UMEM Educational Pearls - Toxicology

Category: Toxicology

Title: Ciguatera Poisoning

Keywords: ciguatera, poisoning, fish (PubMed Search)

Posted: 9/27/2007 by Fermin Barrueto, MD (Updated: 12/7/2021)
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Ciguatera Poisoning - The most commonly reported cause of fishborne poisoning - Most commonly big-game fish: sea bass, grouper, red snapper, yellow-tail, kingfish and sturgeon - Ciguatoxin is bioaccumulated (thus big fish) and is heat and acid stable (unaffected by cooking) - Symptoms: 6-12 hrs post-ingestion GI, paresthesias, metallic taste, ataxia and paresis of legs are possible - The classic symptom is dysesthesias (sensory reversal where cold gives intense burning sensation) - Treatment: Supportive, consider mannitol, calcium, gabapentin - Avoid the following as it may exacerbate symptoms: opioids, barbiturates, steroids

Category: Toxicology

Title: Ethanol Withdrawal

Keywords: ethanol, withdrawal, benzodiazepines (PubMed Search)

Posted: 9/18/2007 by Fermin Barrueto, MD (Emailed: 9/20/2007) (Updated: 12/7/2021)
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Ethanol withdrawal can be measure objectively with the CIWA-Ar Scale. It is a prospectively validated tool to measure whether or not a patient is in ethanol withdrawal and can assist with management. Score Treatment <10 Does not require treatment 10-15 Treatment with either oral or intravenous benzodiazepines, outpatient > 15 Intravenous benzodiazepines with likely admission You must also take into account the patient's history, comorbidities and previous history of ethanol withdrawal/delirium tremens. ***The CIWA Score Sheet has been attached to this pearl***

Attachments

ciwa-ar.pdf (10 Kb)


Category: Toxicology

Title: Toxins that cause Diabetes or Hyperglycemia

Keywords: Hyperglycemia, diabetes, poisoning (PubMed Search)

Posted: 9/13/2007 by Fermin Barrueto, MD (Updated: 12/7/2021)
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There are few medications/toxins that can cause clinically significant diabetes or hyperglycemia, here is the list: Vacor (PNU, an off the market rat poison) Streptozocin Alloxan Pentamidine Quinolones (gatifloxacin>moxifloxacin>ciprofloxacin) Olanzapine Antidote for Vacor, streptozocin, Alloxan: Niacinamide Antidote for Quinolones, Olanzapine: Remove agent, supportive care

Category: Toxicology

Title: Scombroid

Keywords: Fish, scombroid, seafood poisoning (PubMed Search)

Posted: 9/6/2007 by Fermin Barrueto, MD (Updated: 12/7/2021)
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Scombroid is one of the most common seafood poisonings. A classic EM board question. - Caused by ingestion of histamine in fish muscle - Naturally occurring histidine is converted to histamine by bacteria in unrefrigerated fish - Most common fish: tuna, mackerel, bonito, mahi mahi, blue fish and yellow tail - Symptoms: Within minutes to hours - flushing, urticaria, perioral burning, N/V/D - Treatment: Antihistamines, fluids, bronchodilators. Epinephrine and steroid for severe reactions.

Category: Toxicology

Title: Methemoglobinemia

Keywords: pyridium, methemoglobinemia, methylene blue (PubMed Search)

Posted: 8/30/2007 by Fermin Barrueto, MD (Updated: 12/7/2021)
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- Classic Clinical Finding: Cyanosis out of proportion to clinical symptoms (look real blue but not SOB) - Causative Agents: Benzocaine (and other local anesthetics), dapsone, nitrites, phenazopyridine (Pyridium) - When do you treat: significant tissue hypoxia (MI, CVA, Dysrhythmias), and if MetHb >20% asymptomatic - Treatment: Methylene Blue 1-2 mg/kg (0.1 -0.2 mL/kg of 1% methylene blue) over minutes

Category: Toxicology

Title: Colchicine Toxicity - The Point of No Return

Keywords: Colchicine, toxicity, poisoning (PubMed Search)

