Toxicology (main)
Background
Epidemiology
- In 2014, ~2.2million human exposures reported to US poison control centers
- Top 5 substance classes:
- analgesics (11%)
- cosmetics/personal care products (8%)
- household cleaning substances (8%)
- sedatives/hypnotics/antipsychotics (6%)
- antidepressants (4%)
- 1,835 human exposures resulted in death
Autonomic Nervous System
- Parasympathetic - ACh is transm
- Muscarinic
- receptors in heart, eye, lung, GI, skin and sweat glands
- Bradycardia
- Miosis
- Bronchorrhea / Bronchospasm
- Hyperperistalsis (SLUDGE)
- Sweating
- Vasodilation
- Nicotinic
- receptors in both sympathetic and parasympathetic nervous systems
- fasciculations, flaccid paralysis
- ?Mild bradycardia, hypotension
- Muscarinic
- Sympathetic
- ALPHA EFFECTS - vessels, eye, skin
- Mydriasis, hypertension, Sweating
- BETA EFFECTS - heart, lungs
- Tachycardia, Bronchodilation
- ALPHA EFFECTS - vessels, eye, skin
Clinical Features
Toxidrome Chart
| Finding | Cholinergic | Anticholinergic | Sympathomimetic | Sympatholytic^ | Sedative/Hypnotic |
| Example | Organophosphates | TCAs | Cocaine | Clonidine | ETOH |
| Temp | Nl | Nl / ↑ | Nl / ↑ | Nl / ↓ | Nl / ↓ |
| RR | Variable | Nl / ↓ | Variable | Nl / ↓ | Nl / ↓ |
| HR | Variable | ↑ | ↑ (sig) | Nl / ↓ | Nl / ↓ |
| BP | ↑ | ↑ | ↑ | Nl / ↓ | Nl / ↓ |
| LOC | Nl / Lethargic | Nl, agitated, psychotic, comatose | Nl, agitated, psychotic | Nl, Lethargic, or Comatose | Nl, Lethargic, or Comatose |
| Pupils | Variable | Mydriatic | Mydriatic | Nl / Miotic | |
| Motor | Fasciculations, Flacid Paralysis | Nl | Nl / Agitated | Nl | |
| Skin | Sweating (sig) | Hot, dry | Sweating | Dry | |
| Lungs | Bronchospasm / rhinorrhea | Nl | Nl | Nl | |
| Bowel Sounds | Hyperactive (SLUDGE) | ↓ / Absent | Nl / ↓ | Nl / ↓ |
- ^Consider Sympatholytic when looking at Sedative OD or someone who doesn't respond to Narcan
- Withdrawal from substances have the opposite effect
Differential Diagnosis for Specific Signs
Hyperthermia
- Altered Metabolism
- Aspirin (Salicylate) Toxicity
- withdrawal states
- thyroid hormones
- dinitrophenols
- Increased Muscle Activity
- withdrawal, sympathomimetics
- MAOI Toxicity
- PCP, LSD
- Lithium
- Amoxapine
- Serotonin Syndrome
- Impaired Heat Dissipation
- anticholinergics
- antihistamines
- antipsychotics (TCAs)
- Malignant Hyperthermia
- anesthestics
- Neuroleptic Malignant Syndrome
- phenothiazines, Lithium, LevoDopa
Hypothermia
- Exposure
- Ethanol Toxicity
- Sedative hypnotics
- Opioids
- TCAs
- Phenothiazines
- Insulin (Hypoglycemia)
Increased Respiratory Rate
- Direct Stimulation
- Aspirin (Salicylate) Toxicity
- Metabolic Acidosis
- dintirophenol, pentachlorophenol
- hepatorenal failure
- CNS stimulants (cocaine, amphet, theophylline)
- Tissue Hypoxia
Respiratory Depression
- Central Depression
- antipsychotics
- Chlorinated hydrocarbons
- Sedative/Hypnotics (Ethanol Toxicity, glycols)
- Tricyclic (TCA) Toxicity
- Lomitil
- Muscle Failure
- Organophosphates
- Marine Toxins
- Nicotine
- strychnine
- botulinis
- Mojave rattlesnake, Cobra
Evaluation
Toxicological Exam
- All vital signs (Temp, RR, HR, BP)
- Neuro Exam
- Level of consciousness
- Pupillary exam
- Motor response
- DTRs
- Skin Exam - moisture, temp
- Lung Exam
- Bowel Sounds
- EKG (ie. look for QT prolongation, QRS prolongation, etc)
Management
- Depends on agent
- See Antidote
- "Coma cocktail" when suspecting toxic ingestion: Remember "DONT"
- Dextrose (50mg IV)
- Oxygen
- Naloxone (0.2-0.4mg IV/IM, repeat dose 1-2mg) - treat opioid ingestion
- Thiamine (50-100mg) - treat or avoid Wernicke encephalopathy. The administration of dextrose in the setting of thiamine deficiency can be harmful because glucose oxidation is a thiamine-intensive process that may drive the insufficient circulating vitamin B-1 intracellularly, thereby precipitating neurologic injury. So administer Thiamine before giving dextrose when suspecting thiamine deficiency.
Disposition
- Depends on agent