The Poisoned Patient: A Medical Student Review

1
The Poisoned PatientA Medical Student Review

• William Beaumont Hospital
• Department of Emergency Medicine

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Introduction

• All chemicals, especially medicines, have the
  potential to be toxic
• 2006 TESS data
• 2.7 million exposures
• 19.8 were treated in a healthcare facility
• 21.6 of those had more than minor outcomes
  including death
• Over half of poisonings occur in kids lt 5 yo

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The Initial Approach

• Always consider poisoning in differential
  diagnosis
• IV, O2, monitor
• Accucheck
• D50 /- thiamine or naloxone as indicated
• Decontamination, protect yourself
• Enhanced elimination
• Antidotal therapy
• Supportive care

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History

• Name, quantity, dose and route of ingestant(s)
• Time of ingestion
• Any co-ingestions
• Reason for ingestion accidental, suicidal
• Other medical history and medications
• EMS - inquire about scene, notes left, smells,
  unusual materials, pill bottles, etc.

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Pupils

• Dilated anticholinergic, sympathomimetic
• Constricted cholinergic
• Pinpoint opiates
• Horizontal nystagmus ethanol, phenytoin,
  ketamine
• Rotary or vertical nystagmus - PCP

6
Skin

• Hyperpyrexia anticholinergic, sympathomimetic,
  salicylates
• Hypothermic opiods, sedative-hypnotics
• Dry skin anticholinergics
• Moist skin cholinergics, sympathomimetics
• Color cyanosis, pallor, erythema

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Overall Exam

• Stimulants everything is UP
• ? temp, HR, BP, RR, agitated
• Sympathomimetics, anticholinergics, hallucinogens
• Depressants everything is DOWN
• ? temp, HR, BP, RR, lethargy/coma
• Cholinergics, opioids, sedative-hypnotics
• Mixed effects Polysubstance overdose, metabolic
  poisons (hypoglycemic agents, salicylates, toxic
  alcohols)

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Laboratory Studies

• Accucheck
• EKG
• Chemistries (BUN, Cr, CO2)
• UA calcium oxalate crystals in ethylene glycol
  poisoning
• Drugs of abuse comprehensive screen
• Acetaminophen, aspirin ethanol levels
• ABG, serum osmolality, toxic Alcohol screen,
  urine HCG and LFTS if warranted

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General Decontamination

• Remove all clothing
• Wash away external toxic substances
• If suspect transmittable contaminant, perform in
  decontamination area
• If ocular exposure, flush eyes copiously with
  until pH 7 7.5

10
GI Decontamination

• Three methods
• Gastric emptying
• Bind the toxin in the gut
• Enhance elimination
• Always consider the patients mental status, risk
  of aspiration, airway security and GI motility
  before attempting any method

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Orogastric Lavage

• Indications
• Life threatening ingestions
• Present within one hour of ingestion
• Studies show little benefit
• May remove as little as 35 of the substance
• Need secure airway
• Relatively high complication rate

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Activated Charcoal

• Absorbs toxin within the gut
• 1 g/kg PO or via NG tube
• Contraindications
• Bowel obstruction or perforation
• Unprotected airway
• Caustics and most hydrocarbons
• Anticipated endoscopy
• Not effective for alcohols, metals (iron, lead),
  or elements (magnesium, sodium, lithium)

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Multi-dose Activated Charcoal

• Large doses of toxin
• Slow release toxins
• Enterohepatic or enterenteric circulation
• Toxins that form bezoars
• Used for phenobarbital, theophylline,
  carbamazepine, dapsone, quinine

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Cathartics

• 70 sorbitol 1g/kg PO
• Administered with charcoal
• Decreases transit time of both toxin and charcoal
  through the GI tract
• Contraindications
• Children under 5 yo
• Caustic ingestions
• Possible bowel obstruction

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Whole Bowel Irrigation

• Go-Lytely via PO or NG tube at a rate of 2L/hr
  (500 mL/hr in peds)
• Typically used for those substances not bound by
  activated charcoal
• Contraindications
• Potential bowel obstruction

