Experts Consensus Recommendations for the Management of Calcium Channel Blocker Poisoning in Adults.

OBJECTIVE: To provide a management approach for adults with calcium channel blocker poisoning. DATA SOURCES, STUDY SELECTION, AND DATA EXTRACTION: Following the Appraisal of Guidelines for Research & Evaluation II instrument, initial voting statements were constructed based on summaries outlining the evidence, risks, and benefits. DATA SYNTHESIS: We recommend 1) for asymptomatic patients, observation and consideration of decontamination following a potentially toxic calcium channel blocker ingestion (1D); 2) as first-line therapies (prioritized based on desired effect), IV calcium (1D), high-dose insulin therapy (1D-2D), and norepinephrine and/or epinephrine (1D). We also suggest dobutamine or epinephrine in the presence of cardiogenic shock (2D) and atropine in the presence of symptomatic bradycardia or conduction disturbance (2D); 3) in patients refractory to the first-line treatments, we suggest incremental doses of high-dose insulin therapy if myocardial dysfunction is present (2D), IV lipid-emulsion therapy (2D), and using a pacemaker in the presence of unstable bradycardia or high-grade arteriovenous block without significant alteration in cardiac inotropism (2D); 4) in patients with refractory shock or who are periarrest, we recommend incremental doses of high-dose insulin (1D) and IV lipid-emulsion therapy (1D) if not already tried. We suggest venoarterial extracorporeal membrane oxygenation, if available, when refractory shock has a significant cardiogenic component (2D), and using pacemaker in the presence of unstable bradycardia or high-grade arteriovenous block in the absence of myocardial dysfunction (2D) if not already tried; 5) in patients with cardiac arrest, we recommend IV calcium in addition to the standard advanced cardiac life-support (1D), lipid-emulsion therapy (1D), and we suggest venoarterial extracorporeal membrane oxygenation if available (2D). CONCLUSION: We offer recommendations for the stepwise management of calcium channel blocker toxicity. For all interventions, the level of evidence was very low.

Comparison of the 20-hour intravenous and 72-hour oral acetylcysteine protocols for the treatment of acute acetaminophen poisoning.

STUDY OBJECTIVE: To compare outcomes after acute acetaminophen poisoning in 2 large cohorts of patients treated with either the 20-hour intravenous or 72-hour oral acetylcysteine protocol. METHODS: We conducted a retrospective cohort study with historical control comparing patients treated with one of 2 acetylcysteine regimens. Data for the 20-hour group were obtained from a medical record review of patients on whom the 20-hour intravenous protocol was initiated in Canadian hospitals from 1980 to 2005. The 72-hour group consisted of a historical cohort of patients treated in US hospitals with the 72-hour oral protocol from 1976 to 1985. The primary outcome was hepatotoxicity (aminotransferase levels >1,000 IU/L). RESULTS: Of the 4,048 patients analyzed, 2,086 were in the 20-hour group and 1,962 were in the 72-hour group. The incidence of hepatotoxicity was 13.9% in the 20-hour group and 15.8% in the 72-hour group (-1.9% absolute difference; 95% confidence interval [CI] -4.2 to 0.3). The relative risk of hepatotoxicity was lower in the 20-hour group when acetylcysteine was initiated within 12 hours of ingestion. The relative risk was lower in the 72-hour group when acetylcysteine was initiated later than 18 hours after ingestion. There was no significant risk difference between groups when acetylcysteine treatment was started 12 to 18 hours after ingestion. One patient in the 20-hour group received a liver transplant and died because of acetaminophen toxicity compared with no liver transplants and 3 deaths in the 72-hour group. Anaphylactoid reactions to intravenous acetylcysteine were reported in 148 of 2,086 patients (7.1%; 95% CI 6.1% to 8.3%). This study is limited by comparison of 2 separate data sets from different countries and study years. CONCLUSION: The risk of hepatotoxicity differed between the 20-hour and 72-hour protocols according to the time to initiation of acetylcysteine. It favored the 20-hour protocol for patients presenting early and favored the 72-hour protocol for patients presenting late after acute acetaminophen overdose.

Are there teratogenic risks associated with antidotes used in the acute management of poisoned pregnant women?

OBJECTIVE: We reviewed evidence suggesting teratogenic risk associated with the use of antidotes in the acute management of poisoned pregnant women. METHODS: Medline, Toxline, and DART/ETIC searches; references of retrieved articles, pertinent databases and textbooks were also searched. RESULTS: There are case reports or case series of women who received antidotes for poisoning during (*) or after (+) the period of organogenesis who showed no fetal adverse effects. Some antidotes, however, have no teratogenic risk: atropine (cohort/surveillance studies)+, calcium (oral supplement: cohort study)+ and pyridoxine (Bendectin studies). Also, ethanol+, methylene blue (intra-amniotic injection but not oral) and penicillamine* can be considered teratogens but their risks in the treatment of poisonings are unknown. There is no epidemiologic study evaluating the risk of the following antidotes during pregnancy: N-acetylcysteine(*+), BAL (dimercaprol)+, black widow spider antivenin+, calcium EDTA+, crotalidae antivenin, crotalidae polyvalent immune FAB, cyanide antidote kit (amyl and sodium nitrate, sodium thiosulfate), deferoxamine(*+), digoxin immune FAB+, DMSA+, flumazenil+, fomepizole, methylene blue (IV), naloxone, physostigmine, pralidoxime+, protamine+; and parenteral pharmacologic doses of calcium+, folinic acid*, glucagon+, hydroxycobalamin, phytonadione (vitamin K), and pyridoxine. CONCLUSIONS: Despite the limited evidence supporting the risk of antidote use during pregnancy, antidotes should be used when there is a clear maternal indication to decrease the morbidity or mortality associated with poisoning. The only exception may be penicillamine, which is a teratogen. Better antidotes exist for most poisonings that penicillamine could potentially treat. At this time, there is no known fetal indication for all antidotes. Reporting the use of an antidote during pregnancy should be encouraged, especially if used during the critical period of organogenesis.