Clinical toxicology 2

The aim of this lecture is to provide
an overview of the management of various toxic exposures.
emergency medical services that should be immediately contact to provide advanced life support for patient with unstable vital signs resulting from a poisoning exposure.

1. Clinical Toxicology
1)Aim of Lecture
2)Introduction
3) General management
a) Supportive care & ARBC
b) Obtaining a history of exposure
c) Management
4) Management of specific ingestions
5) References

2. The aim of the lecture
The aim of this lecture is to provide
an overview of the management of various
toxic exposures.
emergency medical services that should be
immediately contact to provide advanced life
support for patient with unstable vital signs
resulting from a poisoning exposure.

3. Introduction
Some definitions:
clinical toxicology:concentrate on the effects of the
substances-in
the patients-caused by
accidental poisoning
intentional overdose of medications, drugs of abuse,
household products, or
various other chemicals.

4. Introduction
Intoxication:
The toxicity associated with any chemical
substance
Poisoning:
A clinical toxicity secondary to accidental
exposure.
Overdose:
an intentional exposure with the intent of
causing self-injury or death.

5. * Routine laboratory assessment
1) complete blood cell (CBC) counts
2) serum electrolytes
3) blood urine nitrogen
4) blood glucose
5) urinalysis
6) electrocardiogram
7) chest roentgenogram and/or kidney,
ureters & bladder (KUB) x-ray

6. Toxicological laboratory tests
advantages:
confirm or determine the presence of a particular
agent
predict the anticipated toxic effects or severity of
exposure to some poisons
confirm or distinguish differential or contributing
diagnosis
occasionally help guide therapy

7. Toxicological laboratory tests
disadvantages
 these tests can provide a specific diagnosis for all patients
 all possible intoxication agents can not be screened
 in critical ill patients, supportive treatment is needed before
laboratory results of the toxicology screen are available
 laboratory drug-detection abilities differ
 in general, only qualitative determination of a substance is
necessary.
 however, quantitative levels of the following drugs are
necessary to guide the therapy:
-acetaminophen, carbamazepine, phenytoin, digoxin,
theophylline, valporicacid, iron, lithium, lead, salicylates,
phenobarbitol, mercury, arsenic

8. General management
supportive care & ABCs; evaluation & supporting the
vital functions
( airway, breathing & circulation ) are the mandatory the
first steps in the initial management of drug ingestions.
After the patient is stabilized, the specific issues of poison
management should be addressed.

9. General management:
obtaining a history of exposure
a) identify
i) the substance ingested
ii) the route of exposure
iii) the quantity ingested
iv) the amount of time since ingestion
v) signs & symptoms of the overdose
vi) any associated illness or injury
vii) corroborate history & other physical evidence

10. General management
obtaining a history of exposure
b) neurological examination:
evaluate any seizers, alteration in:
consciousness, confusion, ataxia, slurred speech,
tremors & headache
c) cardiopulmonary examination;
evaluate any syncope, palpitation, cough, chest pain,
shortness or difficulty in swallowing
d) gastrointestinal examination:
evaluation any abdominal pain, nausea, vomiting,
diarrhea or difficulty in swallowing

11. General management
obtaining a history of exposure
e) past medical history should include
i) medication, including nonprescription
(over-the-counter ( OTC)) substances
ii) use of herbal medications
iii) alcohol & drug abuse
iv) psychiatric history
v) allergies
vi) occupational or hobby exposures
vii) travel
viii) prior ingestions
-social history with potential domestic violence neglect
-last normal menstrual period or pregnancy

12. Management
1) Skin decontamination
When the contaminating substance may produce local
toxic effects (acid burns)
-the patient’s clothing is removed, and the areas are
irrigated with copious quantities of water
-neutralization should not be attempted. (for example,
neutralizing acid burns with sodium bicarbonate will
produce exothermic chemical reaction, therapy
exacerbating the patient’s condition

13. Management
2) Gastric decontamination
a) Emesis
But it is contraindicated in
i.children younger than 6 months of the age
ii.patients with central nervous system depression or
seizures
iii.patients who have ingested a strong acid, alkali or sharp
object
iv.patients with compromised airway protective reflexes
( including coma & convulsion )
i.patients who have ingested some types of hydrocarbons
or petroleum distillates
ii.patients who have ingested substances with an
extremely rapid onset of action
iii.patients with emesis after the ingestion