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Hemodialysis

• Used for
• Salicylates
• Methanol
• Ethylene Glycol
• Lithium
• Isopropyl alcohol
• Patients must be hemodynamically stable and
  without bleeding disturbances

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Toxin ? Antidote

• Acetaminophen? N-Acetylcysteine
• Anticholinergic agent ? Physostigmine
• Benzodiazepines ? Flumazenil
• Beta blockers ? Glucagon
• Carbon monoxide ? Oxygen

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Toxin ? Antidote

• Cardiac glycosides ? Digoxin-specific Fab
• Cyanide ? sodium nitrate, sodium thiosulfate,
  hydroxycobalamin
• Ethylene glycol ? Ethanol
• Opiates ? Naloxone
• Organophosphates ? Atropine, 2-PAM
• Tricyclics ? Sodium bicarb

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Case One

• 56 y/o male found unconscious in a basement. He
  has snoring respirations, frothing at the mouth,
  and rales on pulmonary exam. His pupils are
  pinpoint. He wakes up swearing and swinging at
  staff after a little narcan.
• What could it be?

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Toxidrome Opiates

• Examples heroin, morphine, fentanyl
• Signs/Symptoms
• CNS depression, lethargy, confusion, coma,
  respiratory depression, miosis
• Vital signs ? temp, HR, RR, /- BP
• Pulmonary edema, aspiration, resp arrest
• Check for track marks, rhabdomyolysis,
  compartment syndrome

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Toxidrome Opiates

• Treatment
• Naloxone 0.4 - 2 mg IV/IM/SC slowly
• May result in severe agitation
• Monitor closely and re-dose if necessary

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Toxidrome Sympathomimetic
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Toxidrome Sympathomimetic

• Examples cocaine, amphetamines (speed, dex,
  ritalin), phencyclidine (PCP), methamphetamines
  (crank, meth, ice), MDMA (ecstasy, X, E)
• Stimulant meth gt amphetamines gt MDMA
• Hallucinogen MDMA gt meth gt amphetamines
• Signs/Symptoms
• Agitation, ? temp, HR, BP, mydriasis
• Seizures, paranoia, rhabdomyolysis, MI,
  arrhythmias, piloerection

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Toxidrome Sympathomimetic

• Treatment
• Primarily supportive
• Benzos, IV hydration, cooling if hyperthermic
• Treat HTN with benzodiazepines or nitrates
• Avoid beta blockers
• Bodystuffers (small amt, poorly contained)
• Asymptomatic - AC, monitor for toxicity
• Symptomatic - AC, WBI, treat symptoms
• Bodypackers (large amt, well contained)
• Asymptomatic - WBI followed by imaging
• Symptomatic - immediate surgical consult

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Toxidrome Cholinergic
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Toxidrome Cholinergic

• Organophosphates
• Insecticides, nerve gas (Sarin, Tabun, VX)
• Irreversible binding to AChE aging
• Carbamates
• Insecticides (Sevin)
• Reversible binding to AChE short duration
• Examples physostigmine, edrophonium, nicotine
• All increase ACh at CNS, autonomic nervous system
  and neuromuscular junction

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Toxidrome Cholinergic

• Signs/Symptoms
• SLUDGE Syndrome
• Parasympathetic hyperstimulation
• Salivation, Lacrimation, Urinary Incontinence,
  Defecation, GI pain, Emesis
• Killer Bs
• Bradycardia, Bronchorrhea, Bronchospasm
• Bronchorrhea and respiratory failure is often
  the cause of death
• Miosis, garlic odor, ? MS, seizures, muscle
  fasciculations, weakness, respiratory depression,
  coma

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Toxidrome Cholinergic

• Diagnosis RBC or plasma cholinesterase level
• Management
• Decontamination protect yourself
• Supportive therapy
• Atropine - competitive inhibition of ACh
• Large doses required
• End point is the drying of secretions
• Pralidoxime (2-PAM) - breaks OP-AChE bond
• Start with 1-2 g IV over 30 minutes, give before
  aging
• Adjust dose based on response, AChE level

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Case Two

• 22 y/o F presents with decreased urine output.
  She is febrile, confused, flushed and has dilated
  pupils on exam. You also notice a linear,
  vesicular rash on her lower legs.
• What do you want to know?