Posted: 8/23/2007 by Fermin Barrueto, MD (Updated: 12/7/2021)
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- Few medications are uniformly lethal after a certain amount is ingested. - Colchicine is one of those medications, >0.8 mg/kg ingested=100%mortality regardless of treatment. - Many people prescribe it without knowing the adverse effect profile. - In fact, the prescribing instructions tell you to take the patient to toxicity (nausea and vomiting). - After an acute overdose this would be the sequence of events assuming surivival: Phase Signs & Symptoms i Nausea, vomiting, diarrhea, dehydration, leukocytosis (0-24hrs) II Sudden cardiac death (24-36hrs), pancytopenia, renal failure sepsis, ARDS, rhabdo (1-7d) III Alopecia, myopathy, neuropathy, myoneuropathy (>7d) - Colchicine prevents/destroys microtubule spindle formation and thus acts like a chemotherapeutic agent killing the cells that replicate most. - Think twice when prescribing this medication to someone, especially a patient at risk for suicide or medication noncompliance (where they think a little is good so more is better).

Category: Toxicology

Title: Local Anesthetics

Keywords: lidocaine, allergic reaction, toxicity (PubMed Search)

Posted: 8/16/2007 by Fermin Barrueto, MD (Updated: 12/7/2021)
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- Allergic reactions are extremely rare to local anesthetics but may occur with the "Amides". - If they occur, it is more likely due to a preservative found in some multi-dose vials: methylparaben. - Either switch to a single dose vial without preservative or change to an "Ester" where there is no cross-reactivity Amides: Bupivacaine, Etidocaine, Lidocaine, Mepivacaine, Prilocaine, Ropivacaine Esters: Chloroprocaine, cocaine, procaine, tetracaine

Category: Toxicology

Title: Toxic Findings on CxR

Keywords: Chest radiograph, poisoning, amiodarone (PubMed Search)

Posted: 8/9/2007 by Fermin Barrueto, MD (Updated: 12/7/2021)
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Here are some chest x-ray findings and cool toxins that can cause them (not an all-inclusive list): Diffuse airspace filling: salicylates, opioids, paraquat, phospgene, doxorubicin - Disease Process: Acute Lung Injury Focal airspace filling: hydrocarbons - Disease Process: Aspiration pneumonitis Pleural Effusion: Procainamide, hydralazine, INH, methyldopa - Disease Process: Drug-induced SLE Pneumothorax/Pneumomediastinum: "crack" cocaine and marijuana, IVDA into subclavian vein - Disease Process: Barotrauma Lymphadenopathy: Phenytoin, methotrexate - Disease Process: Pseudolymphoma Interstitial Patterns: Amiodarone - Disease Process: Phospholipidosis [Adapated from Goldfrank's Textbook of Toxicologic Emergencies, 8th Edition, Table 6-3, p. 74]

Category: Toxicology

Title: Opioids with Unique Toxicity

Keywords: opioids, adverse drug effect, methadone (PubMed Search)

Posted: 8/2/2007 by Fermin Barrueto, MD (Updated: 12/7/2021)
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Opioids Opioids in general cause respiratory depression, miotic pupils and some mild hypotensions and bradycardia when the patient is comatose. All opioids can cause varying degrees of histamine release. However, not all opioids are similiar, here are the unique toxicities of some various opioids - keep them in mind when you prescribe them: 1) Propoxyphene - seizures and TCA like effects, also not very effect analgesic 2) Meperidine - seizures, serotonergic (thus increased abuse potential) 3) Methadone - long half-life (30+hrs) and QT prolongation 4) Hydromorphone - rare seizures and most common opioid that causes iatrogenic overdose because of its potency. (Easy to write 2 mg of "Dilaudid" but that is equivalent to 14 mg of morphine!) 5) Tramadol - seizure (common) and serotonergic, this is only 20% opioid 6) Fentanyl - rigid chest syndrome with rapid IV administration causes intercostal muscle contraction - not good

Category: Toxicology

Title: Chemical Weapons of Mass Destruction

Keywords: Nerve agents, organophosphates, blistering agents (PubMed Search)

