Introduction to Toxicology - PowerPoint PPT Presentation

Loading...

PPT – Introduction to Toxicology PowerPoint presentation | free to view - id: 8157e-NTkyM



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Introduction to Toxicology

Description:

Introduction to Toxicology. Richard W. Stair, MD, FACEP. Toxic Trivia ... Directed Toxicology Tests. Hepatic Toxin LFT's, NH4, glu, coags, amylase ... – PowerPoint PPT presentation

Number of Views:2655
Avg rating:5.0/5.0
Slides: 40
Provided by: dean180
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Introduction to Toxicology


1
Introduction to Toxicology
  • Richard W. Stair, MD, FACEP

2
Toxic Trivia
  • About 4 million toxic exposures annually
  • Fewer than 1 of overdose patients that reach the
    hospital result in fatality
  • But 13-35 mortality if arrive in deep coma
  • One fourth of suicide attempts are via drugs

3
Its Not Just Swallowing Pills
  • Ingestions account for 79 of exposures
  • Others
  • 7 dermal
  • 6 ophthalmologic
  • 5 inhalations
  • 3 stings and bites
  • .3 injection

4
Toxic Trivia II
  • Leading causes of pharmaceutical death
  • Analgesics
  • Tricyclic antidepressants
  • Sedative/hypnotics
  • Stimulants and street drugs
  • Cardiovascular drugs
  • Alcohols

5
7 Mechanisms of Toxicity
  • 1. Interfere with O2 transport or tissue
    utilization of oxygen
  • (example cyanide, CO)
  • 2. Affect CNS
  • (example cocaine, sedatives)
  • 3. Affect ANS
  • (example organophosphates)

6
7 Mechanisms of Toxicity
  • 4. Affect lungs
  • (example paraquat)
  • 5. Affect cardiovascular system
  • (example TCA, Ca channel blockers)
  • 6. Direct local damage
  • (example acids, bases)
  • 7. Delayed effects on liver or kidneys
  • (example acetaminophen, metals)

7
Initial Assessment
  • Primary Survey
  • Airway (with C spine protection)
  • Breathing
  • Circulation
  • Disability
  • Exposure

8
Obtaining the History
  • Remember the AMPLE history
  • Allergies, Medications, Past medical and surgical
    history,
  • Last meal, Events leading to presentation
  • When in a jam, remember the Ps
  • Paramedics
  • Parents
  • Pals
  • Physicians
  • Pharmacists

9
Physical Exam
  • Vitals
  • Often times no significant physical
    findings,especially if exposure early
  • Beware of changes
  • Odors may give clue to substance
  • Look for easily recognizable toxidromes

10
Odors as Clues to Toxins
  • Acetone acetone, acidosis
  • Alcohol NOT with ethylene
  • glycol
  • Bitter almonds cyanide
  • Hemp (burnt rope) marijuana
  • Garlic arsenic
  • Rotten eggs disulfiram, H2SO4

11
Toxidromes
  • Anticholinergic
  • Cholinergic
  • Sympathomimetic
  • Opioid
  • Phencyclidine Syndrome
  • Torsion Head and Neck Syndrome

12
Anticholinergic Syndrome
  • Dry as a bone (dry skin, urinary retention)
  • Red as a beet (flushing)
  • Blind as a bat (mydriasis)
  • Hot as Hades (hyperthermia)
  • Mad as a hatter (hallucinations)

13
Cholinergic Syndrome
  • Think DUMBELS
  • Defecation
  • Urination
  • Miosis
  • Bronchospasm
  • Excessive salivation
  • Lacrimation
  • Seizures

14
Sympathomimetic Syndrome
  • Hyperthermia, hypertension, tachycardia,
    mydriasis, psychosis, convulsions
  • Mimics Anticholinergic except WET compared to DRY
  • sweating, urination and defecation (NOT
    retention)

15
Opioid Syndrome
  • Triad of
  • Respiratory depression
  • Coma
  • Pinpoint pupils
  • Also see
  • Hypotension
  • Hypothermia
  • Bradycardia

16
The Other Toxidromes
  • Torsion Head Neck
  • dysphonia
  • oculogyric crisis
  • rigidity
  • torticollis
  • tremors
  • Phencyclidine (PCP)
  • rotatory nystagmus
  • miosis
  • combativeness
  • Crazy and No pain

17
Evaluation of Toxicity
  • Evaluate the SATS
  • Substance
  • Amount
  • Time of exposure
  • Symptoms
  • Regional Poison Control Center

18
Management
  • Most toxic exposures will get better simply with
    meticulous supportive care
  • Not everybody needs the full court press
  • Issues to address
  • frequent assessment
  • decontamination
  • enhancement of elimination
  • Antidotes
  • disposition

19
Frequent Assessment
  • Do they need to be here at all?
  • Beware of the Stable patient
  • Consider possible polysubstance exposures
  • Be prepared for deterioration
  • IV access
  • Cardiac monitor
  • Pulse oximetry

20
Decontamination Methods
  • Aim is to prevent absorption and minimize
    exposure
  • Many standard practices now virtually extinct
  • Forced emesis, forced lavage, charcoal anytime
  • Removal of contaminated clothing, substances on
    skin or in eyes
  • Charcoal
  • Gastric lavage
  • Whole Bowel Irrigation

