failure of NIPPV)
• Trend towards reduced mechanical ventilation

 

Thoracic Surgery

• Small study: effective use in achieving extubation/efficient CO2 removal

 

BTT

• 19 (95%) successfully transplanted with ECCO2 with life-threatening hypercapnia  

Ventilator settings (Rita Jocobs)

Notes/Discussions

Volutrama, atelectotrauma, biotrauma all determinants to ventilator-induced lung injury (VILI)

Stress/strain applied to small areas of healthy lung parenchyma (“baby lung”) induces injury

 

ELSO guidelines recommends Vt < 4 mL/kg IBW, but low Vt can induce atelectotrauma, so also recommend PEEP 10 (prevents derecruitment and reduces need for higher FiO2)

 

Driving pressure (Pplt - PEEP): predictor of risk of death (higher Pplt, worse outcomes)

• Rationale: ventilator energy transferred to lung, causes heat and lung tissue damage
• Closely related to RR and dP: low Vt, higher PEEP, sweep gas to reduce vent needs

 

APRV: high CPAP with brief intermittent release

• Incr distribution of ventilation to dependent areas with improved systemic blood flow

 

Proning on ECMO:

• Failure to wean > 7 days, refractory hypoxemia, elevated Pplt
• Significant improvement in P:F after 24 hrs proning without significant events

Weaning from ECMO (Donker)

Notes/Discussions

Depends on underlying disease

No trial within first 24-48 hrs; post-cardiotomy, post-infarction may show recovery in 72-96 hrs; myocarditis effects may last weeks

 

Daily serial assessment; difficult to protocolize, but should have well-defined end-points