Clinical Toxicology 1

Question 0

what are the most common cases of poisoning caused by ?

Answer 0

involving drug misuse
sometimes due to self inflicted either to cause suicide or as a case of parasuicide

accidental poisoning is very uncommon

Question 1

What is clinical toxicology also referred to as?

Answer 1

diagnosis of poisoning and its treatment

Question 2

in the UK in 2005 what were the statistics of poisoning ?

Answer 2

1783 deaths due to poisoning by drugs, medicants and biological substances
910 deaths due to accidental poisoning and noxious substances
761 deaths due to intentional self poisoning
65 deaths were caused by criminal poisoning

Question 3

how many patients per year in the UK are admitted to hospital for treatment of poisoning ?

Answer 3

as many as 170000

Question 4

how is the poisoning of a patients evaluated ?

Answer 4

using ABCDE approach 
airway 
breathing
circulation
disability
exposure

Question 5

what are the affects on the airways and breathing generally caused by poisoning ?

Answer 5

shallow and irregular breathing
low partial pressure of oxygen
build up of carbon dioxide

Question 6

what is usually the first priority when a patients has been poisoned ?

Answer 6

to maintain a clear airway and support their breathing if its needed

Question 7

how do you ensure the airways are clear?

Answer 7

conscious patients- positioning patient on side to prevent them chocking on vomit
unconscious patient- prevent tongue falling back and obstructing pharynx

Question 8

what may be necessary in unconscious patients to maintain clear airways ?

Answer 8

insertion of an endotracheal tube to maintain artifical breathing and deliver oxygen to maintain pressure in blood

Question 9

what drugs if overdosed on can cause respiratory depression?

Answer 9

ethanol
opiates
antidepressants

Question 10

what effects does poisoning often have on circulation ?

Answer 10

cause cardiac dysrhythmias and shock

Question 11

what are the priorities of circulation that have to be checked?

Answer 11

vascular assess- to get blood samples and to correct any abnormal chemistry of the blood
check heart rhythm
check blood pressure

Question 12

what often happens in a TCA overdose ?

Answer 12

block the fast sodium channels in the heart causing reduced contractility and dysrhythmias
can cause hypotension

Question 13

how can an overdose on TCAs be reversed ?

Answer 13

infusion of sodium bicarbonate can reverse blockade of sodium channels
hypotension can be corrected by a vasopressor such as noradrenaline or phenylephrine

Question 14

what can an overdose with MAOIs cause and how is it treated?

Answer 14

cause severe hypertension

treated with a short acting vasodilator such as nitroprusside

Question 15

what is shock and why is it dangerous?

Answer 15

dangerous because it can cause cardiovasular collapse
causes low systolic BP, tachycardia, cold pale skin, acidosis and low oxygen tension in arterial blood
main feature is dilation of venous bed causing poor venous return and decrease in CO

Question 16

how is shock managed ?

Answer 16

expansion of circulation volume by infusion of high molecular weight impermeant substance such as dextran
admin of drugs to increase CO- dopamine, dobutamine
correction of acidosis with infusion of sodium bicaronate - important because it can depress myocardial contractility

Question 17

what is classed as disability by poisoning ?

Answer 17

seizures
agitation 
delirium 
coma 
hyper or hypothermia

Question 18

what is a common cause of delirium and coma ?

Answer 18

hypoglycaemia

easy to detect levels by blood sample and corrected by dextrose

Question 19

why are seizures dangerous ?

Answer 19

they can impair cardio-respiratory function

Question 20

what class of drug can often induce seizures and how is it treated ?

Answer 20

TCAs

controlled by benzodiazepines with anticonvulsant activity- diazepam

Question 21

what drug if overdosed can cause hyperthermia/hypothermia?

Answer 21

hyperthermia- caused by amphetamines

hypothermia- caused by opiates

Question 22

what is associated with hyperthermia and how is it treated ?

Answer 22

> 40 degrees temp
loss of blood caused by prolonged sweating
restored by fluid replacement
in severe cases ice baths are required
also decreases the need for calcium in excitation contraction coupling so muscles contract without exertion generating heat - treated with dantrolene

Question 23

why does hypothermia normally occur ?

Answer 23

due to coma

<35 degrees

Question 24

what are the 4 ways to minimise or prevent entry of an oral toxicant to reduce or prevent exposure?

Answer 24

gastric lavage= stomach is washed 3-4 times to remove contents
emesis= admin of ipecacuanha syrup containing many alkaloids that irritate the stomach and stimulate chemo trigger zone in medulla
adsorption = many organic toxicant bind to activate charcoal so this is best at removing drugs in the gut - given orally at 10x estimated weight of toxicant
bowel irrigation with polyethylene glycol= given a solution at about 2L/hr - good if substance does bind to charcoal well and removing packages of illicit drugs

Question 25

how can you speed up removal of the toxicant from the body to reduce exposure ?

Answer 25

forced diuresis for weakly acidic/basic compounds

dialysis for removal of small molecular weight solutes in body fluids

Question 26

explain forced diuresis

Answer 26

urine made alkaline -pH7-8 by infusion of large volume of sodium hydrogen carbonate - used for barbiturate or salicylate poisoning
acid urine produced by infusion of NH4Cl helps excretioin of weak bases such as amphetamine

Question 27

explain haemodialysis

Answer 27

relies on diffusion of solutes across a semi-permeable membrane
blood is dialysed against continuous stream of toxicant free fluid
this is only useful if toxicant has a small volume of distribution

haemofiltration and haemoperfusion to remove toxic substances from blood

Question 28

what are toxidromes?

Answer 28

they are a group of symptoms which can be useful at diagnosing the type of poisoning

Question 29

what causes cholinergic toxidrome?

Answer 29

caused by organophosphate nerve agents - cause gross activation of the parasympathetic nervous system

Question 30

what are the symptoms of cholinergic toxidrome ?

Answer 30

DUMBBELS 
- diarrhoea
- urination
- miosis= excessive constriction of pupil
- bronchorrhoea= accumulation of fluid in the bronchioles and lungs - can drown from this 
- bronchospasm= difficulty breathing 
- emesis
- lacrimination
- salivation 
also seizures

Question 31

what can cause anticholinergic toxidrome?

Answer 31

arises by atropine and hyoseine administration = plant toxins
-atropine is from deadly night shade and some fungi

Question 32

what are the symptoms of anticholinergic toxidrome ?

Answer 32

dry mouth
dilated pupils
blurred near vision - accommodation becomes paralysed
warm, dry and red skin - particularly in the face
urinary retention and constipation
tachycardia
confusion - delirium

Question 33

what can be used as an antidote for cholinergic toxidrome ?

Answer 33

atropine

Question 34

what can you use to treat anticholinergic toxidrome ?

Answer 34

acetylcholinesterase

Question 35

what are the symptoms of sympathetic toxidrome ?

Answer 35

dilated pupils 
excessive sweating 
agitation
hyperthermia
tachycardia
hypertension 
dysrhythmias

Question 36

why are toxidromes useful ?

Answer 36

useful in clinical situations to determine the type pf poisoning to help guide an appropriate treatment