The Poisoned Patient - I and II Flashcards
Stabilization - ABCs
Airway, Breathing, Circulation (support c-spine)
All patients with altered mental status must immediately be given these four substrates:
1 Oxygen
2 Naloxone (narcotic antagonist) Except in certain patient populations: Opioid dependent without apnea or severe respiratory depression History of “speedball” abuse Agitated/seizing Pregnant and opioid dependent
- Thiamine (to reverse or prevent Wernicke’s)
- Glucose (rapid determination or bolus with dextrose)
Note: glucose may precipitate Wernicke’s and therefore is usually given with thiamine
Physical exam
Start with the vital signs
Hypoventilation:
Hyperventilation:
Bradycardia: (big 4)
Tachycardia:
Hypotension:
Hypertension:
Hypothermia:
Hyperthermia:
Always start with vital signs: pulse rate and pupillary size may be most helpful
Hypoventilation: opiods, sedative-hypnotics
Hyperventilation: generally non-specific; seen more often with stimulants
Bradycardia: beta blockers, Ca++ channel blockers, clonidine and digitalis (big 4)
Tachycardia: non-specific
Hypotension: many agents
Hypertension: many agents
Hypothermia: ethanol is the number one cause in Detroit; antipsychotics (effects on hypothalamus make the patient vulnerable to environmental temperature changes)
Hyperthermia: amphetamines (ie. MDMA), anticholinergics
Eye Changes:
Eye Changes:
Mydriasis: not very helpful unless very dramatic (anticholinergics like atropine)
Miosis: cholinergics
Nystagmus: sedative hypnotics, PCP/ketamine (vertical, horizontal and rotary)
Characteristic Odors:
Bitter almonds: cyanide
Rotten eggs: mercaptans
How do opioids and cholinergics differ?
Bowel sounds are hyperactive with choinergics and decreased with opioids
How do Anticholinergics and Sympathomimetics differ?
Anticholinergics = dry, red, hot skin Sympathomimetics = sweaty
Anticholinergics = decreased bowel sounds Sympathomimetics = normal bowel sounds
Anion gap =
Normal =
Anion Gap= Na – (HCO3 + Cl)
normal is 12 +/- 4 meq/L
Toxins Causing High Anion Gap
MUDPILES o Methanol/metformin o Uremia o Diabetes (ketoacidosis) o Paraldehyde/phenformin/propylene glycol o Iron/isoniazid o Lactate (theophylline/cocaine) o Ethylene glycol o Salicylates
Toxins Causing Low Anion Gap:
Toxins Causing Low Anion Gap:
o Lithium
o Bromide
Measured Osmolality:
Calculated Osmlality:
Osmolal Gap=
By freeing point depression or boiling point elevation (only freezing point depression clinically useful)
Calculated Osmlality: 2 Na + (glucose/18) + (BUN/2.8)
Osmolal Gap= Measured Osmolality – Calculated Osmolality; normal should be less than 10
Toxin Causing Increase in Osmolal Gap:
o Methanol o Ethanol o Isopropanol o Ethyele glycol o Acetone o Osmotic diuretics (mannitol/glycerol)
- Important Point: normal osmolal gaps do NOT rule out toxic alcohol ingestions
What is the gold standard of toxicology screening?
GC-Mass spectrometry
- Some substrates will be radiopaque on x-ray (CHIPES)
o Cholral hydrate o Heavy metals o Iodine/iron o Phenothiazines/TCAs o Enteric coated o Solvents
Important Point: a negative radiograph does not rule out these substances
Substances that Classically Form Concretions (BIG MESS):
Barbituates o Iron o Glutethimide o Meprobamate o ER Theophylline o Salicylates o Sedative-hypnotics
Ipecac
Stimulates:
Contraindication:
Ipecac: most effective emetic
Stimulates the chemoreceptor trigger zone (CTZ) and induces vomiting
By stimulating both central and peripheral (GI tract) receptors
Use in ER: decreasing because of the fact that it increases the time to administration of charcoal
Pre-hospital use is sometimes appropriate if administered by poison specialist
Contraindications:
Very young children (not able to walk or less than 6 months)
Absence of gag reflex
CNS depression or ingestion of a potentially CNS depressing agent
Corrosive substance ingestion
Activated Charcoal
General process
Multidose charcoal therapy
Important point
Contraindications
General Process:
Contains network of tiny pores capable of trapping toxins
Directly adsorbs material to prevent its absorption (reversible binding)
Interrupts enterohepatic recirculation of some
drugs and their metabolites
Creates concentration gradient so that diffusible drugs enter the gut from the blood stream
Initial dose is 1g/kg of body mass (since it is often hard to determine how much of the toxic substance was ingested)
Multidose Charcoal Therapy: administered every 2 hours
- Important Point: not all agents bind to activated charcoal
- Metals, some pesticides, some alcohols poorly bound
- Generally still advisable to give a dose of charcoal early on if substance ingested is unknown
Contraindications:
- Corrosive injury to esophagus or GI tract
- Intestinal obstruction
