defibrillator

1. THE DEFIBRILLATOR Presented by ; KIBIRIGE ARNOLD DAVID U/1803068/BBE

2. content • Introduction • History of defibrillator • Components • Types • Working principle • Uses • Dangers associated with defibrillators • Trouble shooting • Safety and maintenance

3. introduction • Defibrillator Is a device that gives a high energy electric shock to the heart of someone who is in cardiac arrest. • It is used to re-establish a normal heart rhythm in cases of cardiac arrhythmia, ventricular fibrillation and pulseless ventricular tachycardia. • commonly used in Operation theatres, Intensive care areas and ambulance service.

4. history of defibrillation • 1899, Jean Louis Prevost and Frédéric Batelli discovered that small electric shocks could induce ventricular fibrillation in dogs and that larger charges would reverse the condition. • 1930 William Kouwenhoven invented the first external defibrillator through his study of the relationship between the electric shocks and its effects on human heart . • It was first tested on a human in1947 by Dr. Beck • 1970 Diack, wellborn and Rullman invented the first automatic external defibrillator.(AED)

5. defibrillation • This is the therapeutic use of electricity to depolarize the myocardium so that coordinated contractions can occur. • It uses an electrical shock to reset the electrical state of the heart so that it may beat to a rhythm controlled by its own natural pacemaker cells. • It causes current to go from the negative to the positive electrode of defibrillator passing the heart on its way.

6. why would someone need a defibrillator? • When a cardiac arrest happens, there is a problem between the electrical impulses between the brain & the heart. • This prevents the heart from pumping blood to the rest of the body. • Defibrillators save lives by giving a high energy electric shock to the heart through the chest wall when someone is in cardiac arrest.

7. abnormalities of the heart Atrial fibrillation (AF) • This is an abnormal heart rhythm characterized by rapid and irregular beating of the atria. Often it starts as brief periods of abnormal beating which become longer and possibly constant over time. Ventricular fibrillation (VF) • This is a heart rhythm problem that occurs when the heart beats with rapid, erratic electrical impulses. This causes pumping chambers in your heart (the ventricles) to quiver uselessly, instead of pumping blood.

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9. components of a defibrillator Capacitor • it stores a large amount of energy in the form of electrical charge over which a short period of time and releases the stored energy. Inductors • Inductors are made up of coils of wire that produce a magnetic field when current flows through them, prolong the duration of current flow.

10. cont… Power Supply • It provides voltage which operates the defibrillator. • it consists of step-up transformers that increase voltage from 240 V AC to 5000 VAC

11. defibrillator electrodes • These electrodes collect information for rhythm analysis and delivers energy to the patient's heart. hand-held paddles internal paddles self-adhesive disposable

12. Electrode placement anterior-posterior placement • One electrode is placed over the left lower part of the chest, in front of the heart and the other on the back, behind the heart in the region between the scapula. anterior-apex placement • The anterior electrode is placed on the right, below the clavicle and the apex electrode is applied to the left side of the patient, just below and to the left of the pectoral muscle.

13. types of defibrillators Manual external defibrillator • A healthcare provider first diagnoses the cardiac rhythm and then manually determine the voltage and timing for the electrical shock. Manual internal defibrillator • These use internal paddles to deliver the electric shock directly to the heart.

14. Cont… Semi-automated external defibrillator • it reads the victims underlying heart rhythm and if it detects a shockable rhythm, it prompts the user to deliver the electric shock. Its Used during emergency. Automated external defibrillator • It interprets a person's heart rhythm and automatically delivering a defibrillation shock with only minimal input from the operator.

15. cont… Implantable cardioverter defibrillator (ICD) • This is a small battery powered device that will continuously monitor the patient’s heart rhythm. Wearable cardiac defibrillator • This WCD (life vest) is an external device capable of automatic detection and defibrillation of ventricular tachycardia and ventricular fibrillation.

16. principle of operation of defibrillator • The capacitor is charged slowly from the A.C input. • The energy stored is delivered at a relatively rapid rate to the chest of the patient • The capacitor discharges its energy through the patients own resistance.

17. how a defibrillator works • The electrodes are connected to the defibrillator and the pads placed on a patient’s chest. • A defibrillator analyzes the heart rhythms and provide the shock needed for defibrillation. • an electric current is delivered to the heart through the victim’s chest wall through the electrodes. • The shock delivered by a cardiac defibrillator interrupts the chaotic rhythm and allows it to return to normal.

18. energy levels for defibrillation • Most defibrillators are energy-based devices that can deliver the electrical shock in a monophasic, biphasic and triphasic waveform. monophasic waveform • Defibrillators deliver current in one polarity i.e. deliver charge in one direction. • Further classified into damped sinusoidal(A) and truncated exponential(B)

19. cont.. Biphasic wave form • Defibrillator delivers current in two directions. Triphasic waveform. • the second phase has the larger strength to lower the DFT and the third phase the lower strength, to minimize damage. • Rarely used

20. uses of defibrillator • defibrillator is used to measure output energy. • It is to measure cardioversion delay time. • It’s used to measure output energy for pace makers • Stimulates range for ECG wave forms. • Provide clinical training.

21. dangers associated with using defibrillators • Skin burns from repeated shocks. • Myocardial injury and post defibrillation dysrhythmias and ‘stunning’. • Skeletal muscle injury. • Thoracic vertebral fractures. • Arcing as electricity travels through the air directly between electrodes. • Electrical injury to bystanders. • Risk of explosion if oxygen flow continues during shock delivery.

22. Merits and demerits of a defibrillator merits demerits •Relatively high cost. • Limited availability. • Associated electric shocks. • Easy to use(AED) • Better reproducibility. • No ionizing radiations

23. Common faults • Battery damage\failure Damaged/faulty capacitor • Damaged/worn out cables. Relay failure

24. Trouble shooting a defibrillator

25. safety and maintenance of a defibrillator • It must be operated by trained, professional and qualified personnel only. • Never use defibrillator with improper grounding or electrical leak socket. • Keep away the Defibrillator from any x-ray, Ultrasonic or other electronic instruments • Use only the specified patient cable as recommended by manufacturer • Don't use damaged patient cable. • Excessive Gels can cause arcing of the current along the chest wall. • Clean the print head regularly for clear printout.

26. ?? Thanks for listening 1