What are the adverse effects associated with the combined use of intravenous lipid emulsion and extracorporeal membrane oxygenation in the poisoned patient?

Context. Intravenous lipid emulsion (ILE) and veno-arterial extracorporeal membrane oxygenation (VA-ECMO) are being used together or in close succession in the management of circulatory failure secondary to cardiotoxic drug poisoning. There have been reports of mechanical problems, including fat emulsion agglutination, clogging, increased blood clot formation and even cracking of parts of the machine, in patients concurrently receiving VA-ECMO and ILE as part of parenteral nutrition. Objective. To ascertain the adverse effects associated with the combined use of ILE and ECMO in the poisoned patient. Methods. PubMed and OVID (1966 to 9 June 2014) and EMBASE (1947 to 9 June 2014) were searched to identify publications relating to studies and/or case reports where ILE had been used at the same time when VA-ECMO was used -7 were identified. In addition, the abstracts published between 2006 and 2013 inclusive of those from the North American Congress of Clinical Toxicology and the congresses of the European Association of Poisons Centres and Clinical Toxicologists were searched to identify additional cases and 2 were found. Finally all cases posted on lipidrescue. org were reviewed to determine if they related to the use of ILE with VA-ECMO and no new cases were identified. In vitro study. An in vitro study involving the continuous infusion of 20% ILE at 3 mL/h for 24 h demonstrated layering (separation of intact fat emulsion from blood) and agglutination (clumping resulting in little or no flow of fat emulsion through the circuit) in all circuits within 30 min of starting the fat emulsion infusion. Clinical studies. An observational study based in 42 centres that regularly used 'fat emulsion' during VA-ECMO treatment reported cracking of stopcocks (the valve which restricts flow in the VA-ECMO tubing) (n = 10, 23.8%); fat emulsion agglutination (n = 11, 26.2%); clogging and associated malfunction of the membrane oxygenator (n = 2, 4.8%); and increased blood clot formation in the circuits (n = 2, 4.8%). In a prospective observational study of 9 neonates on VA-ECMO receiving intravenous nutrition, layering and agglutination were seen in four sets of VA-ECMO tubing and blood clots were found in seven circuits. Nine case reports were identified where ILE was used with VA-ECMO for the management of circulatory failure/instability secondary to cardiotoxic drug poisoning. In two of these case reports, the authors specifically stated that ILE did not cause any mechanical complications with the VA-ECMO; the other seven reports made no comment as to whether there were any complications or not. Conclusions. There is in vitro and clinical evidence that the combined use of ILE and extracorporeal membrane oxygenation may be associated with fat deposition in the VA-ECMO circuits and increased blood clot formation. Clinicians managing poisoned patients with both of these novel treatment modalities should be aware of these potential complications.