ALS Drugs Flashcards
Name two shockable rhythms
VF
pulseless VT
name two non-shockable rhythms
PEA
Asystole
in the ALS algorithm, once a shock is delivered (if required), how long do you continue to do CPR for?
2 mins
When a pt has a shockable rhythm, after how many shocks have been delivered should you administer adrenaline and how much?
After the first dose of adrenaline has been administered, how often should you then give further adrenaline?
After 3 shocks give 1mg adrenaline IV.
Give further adrenaline 1mg IV after alternate shocks (every 3-5mins).
When should you give amiodarone in ALS and how much?
If it is a shockable rhythm - Initally give 300mg IV after 3 shocks.
After this, further amiodarone of 150mg IV can be given after 5 shocks.
In a non-shockable rhythm do not give amiodarone.
if a pt is in a non-shockable rhythm what drugs would be administered? When is it started and how much and how often?
Adrenaline 1mg IV given as soon as IV access is achieved.
Repeat every 3-5 mins.
what type of hormone is adrenaline?
catecholamine hormone
where is adrenaline normally synthesised in the body? What cells specifically?
normally synthesised from noradrenaline in the adrenal medulla, specifically the chromaffin cells.
what is the mechanism of action of adrenaline?
alpha and beta adrenoceptor agonist.
Name 5 side effects of adrenaline
headache, reduced appetite, hyperglycaemia, hypertension, peripheral coldness, urinary disorders
name three drugs/drug classes that interact with adrenaline and what the interaction is
amitriptyline (increased effects of adrenaline)
beta blockers - severe HTN
MAO inhibitors (hypertensive crisis). MAO is one of the routes of metabolising adrenaline, therefore, inhibiting their action leads to an increase in adrenaline.
1mg of a 1 in 10,000 solution of adrenaline is used in a cardiac arrest. How many mls would you give of this solution?
1:10,000 means there is 100 micrograms in a ml. so to get 1mg you need to multiply the volume by 10. you will then have 1mg in 10ml. hence, you give 10mls.
once adrenaline has been given in a cardiac arrest, what should it be followed with as a flush?
20ml of 0.9% sodium chloride.
why is there a risk of severe HTN when beta blockers and adrenaline interact?
in the absence of a beta-blocker, adrenaline does not have much effect on mean BP because it has both alpha-adrenergic effects (producing vasoconstriction) and beta-adrenergic effects (producing vasodilation). If a pt is taking a beta-blocker and the pt receives adrenaline, the beta blocker prevents beta-adrenergic vasodilation, leaving unopposed alpha vasoconstriction. cardio-selective beta-blockers are not believed to precipitate hypertensive reactions.
what class of drug does amiodarone belong to?
class III anti-arrhythmic
what is the mechanism of action of amiodarone?
prolongs cardiac AP and delays refractory period.
also inhibits K+ channels involved in repolarisation
name 3 challenges of amiodarone that make it difficult to prescribe
incomplete oral absorption.
large volume of distribution.
extremely long half-life
what do the challenges of amiodarone mean for how it is prescribed?
It means a prolonged loading dose regimen is needed before continuing onto the maintenance dose.
e.g. PO administration is prescribed as 200mg TDS for 1 wk, 200mg BD for 1 week, followed by 200mg OD.
name GI side effects of amiodarone
constipation, N&V, taste disturbance
what side effects can amiodarone have on the eyes?
corneal microdeposits. these are reversible on withdrawal of treatment, associated with night glare, if vision is impaired or optic neuritis/neuropathy develops, amiodarone must be stopped to prevent blindness.
what side effects can amiodarone have on the thyroid?
can cause hypothyroidism by preventing conversion of T4 to T3.
can cause hyperthyroidism as it has a high iodine content which can cause destuctive thyroiditis leading to the release of preformed thyroid hormones and refractory thyrotoxicosis.
what skin reactions can you get with amiodarone?
photosensitive skin rashes, blue-grey discolouration
what side effects does amiodarone have on the liver?
hepatotoxicity.
severely abnormal LFTs or clinical signs of hepatic disease means amiodarone needs to be stopped.
what should be suspected in a pt on amiodarone with a new onset SOB or cough?
progressive pneumonitis and lung fibrosis
what side effects can amiodarone have on the heart?
Proarrhythmic effects:
- bradycardia
- heart blocks
- dysrhythmias
- prolonged QT interval
can amiodarone cause neuropathy or myopathy. if so, is it permanent
it can but it is reversible with withdrawal of treatment
what monitoring do you need to arrange for a pt commencing amiodarone?
