acls full lecture

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What is emergency ECG

INTRODUCTION

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Chain of Survival

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Cardiac abnormalities:Acute Coronary Syndromes

Clinical syndromes form spectrum of the same disease process:

Unstable angina

Non-Q wave myocardial infarction

Q wave myocardial infarction3

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Immediate treatment in all acute coronary syndromes

• “MONA”

–Morphine (or diamorphine)

–Oxygen

–Nitroglycerine (GTN spray or tablet)

–Aspirin 300 mg orally (crushed/chewed)

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Patients with ST segment elevation MI or MI with LBBB

Early coronary reperfusion therapy:• Thrombolytic therapy

– streptokinase

– alteplase

• Percutaneous transluminal coronary angioplasty (PTCA)• Coronary artery bypass surgery (CABG)

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CARDIAC MONITORING &

RHYTHM RECOGNITION

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Which patients?• Cardiac arrest or other important

arrhythmias• Chest pain• Heart failure• Collapse / syncope• Shock / hypotension• Palpitations

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How to read a rhythm strip

1. Is there any electrical activity?

2. What is the ventricular (QRS) rate?

3. Is the QRS rhythm regular or irregular?

4. Is the QRS width normal or prolonged?

5. Is atrial activity present?

6. How is it related to ventricular activity?

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ECG rhythm interpretation

• Effective treatment often possible without precise ECG diagnosis

• Haemodynamic consequences of any given rhythm will vary

• Treat the patient not the rhythm

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What is the ventricular rate?

• Normal 60-100 min-1

• Bradycardia < 60 min-1

• Tachycardia > 100 min-1

Rate = 300Number of large squares between consecutive QRS complexes*

* At standard paper speed of 25 mm sec-1, 5 large squares = 1 second

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Is the QRS rhythm regular or irregular?

• Unclear at rapid heart rates

• Compare R-R intervals

• Irregularly irregular = AF

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Is the QRS width normal or prolonged?

• Normal QRS:

–< 0.12 s (< 3 small squares)

–originates from above bifurcation of bundle of His

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• Prolonged QRS (> 0.12 s) arises from:

–ventricular myocardium, or

–supraventricular with aberrant conduction

Is the QRS width normal or prolonged?

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Is atrial activity present?

• P waves (leads II and V1)

• Rate, regularity, morphology

• Flutter waves

• Atrial activity may be revealed by slowing QRS rate with adenosine

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How is atrial activity related to ventricular activity?

• Consistent, fixed PR interval

• Variable, but recognisable pattern

• No relationship - atrioventricular dissociation

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Heart Block: First Degree

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Heart Block: Second DegreeMöbitz Type I (Wenckebach) Block

Möbitz Type II Block

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Heart Block: Third Degree

• Site of pacemaker:– AV node 40 - 50 min-1

– Ventricular myocardium 30 - 40 min-1

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DEFIBRILLATION

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Mechanism of defibrillation

• Definition

“The termination of fibrillation or absence of VF/VT at 5 seconds after shock delivery”

• Critical mass of myocardium depolarised• Natural pacemaker tissue resumes control

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Defibrillation

Success depends on delivery of current to the myocardium

Current flow depends upon:

• Electrode position

• Transthoracic impedance

• Energy delivered

• Body size

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Transthoracic Impedance

Dependent upon:

• Electrode size

• Electrode/skin interface

• Contact pressure

• Phase of respiration

• Sequential shocks

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Ventricular fibrillation• Bizarre irregular waveform• No recognisable QRS complexes• Random frequency and amplitude• Unco-ordinated electrical activity• Coarse / fine• Exclude artifact

– movement– electrical interference

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Pulseless ventricular tachycardia

• Monomorphic VT

–Broad complex rhythm

–Rapid rate

–Constant QRS morphology

• Polymorphic VT

–Torsade de pointes

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Asystole

• Absent ventricular (QRS) activity

• Atrial activity (P waves) may persist

• Rarely a straight line trace

• Consider fine VF

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Pulseless Electrical Activity

• Clinical features of cardiac arrest

• ECG normally associated with an output

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Cardiac Arrest

Precordial Thump if appropriate

BLS Algorithm if appropriate

Attach Defib-Monitor

AssessRhythm

+/- Check PulseVF/VT Non-VF/VT

Defibrillate X 1

CPR 2 min CPR 2 min

During CPRCorrect reversible causesIf not already:•check electrodes, paddle position and contact•attempt / verify airway & O2

i.v. access•give epinephrine every 3 minConsider:amiodarone, atropine / pacing buffers

Potential reversible causes:•Hypoxia•Hypovolaemia•Hypo/hyperkalaemia & metabolic disorders•Hypothermia•Tension pneumothorax•Tamponade•Toxic/therapeutic disorders•Thrombo-embolic & mechanical obstruction

Universal ALSAlgorithm

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Cardiac Arrest

Precordial Thump if appropriate

BLS Algorithm if appropriate

Attach Defib-Monitor

AssessRhythm

+/- Check Pulse

VF/VT Non-VF/VT

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Case ECG

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