Toxicology (main): Difference between revisions
 
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==Tox Exam==
==Background==
# All VS (Temp, RR,HR, BP)
===Epidemiology===
# Neuro Exam
*In 2014, ~2.2million human exposures reported to US poison control centers
##Level of consciousness
*Top 5 substance classes:
##Pupillary exam
**analgesics (11%)
##Motor response
**cosmetics/personal care products (8%)
#Skin Exam - moisture, temp
**household cleaning substances (8%)
# Lung Exam
**sedatives/hypnotics/antipsychotics (6%)
# Bowel Sounds
**antidepressants (4%)
*1,835 human exposures resulted in death


== Toxidromes  ==
{{Autonomic nervous system receptors}}


{| cellspacing="1" cellpadding="1" border="1" width="200"
==Clinical Features==
|-
{{Template:Toxidrome Chart}}
| '''Finding<br>'''
| '''Mixed Cholinergic '''([[Organophosphates]])<br>
| '''Anticholinergic '''([[Tricyclic Antidepressants Overdose|TCAs]], antihist, phenothiazines)'''<br>'''
| '''Sympathomimetic'''^ (Cocaine, [[Amphetamines]], ketamine)<br>
| '''Sympatholytic'''^^ (Clonidine)<br>
| '''Sedative/Hypnotic''' ([[Alcohol (ETOH) Intoxication|ETOH]])<br>
|-
| ''Temp'''''<br>'''
| Nl<br>
| Nl/Inc<br>
| Nl/Inc<br>
| Nl/Dec<br>
| Nl/Dec<br>
|-
| ''RR''<br>
| Varriable<br>
| Nl/Dec<br>
| Varriable<br>
| Nl/Dec<br>
| Nl/Dec<br>
|-
| ''HR''<br>
| Varriable<br>
| Inc
| Inc (sig)<br>
| Nl/Dec<br>
| Nl/Dec<br>
|-
| ''BP''<br>
| HTN<br>
| Inc<br>
| Inc<br>
| Nl/Dec<br>
| Nl/Dec<br>
|-
| ''LOC''<br>
| Nl/Lethargic<br>
| Nl, agitated, psychotic, comatose<br>
| Nl, agitated, psychotic <br>
| Nl, Lethargic, or Comatose <br>
| Nl, Lethargic, or Comatose <br>
|-
| ''Pupils''<br>
| Varriable<br>
| Mydriatic<br>
| Mydriatic<br>
| Nl/Miotic <br>
| <br>
|-
| ''Motor''<br>
| Facciculations, Flacid Paral <br>
| Nl<br>
| Nl/Agitated<br>
| Nl<br>
| <br>
|-
| ''Skin''<br>
| Sweating (sig)<br>
| Hot, dry<br>
| Sweating<br>
| Dry<br>
| <br>
|-
| ''Lungs''<br>
| Bronchospasm/ rhinorrhea <br>
| Nl<br>
| Nl<br>
| Nl<br>
| <br>
|-
| ''Bowel Sounds''<br>
| Hyperactive (SLUDGE) <br>
| Dec/Absent<br>
| Nl/Dec<br>
| Nl/Dec<br>
| <br>
|}


^^Consider Sympatholytic when looking at Sedative OD or someone who doesn't respond to Narcan
==Differential Diagnosis for Specific Signs==
===[[Hyperthermia]]===
*Altered Metabolism
**[[Aspirin (Salicylate) Toxicity]]
**Withdrawal states (e.g. [[baclofen withdrawal]]
**[[Thyroid]] hormones
**[[Dinitrophenol]]s
*Increased Muscle Activity
**Withdrawal, [[sympathomimetics]]
**[[MAOI Toxicity]]
**[[PCP]], [[LSD]]
**[[Lithium]]
**[[Serotonin Syndrome]]
*Impaired Heat Dissipation
**[[Anticholinergics]]
**[[Antihistamines]]
**[[Antipsychotics]], TCAs
**[[Phenothiazines]], [[Lithium]], LevoDopa
*[[Malignant Hyperthermia]]
**Anesthetics
*[[Neuroleptic Malignant Syndrome]]


==DDx==
===[[Hypothermia]]===
===Hyperthermia===
*Exposure
#Altered Metabolism
**[[Ethanol Toxicity]]
## salicylates
**[[Sedative/Hypnotics]]
## withdrawal states
**[[Opioids]]
## thyroid hormones
**[[TCAs]]
## dinitrophenols
**[[Phenothiazines]]
# Increased Muscle Activity
**[[Insulin]] ([[Hypoglycemia]])
## withdrawal, sympathomimetics
**[[Carbon monoxide]]
## MAOI
##PCP, LSD
## lithium, amoxapine
# Impaired Heat Dissipation
## anticholinergics
## antihistamines
## antipsychotics (TCAs)
# Malignant Hyperthermia
## anesthestics
# Neuroleptic Malignant Syndrome
## phenothiazines, Lithium, LevoDopa


