Poisoning Management Flashcards
Poisoning Assessment
- History - who, what, how, how much, why, when
- Physical Examination (toxidrome)
- Laboratory Findings
History Pearls
- Directed approach
- 50% history is accurate
- Verify with friends, family, EMS, etc
- Etiology (dose, timing, formulation)
- Acuity
- HPI, PMHx, PSHx, Allergies
- Whose meds were these?
Tox Screen - ALWAYS Need
- Serum APAP level
- Serum salicylate level
- +/- blood ethanol level
Urine Tox Screens
- General: performed on urine using EMIT technique, usually available in 6 hours
- Do not change medical management
- Know what meds are being screened: negative could mean not detected, below detectable range, or not included in the screen
-Non-drug specific: osmolality (not useful), radiographs for radio opaque poisons
X-ray
-KUB, CXR, US, CT
-Remember CHIPES
C - Chloral hydrate
H - heavy metals
I - Iron/Iodine
P - Phenothiazindes
E - Enterics
S - Solvents
Quantitative Tests
- Guide patient management
- For use of dialysis/hemoperfusion, ethylene glycol, methanol, lithium, salicylates, and theophylline
- Use of antidote APAP, carboxyhemoglobin, methemoglobin, digoxin, heavy metals, iron
Poison Treatment Strategies
- Supportive Care/Stabilization**
- Prevent Absorption**
- Enhance Elimination**
- Provide Antidote
Monitoring
- Part of stabilization
- Cardiac monitoring
- 12 lead ECG
- Pulse Oximetry
- Non-invasive BP
- Core Temperature
Temperature + Causers
Hyperthermia: sympathomimetics, salicylates, and other uncouplers
Hypothermia: barbiturates. sedative-hypnotics
Preventing Absorption Methods
- Inhalation => fresh air/oxygen
- Dermal => irrigation/soap, remove contaminated clothing
- Ocular => irrigation
- Ingestion => gastric lavage, activated charcoal/cathartic, whole bowel irrigation
Syrup of Ipecac
- Limited supporting literature
- Average removal of 30% of bowel contents
- May push contents through pylorus and enhance absorption
- No indications, not available, MANY CI
General GI Decontamination Indications
- Substantial risk of serious toxicity associated with exposure
- Recent ingestion (Liquids =< 1 hour, Solids =< 2 hours)
- GI decontamination procedure can be performed safely
- GI decontamination procedure will work
- No alternate that is safer or more effective is available
General GI Decontamination CI
- Rapid onset of seizures
- Rapid onset of CNS depression
- Alkaline corrosives (acids = controversial)
- Loss of gag reflex
- Recent bariatric surgery (Roux en Y pouch = 15-30 mL)
- Hemorrhagic diathesis
- Ingestion of sharp objects
Lavage
- 18-28 F - kids, 28-36F - adults
- Orogastric or nasogastric
- Saline used for kids (10 cc/kg aliquots)
- Water used from adults (300 cc aliquots)
- Endpoint: clear returns
- SE: aspiration, esophageal/gastric bruising, fluid/electrolyte imbalance, EKG changes, esophageal rupture, hypoxia
- Efficacy: 30% reduction in bioavailability
Lavage Indications/CI
Indications
-Minimal: rare, lethal, recent, and not bound to charcoal
CI
- CNS depressed patients can only be lavaged if they are intubated with cuffed endotracheal tube first
- Epileptic patients only lavaged with controlled seizures and when intubated
- Cannot lavage preps that are too large to fit through lavage tube
Single-Dose Activated Charcoal
- Adcorbent
- Dose: 1 gm/kg or 10:1 ratio (kids: 15-30g, adults: 30-60g)
- Preps: powdered, pre-mixed aqueous or sorbitol solutions
- No evidence for specific indications to utilize, potentially toxic, “within 1 hour” (might be changing)
Activated Charcoal AE
- Vomiting
- Constipation
- Aspiration
- Charcoal empyema
- GI obstruction
- GI perforation
- Efficacy: 40% reduction in bioavailability
Poorly Charcoal Adsorbed Substances
- Low molecular weight, charged compounds: cyanide, bromide, potassium, ethanol, methanol, iron, lithium, alkaline corrosives, and mineral acids
- Highly lipophilic substances: hydrocarbons (gasoline, kerosene)
Commonly Used Cathartics
Saline
- Magnesium citrate (4cc/kg to 300 cc)
- Magnesium sulfate (240 mg/kg to 30 mg)
- Sodium sulfate (250 mg/kg to 30 mg)
Hyperosmotic
-Sorbitol (0.5-0.9 gm/kg to 50 g)
Cathartic Use in Poisoning
-Rationale: prevent de-adsorption
-Dose: No more than 1 dose per 24 hours
-Efficacy is questionable
Precautions
-May cause hypovolemia and electrolyte imbalance
-Magnesium containing cathartics should not be used in patients with renal impairment
Whole Body Irrigation
- Products: Polyethylene glycol electrolyte solution (GoLYTELY)
- Better efficacy than lavage or ipecac
- Procedure varies based on age
- Endpoint is to clear rectal effluent
- Efficacy: 67% reduction of bioavailability
Whole Body Irrigation Indications/Outcomes
Indications
- Toxic doses of modified released products (Wellbutrin XL)
- Fe, Li, K
- Body packers
Outcomes
-No studies showing improvement
Whole Body Irrigation CI
- Bowel perforation
- Adynamic ileus
- Intestinal obstruction
- Hemodynamic instability
Enhancing Poison Elimination Indications
- Impaired normal route of elimination
- Severe presentation
- Progressive deterioration despite full supportive care
- Significant toxicity expected**
- Exists a method that works
Methods to Enhance Poison Elimination
- Multiple dose activated charcoal (MDAC)
- Ion trapping with sodium bicarbonate
- Hemodialysis
- Hemoperfusion (not readily available)
- Plasmapheresis
- Exchange transfusions
Ideal PK Characteristics for Hemodialysis
- Low Vd (<1 L/kg)
- Single compartment kinetics
- Low endogenous clearing (<4 mL/min/kg)
- MW < 500 daltons
- Water soluble
- Not bound to plasma proteins
MDAC Mechanism
- Interrupts entero-enteric and entero-hepatic recirculation of poison or metabolite
- “Gut dialysis”
Possible MDAC Indications
- Limited number of substances with no effect on clinical outcomes
- Reduce elimination rates
“Some of These Patients Drink Charcoal Quickly”
- Salicylate
- Theophylline/caffeine
- Phenobarbital
- Dapsone
- Carbamazepine
- Quinine/quinidine
- Valproate and phenytoin?
MDAC
- 0.5-1 g/kg every 2-6 hours
- Possible complications: pulmonary aspiration, constipation, and fluid/electrolyte imbalance
Altering Urine pH
- “Trap” drug in tubule by adjusting tubular filtrate pH so poison is in ionized form
- Creates a [gradient] favoring elimination
Urine Alkalinization
- Agent: Sodium bicarbonate
- Dose: 1-2 mEq/kg every 3-4 hours
- Goal: Urine pH > 7.5
- Indications: phenobarbital, salicylates
- Agents not Used: Acetazolamide, THAM