21
Charcoal
  • Works by substances being adsorbed to the
    surface, which is size dependent
  • Window of opportunity around one hour post
    ingestion
  • Has some indications for multiple dosing
  • drugs that have enterohepatic circulation
  • drugs that can be eliminated by gut dialysis

22
Charcoal Contraindications
  • Charcoal doesnt bind CHARCOAL
  • Caustics and corrosives
  • Heavy metals
  • Alcohols
  • Rapid absorption (cyanide, strychnine)
  • Chlorine and iodine
  • Other agents insoluble in water
  • Aliphatics (petroleum distillates)
  • Laxatives (Mg, K, Na)

23
Charcoal Contraindications
  • Loss of protective reflexes
  • drugs likely to cause rapid depressed
    consciousness or early seizures
  • infants lt 6 months of age
  • ingested foreign body
  • neurologically impaired
  • absent bowel sounds or obstruction
  • unstable patients

24
Multi-dose CharcoalEnterohepatic Circulation
  • Chloral hydrate
  • colchicine
  • digitalis preparations
  • glutethimide
  • isoniazid
  • methaqualone
  • NSAIDS
  • phencyclidine
  • phenothiazines
  • phenytoin
  • salicylates
  • TCAs

25
Multi-dose CharcoalGut Dialysis
  • Pretty Damn Short QTc
  • Phenobarbital
  • Dapsone
  • Salicylates
  • Quinine
  • Theophylline
  • Carbemazepine

26
Decontamination Methods
  • Gastric lavage
  • Used far less now than in past
  • Having your stomach pumped, with large tube
    inserted into stomach, suctioned, and lavaged
  • Risk of perforation, aspiration, and simply not
    working
  • Contraindicated in comatose or seizing patients,
    unprotected airways, extended release preparations

27
Decontamination Methods
  • Whole Bowel Irrigation
  • cleanses gut of intoxicants
  • PEG solutions at 2 Liters/hour
  • effective for use in LA preparations, body
    packers/stuffers, and some substances poorly
    absorbed by charcoal (ex iron)
  • contraindicated if hematemesis, ileus,
    obstruction, perforation, or peritonitis

28
Enhancement of Elimination
  • In other words, get rid of the toxin faster
  • Cathartics - used, but no study showing benefit
  • Alkalinization salicylates
  • Hemodialysis
  • Hemoperfusion

29
Hemodialysis
  • Invasive, time consuming procedure
  • Patients unstable despite supportive treatment
  • Drugs must be amenable to hemodialysis
  • Must have small volume of distribution (ie, drug
    must be in plasma, not tissues)
  • Must not be tightly protein bound

30
Hemodialysis
  • I STUMBLE (the common ones)
  • Isoniazid
  • Salicylates
  • Theophylline
  • Uremia
  • Methanol
  • Barbiturates
  • Lithium
  • Ethylene glycol

31
Antidotes
  • Very limited number of antidotes given the vast
    array of pharmaceuticals and chemicals
  • Coma Cocktail
  • glucose
  • thiamine
  • naloxone
  • NOT flumazenil

32
Common Antidotes
  • Toxin
  • APAP
  • Tricyclics
  • Opiates
  • Organophosphates
  • Heavy metals
  • Ca and beta blockers
  • Iron
  • Digoxin
  • Antidote
  • N acetylcysteine
  • Na bicarbonate
  • Naloxaone
  • 2 PAM
  • BAL
  • Glucagon
  • Desferoxamine
  • Dig Fab (Digibind)

33
Common Antidotes
  • Toxin
  • Methanol, ethylene glycol
  • Methemoglobinemia
  • Anticholinergics
  • Isoniazid
  • Snakebites
  • Antidote
  • Fomepizole (Antizole)
  • Methylene blue
  • Physostigmine
  • Pyridoxine
  • Antivenom

34
Agitated, Violent, and Psychotic Patients
  • Reports of sudden death from overzealous physical
    restraint
  • Must maintain safe environment for the patient,
    other patients, staff (and yourself)
  • Combination of Physical and Chemical Restraints

35
Ancillary Testing
  • EKG and cardiac monitor, pulse oximetry
  • Consider acetaminophen and salicylates
  • Acid-base status determinations
  • MUDPILES, etc
  • Osmolal gap determination
  • 2Na BUN/2.8 glu/18 EtOH/4.6
  • Directed toxicology (very limited role)

36
Directed Toxicology Tests
  • Comatose Tox screen, glu, NH4, CT scan, CSF
    analysis
  • Respiratory toxin ABG, CXR, spirometry,
    pulse ox
  • Cardiac toxin EKG, ECHO, cardiac enzymes,
    hemodynamic monitoring

37
Directed Toxicology Tests
  • Hepatic Toxin LFTs, NH4, glu, coags,
    amylase
  • Nephrotoxin Chem 7, UA, serum urine
    osmolarity, 24 hr urine heavy
    metals
  • Bleeding Coags, platelets, FSP,
    fibrinogen, TS

38
High Risk Patients (ICU wannabees)
  • Needs circulatory or respiratory support
  • altered mental status gt 3 hours
  • seizures
  • arrhythmia
  • second or third degree heart block
  • widened QRS
  • unresponsive to verbal stimuli
  • arterial pCO2 gt 45 mmHg

39
Disposition
  • Home if stable after appropriate evaluation and
    observation period, unintentional or simple
    gesture with support structure
  • Psychiatry evaluation if intentional, or risk to
    harm self or others
  • Admission if unstable, long-acting or sustained
    release, needing therapies
About PowerShow.com