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Case Two

• Meds
• She has been using oral benadryl and topical
  caladryl lotion for the poison ivy
• What is her toxidrome?

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Anticholinergic Agents

• Antihistamines
• Diphenhydramine, meclizine, prochlorperazine
• Antipsychotics
• Chlorpromazine (Thorazine), thiroidazine
  (Mellaril)
• Belladonna alkaloids
• Jimsonweed, atropine, scopolamine
• Cyclic antidepressants
• Amitriptyline, nortriptyline, fluoxetine
• OTCs
• Excedrin PM, Actifed, Dristan, Sominex
• Muscle relaxants
• Orphenadrine, cyclobenzaprine
• Amanita mushrooms

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Toxidrome Anticholinergic

• Signs/Symptoms
• Dry as a bone lack of sweating
• Red as a beet flushed, vasodilated
• Hot as hades hyperthermia
• Blind as a bat mydriasis
• Mad as a hatter delirium, hallucinations
• Stuffed as a pipe hypoactive bowel sounds,
  ileus, decreased GI motility, urinary retention
• VS ? temp, HR, BP

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Toxidrome Anticholinergic

• Rule out psychiatric disorders, DTs,
  sympathomimetic toxicity
• Management
• Sedation with benzodiazepines
• Temp control
• Treat wide QRS and dysrhythmias with bicarb
• Physostigmine
• Use only in clear cut cases
• Monitor for excess cholinergic response - SLUDGE

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Toxidrome Salicylates
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Toxidrome Salicylates

• Examples aspirin, oil of wintergreen, OTC
  remedies
• Signs/Symptoms
• Altered mental status
• Tinnitus
• Nausea and vomiting
• Tachycardia
• Tachypnea (Kussmaul respirations)
• Hyperthermia

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Toxidrome Salicylates

• Diagnosis
• Metabolic acidosis and respiratory alkalosis
• Anion gap
• Salicylate level gt 30mg/dL

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Toxidrome Salicylates

• Treatment
• Multi-dose AC
• Alkalinize urine
• HD if levels gt 100 mg/dl, altered MS, renal
  failure, pulmonary edema, severe acidosis or
  hypotension

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Toxidrome Serotonin Syndrome
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Toxidrome Serotonin Syndrome

• Examples SSRIs, MAOIs, meperidine, tricyclics,
  trazadone, mertazapine, dextromethorphan, LSD,
  lithium, buproprion, tramadol
• May be caused by any of the above, but usually
  occurs with a combination of agents, even if in
  therapeutic doses

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Toxidrome Serotonin Syndrome

• Signs/Symptoms
• Altered MS, mydriasis, myoclonus, hyperreflexia,
  tremor, rigidity (especially lower extremities),
  seizures, hyperthermia, tachycardia, hypo or
  hypertension
• Citalopram and escitalopram - prolonged QT and
  QRS
• No confirmatory test diagnosis based on
  clinical suspicion

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Toxidrome Serotonin Syndrome

• Treatment
• Supportive care
• Single dose AC (ensure airway control)
• Benzodiazepines to treat discomfort, muscle
  contractions or seizures
• Cooling measures
• Treat prolonged QT with magnesium
• Treat widened QRS with bicarb
• Cyproheptadine (anti-serotonin agent)

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Acetaminophen Poisoning
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Acetaminophen Poisoning

• Signs/Symptoms
• Stage I 0-24 hrs
• Nausea, vomiting, anorexia
• Stage II 24-72 hrs
• RUQ pain, elevation of AST and ALT, also
  elevation of bilirubin and PT if severe poisoning
• Stage III 72-96 hrs
• Peak of AST, ALT, bilirubin and PT, possible
  renal failure and pancreatitis
• Stage IV gt 5 days
• Resolution of hepatotoxicity or progression to
  multisystem organ failure

