Drugs Flashcards
Adrenaline Indications and doses
- Cardiac Arrest: 1 mg IV / IO every 3-5 min
- Second-line treatment for cardiogenic shock: 0.05–1 mcg kg-1 min-1
- Can be used for Bradycardia which has not responded to atropine, and external pacing is unavailable or unsuccessful
- Anaphylaxis: 0.3-0.5mg IM (0.5ml per 1:1000 vial) or 50-100mcg IV in severe cases
What receptors does adrenaline stimulate?
Alpha and Beta receptors to produce peripheral vasoconstriction
This increases systemic vascular resistance (SVR) during CPR and improves both cerebral and coronary perfusion pressures.
Why do you need to be careful to avoid using adrenaline in Myocardial Ischaemia
In the beating heart, the action of adrenaline on β1 receptors increases heart rate and force of contraction.
This increases myocardial oxygen consumption which may worsen ischaemia.
Adrenaline increases myocardial excitability and is therefore potentially arrhythmogenic, especially during myocardial ischaemia.
Indications and Doses for Amiodarone
-
Refractory VF/pulseless VT :
- 300mg IV
- Control of haemodynamically stable VT, polymorphic VT, and broad-complex tachycardia of uncertain origin
- Paroxysmal SVT when adenosine, vagal manoeuvres, and AV nodal blockade are unsuccessful.
- To control rapid ventricular rate caused by accessory pathway conduction (WPW) in pre-excited atrial arrhythmias
- 300 mg IV over 20-60 min followed by an infusion of 900mg over 24 h
Why can amiodarone by arrthymogenic
Bc it prolongs the QTc
main SE of amiodarone
Hypotension and bradycardia
These can be prevented by slowing the rate of infusion
- prolonged oral use: photosensitivity, thyroid & hepatic dysfunction, peripheral neuropathy & pulmonary inflammation/fibrosis.
Why is it preferred to administer amiodarone into a central vein?
may cause thrombophlebitis;
a central vein is preferable otherwise use a large peripheral vein followed by a 20 ml flush.
Consideration of amiodarone with Warfarin or digoxin?
The plasma levels of warfarin and digoxin are increased by amiodarone;
therefore their doses should be readjusted.
INR for warfarin and digoxin levels should be monitored.
Indications and dose for Aspirin
- Acute Coronary Syndrome: 300mg to be chewed
Followed by 75mg OD
Aspirins mechanism of action?
Antiplatelet activity (prevents platelet adhesions)
Indications and doses for Atropine
Sinus, atrial or nodal bradycardia when patient is symptomatic: 0.6mg increments IV to a maximum of 3 mg
Atropines mechanism of action
antagonises the NT acetylcholine at the muscarinic receptors. This blocks the vagal activity at the SA and AV node
Side effects of atropine?
blurred vision, dry mouth and urinary retention
Indications and dose for Adenosine?
- Stable narrow-complex tachycardia (or broad-complex tachycardia: 6 mg, 12 mg, IV
- known to be a supraventricular tachycardia (SVT) with bundle branch block) which is not responding to vagal manoeuvres.
How must Adenosine be administered
In a monitored environment as it can briefly cause ventricular asystole
How can adenosine be used as a diagnostic tool?
it can be given to a patient with a broad-complex tachycardia of uncertain aetiology.
The ventricular rate in SVT will be slowed
but ventricular tachycardia (VT) is unchanged.
Side effects of adenosine
nausea, flushing, and chest discomfort, sense of impending doom
Adenosine is contraindicated in what cardiac arrhythmia?
in patients with WPW syndrome, as the conduction blockade through the AV node by adenosine may promote conduction down the accessory pathway. In the presence of pre-excited atrial fibrillation or flutter, this may cause a dangerously rapid ventricular response.
Indications and dose examples for B-adrenergic drugs (B-blockers)
Narrow-complex tachycardias uncontrolled by vagal manoeuvres and/or adenosine in the patient with preserved ventricular function.
To control rate in AF and atrial flutter with < 48h duration and preserved ventricular function.
Atenolol (β1) 5 mg IV over 5 min
Side effects of b-blockade
bradycardia, AV conduction delay, hypotension and bronchospasm
B-blockers are contraindicated in?
Contraindicated in second- or third-degree heart block, hypotensive states, CHF and asthma.
Indications and dose examples of Calcium channel blockers in an acute setting
- Stable narrow complex tachycardia that is not terminated by vagal manoeuvres or adenosine
- Control of ventricular rate in patients with AF or atrial flutter (< 48h)
ONLY USE IF SVT IS CONFIRMED (v negative inotropic effect)
Verapamil 2.5–5mg IV over 2 min or
Diltiazem 15-20 mg IV over 2 min
How do CCB work?
calcium channel blocking drugs that slow conduction and increase the refractory period in the AV node.
These actions may terminate re-entry arrhythmias that involve the AV node (e.g. SVT) and contribute to control of ventricular response rate in patients with other atrial tachycardias.
Indications and dose of dopamine in the acute setting?
Hypotension in the absence of hypovolemia
1-10 mcg kg-1 min-1