Posted: 7/26/2007 by Fermin Barrueto, MD (Updated: 12/7/2021)
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Chemical Weapons of Mass Destruction There are a variety of chemicals utilized as WMD and can be categorized as: nerve agent, blistering agent or incapacitating agent: Nerve Agents: (Sarin, VX) cause a parasympathetic toxidrome due to inhibition of Acetylcholinesterase. Antidote is pralidoxime, benzodiazepines and atropine. Blistering Agents: (Mustard Gas) Must be treated like a severe burn patient causing extreme pain and sloughing of the skin. Incapacitating Agents: (BZ) Causes anticholinergic toxidrome, your whole army starts to hallucinate and develop urinary retention. People armed, hallucinating and needing to pee makes for a highly ineffective military force.

Category: Toxicology

Title: Activated Charcoal

Keywords: Gastrointestinal decontamination, activated charcoal, poisoning (PubMed Search)

Posted: 7/19/2007 by Fermin Barrueto, MD (Updated: 12/7/2021)
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Gastrointestinal Decontamination - Activated Charcoal Pharmacist P.f. Touery, in 1831, making a demonstration of the effectiveness of charcoal before the French academy of Medicine, survived after swallowing 15 g of strychnine (10x lethal dose) and an equal amount of charcoal - 3 tablespoons. (That's for you Dr. Rolnick) - Assess the patients' chance of becoming unresponsive or vomiting in relation to the ingestion if known. - Maximal benefit if given within 1 hour of ingestion, drug is likely still in the stomach. - No study has yet to show decrease in morbidity or mortality when empirically given to all ingestions. - Only one study has shown multi-dose activated charcoal to decrease morbidity and mortality and that was with a drug (oleander is like digoxin) that is enterohepatically metabolized. de Silva HA, et al. Multiple-dose activated charcoal for treatment of yellow oleander poisoning: a single-blind, randomised, placebo-controlled trial. Lancet. 2003 Jun 7;361(9373):1935-8.

Category: Toxicology

Title: One Pill Killers for Children

Keywords: pediatric, poisoning, overdose (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/12/2007) (Updated: 12/7/2021)
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One Pill Killers for Children Drug Class Mechanism of Action that Kills Sulfonylureas These hypoglycemic agents (ie. Glyburide) also have a long t Opioids Respiratory depression Imidazoline Clonidine and Oxymetazolone (nasal spray) cause bradycardia and respiratory depression Ca Channel Blockers Bradycardia & hypotension, especially diltiazem and verapamil Beta Blockers Extended release preparations are problematic There are some others but these are the most commonly prescribed pharmaceuticals. Remember, children under age 6 will not be able to swallow a pill and the pill itself is choking hazard. Proper poison prevention education for the parents is also needed.

Category: Toxicology

Title: Acetaminophen Toxicity

Keywords: acetaminophen, hepatic failure, hepatitis (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/8/2007) (Updated: 12/7/2021)
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Acetaminophen Toxicity Hepatoxicity defined by AST >1000 King s College Criteria to prognosticate hepatic failure and need for transplant: o pH <7.3 o Creatinine >3.4 mg/dL o INR >6.5 o Hepatic encephalopathy Grade III or IV Low phosphate (<1.2 mmol/L) may be predictor of survival and elevated may be indicator of impending hepatic failure. (Especially 48 96 hrs post-ingestion) o Theory is phosphate used in regeneration/healing liver Gow PJ, Sood S, Angus PW. Serum phosphate as a predictor of outcome in acetaminophen-induced fulminant hepatic failure. Hepatology. 2003; 37(3):711.

Category: Toxicology

Title: Botulinum Toxin

Keywords: botulinum toxin, paralysis, heroin (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/8/2007) (Updated: 12/7/2021)
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Botulinum Toxin Most potent toxin on the planet where 7 picograms IV are lethal to a human Characterized by a descending flaccid paralysis w/o fever bulbar findings 1st Weapon of Mass Destruction but also seen in the IVDA Heroin population Black Tar Heroin outbreak with necrotic ulcers that produced C. botulinum o Most recently in Washington DC 2003 Centers for Disease Control and Prevention (CDC). Wound botulism among black tar heroin users--Washington, 2003. MMWR Morb Mortal Wkly Rep. 2003;52(37):885-6.