14. Management
2) Gastric decontamination
b) Gastric lavage
Procedure
Patients are placed in the left lateral decubitus position.
Lavage is performed after cuffed endotracheal tube is in
place to protect the airway
After aspiration of the gastric content 250-300 ml of tap
water or saline is instilled and then aspirated
the sequence should be repeated till the return is
continuously clear for at least 2 L
Contraindication
In patient who have ingested acids, alkali or hydrocarbons
if patient is at risk for GI perforation or if they are
combative

15. Management
2)Gastric decontamination
c) Activated charcoal
Adsorb almost commonly ingested drugs & chemicals and is
usually administered to most Overdose patients as quickly as
possible
Commonly ingested substances not adsorbed include ethanol, iron,
lithium, cyanide, ethylene Glycol, lead, mercury, methanol, organic
solvents, potassium, strong acids & strong alkali
Toxic ingestion with drugs have enterohepaticcirculations
(carbamazepine, theophylline, phenobarbitol, tricyclic antidepressants,
phenothiazines, digioxin) generally require that the charcoal be re-
administered every 6 hours to prevent reabsorption during
recirculation
Dosage
Adult: 25-100 g
Children: up to 1 year: 1 g/kg
1-12 years : 25-50 g

16. Management
3) Whole bowel irrigation
particularly when activated charcoal lacks efficacy
Use polyethylene glycol in dosage 1-2 L/hrgiven orally
or by nasogastric tube till rectal effluent is clear

17. Management
4)Forced diuresis
Used to enhance the elimination of substances whose
elimination is primarily renal, if the substance has a
relatively small volume of distribution with little protein
binding.
For example alkaline diuresis (by sodium bicarbonates)
promotes the ionization of weak acids (as long acting
barbiturates, salicylates) therapy preventing their re-
absoptionby the kidney

18. Management
5) Dialysis
In patients who fail to respond to the measures of
decontamination already outlined.
Hemodialysis and less extent peritoneal dialysis may
enhance drug elimination.
Drugs which eliminated by hemodialysis are
water soluble
have a small volume of distribution
have a low molecular weight
are not binding to plamaproteins
this technique used to enhance the elimination of ethanol,
theophlline, salicylates, lithium & long acting barbiturates

19. Management
6) Hemoperfusion
Is a technique in which anticoagulants are passed through a
column containing activated charcoal or resin particales.
This method clears substances from blood more rapidly
than hemodialysis.
but it does not correct the electrolyte abnormalities as
does hemodialysis
It is more effective in removing phenytoin, carbamazapine,
methotrexate & theophylline than hemodialysis .

20. Calcium channel blockers
Examples:verapamil, diltiazem, nifedipine
Toxicity &overdose:cause hypotension, bradicardia,
pulmonary edema
Laboratory data:include ECG &serum electrolytes
Treatment:
i) GI decontamination (gastric lavage, activated
charcoal, whole-bowel irrigation (especially for sustained
release products)
ii) calcium: for management of hypotension, bradycardia
iii) glucagon: for management of hypoglycemia

21. cocaine
Toxicity &overdose: include CNS & sympathetic
stimulation (hypotension, tachycardia, tachypnea, seizures)
-Death may result from respiratory failure, myocardial
infarction or cardiac arrest
Laboratory data:include cocaine & cocaine metabolite urine
screen
Treatment:is supportive
benzodiazepine for seizures
labetalol for hypertension
neuroleptics for psychosis

22. Digoxin
Toxicity &overdose:
-include confusion, anorexia in mild cases.
-in more severe cases, cause cardiac dysrhythmias
Laboratory data:
-include ECG, serum digoxin level, electrolytes, serum
potassium level
Treatment:
i)Decontamination with activated charcoal
ii)Supportive therapy; management of hypokalemia,
intropicsusport
iii)Digoxin-specific fab antidote ( Digibind)

23. Opiates
Toxicity &overdose:
-include respiratory depression &
-decreased level of consciousness.
-Rare effects include hypotension, bradycardia,
pulmonary edema
-Laboratory data:
include baseline ABGs and toxicology screens
-Treatment:
i) Naloxone

24. salicylates
Toxicity &overdose:
-mild toxicity: include nausea, vomiting, tinnitus, malaise
-Severe overdose: include lethargy, convulsion, coma, metabolic
acidosis.
-Toxic dose: include GI bleeding, increased PT, hepatic toxicity,
pancreatitis, proteinuria.
Laboratory data:
-the following 6-hr post ingestion levels are
40-60 mg/dl -----tinnitus
60-95 mg/dl -----moderate toxicity
> 95 mg/dl -------severe toxicity
-leukocytosis, thrombocytopenia, hypokalemia, increase serum BUN,
creatinine, ketones
Treatment:
i) decontamination with activated charcoal
ii) Hemodialysis
iii) Alkaline diuresis
iv) Fluid & electrolyte replacement
v) Vitamin k & fresh frozen plasma to correct any coagulopathy