===Hypothermia===
===Increased Respiratory Rate===
# Exposure
*Direct stimulation
## alcohol, sedative hypnotics
**[[Aspirin (Salicylate) Toxicity]]
## narcotics, TCAs, phenothiazines
**[[Metabolic Acidosis]]
## Insulin (hypoglycemia)
**[[Dinitrophenol]], pentachlorophenol
**[[Hepatic failure|hepatic]]/[[renal failure]]
**CNS stimulants ([[cocaine]], [[amphetamine]], [[theophylline]])
*Tissue [[Hypoxia]]
**[[CO]]
**[[Cyanide]]
**[[Hydrogen Sulfide]]
**[[Methemoglobinemia]]
 
===[[Respiratory failure|Respiratory Depression]]===
*Central Depression
**[[Antipsychotics]]
**Chlorinated [[hydrocarbons]]
**[[Sedative/Hypnotics]] ([[Ethanol Toxicity]], glycols)
**[[Tricyclic (TCA) Toxicity]]
**[[Lomotil toxicity]]
**[[Opioids]]
**[[Marijuana]]
*Muscle Failure
**[[Organophosphates]]
**[[Marine Toxins]]
**[[Nicotine Poisoning|Nicotine]]
**[[Strychnine]]
**[[Botulism]]
**Mojave [[rattlesnake]], Cobra
 
===[[Bradycardia]]===
PACED
*[[Propranolol]]/[[beta-blockers]], poppies ([[opiates]]), propoxyphene,
[[physostigmine]]
*[[Acetylcholinesterase inhibitors|Anticholinesterases]], [[antiarrhythmics]]
*[[Clonidine]], [[calcium channel blockers]]
*[[Ethanol]] or other [[toxic alcohols|alcohols]]
*[[Digoxin]], [[digitalis]]
 
===[[Tachycardia]]===
FAST
*Free base or other forms of [[cocaine]]
*[[Anticholinergics]], [[antihistamines]], [[antipsychotics]], [[amphetamines]], [[alcohol withdrawal]]
*[[Sympathomimetics]] (cocaine, caffeine, amphetamines, PCP), solvent abuse, strychnine
*[[Theophylline]], [[TCA]], [[thyroid]] hormones
 
===Hypotension===
CRASH
*[[Clonidine]], [[calcium channel blockers]]
*Rodenticides (with [[arsenic]], [[cyanide]])
*Antidepressants, [[aminophylline]], [[antihypertensives]]
*[[Sedative/Hypnotics]]
*[[Heroin]] or other [[opioids]]
 
===[[Hypertension]]===
CT SCAN
*[[Cocaine]]
*[[Thyroid]] supplements
*[[Sympathomimetics]]
*[[Caffeine]]
*[[Anticholinergics]], [[amphetamines]]
*[[nicotine toxicity|Nicotine]]
 
===Miosis===
COPS
*[[Cholinergic]]s, [[clonidine]], [[carbamates]]
*[[Opioids]], [[organophosphates]]
*[[Phenothiazines]], pilocarpine, pontine hemorrhage
*[[Sedative/Hypnotics]]
 
===Mydriasis===
SAW
*[[Sympathomimetics]]
*[[Anticholinergics]]
*Withdrawal syndromes
 
===[[Coma]]===
LETHARGIC
*[[Lead]], [[lithium]]
*[[Ethanol]], [[Ethylene glycol toxicity|ethylene glycol]]
*[[TCA]], [[thallium]], [[toluene]]
*[[Heroin]], hemlock, [[hepatic encephalopathy]], [[heavy metals]], [[hydrogen sulfide]], hypoglycemics
*[[Arsenic]], antidepressants, [[anticonvulsants]], [[antipsychotics]], [[antihistamines]]
*[[Rohypnol]], [[risperidone]]
*[[GHB]]
*[[Isoniazid]], [[insulin]]
*[[Carbon monoxide]], [[cyanide]], [[clonidine]]
 
===[[Seizures]]===
OTIS CAMPBELL
*[[Organophosphates]], oral hypoglycemics (e.g. [[sulfonylurea]])
*[[TCA]], [[theophylline]], [[tramadol]]
*[[Isoniazid]], [[Insulin]]
*[[Sympathomimetics]], [[salicylates]], [[strychnine]]
*[[Camphor toxicity|Camphor]], [[carbon monoxide]], [[cyanide]], chlorinated [[hydrocarbons]], [[cocaine]]
*[[Anticholinergics]] (antihistamines), [[amphetamines]], antidepressants (citalopram, [[Tricyclic antidepressant toxicity|TCAs]], [[bupropion]])
*[[Methanol]], Methylxanthines ([[theophylline]], [[caffeine]]), [[MAOI Toxicity|MAOI]]
*[[PCP]], [[propranolol]]
*[[Benzodiazepine withdrawal]], [[bupropion]], botanicals (hemlock, [[nicotine toxicity|nicotine]]), [[GHB]]
*[[ETOH withdrawal]], [[ethylene glycol]]
*[[Lead]], [[lithium]]
*[[Lidocaine]], [[lindane]] (pesticide, scabies)


