Toxicology – ED

Toxicology

1. In a patient with a suspected toxic exposure, gather available collateral history from the scene (e.g., EMS history, empty pill bottles, recent prescriptions) to better identify the likely toxins.

2. Given a patient with a toxic ingestion:

a) Identify specific toxidromes based on patterns of clinical findings

  1. Sympathomemetic
    1. Mydriasis
    2. Tachycardia, HTN, Hyperthermia
    3. Diaphoresis
    4. Seizure, CNS excitation
  2. Cholinergic toxidrome
    1. Muscarinic – DUMBBELLS – tx with Atropine
      1. Diarrhea, Urination, Miosis,
      2. Bradycardia, Bronchorrhea, Bronchospasm (the killer Bs)
      3. Emesis, Lacrimation, Lethargy, Salivation
    2. Nicotinic (Atropine won’t treat – needs Pralidoxime (reactivate acetylcholinesterase)
      1. Tachycardia, HTN
      2. Muscle weakness, fasciculations
  3. Anticholinergic
    1. Red as a beet (flushing), Dry as a bone (dry skin)
    2. Mad as a hatter (delirium, hallucination)
    3. hot as hades (hyperthermia), Tachy as a leisure suit (tachycardia)
    4. blind as a bat (mydriasis, dec accomodation)
    5. Full as a flask (urinary retention), bloated as a toad (ilus)
    6. HTN, Sz
  4. Opiod
    1. CNS Depression
    2. Respiratory Depression
    3. Miosis
  5. Withdrawal toxidrome – Life threatening withdraw: BZD, Barbituate, baclofen
    1. Diarrhea, abdominal cramp, lacrimation, mydrasis, tachycardia, HTN, Sz
    2. Piloerection, yawning
    3. similar to sympathomimetic toxidrome

Seizure Causes (tox): OTIS CAMPBELL

  • Oral hypoglycemic agents, organophosphates, opiates (meperidine)
  • Theophylline – catecholamine release – tachydysrhythmias, HoTN
    • Metabolic acidosis, HypoK/P, hyperglycemia
    • Tx: esmolol – tachy/HoTN, BZD/ barbiturate – Sz
    • HD: refractory HoTN, dysrhythmias, Sz, >65-100mg/L
  • TCA – narrow therapeutic index / CNS, Alpha block, anticholinergic
    • anticholinergic
    • CV – QRS prolongation / prolong PR/QT – V Tachy/Fib, torsades, tall R wave on aVR
    • Neuro – AMS, Sz
    • Intubate early, AC if within 1hr
    • Tx Sodium Bicarb if QRS prolongation, acidosis, HoTN
  • INZ, Insulin
  • Salicylates, Sympathomimetics
  • CO, Cocaine, Cyanide, Camphor
  • Mushrooms(gyromitra), Methylxanthines
  • PCP (rotary nystagmus), Paraldehyde, Plants (Jimson weed, water hemlock)
  • Bb (propranolol), BZD/Barbiturate withdrawal
  • Ethanol withdrawal
  • Lithium – chronic worse than acute
    • Neuro: depress neural excitation  – common in chronic intoxication
      • Mild-mod: lethargy, weak, slurred, ataxis, tremor, myoclonus, hyperreflexia, fasciculation
      • Severe: agitated delirium, coma, Sz
    • GI: N/V/D – common in acute intoxication
    • Renal: nephrogenic DI
    • CV: TWI, bradycardia, sinus node arrest
    • renal excretion – toxicity triggered by dehydration, sodium depletion, inc sodium reabsorption. Eg. NSAIDs, ACEi, diuretics, gastroenteritis
    • Tx: IVF, avoid diuretics
    • HD: AMS, Sz, Renal failure, V. dysrhythmias, CHF-can’t tolerate fluid
  • Lead, Lindane, LSD

b) Use antidotes judiciously based on the clinical toxidrome, considering the indications and contraindications as well as other data.

3. When managing a patient with a toxic exposure, maintain a high level of suspicion for multidrug ingestion, especially with a mixed pattern of physical signs and symptoms (mixed toxidromes) or abnormal lab values (e.g., unexpected abnormal osmolar gap).

Routine Tylenol and ASA levels useful

  • both may be asymptomatic / subtle initially
  • Antidote/Tx available
  • both widely available

Osmole gap = measured – calculated (2Na+Glu+BUN) – normal -14 to +10

  • methanol
  • Ethylene glycol
  • Isopropanol
  • Ethanol 

Anion Gap = Na – HCO3 – Cl – normal 8-12

Anion gap metabolic acidosis: MUDPILES CAT

  • methanol
  • Uremia
  • DKA
  • Paraldehyde
  • INH, Iron
  • Lactate acidosis (metformin)
  • Ethylene glycol
  • Salicylate
  • CO, Cyanide
  • Alcohol – Ethanol
  • Toluene (CNS depression, sensitize to catecholamines – avoid epi, Tx supportive care & 6hr observation)

4. In the patient with a toxic ingestion, select specific treatments based on the combined information from the clinical toxidrome and from the presumed ingestion or exposure (e.g., avoid beta blockers in sympathomimetic OD – unopposed alpha – so use phentolamine, order sodium bicarbonate in TCA toxicity with wide complex tachycardia).

