Early Defibrillation Dr. M. Ravishankar
THE CHAIN OF SURVIVAL CONCEPT Early Access Early CPR Early Defibrillation Early Advance Care 1 st Link 2 nd Link 3 rd Link 4 th Link
Why early defibrillation VF causes more cardiac arrests than any other rhythm (about 80% to 90% of cases). Most sudden cardiac arrest victims are in ventricular fibrillation (VF). The sooner one provides defibrillation, the better the victim's chances of survival.
Why early defibrillation If defibrillation is provided within the first 5 minutes about 50% of times the victim's life can be saved. Each passing minute during a cardiac arrest, the chance of successful resuscitation is reduced by 7% to 10%. After 10 minutes there is very little chance of successful rescue.
THE DEFIBRILLATOR The defibrillator is an instrument in which electric charge is stored in a capacitor and then released in a controlled fashion.
Stored Energy Coulombs (C) = ampere (A) x seconds (S) Available energy (J) Stored charge (C) x Potential (V) Energy (joules) = potential difference (volts) x current (amperes) x duration (seconds)
How to defibrillate Two electrodes are placed on the patient s chest; One is placed just to right side of the sternum and The other over the apex of the heart. The energy stored in the capacitor is released as a current pulse through the patient s chest and heart.
What does the current do? This current pulse gives a synchronous depolarization of the myocardium after which a refractory period and normal or near-normal beats may follow.
Practical Considerations The first is the energy output of the defibrillator. successful removal of VF is critically dependent upon the amount of energy available from a defibrillator
It is strongly recommended that all defibrillators be checked at least once daily Using a standardized checklist TO make sure that the devices will operate properly when needed.
Second Consideration The resistance to current flow Excessive resistance because of poor technique can impede the transthoracic flow of adequate current to permit complete depolarisation to occur
Ensure proper electrode position firm pressure against each hand-held paddle (11 kg/paddle), optimal electrode-chest wall coupling medium such as electrode paste defibrillation at end-expiration
TYPES OF DEFIBRILLATORS DC defibrillator Monophasic Biphasic AC defibrillators Automated External Defibrillator (AED) Automated Implantable Cardioverter Defibrillator (AICD)
Mono & Biphasic defibs In monophasic defibrillators the current is passed in a single direction In biphasic the polarity is changed immediately after the first wave is transmitted and travels back to the place of origin.
Steps in defibrillation Manual Defibrillation 1. Select DEBIB Energy select Prepare paddles Apply paddles to chest 2. CHARGE DEFIBRILLATOR 3. DELIVER SHOCK
1. Select DEBIB Connect to power and switch ON. Turn the selector switch to DEFIB. The unit automatically defaults to 200 joules or manually select the level
Energy select Observe the display and verify the selected energy is appropriate. One control is located on the front panel of the unit; Other control is located on the sternum paddle. The selected energy level will be shown on the display.
Prepare paddles Remove the paddles from their holders by grasping the handles and pressing down on the paddle release latch Apply a liberal amount of electrolyte gel to the electrode surface of each paddle. Rub the electrode surface together to evenly distribute the applied gel.
Apply paddles to chest 1. Apply the paddles firmly to the anterior wall of the chest. 2. Place the sternum paddle to the right of the patient s sternum, just below the clavicle. 3. Place the Apex paddle on the chest wall, just below and to the left of the patient s left nipple, along the anterior axillary line. 4. Rub the paddles against the skin to maximize the paddle to patient contact.
2. CHARGE DEFIBRILLATOR Press the CHARGE button on the front panel or on the apex paddle handle. After charging to the selected energy, the charge indicator on the apex paddle will light. A distinctive charge ready tone sounds and the energy ready message will be displayed. If the charge is not delivered in 60 seconds the unit will disarm.
3. DELIVER SHOCK Using your thumbs, simultaneously press and hold both SHOCK buttons until energy is delivered to the patient.
Semiautomatic Defibrillators ADVISORY DEFIBRILLATION The device can identify shockable rhythms using its built in ECG analysis capability when using Multi function electrode (MFE) pads to monitor ECG and defibrillate. The operator must read the advisory messages, charge the defibrillator and use acording to patient condition
Automatic External Defibrillators (AED) Analysis is always active in the background of the semi automatic mode when MFE pads or ECG cable and electrode are in use. This analysis consists of 3 consecutive 3 seconds ECG rhythm analysis.
AED Analysis If at least 2 of the 3 analyses determine that the patient has a shockable rhythm, the unit will automatically charge to the pre configured energy level and prompt the operator to deliver the shock.
Multifunction Electrodes (MFE) application Remove all clothing covering the patient s chest. Dry chest if necessary. If the patient has excessive chest hair, clip it to ensure proper adhesion of electrodes. Ensure that all MFE pads are making good contact with the patient s skin and are not covering any part of the ECG electrodes.
MFE PAD APPLICATION Apply one edge of the pad securely to the patient. Roll the pad smoothly from that edge to the other being careful not to trap any air pockets between the gel and skin. The message CHECK PADS will be displayed and energy will not be delivered if the MFE pads are not making good contact with the patient
Press analyze Button Press the ANALYZE button to begin analysis of the patient s ECG rhythm. The device announces and displays a STAND CLEAR message.. An ANALYZING ECG message is then displayed for up to 12 seconds while the patient s ECG is analyzed.
Analysis Completed When a non shockable rhythm is detected the unit displays a NO SHOCK ADV message. If the patient s rhythm is shockable the unit will display a SHOCK ADVISED message.
The defibrillator will begin charging automatically to the pre configured energy setting and display a CHARGING message. When charging is completed the monitor displays the energy level to which the defibrillator has been charged, XXXJ READY.
3. PRESS SHOCK Once the unit has charged to the selected energy, the SHOCK button will illuminate and the PRESS SHOCK message will be announced and displayed. A continuous tone will sound for 10 seconds, followed by an intermirrent beeping for 5 seconds. The shock must be delivered with in this 15 seconds interval or the defibrillator will disarm itself.
Automatic Energy Levels For non biphasic units shock no.1 is set at 200 joules, shock 2 is set at 200 joules and shock 3 and up is set at 360 joules. For biphasic units shock no.1 is set at 120 joules, shock 2 is set at 120 joules and shock 3 is set at 200 joules.
REPEAT ANALYSIS Press the analyze button to restart an ECG analysis and determine if additional shocks are required. Some AED s Automatically reanalyze and advise regarding shock or continue CPR
Public Access Defibrillation. AHA wants to place AEDs in the hands of trained, nontraditional rescuers. police, security guards, and family members of patients at high risk for cardiac arrest. Public access defibrillation (PAD) programs place AEDs in homes, police cars, worksites, and public gathering places, under the supervision of licensed physicians.