===Increased Respiratory Rate===
===Skin findings===
# Direct Stimulation
====Diaphoresis====
## salicylates
SOAP
## metabolic acidosis
*[[Sympathomimetics]]
## dintirophenol, pentachlorophenol
*[[Organophosphates]]
## hepatorenal failure
*[[Acetylsalicylic acid]] and other salicylates
## CNS stimulants (cocaine, amphet, theophylline)
*[[Phencyclidine toxicity|PCP]]
====Dry skin====
*[[Antihistamines]], [[anticholinergics]]
====Bullous lesions/blisters====
*[[Barbiturates]]
*[[Mustard agent (vesicants|Mustard gas]]
*[[Snake bites|Snakes]] and [[spider bites|spiders]]
====Flushed/red appearance====
*[[Anticholinergics]]
*[[Niacin]]
*Boric acid
*[[Carbon monoxide]]
*[[Cyanide]]
====Cyanosis====
*[[Benzocaine]] and other local anesthetics
*[[Cyanokit]], nitrites, nitrates, well water (nitrates)
*[[Antimalarials]]
*[[Quinolones]]
*[[Dapsone]] (used to treat leprosy, PCP pneumonia, toxoplasmosis, dermatitis herpetiformis, brown recluse bite)
*Aniline dyes
*Phenazopyridine<ref>Jeffery WH, Zelicoff AP, Hardy WR. Acquired methemoglobinemia and hemolytic anemia after usual doses of phenazopyridine. Drug Intell Clin Pharm. 1982 Feb;16(2):157-9.</ref>
*Nitrates, nitrites
*Ergotamine toxicity|Ergotamine]]
====Acneiform [[rash]]====
*Bromides
*Chlorinated aromatic [[hydrocarbons]]
 
==Evaluation==
===Toxicological Exam===
*All vital signs (Temp, RR, HR, BP) + bedside glucose
*[[Neurologic exam]]
**Level of consciousness
**Pupillary exam
**Motor response
**DTRs
*Skin Exam - moisture, temp, evidence of injection drug abuse
*Lung Exam
*Bowel Sounds
*[[ECG]] (ie. look for [[QT prolongation]], QRS prolongation, etc)
*Consider CBC, BMP, urinalysis (with ẞ-HCG if appropriate), urine toxicology screen, serum alcohol concentration, VBG
**The urine screen is a qualitative test -> positivity ≠ acute toxicity
**It can be falsely positive due to cross-reactivity
**It can be falsely negative if the substance ingested does not cross-react with the tested analyte
**The diagnosis of intoxication is clinical!!!


===Tissue Hypoxia===
==Management==
# CO
*Depends on agent
# cyanide
*See [[antidotes]]
#hydrogen sulfide
*"Coma cocktail" when suspecting toxic ingestion (mnemonic = "DONT")
# methemoglobinemia
*#[[Dextrose]] (50mg IV)
*#[[Oxygen]]
*#[[Naloxone]] (0.2-0.4mg IV/IM, repeat dose 1-2mg)
*#*Empiric opioid ingestion treatment
*#[[Thiamine]] (50-100mg)
*#*Treat or avoid [[Wernicke encephalopathy]]
*#*Though some suggest giving thiamine prior to dextrose, do NOT let this delay treatment of hypoglycemia!
*#*Case reports of dextrose precipitating Wernicke's involved thiamine-deficient patients receiving prolonged course of IV glucose, NOT with single bolus<ref>Donnino MW, Vega J, Miller J, Walsh M. Myths and misconceptions of Wernicke's encephalopathy: what every emergency physician should know. Ann Emerg Med. 2007;50(6):715-21.</ref><ref>Gussow, L. Myths of Toxicology: Thiamine Before Dextrose. Emergency medicine news. 2007;29(4):3-11.</ref>


===Respiratory Depression===
==Disposition==
# Central Depression
*Depends on agent
## antipsychotics
##chlorinated hydrocarbons
## alcohols/glycols, sedative/hyp
## TCAs
## Lomitil
# Muscle Failure
## organophosphates
##marine toxins
## nicotine
## strychnine
## botulinis
## Mojave rattlesnake, Cobra