Category: Toxicology

Title: Diagnosing Salicylate Toxicity

Keywords: Salicylate, aspirin, ferric chloride (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/8/2007) (Updated: 12/7/2021)
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Diagnosing Salicylate Toxicity - Acute ingestion can initiially present with nausea, vomiting and a respiratory alkalosis - Toxicity defined by an anion gap metabolic acidosis with ketosis and normal glucose - Ferric chloride test (can get from chemistry set): couple of drops into urine, if it changes color to deep purple sensitive positive for presence of salicylate (sensitive but not specific)

Category: Toxicology

Title: Hyperthermia

Keywords: hyperthermia, serotonin syndrome, neuroleptic malignant syndrome (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/8/2007) (Updated: 12/7/2021)
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Hyperthermia Neuroleptic Malignant Syndrome (Dopamine Inhibition): treat with bromocriptine Serotonin Syndrome (5-HT1A agonism): treat with serotonin antagonist Malignant Hyperthermia (Genetic): treat with dantrolene

Category: Toxicology

Title: Lithium Toxicity Management

Keywords: lithium, renal failure, neurologic (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/8/2007) (Updated: 12/7/2021)
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Lithium Toxicity Management Initial Therapy: 2x maintenance fluid with normal saline Hemodialysis is controversial but will remove lithium quickly Association of permanent neurologic sequelae with elevated lithium level(1) o Looks like a cerebellar stroke 1- Adityanjee. The syndrome of irreversible lithium-effectuated neurotoxicity (SILENT). Pharmacopsychiatry. 1989 Mar;22(2):81-3.

Category: Toxicology

Title: Digoxin Toxicity

Keywords: digoxin, cardiac glycoside, toxicity (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/8/2007) (Updated: 12/7/2021)
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Digoxin Toxicity Most common finding on ECG when digoxin toxic: PVCs Most classic ECG in digoxin toxicity: PAT with block Pathognomonic finding (RARE): Bidirectional ventricular tachycardia Easy formula for administration of digoxin specific Fab (Digibind?? or DigiFab?). Remember to round up even if its 2.3 vials, give 3. [(Dig Serum Concentration(ng/mL)) x wt(kg)] / 100 = # vials

Category: Toxicology

Title: Tricyclic Antidepressants (TCA)

Keywords: tricyclic antidepressant, electrocardiogram, cardiac toxicity (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/8/2007) (Updated: 12/7/2021)
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Tricyclic Antidepressants (TCA) - Lack of terminal 40msec R wave (R wave in AvR, S wave in I, AvL) means the patient is NOT TCA toxic. - 40msec R wave + QRS >100msec = possible TCA toxicity, treat with NaHCO3 and recheck ECG. - TCA toxicity defined by ECG; if QRS > 100msec, 33% seizures; if QRS > 160msec, 50% v tach Boehnert MT, Lovejoy FH Jr. Value of the QRS duration versus the serum drug level in predicting seizures and ventricular arrhythmias after an acute overdose of tricyclic antidepressants. N Engl J Med. 1985 Aug 22;313(8):474-9.

Category: Toxicology

Title: Urine Drug Screens

Keywords: drug abuse, urine drug screen, cocaine (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/8/2007) (Updated: 12/7/2021)
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Urine Drug Screens Though we order them often, be sure you know what your results mean: Cannabinoids: an accurate test though clinically not important information, positive for 5 days to a full month with chronic users. Cocaine: the most accurate and precise test, positive for 3-5 days. Amphetamine: the most imprecise with many false positives and false negatives. Cough/cold preparations that contain pseudephedrine, phenylephrine or other decongestants can turn it falsely positive. BDZ: only benzodiazepines that are metabolized to oxazepam will turn positive. You can see false negatives with alprazolam and even lorazepam. Opioids: Semisynthetics like oxycodone and hydrocodone may give false negatives at low levels. This screen will NOT catch methadone, meperidine, fentanyl, propoxyphene, tramadol. PCP: False positives from dextromethorphan and ketamine