B43 - cardio, anaphylaxis

Question 1

Shockable rhythms (2)

Answer 1

VF, pulseless VT

Question 2

Non-shockable rhythms

Answer 2

include pulseless electrical activity/asystole

Question 3

Patient in VF, 3 shocks administered. What next? (3 steps)

Answer 3

Give 1mg adrenaline IV (every 3-5 mins) and amiodarone 300mg IV (after 3 shocks) whilst performing further CPR.
Give further adrenaline 1mg IV after alternate shocks.
Further amiodarone 150mg IV may be administered after a total of five defibrillation attempts.

Question 4

How would drug choice change in CPR if rhythm was non-shockable (as opposed to adrenaline every 3-5 mins and amiodarone after 3 shocks in shockable)

Answer 4

Amiodarone would not be administered but adrenaline 1mg IV is given as soon as intravascular access is achieved and repeated every 3-5 minutes

Question 5

What is adrenaline?

Answer 5

endogenous catecholamine hormone and neurotransmitter in the sympathetic nervous system.

Question 6

Where and from what is adrenaline normally synthesised?

Answer 6

from noradrenaline in the adrenal medulla, specifically chromaffin cells.

Question 7

Adrenaline MOA

Answer 7

α and β adrenoceptor agonist

Question 8

Actions of adrenaline on α1 (4)

Answer 8

vasoconstriction
relaxation of smooth muscle in GI
saliva secretion
hepatic glycogenolysis

Question 9

Actions of adrenaline on α2 (3)

Answer 9

vasoconstriction
inhibition of transmitter release
platelet aggregation

Question 10

Actions of adrenaline on β2

Answer 10

position ionotropic and chonotropic effects

Question 11

Actions of adrenaline on β2 (2)

Answer 11

broncodilation

vasodilation

Question 12

Action of adrenaline on β3

Answer 12

lipolysis

Question 13

Actions of adrenaline with regards to cardiac arrest scenario

Answer 13

increases coronary and cerebral perfusion pressure as a result of vasoconstriction

thought to increase the chance of restoring a heartbeat and of improving long-term neurological outcome.

Question 14

Adrenaline cautions in non-emergency situations (11)

Answer 14

ischaemic heart disease, 
cerebrovascular disease, 
diabetes, 
hypertension, 
hyperthyroidism 
Hypokalaemia
hypertension (risk of cerebral haemorrhage)
hypokalemia
palpitations - dysrhythmias
tissue necrosis (e.g. ring blocks)
metabolic acidosis

Question 15

Adrenaline side effects (10)

Answer 15

hypersalivation,
 headache,
 hyperhidrosis, 
angle closure glaucoma, 
reduced appetite, 
hyperglycaemia, 
hypertension, 
mydriasis, 
peripheral coldness, 
urinary disorders

Question 16

Adrenaline interactions (3)

Answer 16

Amitriptyline (increased effects of adrenaline)
Beta blockers (severe hypertension)
MAO inhibitors (hypertensive crisis - MAO is one of the routes of metabolising adrenaline, therefore inhibiting their action leads to an increase in adrenaline.)

Question 17

Route and dose adrenaline administered in cardiac arrest

Answer 17

1mg by IV injection using 1 in 10,000 solution (100micrograms/mL) i.e. 10ml
Followed by 20ml flush of 0.9% sodium chloride

Flush is required to aid entry into central circulation.

Question 18

Beta blockers can be used as antihypertensive drugs.Why is there a risk of severe hypertension when beta blockers and adrenaline interact?

Answer 18

In the absence of a beta-blocker, adrenaline does not have much effect on mean blood pressure because it has both alpha-adrenergic effects (producing vasoconstriction) and beta-adrenergic effects (producing vasodilation). If a patient on a nonselective beta-blocker receives adrenaline however, the beta-blocker prevents the beta-adrenergic vasodilation, leaving unopposed alpha vasoconstriction. Cardio-selective beta-blockers would not be expected to precipitate hypertensive reactions.

