poisoning

Question 1

toxicity

Answer 1

capacity of a chemical including drugs to cause injury

Question 2

route of entry of toxins

Answer 2

skin contact
inhalation
ingestion

Question 3

common target tissues for toxins

Answer 3

lungs
liver
brain
kidneys 
heart

Question 4

toxic actions of chemicals

Answer 4

selective vs non selective

Question 5

selective actions

Answer 5

interferes with specific biochemical pathways

chemical has to be absorbed and distributed to a specific pathway

Question 6

non selective actions

Answer 6

local irritation( site of exposure)
injury caused by denaturing macromolecules

Question 7

duration of action of chemicals

Answer 7

delayed- late symptoms

immediate- quick symptoms

Question 8

Management

Answer 8

HABCDEFG

Question 9

what do we need to know from history

Answer 9

toxic substance
time of ingestion
amount ingested
reason for ingesting

Question 10

special investigations

Answer 10

blood gas, electrolytes and glucose, LFT and KFT,FBC and ESR,INR
urinalysis, ECG, plasma poison concentration

Question 11

ways of deconatamination

Answer 11

skin- remove clothes, wash with soap and water
eyes- irrigate with tap water/ normal saline
emesis
activated charcoal
whole bowel irrigation

Question 12

emesis

Answer 12

used for children
if ingested less than an hour ago
if charcoal not indicated 
methods
pharyngeal stimulation
ipecac
contraindications:
unconscious
corrosive substance 
hydrocarbons
risk of seizures

Question 13

gastric lavage

Answer 13

-if ingestion less than 1-2 hours ago
-large amount of toxic solid substance
-use large bore catheter
200-300ml tap water in adults
10ml body temp saline in kids
small water to minimize risk of gastric contents entering duodenum
-contraindications:
corrosive substance and hydrocarbons
risk of GI hemorrhage

Question 14

activated charcoal

Answer 14

-used in TCA, paracetamol, digoxin
- if ingested less than 2 hours ago
Multiple dose activated charcoal used in:
severely poisoned
sustained release tables- drug released slowly over an extended period of time
Enterohepatic cycling- drug absorbed into intestine, into the portal circulation and secreted with bile back into the intestine and back into circulation
drugs secreted into bile or intestine

Question 15

adverse effects of activated charcoal

Answer 15

Adverse effects:
Vomiting
Constipation/diarrhea
Intestinal obstruction

Question 16

contraindications of charcoal

Answer 16

contraindications:
Strong acids or alkalis
Iron salts
Lithium
Petroleum products 
Cyanide
Endoscopy due
Antidote by mouth

Question 17

monitoring of charcoal

Answer 17

in stool 6 hours later

hydration

Question 18

dose of charcoal used

Answer 18

oral/NG tube
adults 50-100g with 500ml of water
kids 10-50g in 100-300ml of water

Question 19

whole bowel irrigation

Answer 19

PEG electrolyte solution orally 
stimulates peristalsis 
contraindications 
bowel obstruction/perforations
ileus 
compromised airway

Question 20

enhancing drug clearance

Answer 20

urinary alkalinization
hemodialysis
charcoal hemoperfusions

Question 21

urinary alkalinsation

Answer 21

Used in salicylate overdose
Increases elimination by maintaining urine pH > 7.5
IV administration of sodium bicarbonate
Monitor potassium

Question 22

charcoal haemoperfusion

Answer 22

Removal of toxic substances by adhesion to activated charcoal
Extracorporeal – large volumes of blood passed over absorbent substance
Removes barbiturates, carbamazepine and theophylline
MDAC as effective for many drugs

Question 23

further care

Answer 23

monitor and treat:
seizures 
hypoventilation-opiods
Hypoglycaemia eg salicylates
Hypothermia/hyperthermia
CVS compromise
Liver/kidney failure

Question 24

Give antidote

Answer 24

Digoxin: digoxin immune fab
Paracetamol: acetylcysteine
Opioids: naloxone
Benzodiazepines: Flumazenil tests for benzodiazepine poisoning 
Iron: Deferoxamine