25. Theophylline
Toxicity &overdose:
-include cardiac dysrhythmias, seizures, neusea, vomiting
Laboratory data:
-theophylline level, serum electrolytes, BUN,
hepatic function, ECG, monitor hyperglycemia,
hypokalemia
Treatment:
i) supportive therapy:
maintaining airway, treating seizures &dysrhythmias
ii) decontamination ( activated charcoal, whole bowel
irrigation, hemoperfusion&hemodialysis
iii) B-blockers: to treat hypertenson, tachycardia

26. organophosphates
Present in pesticides
Toxicity &overdose:
-include excessive cholinergic stimulation
Laboratory data:
-include RBCs acetylcholinesreaseactivity
Treatment:
i) decontamination
ii) atropine
iii) Pralidoxime

27. Lead
Present in lead-containing paints or gasoline fume
inhalation
Toxicity &overdose:
-include convulsion, coma, abdominal pain, peripheral
neuropathies, vomiting
Laboratory data:
-include anemia, elevated blood-lead level
Treatment:
I) Edetatecalcium disodium
2) dimercaprol

28. Cyanide
Present in industrial chemicals, some nail-polish removers
Toxicity &overdose: include headache, dyspnea, nausea, vomiting,
ataxia, coma, seizures, death
Laboratory data: include cyanide level, ABGs, electrolytes, ECG
Treatment:
1.a cyanide antidote kit is used.
It contains the following:
i) amyl nitrite pearls are crushed & hold under the patient’s nostrils
ii) sodium nitrates convert hemoglobin to metheglobinwhich bind to
the cyanide ion
iii) sodium thiosufate
2. oxygen
3. sodium bicarbonate as needed for severe acidosis
4. hyperbaric oxygen for patients not responding to already outlined
treatment

29. Iron
Present in numerous OTC products
Toxicity & overdose:
Toxicity based on the amount of elemental iron ingested
-phase I. nausea, vomiting, diarrhea, GI bleeding, hypotension
-phase II. Clinical improvement seen 6-24 hrspost ingestion
-phase III. Metabolic acidosis, renal &hepatic failure, sepsis, pulmonary
edema & death
Laboratory data: include Fe serum levels, liver function tests,
hemoglobin, total iron binding capacity
Treatment:
1) decontamination ( gastric lavage, whole-bowel irrigation
2) supportive treatment
3) deferoxamine(antidote) used to chelate iron

30. Isoniazide(INH)
Toxicity &overdose:
include nausea, vomiting, slurred speech, coma, ataxia,
generalized tonic-clonicseizures
Laboratory data: include severe lactic acidosis,
hypoglycemia, leukocytosis, mild hyperkalemia
Treatment:
1) decontamination: with activated charcoal (avoid emesis as
patients are at high risk for developing seizures)
2) pyridoxine: (reverse seizures)
3) sodium bicarbonate: to correct acidosis

31. Corrosive
Strong acids or alkali
Toxicity &overdose: strong acids or alkali
Laboratory data: include arterial blood gases (ABGs), chest
radiographs
Treatment:
1) decontamination
2) exposed skin must be irrigated with water
(neutralization should be avoided because these
reactions are exothermic & will produce farther
tissue damage)

32. Electrolytes
Magnesium
Toxicity &overdose:
i) mild: depressing of deep tendon reflexes
ii) severe: respiratory paralysis & heart block
Laboratory data:
i) mild: > 4 mEq/ml
ii) severe: > 10 mEq/ml
Treatment:
1) calcium chloride ( antagonize the cardiac effects of
magnesium)
2) in severe cases, hemodialysis may be required

33. Electrolytes
Potassium
Toxicity &overdose: include cardiac irritability, peripheral weakness,
cardiac dysrhythmias
Laboratory data: ECG
Treatment:
1) calcium (antagonize hyperkalemia)
2) sodium bicarbonate: increase serum PH, causes intracellular shift of
potassium
3) glucose & regular insulin: to shift potassium from the extracellular
fluid into the cells)
4) cationexchange resins: bind potassium in exchange for another
cation(sodium) [sodium polystyrene sulfonate) can be given orally or
rectally as retention enema
5) hemodialysis: is reserved for life-threatening hyperkalemia that does
not respond to the above measures