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Acetaminophen Poisoning

• Rummack-Mathew nomogram
• Acetaminophen levels vs. time
• Plot 4 hr level
• Useful for single acute ingestion only

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Acetaminophen Poisoning

• Management
• AC, assume polypharmacy OD
• NAC - N-acetylcysteine (NAC)
• Ingested over 140 mg/kg OR toxic level on
  nomogram
• Draw baseline LFTs and PT
• IV or PO dose

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Case Three

• 17 y/o M brought in by family for acting drunk.
  He is lethargic, confused, disoriented. Vitals
  130, 90/60, 16, 37 C.
• Labs ETOH 0, CO2 12
• What else do you want to know?

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Case Three

• Accucheck 102
• Serum osmolality 330
• Na 140, K 4.0, Cl 100, CO2 12, glucose 90
• BUN 28, Cr 2.0
• UDS, APAP, ASA are all negative
• UA has calcium oxalate crystals
• What are we hinting at?

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Toxic Alcohols

• Typical Agents
• Ethanol
• Isopropanol
• Methanol
• Ethylene glycol (EG)

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Toxic Alcohols

• All toxic alcohols cause an osmolar gap
• Methanol, ethanol and ethylene glycol cause an
  anion gap acidosis
• M methanol
• U uremia
• D DKA
• P paraldehyde, propylene glycol
• I iron, isoniazid
• L lactic acid
• E ethanol, ethylene glycol
• S salicylates

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Useful Equations

• Anion Gap (mEq/L)
• Na - (Cl HCO3)
• Calculated Osmolarity (mosm/L)
• 2Na BUN/2.8 Glu/18 ETOH/4.6

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Toxic Alcohols Isopropranol
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Toxic Alcohols Isopropanol

• Examples rubbing alcohol, antifreeze,
  disinfectants
• Second most commonly ingested alcohol
• Isopropyl alcohol has twice the CNS depressing
  potency and up to 4 times the duration as ethanol
• Metabolized by alcohol dehydrogenase to acetone

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Toxic Alcohols Isopropanol

• Signs/Symptoms
• Fruity breath
• Appear intoxicated
• Nausea, vomiting, abdominal pain
• Hypotension
• Respiratory depression ? coma
• Lab abnormalities
• Ketonuria
• Osmolar gap
• Normal pH, no acidosis

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Toxic Alcohols Methanol
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Toxic Alcohols Methanol

• Examples paint removers, antifreeze, windshield
  washer fluid, bootleg liquor
• Metabolized to toxic formaldehyde and formic acid
• Can cause permanent retinal injury and blindness
  as well as parkinsonian syndrome if not treated
  promptly
• May have a long latent period (12 to 18 hours),
  especially if co-ingested with ethanol

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Toxic Alcohols Methanol

• Signs/Symptoms
• Lethargy, nausea, vomiting, abd pain
• Visual symptoms seen in 50 - blurring, tunnel
  vision, color blindness
• ? HR, RR, BP
• CNS - headache, seizures or coma
• Lab abnormalities
• Wide anion-gap metabolic acidosis
• Osmolar gap
• Toxic alcohol screen to confirm

57
Toxic Alcohols Ethylene Glycol
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Toxic Alcohols Ethylene Glycol

• Examples antifreeze
• Seen with alcoholics, suicide attempts and
  children
• Colorless, odorless and sweet
• Is rapidly absorbed and converted to toxic acids
  responsible for clinical signs and symptoms
• Treatment similar to methanol

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Toxic Alcohols Ethylene Glycol

• Signs/Symptoms
• 1-12 hours CNS depression
• Inebriation, vomiting, seizures, coma, tetany
  (hypocalcemia)
• 12-24 hours cardiopulmonary phase
• hypotension, tachydysrhythmias, tachypnea and
  ARDS
• 24-72 hours nephrotoxic phase
• Oliguric renal failure, ATN, flank pain, calcium
  oxylate crystalluria

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Toxic Alcohols Ethylene Glycol

