Faculty Bibliography

BACKGROUND: The use of intravenous lipid emulsion (ILE) therapy for the treatment of lipophilic drug toxicity is increasing. Despite this, the evidence for its effect in non-local anesthetic toxicity remains sparse. Furthermore, many case reports describe ILE use for substances in which no clear efficacy data exists. The American Academy of Clinical Toxicology established a lipid emulsion workgroup. The aim of this group is to review the available evidence regarding the effect of ILE in non-LA drug poisoning and develop consensus-based recommendations on the use of this therapy. METHODS: A systematic review of the literature was performed to capture articles through 15 December 2014. Relevant articles were determined based upon a predefined methodology. Articles involving pre-treatment experiments, pharmacokinetic studies not involving toxicity, and studies not addressing antidotal use of ILE met pre-defined exclusion criteria. Agreement of at least two members of the subgroup was required before an article could be excluded. RESULTS: The final analysis included 203 articles: 141 for humans and 62 for animals. These include 40 animal experiments and 22 case reports involving animal toxicity. There were three human randomized control trials (RCT): one RCT examined ILE in TCA overdose, one RCT examined ILE in various overdoses, and one study examined ILE in reversal of sedation after therapeutic administration of inhaled anesthesia. One observational study examined ILE in glyphosate overdose. In addition, 137 human case reports or case series were identified. Intravenous lipid emulsion therapy was used in the management of overdose with 65 unique substances. CONCLUSIONS: Despite the use of ILE for multiple substances in the treatment of patients with poisoning and overdose, the effect of ILE in various non-local anesthetic poisonings is heterogenous, and the quality of evidence remains low to very low.

The Extracorporeal Treatments in Poisoning (EXTRIP) Workgroup conducted a systematic literature review using a standardized process to develop evidence-based recommendations on the use of extracorporeal treatment (ECTR) in patients with phenytoin poisoning. The authors reviewed all articles, extracted data, summarized findings, and proposed structured voting statements following a predetermined format. A 2-round modified Delphi method was used to reach a consensus on voting statements, and the RAND/UCLA Appropriateness Method was used to quantify disagreement. 51 articles met the inclusion criteria. Only case reports, case series, and pharmacokinetic studies were identified, yielding a very low quality of evidence. Clinical data from 31 patients and toxicokinetic grading from 46 patients were abstracted. The workgroup concluded that phenytoin is moderately dialyzable (level of evidence = C) despite its high protein binding and made the following recommendations. ECTR would be reasonable in select cases of severe phenytoin poisoning (neutral recommendation, 3D). ECTR is suggested if prolonged coma is present or expected (graded 2D) and it would be reasonable if prolonged incapacitating ataxia is present or expected (graded 3D). If ECTR is used, it should be discontinued when clinical improvement is apparent (graded 1D). The preferred ECTR modality in phenytoin poisoning is intermittent hemodialysis (graded 1D), but hemoperfusion is an acceptable alternative if hemodialysis is not available (graded 1D). In summary, phenytoin appears to be amenable to extracorporeal removal. However, because of the low incidence of irreversible tissue injury or death related to phenytoin poisoning and the relatively limited effect of ECTR on phenytoin removal, the workgroup proposed the use of ECTR only in very select patients with severe phenytoin poisoning.

Extracorporeal treatments (ECTRs) such as hemodialysis (HD), enhance the elimination of a small number of toxins. Changes in overdose trends, prescribing practices, antidotes, and dialysis techniques may alter the indications and rates of ECTR use over time. This study analyzed trends in ECTR for poisonings in four countries. A retrospective study of national poison center databases from the United States, Denmark, United Kingdom, and five regional databases within Canada was performed. All cases of patients receiving an ECTR were included. ECTR cases were totalled annually and reported as annual rates per 100,000 exposures with stratification per types of ECTR and toxins. The data collection varied by countries. United States, 1985-2014; United Kingdom, 2011-2013; Denmark, 2005-2014, and regions of Canada as follows: Alberta, 1991-2015; Saskatchewan, 2001-2015; Nova Scotia-PEI, 2006-2015; Quebec, 2008-2014; Ontario-Manitoba, 2009-2015; British Columbia, 2012-2015. During the study period, the total number of ECTRs and rates per 100,000 exposures, respectively, were: United States, 40,258 and 65.7; United Kingdom, 343 and 232.6; Denmark, 616 and 305.5; Canada, 2709 and 177.5; case rates increased over time for the United States, Denmark, and Canada, but decreased in the United Kingdom. Across the United States and Denmark, HD was the preferred modality used. Toxins for which ECTR was most often used were: United States, ethylene glycol; Canada, methanol; United Kingdom, ethylene glycol; Denmark, salicylates. A high number of ECTRs were performed for atypical toxins such as acetaminophen and benzodiazepines. These data demonstrate a growing use of HD for poisoning with significant regional variations in the overall rates and indications.