Question 19

Amiodarone drug class

Answer 19

Class III anti-arrhythmic

Question 20

Amiodarone MOA (3)

Answer 20

Multiple anti-arrhythmic actions across all four groups
Prolongs cardiac action potential and delays refractory period
Inhibits K+ channels involved in repolarisation

Question 21

Challenges of amiodarone (3)

Answer 21

Incomplete oral absorption
Large volume of distribution
Extremely long half-life

Question 22

Amiodarone SE

Answer 22

• GI disturbance (constipation, nausea, vomiting, taste disturbance)
• Corneal microdeposits (reversible on withdrawal of treatment, associated with night glare, if
  vision impaired or optic neuritis/neuropathy develops amiodarone must be stopped to
  prevent blindness)
• Hypo/Hyperthyroidism
• Skin reactions – photosensitive skin rashes and blue-grey discolouration
• Hepatotoxicity – severe LFT abnormalities or clinical signs of liver disease require
  discontinuation of treatment.
• Progressive pneumonitis and lung fibrosis – should be suspected if new onset SOB or
  cough
• Proarrhythmic effects
• Peripheral neuropathy/myopathy – reversible with withdrawal of treatment

Question 23

Amiodarone eye SE

Answer 23

Corneal microdeposits – reversible on withdrawal of treatment, associated with night glare, if vision impaired or optic neuritis/neuropathy develops amiodarone must be stopped to prevent blindness

Question 24

Amiod

Question 25

How does amiodarone cause hypothyroidism

Answer 25

prevents conversion of T4 to T3 resulting in hypothyroidism requiring replacement with thyroxine

Question 26

How does amiodarone cause hyperthyroidism

Answer 26

high iodine content, can cause a destructive thyroiditis leading to release of preformed thyroid hormones and refractory thyrotoxicosis

Question 27

Amiodarone monitoring

Answer 27

TFT and LFT should be checked before treatment and every 6 months Check potassium levels and chest x-ray before treatment With IV use ECG monitoring must be available

Question 28

Amiodarone CI (5)