• Lab and EKG abnormalities
• Hypocalcemia secondary to precipitation with
  oxylate, excreted as urinary calcium oxylate
  crystals
• Urine may also fluoresce secondary to
  fluorescence dye in antifreeze
• EKG QT prolongation (hypocalcemia) and peaked
  Ts (hyperkalemia)
• Myalgias, secondary to acidosis and elevated CPK

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Toxic Alcohols Ethylene Glycol

• Always consider EG in an inebriated patient
  without alcohol breath, with an anion-gap
  metabolic acidosis, osmolar gap and calcium
  oxylate crystalluria

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Treatment of EG and Methanol

• Supportive, especially airway
• Correct acidosis with bicarb, 1meq/kg IV
• Benzos if seizure
• Folic acid 50mg IV q 4 hrs for both
• Ca gluconate 10 ml of 10 IV to correct
  hypocalcemia EG only

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Treatment of EG and Methanol

• Block production of toxic metabolites
• Ethanol IV or PO
• Fomepizole - preferred method
• Has 8000 times the affinity for ADH as ETOH
  without CNS depression and hypoglycemia

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Treatment of EG and Methanol

• Hemodialysis indicated if
• Serum level gt 50 mg/dl
• Signs of nephrotoxicity (EG) or CNS or visual
  disturbances (methanol)
• Severe metabolic acidosis

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Tricyclics
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Tricyclics

• Agents
• Amitriptyline (Elevil), desipramine (Norpramin),
  imipramine (Tofranil) and nortriptyline (Pamelor)
• Narrow therapeutic index
• Have returned to popularity with non-depression
  indications such as chronic pain, migraines, ADHD
  and OCD

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Tricyclics

• Signs/Symptoms
• CNS decreased LOC
• Confusion, hallucinations, delirium, seizures
• Cardiovascular arrhythmias and hypotension
• QRS gt 100 msec, conduction delays
• Arrhythmias such as V-tach torsades may develop
  as QRS widens and QT prolongs
• Anticholinergic toxidrome
• Tachycardia, mydriasis, hyperthermia, anhydrosis,
  urinary retention, decreased bowel sounds

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Tricyclics

• EKG during TCA toxicity and after treatment with
  bicarb. Note wide QRS, prolonged QT and terminal
  Rs gt 3mm in AVR

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Tricyclic Overdose Treatment

• AC
• Na Bicarb to treat QRS prolongation gt 100 msec
  and hypotension refractory to IV fluids
• Benzos to treat seizures and hyperthermia
• Magnesium and lidocaine for ventricular
  arrythmias refractory to bicarb
• Magnesium for QT prolongation or Torsades

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Carbon Monoxide
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Carbon Monoxide

• Sources
• Fossil fuel combustion (car exhaust), smoke,
  kerosene or coal heaters, steel foundries
• CO binds to hemoglobin with 230 times the
  affinity to oxygen, decreasing its ability to
  transport oxygen

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Carbon Monoxide

• Signs/Symptoms
• Nausea, malaise, headache, decreased mental
  status, dizziness, paresthesias, weakness,
  syncope
• May progress to vomiting, lethargy, coma,
  seizures, CVA , MI or respiratory arrest
• Need a high index of suspicion multiple family
  members with flu like symptoms without fever,
  winter months

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Carbon Monoxide

• COHb level may not represent the severity of the
  poisoning
• Pulse oximetry also may be misleading
• Half-life of COHb
• 4 hours on room air
• 60 minutes breathing 100 normobaric O2
• 15 to 23 minutes breathing 100 hyperbaric O2

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Carbon Monoxide Treatment

• 100 O2 via NRB for 4 hrs minimum if mild
  symptoms (nausea, heachache, malaise)

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Carbon Monoxide Treatment

• 100 O2 HBO if any of the following
• Altered mental status or coma
• History of LOC or near syncope
• History of seizure
• Hypotension during or after exposure
• MI
• Pregnant with COHb gt 15
• Arrythmias
• /- COHb gt 25-40

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The End