- Ileus (obstruction of normal propulsive activity of the GI tract)
Gastric Lavage:
Uses
Not employed routinely
If patient arrives within 60-90 minutes of ingestion of life-threatening substance
Altered mental status or critically ill patient within 60-120 minutes of ingestion
Later, if there are concretions, delayed gastric emptying or sustained released
Frequent complications
Catartics
Commonly used ones:
Mechanisms:
Goal:
Commonly Used:
Saline (Mg citrate, Mg sulfate)
Saccharide (sorbitol)
Mechanism: add osmotic load to the gut
- Large volumes of fluid in the gut
- Increased small bowl peristalsis
- Mg sulfate also stimulates release of CCK (increases motor and secretory action of GI tract)
Goal: allow the activated charcoal-drug complex to be removed from the body ASAP (prior to desorption, since charcoal reversibly binds)
- Sorbitol is the most rapidly acting
- Multiple doses may be dangerous (one dose per day generally)
Whole Bowel Irrigation (golytely)
Uses:
Indications:
Contraindications:
Use: allows for mechanical cleansing of the gut without the risk of fluid or electrolyte imbalance
Potential Indications:
Ingestions of massive amounts of a toxic substance
Metals (do not adsorb to charcoal- iron or lithium, for example)
Sustained-release preparations
Body-packers (wrapped packages of illicit drugs)
Presence of concretions
Contraindications: Inadequate airway protection Obstruction Ileus (bowel obstruction) Perforation
Ion Trapping (pH Alteration):
Mech
Alkalization of urine
Acidification of urine
Ion Trapping (pH Alteration):
Mechanism: drugs that are weak acids or weak bases ionize in solution
Renal excretion of certain drugs can be enhanced by ion-trapping in the renal tubule
Alkalization of Urine: o Salicylates o Phenobarbitol o 2,4-D o Chlorpropamide
Acidification of Urine:
o Risk to patient outweighs potential benefit (causes rhabdomyolysis)
Hemodialasis
Use:
Indications:
Use: depends on physical characteristics of toxin
Drug must be able to freely pass the dialysis membrane (low molecular weight, high water solubility, low protein binding, small volume of distribution)
Therefore, not a lot of things can be removed by dialysis
Indications:
o Salicylates
o Phenobarbitol
o Toxic alcohols (ethanol, methanol, ethylene glycol)
o Lithium
o Certain toxins in patients with renal failure
Hemoperfusion
Use:
Mechanism:
Indications:
Complications:
Hemoperfusion:
Use: unlike dialysis, use is not limited by water solubility or molecular weight
Of particular benefit when the drug is highly protein bound
Mechanism: pump blood through a cartridge filled with charcoal or resin beads that remove drugs
Indications:
o Theophylline
o Others possible (anticonvulsants, colchicines)
Complications: o Thrombocytopenia o Leukopenia o Reduced glucose and Ca++ levels o Hemorrhage secondary to heparinization
Multidose Activated Charcoal
Use:
Indications
Use: several doses of activated charcoal given to enhance elimination (reversible binding, keeps things bound)
Via interruption of enterohepatic, enterogastric and enteroenteric circulation
Indications: o Phenobarbitol o Dapsone o Theophylline o Carbamazepine o Quinine o Phenytoin (sometimes)
Hyperbaric Oxygen:
Use:
Potentially of benefit in CO, CN and hydrogen sulfide poisonings (also possibly CCl4)
Antidotes:
Antivenin:
Digoxin-Specific Antibodies (Digibind):
Cyanide Antidote Kit
Naloxone
N-acetylcysteine (Mucomyst)
Methylene Blue
Ethanol
Flumazenil
Antivenin: snake bites, black widow spiders, scorpions, jelly fish
Digoxin-Specific Antibodies (Digibind): Digoxin, variety of plants (ie. foxglove, lily of the valley)
Oxygen: carbon monoxide
Cyanide Antidote Kit: cyanide, hydrogen sulfide
Naloxone: opiates/narcotics, clonidine, dextromethophan
N-acetylcysteine (Mucomyst): acetaminophen, CCl4, pennyroyal oil, cyclopeptide mushrooms
Methylene Blue: drugs causing methemoglobinemia (patient will have dark blood)
Ethanol: methanol, ethylene glycol, glycol ethers
Flumazenil: benzodiazepines (however, not often given because it can precipitate withdrawal, which is life threatening)
Other Antidotes:
Atropine
Calcium
Glucagon
Glucose
Hydroxocobalamin
Pralidoxime (2-PAMCl)
Protamine
Pyridoxine (Vitamin B6)
Thiamine
Vitamin B12a
Atropine: Organophosphates, Carbamate, Physostigmine, Clitocybe/Inocybe mushrooms
Calcium: Hydrofluoric acid, Calcium channel blocker
Glucagon: Beta blockers, Calcium channel blockers, Insulin/oral hypoglycemic agents
Glucose: Insulin/oral hypoglycemic agents
Hydroxocobalamin: (Vitamin B12a) Cyanide
Pralidoxime (2-PAMCl): Organophosphates, Carbamates
Protamine: Heparin
Pyridoxine (Vitamin B6): Isoniazid, Gyromitra esculenta, Ethylene glycol, Disulfiram, Carbon disulfide
Thiamine: Ethanol, Ethylene glycol
Vitamin B12a: Cyanide, nitroprusside