===Autonomic Nervous System===
==See Also==
# Parasympathetic - ACh is transm
*[[Altered mental status]]
## Muscarinic
*[[Traditional chinese medicine toxicology]]
###receptors in heart, eye, lung, GI, skin and sweat glands
*[[Drug_levels|Drug Levels]]
### Bradycardia
*[[Antidote]]
### Miosis
*[[Camphor toxicity]]
### Bronchorrhea / Bronchospasm
*[[In-Training Exam Review]]
### Hyperperistalsis (SLUDGE)
### Sweating
### Vasodilation
## Nicotinic
### receptors in both sympathetic and parasympathetic nervous systems
### fasciculations, flaccid paralysis
###tachycardia, hypertension?
# Sympathetic
##ALPHA EFFECTS - vessels, eye, skin
### Mydriasis, HTN, Sweating
##BETA EFFECTS - heart, lungs
### Tachycardia, Bronchodilation


==Source==
==References==
DONALDSON (Adapted from BIRNBAUMER - 7/18/02)
<references/>


[[Category:Tox]]
[[Category:Toxicology]]
[[Category:EMS]]

Latest revision as of 19:18, 20 February 2021

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 Receptors and Their Effects

  • Parasympathetic - ACh is transm
    • Muscarinic
      • receptors in heart, eye, lung, GI, skin and sweat glands
      • Bradycardia
      • Miosis
      • Bronchorrhea / Bronchospasm
      • Hyperperistalsis (SLUDGE)
      • Sweating
      • Vasodilation
    • Nicotinic
  • Sympathetic
    • Alpha effects (vessels, eye, skin)
    • Beta effects (heart, lungs)

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

Hypothermia

Increased Respiratory Rate

Respiratory Depression

Bradycardia

PACED

physostigmine

Tachycardia

FAST

Hypotension

CRASH

Hypertension

CT SCAN

Miosis

COPS

Mydriasis

SAW

Coma

LETHARGIC

Seizures

OTIS CAMPBELL

Skin findings

Diaphoresis

SOAP

Dry skin

Bullous lesions/blisters

Flushed/red appearance

Cyanosis

  • Benzocaine and other local anesthetics
  • Cyanokit, nitrites, nitrates, well water (nitrates)
  • Antimalarials
  • Quinolones
  • Dapsone (used to treat leprosy, PCP pneumonia, toxoplasmosis, dermatitis herpetiformis, brown recluse bite)
  • Aniline dyes
  • Phenazopyridine[1]
  • Nitrates, nitrites
  • Ergotamine toxicity|Ergotamine]]

Acneiform rash

Evaluation

Toxicological Exam

  • All vital signs (Temp, RR, HR, BP) + bedside glucose
  • Neurologic exam
    • Level of consciousness
    • Pupillary exam
    • Motor response
    • DTRs
  • Skin Exam - moisture, temp, evidence of injection drug abuse
  • Lung Exam
  • Bowel Sounds
  • ECG (ie. look for QT prolongation, QRS prolongation, etc)
  • Consider CBC, BMP, urinalysis (with ẞ-HCG if appropriate), urine toxicology screen, serum alcohol concentration, VBG
    • The urine screen is a qualitative test -> positivity ≠ acute toxicity
    • It can be falsely positive due to cross-reactivity
    • It can be falsely negative if the substance ingested does not cross-react with the tested analyte
    • The diagnosis of intoxication is clinical!!!

Management

  • Depends on agent
  • See antidotes
  • "Coma cocktail" when suspecting toxic ingestion (mnemonic = "DONT")
    1. Dextrose (50mg IV)
    2. Oxygen
    3. Naloxone (0.2-0.4mg IV/IM, repeat dose 1-2mg)
      • Empiric opioid ingestion treatment
    4. Thiamine (50-100mg)
      • Treat or avoid Wernicke encephalopathy
      • Though some suggest giving thiamine prior to dextrose, do NOT let this delay treatment of hypoglycemia!
      • Case reports of dextrose precipitating Wernicke's involved thiamine-deficient patients receiving prolonged course of IV glucose, NOT with single bolus[2][3]

Disposition

  • Depends on agent

See Also

References

  1. ↑ Jeffery WH, Zelicoff AP, Hardy WR. Acquired methemoglobinemia and hemolytic anemia after usual doses of phenazopyridine. Drug Intell Clin Pharm. 1982 Feb;16(2):157-9.
  2. ↑ Donnino MW, Vega J, Miller J, Walsh M. Myths and misconceptions of Wernicke's encephalopathy: what every emergency physician should know. Ann Emerg Med. 2007;50(6):715-21.
  3. ↑ Gussow, L. Myths of Toxicology: Thiamine Before Dextrose. Emergency medicine news. 2007;29(4):3-11.
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