Defibrillation

Defibrillation:Defibrillation: Advanced Cardiac Life Support 2006

Jamie Ranse

Registered Nurse

Emergency Department

The Canberra Hospital

Overview

• History• Chain of Survival• Indications• How it works• Safety

History

• 1849: Ludwigg and Hoffa – VF induced by electrical stimuli

History

• 1899: Prevost and Batelli - while a weak stimulus can produce fibrillation, a stimulus of higher strength applied to the heart could arrest ventricular fibrillation and restore normal sinus rhythm.

History

• 1947: First defibrillation on humans

History

• 1966: Belfast Ambulance transported physicians performed first pre-hospital defibrillation.

• 1969: First pre-hospital defibrillation by non physicians.

• 1970’s: Diack, Wellborn and Rullman developed first AED’s.

Chain of Survival

• Early Recognition and Assessment

• Early Access

• Early CPR

• Early Defibrillation

• Early Advanced Cardiac Life Support

Chain of Survival

Sudden cardiac arrest survival rate:

• Pre-Hospital: 10%• In-Hopsital: 10%

Indications

• Pulseless VT

• VF

How does it work?

• Electronic counter-shock between to paddles or pads

• Depolarises all cardiac cells and interrupts arrhythmia

• Allows SA node to recommence its dominant role

Defibrillation is the most time critical intervention in a patient with a

shockable rhythms

How does it work?

Thoracic Impedance• Impedance is the natural resistance to the flow of

electrical current, measured in Ohms.• Impedance is determined by a number of factors,

such as:– Underlying structures and pathology– Paddle or adhesive pad position

How does it work?

Monophasic Defibrillation• Delivers ‘shock’ in one phase• Adult: 200J, 300J, 360J, all subsequent shocks

at 360J• Child: 2J/Kg, 2J/Kg, 4J/Kg, all subsequent

shocks at 4J/Kg

How does it work?

Biphasic Defibrillation• Two phases to the delivery of the ‘shock’• Adjusts ‘shock’ according to thoracic impedance• Adult: 150J, 150J, 150J• Child: 1– 2J/Kg

How does it work?

Monophasic v Biphasic Defibrillation• Peak current decreased resulting in less

myocardial damage

How does it work?

Semi-Automatic External Defibrillation• Primarily used by laypersons in the pre-hospital

setting• Survival rate increased to ~ 70% pre-hospital

and 80% in-hospital• Considered BLS

“audible and visual prompt to

discharge the defibrillator and

deliver a shock when it

recognises a shockable rhythm”

Transcutaneous Pacing

• Early asystole with reversible cause• Attach adhesive pad anterior / posterior• Set rate• Set Milliamps until capture is achieved

Transcutaneous Pacing

• Temporary • Consider other pacing options• Sedate patient

Safety

General Safety

• Yourself, other staff– Dry surface area– Oxygen

• Chest wall– GTN patch– Jewellery– Paddles / Pads not touching

• Technique– One Person– Two Person– Adhesive Pads

Safety

Operator Safety• Assertive• Announce:

– CHARGING, – ALL CLEAR / STAND CLEAR (Visual Check of Area), – SHOCKING

• Check rhythm• Discharge Shock• Continue as per algorithm

Questions