Published on October 28, 2016
1. Dr. Dharmendra Joshi (DJ) Defibrillation & Cardioversion
2. • History • Case & Census • Definition • Types • Principles • Indications • Contraindications • Anaesthesia • Equipments • Positioning • Technique • Safety • Complications • Troubleshooting Topics
3. History • 1849: Ludwigg and Hoffa – VF induced by electrical stimuli
4. 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.
5. History • 1947: First defibrillation on humans.
6. 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.
7. Chain of Survival • Early Recognition and Assessment • Early Access • Early CPR • Early Defibrillation • Early Advanced Cardiac Life Support
8. Chain of Survival Sudden cardiac arrest survival rate: • Pre-Hospital: 10% • In-Hopsital: 10%
9. • No record found about patient who was treated by defibrillation or cardioversion in KMCTH, Duwakot in last one month!!! Case Scenario & Census
10. • Defibrillation is a non-synchronized delivery of energy during any phase of the cardiac cycle. • Cardioversion is the delivery of energy that is synchronized to the large R waves or QRS complex. Definition
11. 11 TYPES OF DEFIBRILLATORS Internal External
12. DEFIBRILLATOR ELECTRODES Types of Defibrillator electrodes:- a) Spoon shaped electrode • Applied directly to the heart. b) Paddle type electrode • Applied against the chest wall. c) Pad type electrode • Applied directly on chest wall.
13. DEFIBRILLATOR ELECTRODES
14. Fig.- Pad electrode DEFIBRILLATOR ELECTRODES
15. PRINCIPLE OF DEFIBRILLATION Energy storage capacitor is charged at relatively slow rate from AC line. Energy stored in capacitor is then delivered at a relatively rapid rate to chest of the patient. Simple arrangement involve the discharge of capacitor energy through the patient’s own resistance.
16. PRINCIPLE OF DEFIBRILLATION
17. PRINCIPLE OF DEFIBRILLATION The discharge resistance which the patient represents as purely ohmic resistance of 50 to 100Ω approximately for a typical electrode size of 80 cm2. This particular waveform Fig 13.9(b) is called ‘ Lown’ waveform. The pulse width of this waveform is generally 10 ms.
18. power supply energy storage patient ECG monitor timing circuitry gate charge discharge standby switch is under operator control applies shock about 20 ms after QRS complex, avoids T-wave
19. current(amps) pulse duration defibrillation occurs no defibrillation
20. • Minimum defibrillation energy occurs for pulse durations of 3 - 10 ms (for most pulse shapes). • Pulse amplitude in tens of amperes (few thousand volts).
21. – intrinsic characteristics of patient – patient’s disease – duration of arrhythmia – patient’s age – type of arrhythmia (more energy required for v. fib.) • Operator selects energy delivered: 50-360 joules, depends on:
22. 22 THE POWER OF DEFIBRILLATION • Higher voltages are required for external defibrillation than for internal defibrillation. • A corrective shock of 750-800 volts is applied within a tenth of a second. • That is the same voltage as 500-533 no. of AA batteries!
23. ECG tracingElectrical pattern
24. Occlusion of the coronary artery leads to ischemia Ischemia leads to infarct which causes interruption of normal cardiac conduction Infarct = VF/VT
25. Ventricular Fibrillation Ventricular Tachycardia
26. • Indications for synchronized electrical cardioversion: Supraventricular tachycardia Atrial fibrillation Atrial flutter Ventricular tachycardia Reentrant tachycardia with narrow or wide QRS complex. Indications
27. 1. Pulse less ventricular tachycardia (VT) 2. Ventricular fibrillation (VF) Indications: Defibrillation
28. • Dysrhythmias • Multifocal atrial tachycardia Contraindications
29. • Cardioversion: – Almost always under induction or sedation. – Exceptions: hemodynamic instability or if cardiovascular collapse is imminent. • Defibrillation – is an emergent maneuver and performed promptly. Anesthesia
30. • Defibrillators (automated external defibrillators [AEDs], semi-automated AED, standard defibrillators with monitors) • Paddle or adhesive patch • Conductive gel or paste • ECG monitor with recorder • Oxygen equipment • Intubation kit • Emergency pacing equipment Equipments
31. • Antero-lateral • Antero-posterior Positioning Fig. anterior –apex scheme of electrode placement (AED)
32. – Emergent application – Elective cardioversion – Repetitive, futile attempts – Advanced cardiac life support (ACLS) Technique
33. Waveforms Monophasic Biphasic Charge Only one direction Two direction (opposite) Effectiveness Less effective More effective and at lower energies Technique Contd…
34. 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
35. Biphasic Defibrillation • Two phases to the delivery of the ‘shock’ • Adjusts ‘shock’ according to thoracic impedance • Adult: 150J, 150J, 150J • Child: 1– 2J/Kg
36. Energy selection: Cardioversion: • Begins with 25-50 J for atrial flutter. • 50-100 J (or the biphasic equivalent) to treat atrial fibrillation. Technique Contd…
37. Defibrillation: • Immediate • Rapid polymorphic ventricular tachycardia (rate >150 bpm) >> 200-360 J (or biphasic equivalent [100-200 J). • Monomorphic ventricular tachycardia >> 100- 200 J (or biphasic equivalent [50-100 J]). • Ventricular fibrillation >> 200-360 J (or biphasic equivalent [100-200 J]). Technique Contd…
38. Classes of discharge waveform Fig:- Generation of bi-phasic waveform
39. The biphasic waveform is preferred over monophasic waveform to defibrillate, WHY????? • A monophasic type, give a high-energy shock, up to 360 to 400 joules due to which increased cardiac injury and it burns the chest around the shock pad sites. • A biphasic type, give two sequential lower-energy shocks of 120 - 200 joules, with each shock moving in an opposite polarity between the pads. Classes of discharge waveform
40. AUTOMATIC EXTERNAL DEFIBRILLATOR
41. Rhythm Analysis and the Defibrillator Video Demonstration
42. 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
43. Safety Operator Safety • Assertive • Announce: – CHARGING, – ALL CLEAR / STAND CLEAR (Visual Check of Area), – SHOCKING • Check rhythm • Discharge Shock • Continue as per algorithm
44. PRECAUTIONS IN DEFIBRILLATION PROCESS The paddles used in the procedure should not be placed:- • on a woman's breasts. • over an internal pacemaker patients. Before the paddle is used, a gel must be applied to the patient's skin.
45. Common: • Atrial, Ventricular and Junctional premature beats Serious: • Ventricular fibrillation (VF) • Digitalis toxicity • Severe heart disease • Thromboembolization (1-3%) • Myocardial necrosis • Pulmonary edema • Painful skin burns Complications
46. • Attach the external and internal paddles if the monitor reads, "No paddles." • Check to ensure that the leads are securely attached if the monitor reads, "No leads." • Connect the unit to AC power if the message reads, "Low battery." • Verify that the Energy Select control settings are correct if the defibrillator does not charge. TROUBLESHOOTING
47. • Change the electrodes and make sure that the electrodes adapter cable is properly connected if you receive a message of "PACER FAILURE." Restart the pacer. • Close the recorder door and the paper roll if the monitor message reads, "Check recorder”. TROUBLESHOOTING
48. Video Demonstration
49. ‘’Success depends on delivery of current to the myocardium’’
50. Thank You!!!