Antidotes of OD

  • tylenol – NAC (N-AcetylCysteine)
    • NAC 21hr IV: anaphylactoid reaction – stop NAC, give epi/benadryl and restart at slower rate 1hr after, switch to oral if persist symptoms
      • Preferred in 1.pregnant, 2.APAP-induced liver failure, 3.intractable vomiting
    • NAC po 72hr: N/V/D/urticaria; no anaphylactoid reaction
    • NAC IV/PO equally efficacious
    • toxic metbolite – NAPQI; detoxified by glutathione
    • Stage 1: 0.5-24hr: anorexia, N/V/malaise, diaphoresis, pallor or asymptomatic
    • stage 2: 24-48hr: RUQ pain, abn LFT/PT, abn Cr/oliguria
    • Stage 3 72-96hr: florid hepatic/renal failure
    • Stage 4: 40hr-14 days: resolution of hepatic/renal dysfunction or death
  • Rattlesnakes, Copperhead – CroFab, scorpion – Anascorp,
  • black widow spider – Latrodectus
  • Organophosphates / Carbamates – Atropine 5mg IV double Q5min until resolution of bronchorrhea, 2-PAM 2g bolus over 5min (pralidoxime)
    • Intubate early – use rocuronium (succinylcholine prolonged due to Ach)
    • Organophosphate – “aging” – irreversible bond – needs 2-PAM to reverse nicotinic effect – reverse muscle weakness and fasciculation
    • carbamate – only atropine needed as reversible bonding (no aging)
  • Clostridium botulinum – botulism anti-toxin (ABE)
  • HF acid / CCB – calcium gluconate
  • Betablocker (hypoglycemia) / CCB (hyperglycemia – block insulin)
    • glucagon 10mg IV bolus,
    • high dose Insulin 1u/kg/hr + D50 + D10W maintenance – D50 before insulin
    • IV intralipid 20% 100ml bolus
  • Lead – calcium disodium EDTA
  • Serotonin syndrome – Cyproheptadine
    • BZD for tremor, agitation, hyperthermia, tachycardia (esmolol)
    • cyproheptadine – failure of high dose BZD
  • Iron (toxic 40-60mg/kg) – deferoxamine 10mg/kg/hr IV (Vin rose urine)
    • stage 1. 1-4hr: corrosive effect: N/V/bloody, fluid loss, renal failure, death
    • Stage 2. over next 12hr – latent
    • Stage 3. 12-24hr – cellular toxicity (lactic acidosis) – Coma, shock, Sz, death, hepatic failure, coagulopathy
    • Stage 4. scarring from corrosive effect – pyloric stricture, obstruction
    • Tx: GI decontamination with gastric lavage, endoscopic removal of bezoar
      • Deferoxamine – Severe GI, shock, acidosis, >500mcg/dL; s/e: HoTN
  • Insulin/oral hypoglycemic agents – Dextrose
  • Digoxin, foxglove, Oleander – Digoxin Fab (K>5, severe dysrhythmias)
    • Vagal tone – dec sinus/AV conduction: PVCs>bradycardia, blocks, PAT + blocks
    • Visual: yellow halos
    • Neuro – AMS, weak, anorexia, confusion, depression, hallucination
    • Hyperkalemia – acute, hypokalemia – chronic
    • Tx – hyperkalemia with digibind (Ca controvertial); Atropine / pacing
  • Lead with encephalopathy – BAL
  • Ethylene glycol, methanol – Ethanol, Fomepizole (don’t give both together)
    • Methanol – folic acid (enhance conversion of formic acid to nontoxic product)
    • Ethylene glycol – pyridoxine (B6), Thiamine, Magnesium (enhance conversion of glyoxylic acid to nontoxic products); oxalic acid – renal injury
    • HD: 1) Renal failure 2) Visual symptoms 3) intractable acidosis 4) >50mg/dL
    • EtOH – alcoholic ketoacidosis Tx with IVF and glucose
  • BZD – flumazenil
  • Calcium chanel blocker, betablocker – glucagon, insulin (high dose)
  • Cyanide – hydroxocobalamine, nitrites, sodium thiosulfate
  • Methemoglobinemia (nitrites, nitrates, aniline dyes) – methylene blue
  • Radioactive iodine – potassium iodide
  • Anticholinergics – physostigmine
  • Carbon monoxide – oxygen and hyperbaric oxygen
  • Methotrexate – Folinic acid, glucarpidase
  • Sulfonylureas – octreotides
  • Heparin – protamine sulfate
  • INH – pyridoxine 5g IV (vit B6)
    • inhibit GABA/lactate conversion (lactic acidosis)
    • Intractable seizure, coma, slurred speech + lactic acidosis
    • BZD 1st line
  • ASA / TCA – sodium bicarbonate 1-2mEq/Kg then infusion of 3amp in 1L D5W at 2x maintenance rate (Aspirin, wintergreen, pepto-Bismol)
    • 1) medullary stimulation – hyperventilation
    • 2) uncoupling of oxidative phosphorylation – metabolic acidosis
    • 3) Overwhelming metabolic acidosis
    • CNS – Tinnitus, confusion, Sz, coma, lethargy; GI – N/V/GIB, Coag – plt dysfunction, inc PT, Metabolic – hyperthermia, hypoK, AGMC + Resp Alkalosis
    • Cerebral edema and noncardiogenic pulmonary edema
    • Tx: IVF, K repletion, urinary alkalinization (U pH 7.5-8), MDAC
    • HD: renal failure, noncardiogenic pulmonary edema, CHF, CNS/Cerebral edema/Sz, refractory acidosis, lyte abn, >100mg/dL or >60mg/dL (chronic)
  • Warfarin – Vit K