Answer 28

``` Severe cardiac conduction disturbances (unless pacemaker fitted) Thyroid dysfunction Iodine sensitivity Severe respiratory failure Circulatory collapse ```

Question 29

What does amiodarone interact with to cause bradycardia (3)

Answer 29

Beta blockers Calcium channel blockers Digoxin

Question 30

What does amiodarone interact with to cause prolonged QT (2)

Answer 30

Lithium | Ondansetron

Question 31

What does amiodarone interact with to cause hypokalaemia (3)

Answer 31

Steroids Thiazide diuretics Loop diuretics

Question 32

What does amiodarone interact with to cause peripheral neuropathy (1)

Answer 32

Phenytoin

Question 33

What does amiodarone interact with to cause rhabdomyolysis (1)

Answer 33

Statins

Question 34

What is the effect of amiodarone interaction with warfarin?

Answer 34

increased anticoagulant effect

Question 35

Narrow complex tachycardia Mx

Answer 35

Monitor/record ECG continuously 1) Vagal maneouvres 2) adenosine 6mg IV bolus large cannula and large vein (antecubital fine) followed by NaCl flush 3) if no effect give adenosine 12mg IV 4) if no effect give further 12mg bolus

Question 36

What does failure to terminate a regular narrow-complex tachycardia with adenosine suggest?

Answer 36

atrial tachycardia such as atrial flutter (unless the adenosine has been injected too slowly or into a small peripheral vein).

Question 37

Narrow complex tachycardia Mx If adenosine is contra-indicated, or fails to terminate a regular narrow-complex tachycardia without demonstrating that it is atrial flutter:

Answer 37

consider giving verapamil 2.5–5 mg IV over 2 min.

Question 38

Adenosine MOA

Answer 38

Adenosine A1 receptor agonist Inhibits adenylyl cyclase enzymes resulting in reduced production of cyclic AMP (cAMP). This promotes opening of adenosine-sensitive potassium channels and increased K+ efflux out of myocardial cells – as a result cells become hyperpolarised. This slows the rate of rise of the pacemaker potential. This is transient, with the effects of a bolus dose of adenosine lasting only 20-30 seconds

Question 39

Why is adenosine useful in SV tachycardia

Answer 39

it has potent effects on the SA node inducing sinus bradycardia and slows impulse conduction through the AV node, with no effect on conduction in the ventricles. Therefore, it is useful in the emergency management of supraventricular tachycardia (SVT) for rapid conversion back to sinus rhythm

Question 40

Adenosine CI (5)

Answer 40

Asthma/COPD  Decompensated heart failure Long QT syndrome/AV block/sick sinus syndrome Severe hypotension Many cautions associated with cardiac disease

Question 41

Adenosine interactions (3)

Answer 41

Dipyridamole (increased adenosine exposure) Aminophylline/Theophylline (decreased adenosine efficacy) Some local anaesthetic agents (risk of cardiodepression)

Question 42

Adenosine SE (15)

Answer 42

Side effects common but last <1 min ``` Arrhythmias chest discomfort/pain dizziness dyspnoea (bronchospasm, resp failue) flushing headache hypotension apprehension sweating metallic taste blurred vision nausea/vomiting cardiac arrest apnoea loss of consciousness ```

Question 43

Most important step after administering adenosine

Answer 43

12 lead ECG - see if returned to sinus rhythm

Question 44

What does a fluid challenge usually consist of?

Answer 44

500ml of a sodium containing crystalloid (0.9% Sodium Chloride or Hartmann’s solution) given over 15 minutes.

Question 45

Sinus bradycardia Mx

Answer 45

ABCDE | adverse features -> atropine 500mcg IV

Question 46

Atropine Class and MOA

Answer 46

Class: Muscarinic antagonist Mechanism of action: Increases firing of the SA node by blocking actions of the vagus nerve on the heart. Achieved by inhibiting potassium channels and preventing hyperpolarisation of the cell membrane (opposite effect of adenosine).

Question 47

Atropine SE (lots)

Answer 47

Able to predict effects by considering the function of the parasympathetic nervous system Eyes (pupillary dilatation): blurred vision, mydriasis, angle closure glaucoma GI tract (decreased motility/secretions/tone): constipation, abdominal distension, nausea, vomiting, dysphagia CVS (increased HR, contractility, BP): tachycardia, palpitations, angina, hypertension, arrhythmias Secretions (decreased sweat/salivary gland secretion): dry mouth, anhidrosis, thirst, increased body temperature Urinary tract (decreased detrusor function and increased sphincter tone): urinary retention, CNS: confusion, hallucination

Question 48

Atropine CI (3ish)

Answer 48

GI: obstruction, paralytic ileus, pyloric stenosis, severe ulcerative colitis, toxic megacolon Urinary tract: bladder outflow obstruction, prostatic enlargement, retention Myasthenia gravis

Question 49

Atropine interactions (6)

Answer 49

``` Tricyclic anti-depressants Muscarinic antagonists Antihistamines Antipsychotics Phenylephrine (severe hypertension) Levodopa (decreased absorption levodopa) ```

Question 50

Immediate Mx suspected anaphylaxis

Answer 50

Adrenaline. | Additional measures include call for help, lie patient flat, raise patients legs and remove trigger if known/possible.

Question 51

Anaphylaxis steps after adrenaline when skills and equipment available (6)

Answer 51

``` establish airway high flow O2 IV fluid challenge chlorphenamine hydrocortisone Monitor: pulse oximetry, BP, ECG ```

Question 52

Adrenaline doses for anaphylaxis by age

Answer 52

Adult/child >12y - 500mcg IM Child 6-12y - 300mcg IM Child <6y - 150mcg IM

Question 53

Adrenaline MOA anaphylaxis

Answer 53

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.

Question 54

Adrenaline administration route/timing

Answer 54

Further doses at 5 minute intervals if no improvement Anterolateral aspect of the middle third of the thigh