ECMO in Poisoning Journal Club

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We recently had a interesting
toxicological case that involved ECMO, so we’re going to discuss the utility of
ECMO in poisoning.

Case

7 month old child with a history
of ectopic atrial tachycardia was put in the care of his aunt. He is on a
strict medication regimen. His aunt gives his usual medication and within a few
minutes later, he had become pale and distressed. She calls 911 and the
paramedics arrive and on the cardiac monitor, the see the following rhythm:

 

The EMS find that the aunt had
given 4 times the dose of his medication, which was flecainide. The aunt had
counted 1 line from the top of the 5 ml syringe rather than from the bottom. He
was taken to the hospital and lost pulses. Pt had to undergo CPR and the poison
control was consulted. At that point, the poison control center recommended
intralipid and sodium bicarbonate. He had a return of pulses afterwards.

At this point, he was started on
ECMO. Since this was a poisoning, ECMO could give the child more time to
metabolize the flecainide. He was eventually taken off of ECMO on day 3 and
child was eventually discharged from the hospital playful and acting like his
normal self.

ECMO

ECMO is similar to dialysis. The
basic principle is to remove blood, replace what is needed, and return the
blood to the body. In the case of ECMO, gas exchange and/or cardiac output are
the processes replaced for the body.

Two forms of ECMO exist. There is
Venovenous (VV)  or Venoarterial (VA)
ECMO. For VV ECMO, this is solely replacing the lungs for gas exchange. The
blood is removed from a vein, oxygenated, and returned back into the venous
system This can be helpful particularly as a salvage therapy when positive
pressure ventilation is either ineffective. VV ECMO is also used when patients
are unable to handle high inspiratory pressures or pressure/volume limited
ventilation strategies.

VA ECMO is where blood is removed
from a vein, oxygenated, and then pumped into an artery (usually the aorta). In
addition to oxygenating blood, VA ECMO also replaces the heart’s pumping
function, so blood is returned at higher pressures to perfuse the rest of the
body. VA ECMO is usually reserved for refractory circulatory shock.

Indications
for ECMO

According to the Extracorporeal
Life Support Organization (ELSO), VV-ECMO should be considered for the
following:

Risk
of death is > 50% and indicated if >80%.
Murray
score  >= 3 or 4 associated with 80-90% risk of death (http://bit.ly/1k0BYjf).

ECMO found particularly use
during the past SARS epidemic. This parallels poisoning as the patient should
improve after given enough time to metabolize the toxin.

Complications
of ECMO

The most common complications are
bleeding and clotting. As the blood runs through the circuit, risk of clotting
and passing emboli increases, so an anticoagulant is used. Overall bleeding
complications is 10-36% and intracranial hemorrhage is around 6%. Additionally,
red blood cells are hemolyzed passing through the ECMO circuit. On average,
patients require about 1 unit of blood transfused per day.

Poisoning
and ECMO

Most of the evidence is from case
reports. The best evidence we have so far is a non-randomized, retrospective
study done in France. All patients had persistent cardiac arrest or severe
shock following poisoning due to drug intoxication. ECMO was performed on 14
patients and 48 patients had conventional treatments. 56% of the patients in
the conventional arm survived while 86% of the ECMO arm did. After adjusting
for Simplified Acute Physiology Score (SAPS II) and beta blocker toxicity, the ECMO
arm were associated with lower mortality (OR: 0.18 [0.03-0.96], p =0.04).

ECMO
in Action

The “French” model is that ECMO
comes to the patient. In France, a doctor is always traveling in the ambulance,
which is different from the American “scoop and run” model for EMS.
Resuscitation can be done in the ambulance. Additionally, ECMO cannulation can
be started in the ambulance or sending site and then finished at the receiving
site.

In the book Checklist
Manifesto, there was a case of a young girl who drowned but was fished out
in 45 minutes. She had no signs of life, but was put on ECMO. Over the course
of 6 days, patient recovers back to her normal self. This story illustrates the
need for an enormous amount of coordination for ECMO to be successful. However,
currently ECMO is only available at certain centers and requires a lot of
training and expertise. It is also expensive (approximately $31,000 per patient).
Much more clinical and basic science research needs to be done for ECMO before
we can consider widespread usage.

An ECMO Poisoning Story on YouTube

References:

Shenoi AN, et al. Refractory Hypotension From Massive Bupropion Overdose Successfully Treated With Extracorporeal Membrane Oxygenation. Pediatric Emergency Care. Jan 2011;27:43-45.
Megarbane B, et al. Extracorporeal life support in a case of acute carbamazepine poisoning with life-threatening refractory myocardial failure. Intensive Care Medicine. 2006;32:1409-1413.
De Lange DW, Sikma MA, Meulenbelt J. Extracorporeal Membrane Oxygenation in the Treatment of Poisoned Patients. Clinical Toxicology. 2013;51:385-393. 
Masson R, Colas V, Parienti JJ, Lehoux P. Massetti M, Charbonneau P, Saulnier F, Daubin C. A Comparison of Survival With and Without Extracorporeal Life Support Treatment
for Severe Poisoning Due to Drug Intoxication. Resuscitation. 2013;83:1413-1417.
Goodwin DA, Lally KP, Null DM. Extracorporeal Membrane Oxygenation Support for Cardiac Dysfunction from Tricyclic Antidepressant Overdose. Critical Care Medicine. 1993;21:625-627.
Extracorporeal Membrane Oxygenation for ARDS in Adults. NEJM. Feb 2012;366:575-576.
Marcinak KE, Thomas IH, et al. Massive Ibuprofen Overdose Requiring Extracorporeal Membrane Oxygenation for Cardiovascular Support. Pediatric Critical Care Medicine. 2007;8:180-182.
Brodie D, Bacchetta M. Extracorporeal Membrane Oxygenation for ARDS in Adults. NEJM. Nov 2011;365:1905-1914.
Gawande A. The Checklist Manifesto: How to Get Things Rights. Macmillan Publishers. 2009. Available at: http://us.macmillan.com/BookCustomPage_New.aspx?isbn=9780312430009. Accessed August 5,2013.