5. Given a patient with a toxic exposure, anticipate and identify complications that may arise secondary to the ingestion (e.g., respiratory depression, dysrhythmia).

Initial stabilization: ABCs, glucose, thiamine, naloxone

Sz – BZD, barbiturates, Pyridoxine, paralysis + EEG

6. In a patient with a toxic exposure, use decontamination or elimination techniques when appropriate, based on time of exposure and on the pharmacokinetics of the toxins (e.g., sustained release medications, iron).

RadioOpaque – CHIPES

  • Chloral hydrate
  • Heavy metals – Iron
  • Iodine
  • Potassium, Packets (cocaine/Heroin), Phenothiazines
  • Enteric coated products
  • Solvent, slow release forms

Decontamination

  • Eye: irrigate ASAP with NS
  • Skin: remove clothes, wash skin with soap and water
  • HAZMAT
  • GI if within 1hr
    • Activated charcoal 50-100g po; Not for liquids/metals (prevent absorption)
      • Caustics, Lithium, Iron, Methanol, Metals, Ethylene glycol, alcohols
    • Orogastric lavage – consider for ASA, Iron, CCB
    • MDAC – prevent absorption & enhanced elimination (not w/ sorbitol)
      • ASA, theophylline, phenobarbital, carbamazepine
    • Whole bowel irrigation – PEG 2>/hr until rectal effluent clear
      • Iron, heavy metals, Lithium, sustained-released/enteric coated
      • body packers/stuffers; FB (batteries)

Elimination

  • Alkalinization of urine: ASA, phenobarital
  • HD – low protein binding, low distribution, low MW, and water soluble
    • ISTUMBLE: Isopropanol, Salicylates, Theophylline, Uremia, Methanol, Barbibuates, Lithium, Ethanol, Ethylene glycol
    • General indications: Renal failure, Pulmonary edema, CHF, AMS, Seizure, refractory acidosis, Electrolyte abn, very toxic level

7. Given a patient with a toxic exposure, judiciously select ancillary investigations that provide information that will affect management, as opposed to simply suggesting the presence of toxins (e.g., ECG, ABG, anion/osmolar gap, specific serum levels versus urine/gastric screens).

Carboxyhemoglobin level for CO exposure

  • Tx oxygen 100% tight-fitting NRB (T1/2 = 90min)
  • HBO (t1/2=20min) if end-organ toxicity (MI, LOC, severe acidosis, abn neuro exam) or COHb >25% or 15% in pregnant women

Body packers / body stuffers

  • Negative plain film inadequate (useful if positive), confirmatory CT abd/pelvis after a negative plain film
  • WBI until all packets retrieved – need in-patient observation x24 or passage of 2 packet-free stool
  • Surgery if cocaine packet rupture of severe sympathomimetic toxicity

8. In a patient in withdrawal or claiming to be in withdrawal (e.g., from alcohol, from opioids) assess the patient, including the use of objective signs, to determine what degree of withdrawal is present or imminent and the priorities for management.

Common drug/EtOH withdrawal symptoms: dysphoria, insomnia, anxiety, irritability, nausea, agitation, tachycardia, HTN

Tx:

  • ABCs
  • Withdrawal related complications: hypoglycemia, Electrolytes imbalance, alcoholic ketoacidosis, N/V
    • Aggressive BZD/Barbiturates to control HTN, Tachycardia, tremor, prevent Sz
    • CIWA once pt stablized
Posted in Uncategorized

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Follow Preparing for the CCFP Exam 2015 on WordPress.com
CCFP ExamApril 30th, 2015
The big day is here.
August 2020
M T W T F S S
 12
3456789
10111213141516
17181920212223
24252627282930
31  
%d bloggers like this: