Poisoning – McMaster Module

1 As part of well-child care, discuss preventing and treating poisoning with parents (e.g., “childproofing”, poison control number).

  • Keep items locked and out of reach/sight.
  • Don’t refer to medicine as “candy”.
  • Keep meds in their original containers with safety lids, don’t put them in food containers.
  • Don’t take meds in view of children. More danger of children getting poisoned away from home (ie friends/family).
  • Most commonly ingested substances are personal care products, analgesics, and cleaning products.
  • Most commonly causing fatalities are analgesics, batteries, hydrocarbons, and plants.
  • Highly hazardous medications include iron supplements, TCAs, Cardio meds, methyl saliclyate, hydrocarbons, pesticides, sulfonylureas, CCBs, toxic alcohols, clonidine, and opioids.

2 In intentional poisonings (overdose) think about multi-toxin ingestion.

  • Remember, patient’s history is often unreliable – use collateral sources (paramedics, police, family, friends, pharmacist)
  • Remember to ask about OTC meds, family/friends medications that might be in the house.
  • Regularly screen overdose patients for presence of Acetaminophen, Salicylates with blood work
  • Urine drug screen
Suspect Overdose when:
  1. Altered LOC / coma
  2. Young pt with life-threatening dysrhythmia
  3. Trauma pt
  4. Bizarre or puzzling clinical presentation

Acetaminophen Overdose
  • Often clinically silent; evidence of liver / renal damage delayed >24hr
  • Toxic dose >200mg/kg (>7.5g adult)
  • Monitor drug level 4h post-ingestion & LFT, INR/PTT, BUN/Cr
  • Hypoglycemia, metabolic acidosis, encephalopathy – poor prognosis
Tx:
  • Decontaminate (SDAC)
  • NAC (N-acetylcysteine)

Warfarin OD
  • INR < 5 – stop warfarin, observation, serial PT/INR
  • INR 5.1-9 – hold warfarin x 1-2d & reduce dose OR Vit K 1-2mg po if increased risk of bleeding
  • INR 9.1-20 – hold warfarin, Vit K 2-4mg po, serial PT/INR & vit K prn
  • INR >20 – Hold warfarin, Vit K 10mg IV over 10min, Vit K q4h prn
Unfractionated Heparin OD –
  • Protamine Sulfate 25-50 mg IV 

3 When assessing a patient with a potentially toxic ingestion, take a careful history about the timing and nature of the ingestion.

Hx: patient’s history is often unreliable – use collateral sources
  • Age, wt, PMH, medications
  • Substance and how much
  • Time since exposure determines prognosis & need for decontamination, symptoms since
    • GI decontamination has the greatest benefit within 1 hour of ingestion, however, history often unreliable.
    • Risk outweighs benefit if truly delayed presentation.
  • rout, intention, suicidality – assume the worst case scenario

4 When assessing a patient with a potential poisoning, do a focused physical examination to look for the signs of toxidromes.

PEx: Focus on ABCs, LOC/GCS, vitals, pupils (miosis, mydriasis, nystagmus)
  • Airway (stabilize C-spine) & intubate if can’t secure airway
  • Breathing
  • Circulation
    • physiological depression – miosis, ↓ LOC, HoTN, bradycardia, shallow breathing, hypothermia
    • caused by cholingergic, sympatholytic, opiates, EtOH, sedative-hypnotics
    • Mixed – think polydrug, hypoglycemia, toxic alcohols, heavy metals, antiarrhythmics, TCAs
  • Drugs: ACLS, universal antidotes
  • Draw bloods
    • CBC, lytes, BUN/Cr, glucose, INR/PTT, osmolality
      • ↑ Anion gap: MUDPILES
        • Methanol / Metformin,
        • Uremia,
        • DM/EtOH ketoacidosis,
        • Paraldehyde / Poisons,
        • Isoniazid / Iron,
        • Lactic Acidosis (cyanide, CO, sulfides),
        • Ethylene glycol,
        • Salicylates / Sympathomimetics
    • ABGs, measure O2 sat
    • ASA, acetaminophen, EtOH levels
    • Potentially useful: drug levels, Ca, Mg, PO4, protein, albumin, lactate, ketones, LFT, CK
  • Decontamination (↓absorption)
  • Expose (look for specific toxidromes) / Examine the pt
  • Full VS – pulse oximetry, ECG monitor, Foley, X-ray
  • Give specific antidotes, establish IV access & Tx
  • Go back & reassess, call poison control, obtain corroborative hx from family, bystanders

Specific Toxidromes
1) Anticholinergics
  • Hyperthermia “hot as a hare”
  • Dilated pupils “blind as a bat”
  • Dry skin “Dry as a bone”
  • Vasodilation “Red as a beet”
  • Agitation / hallucinations “mad as a hatter”
  • Ileus, urinary retention, Tachycardia “bowel and bladder lose their tone & the heart goes on alone”
Drugs
  • Antidepressants – TCAs (Tx with sodium bicarbonate), Antipsychotics
  • Cyclobenzaprine – Flexeril, antispasmotics, Carbamazepine
  • Antihistamines – diphenhydramine, Belladonna alkaloids: atropine
  • Antiparkinsonians

2) Cholingergics
DUMBELS
  • Diaphoresis, Diarrhea, Decreased BP
  • Urination
  • Miosis
  • Brochospasm, Bronchorrhea, Bradycardia
  • Emesis, Excitation of skeletal mm
  • Lacrimation
  • Salivation, Sz
Drugs
  • Natural plants: mushrooms, trumpet flower
  • Insecticides: organophosphates, carbamates, Nerve gases
  • Anticholinesterases: physostigmine

3) Extrapyramidal (acute dystonic reaction)
  • Dysphonia, dysphagia
  • Rigidity, dystonia (muscle spasms, laryngospasm, trismus, oculogyric crisis, torticollis)
  • tremor, motor restlessness, constant movements (dyskinesia), crawling sensation (akathisia)
Drugs
  • Major tranquilizers
  • Antipsychotics
Tx
  1. Benztropine (cogentin – euphoric effect – abuse potential) 1-2mg IM/IV then 2mg po x 3 d
  2. Diphenhydramine 1-2mg/kg IV then 25mg po qid x 3 d

4) Hgb derangement
  • ↑RR, ↓ LOC, Sz
  • Cyanosis unresponsive to O2, lactic acidosis
Drugs
  • CO poisoning: carboxyhemoglobin
  • Drug ingestion: methemoglobin, sulfmethemoglobin

5) Narcotic/Opioid, sedative/hypnotics, EtOH
  • Hypothermia, HoTN, Respiratory depression
  • Dilated pupils (constricted – pinpoint pupils in opioid OD)
  • CNS derpession
Drugs
  • EtOH, BZD,
  • Opioids, Barbiturates, Gamma hydroxybutyrate
Tx
  • BZD – Flumazenil + supportive care

6) Sympathomimetics
  • ↑ temperature, tachycardia, HTN
  • CNS excitation including Sz
  • N/V/diaphoresis
  • dilated pupils
Drugs
  • Amphetamines, caffeine, cocaine, LSD, phencyclidine
  • Ephedrine and other decongestants
  • Thyroid hormones
  • Sedative / EtOH withdrawal

ASA poisoning & hypoglycemia mimic sympathomimetic toxidrome


7) Serotonin Syndrome
  • Mental Status changes
  • Autonomic hyperactivity: hyperthermia, HTN, diarrhea
  • Neuromuscular abnormalities
Drugs
  • MAOI, TCA, SSRI
  • Opiate analgesics
  • Cough medicine, wt reduction medications

5 When assessing a patient exposed (contact or ingestion) to a substance, clarify the consequences of the exposure (e.g., don’t assume it is non-toxic, call poison control)


6 When managing a toxic ingestion, utilize poison control protocols that are current.

Most pt with toxic ingestions should be observed for 6hr in ED and if severe, pt should go to ICU
Universal Antidotes: DON’T
  • Dextrose: measure BG before administration if possible
    • Adults: 1g/kg (1-2mL/kg) IV D50W
    • Children: 0.25g/kg (2-4ml/kg) IV D25W
  • Oxygen
    • Don’t deprive a hypoxic pt of O2 no matter what PMH (ie COPD with CO2 retention)
    • If depression of hypoxic drive, intubate & ventilate
    • Exception: herbicides (paraquat / diquat) inhalation or ingestion (O2 radicals ↑ morbidity)
  • Naloxone (shorter T1/2 – 30-80min than naltrexone)
    • antidote for opioids: both dx and Tx (1min onset of action)
    • For undifferentiated comatose pt
    • Adults: 2mg bolus IV/IM/SL/SC/ETT (2x IV dose), Q2m with 2mg increments, max 10mg
    • Child: 0.01mg/kg bolus IV/IO/ETT, 0.1mg/kg if no response & max of 10mg
  • Thiamine (must give BEFORE dextrose)
    • At risk for thiamine deficiency: alcoholics, anorexics, hyperemesis of pregnancy, malnutrition states
    • 100mg IV/IM with IV/PO glucose to all pt
    • Prevent / Tx wernicke’s encephalopathy
HD
  • Salicylates, ethylene glycol, methanol, lithium, acidosis or hyperkalemia
Antidotes:
  • Naloxone for opioids
  • Flumazenil for BZD
  • NAC for Tylenol (4hr or greater nomogram) – 100% effective if given within 8-10hr
  • Urine alkylinization (acids), glucose for ASA, phenobarbital
  • Fomipazole / Ethanol, folic acid for toxic alcohols

7 When managing a patient with a poisoning,
a) Assess ABC’s,
b) Manage ABC’s,
c) Regularly reassess the patient’s ABC’s
(i.e., do not focus on antidotes and decontamination while ignoring the effect of the poisoning on the patient).

  • Airway – intubate if GCS <8
  • Breathing – bag and consider LMA before ETT inserted
  • C – check for pusles, ECG – possible toxidrome
    • Abnormal ECG – Provide MgSO4 to stabalize myocardial cell membranes (? digoxin toxicity) ± NaCO3 (? TCA toxicity)

References:

  • McMaster Module: Poisoning
  • TN2014

 

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Posted in 75 Poisoning, 99 Priority Topics, FM 99 priority topics, Others

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