TFT and LFTs - check before treatmetn and every 6 months.
check potassium levels and CXR before treatment.
with IV use, ECG monitoring must be available
what contra-indications are there for amiodarone? (5)
- severe cardiac conduction disturbances (unless pacemaker fitted)
- thyroid dysfunction
- iodine sensitivity
- severe resp. failure
- circulatory collapse
what can interact with amiodarone to cause bradycardia?
beta blockers, calcium channel blockers, digoxin
what can interact with amiodarone to cause prolonged QT interval?
lithium
ondansetron
what can interact with amiodarone to cause hypokalaemia
steroids, thiazide diuretics, loop diuretics
what can interact with amiodarone to cause peripheral neuropathy?
phenytoin
what can interact with amiodarone to cause rhabdomyolysis
statins
what can interact with amiodarone to cause an increased anticoagulant effect?
warfarin
what is the first step in management of adult tachycardia?
vagal manoeuvres - e.g. carotid sinus massage or valsalva maneouvre
how does carotid sinus massage hellp to reduce HR and BP?
baroreceptors at the bifurcation of the common carotid artery control BP and HR by measuring degree of stretch within the vessels. high BP results in reduced sympathetic and increased parasympathetic response so you get slowing of SA node firing, AV node conduction slows and reduced vascular tone.
what does the valsalva manoeuvre consist of? how does it work to slow the HR?
forced exhalation against a closed airway for 15-20s. it alters venous return and induces bradycardia.
if, after trying vagal manoeuvres, an adult tachycardia persists and is not Atrial flutter, what should you give and how much and in what way?
adenosine 6mg as a rapid IV bolus. followed by rapid saline flush.
what should you tell the pt before giveing them adenosine for tachycardia?
warn them that they will feel unwell and probably expericence chest discomfort for a few seconds after the injection.
what should be recorded whilst adenosine is being given?
ECG
if there is no slowing or termination of the tachyarrhythmia after giving adenosine, what should be given?
a 12mg IV bolus.
if after giving a 6mg IV bolus followed by a 12mg IV bolus of adenosine, there is no response, what should be given to slow the tachyarrhythmia?
a further 12mg bolus IV
failure to terminate a regular narrow-complex tachycardia with adenosine or vagal manoeuvres suggests it is likely to be what?
atrial tachycardia e.g. atrial flutter. unless the adenosine has been injected too slowly into a small peripheral vein.
in an adult with tachycardia for whom vagal manoeuvres have not worked, if adenosine is contraindicated, or does not work, what could you consider giving?
verapamil 2.5-5mg IV over 2 mins
what is the mechanism of action of adenosine?
inhibits adenyl cyclase enzymes resulting in a reduced production of cAMP. this causes increased influx of K+ and slows conduction through AV node. hence, it is useful for rapid conversion back to sinus rhythm
what type of receptor does adenosine attach to?
G protein-coupled adenosine A1 receptor
name contra-indications for using adenosine
asthma/COPD
decompensated HF
long QT syndrome/AV block/sick sinus syndrome
severe hypotension
many cautions associated with cardiac disease.
name 3 drugs that interact with adenosine
dipyridamole (increases adenosine exposure)
aminophylline/theophylline (decreases adenosine efficacy)
some local anaesthetic agents (risk of cardiodepression)
how long do side effects tend to last for with adenosine?
<1 minute
what should you do immediately after administering adenosine?
ECG
a pt has sinus bradycardia and is showing adverse features, what is the management?
atropine 500mcg IV
what class of drug is atropine?
muscarinic antagonist
what is the MoA of atropine?
increases firing of the SA node by blocking actions of the vagus nerve on the heart.
what are some side effects of atropine?
eyes: pupil dilatation, blurred vision, mydriasis, angle closure glaucoma.
GI tract: decreased motility/secretions/tone, constipation, abdominal distension, N&V, dysphagia.
CVS: tachycardia, palpitations, angina, HTN, arrhythmias
secretions: dry mouth, anhidrosis, thirst, increasing body temp
Urinary retention
confusion, hallucination
name some contraindications for using atropine
GI obstruction, paralytic ileus, pyloric stenosis, severe ulcerative colitis, toxic megacolon, bladder outflow obstruction, prostatic enlargement, retention, myasthenia gravis
many drugs can act as a muscarinic antagonist, both as part of its mechanism of action or as a side effect, thus exacerbating the effects of atropine. name some drug classes that interact with atropine.
Tricyclic antidepressants, muscarinic antagonists, antihistamines, antipsychotics
what is the life saving treatment for anaphylaxis?
adrenaline
how does adrenaline work to reduce the symptoms of anaphylaxis?
as an alpha-receptor agonist, it reverses peripheral vasodilation and reduces oedema. its beta-receptor activity dilates bronchial airways, increases force of myocardial contraction and suppresses histamine release.
what is the dose of adrenaline used in anaphylaxis and by what route?
500 micrograms by IM of 1 in 1000 solution
i.e. 1mg/mL i.e. 0.5ml
how soon after administering the first dose of adrenaline in anaphylaxis should you give a second dose if there is no improvement?
5 minutes
what is the best site to give adrenaline in an anaphylaxis?
anterolateral aspect of the middle third of the thigh
with the auto-injectors for anaphylaxis, how long should the pen be held firmly in place for after injecting the adrenaline?
10s
after adrenaline has been given for anaphylaxis, what further treatment shoudl be given?
anti-histamines and corticosteroids.
