Defibrillators WHO. “Defibrillator, External, Automated; Semiautomated.” From the publication: Core Medical Equipment. Geneva, Switzerland, 2011.

Summary Quiz Commercial Examples Clinical Use Preventive Maintenance History Specifications Principles of Operation Block Diagram Commercial Examples Preventive Maintenance Common Problems Test Procedures

Quiz What is the 2 main clinical cases that require the use of defibrillator? What are the different types of defibrillator? What is the defibrillator waveform polarity? Does one need to use gel? Why?

Quiz What kind of paddles can be used? Draw the 2 possible of paddles placement in the case of external electrodes. Can one use a defibrillator with a patient on a OR table? Why? What are 2 ways to test a defibrillator What is the most common problem in defibrillators from the developing world?

Fibrillation Cardiac arrest occurs in more than 500,000 people annually in the United States Atrial fibrillation (AF) is relatively common and can be well tolerated by the patient

Fibrillation Jer5150 (2012) Fibrillation [Image], retrieved from https://commons.wikimedia.org/wiki/File:Ventricular_fibrillation.png

Ventricular Fibrillation Ventricular fibrillation (VF) causes the heart to stop pumping blood immediately Irreversible brain damage or death after 5 minutes Most common cause of death http://www.skillstat.com/ECG_Sim_demo.html

Clinical Use Reverse fibrillation of the heart (300 J to 360 J) Restoring the heart’s normally coordinated contractions (below 200 J) – Requires ECG [Drawing of defibrillator pads placement] retrieved from www.wikipedia.com

History 1899 Physiologists Prevost and Batelli from University of Geneva used small electric shocks to induce ventricular fibrillation in dogs, and larger charges to reverse the condition Beck's theory was that ventricular fibrillation often occurred in hearts which were fundamentally healthy, in his terms "Heart too good to die", and that there must be a way of saving them. Beck first used the technique successfully on a 14 year old boy who was being operated on for a congenital chest defect. The boy's chest was surgically opened, and manual cardiac massage was undertaken for 45 minutes until the arrival of the defibrillator. Beck used internal paddles on either side of the heart, along with procainamide, a heart drug, and achieved return of normal sinus rhythm. Until the early 1950s, defibrillation of the heart was possible only when the chest cavity was open during surgery. The technique used an alternating current from a 300 or greater volt source delivered to the sides of the exposed heart by 'paddle' electrodes where each electrode was a flat or slightly concave metal plate of about 40 mm diameter. The closed-chest defibrillator device which applied an alternating current of greater than 1000 volts, conducted by means of externally applied electrodes through the chest cage to the heart, was pioneered by Dr V. Eskin with assistance by A. Klimov in Frunze, USSR in mid 1950s.

History 1947 First use on a human by Claude Beck, professor of surgery at Case Western Reserve University

Specifications Input Electrical: ECG signal Output Electrical: 3000 V pulse during 10 ms Electronically (display) PhilippN, (November 2007), Position of Electrodes during Defibrillation, retrieved from https://commons.wikimedia.org/wiki/File:Defibrillation_Electrode_Position.jpg

Principles of Operation Electric current is placed through electrodes: Directly on the heart - low current – 300 V AC. Transthoracically – large area electrodes, higher current – 1000 V AC Energy Discharge: 0 to 360 watt/ seconds (Joules)… around 50 mA [Photograph of defribrilator] retrieved from www.wikipedia.com

Types of Defibrillators Manual defibrillator (most common in developing world) Automated external defibrillators AED (Home defibrillator) Implantable defibrillator WHO. “Defibrillator, External, Automated; Semiautomated.” From the publication: Core Medical Equipment. Geneva, Switzerland, 2011. Steven Rodriquez (2007), Defibrillator [photograph], retrieved from https://www.flickr.com/photos/n28ive1/431939091

Output Pulses Edmark Waveform Maximum Pulse 7,500 V Common in the poor world Severe damage (death) Be clear of the patient during the discharge vp 2kv ~10 ms Virginia Reid (2015), Waveform [drawing]

Output Pulses Biphasic truncated exponential Virginia Reid (2015), Output Pulses, [drawing] Biphasic truncated exponential Monophasic truncated exponential Safest Waveform

Manual Defibrillators ECG ECG leads can also be connected from the device to the patient However, most can monitor the ECG through the defibrillation paddles as well. Aededitor (2011), Semi-automated external monitor defibrillator [photograph], retrieved from https://commons.wikimedia.org/wiki/File:Semi-automated-external-monitor-defibrillator.jpg 

Synchronization Shock point Husche (2015), ECG Figure EN [diagram]. Adapted from https://commons.wikimedia.org/wiki/File:CCM_ECG_Figure_EN.png

ECG Synchronization Relevance??? Anthony Atkielski (2012), Sinus Rhythm Labels [diagram]. Retrieved from https://commons.wikimedia.org/wiki/File:SinusRhythmLabels_fi.svg

Paddles Excellent contact with the body is essential Gel required Serious burns can occur if proper contact is not maintained during discharge Sufficient insulation is required Prevents discharge into the physician

Paddles Types Internal: direct cardiac stimulation External: transthoracic stimulation Adult Pediatric Disposable: used externally

Paddles Types Disposable Internal External Yury Masloboev (2007), Defibrillator, [photograph]. Retrieved from https://commons.wikimedia.org/wiki/File:Defibrillator_(UOMZ).jpg

  Paddles Position DHTLab (2015), Defibrilator Packet, retrieved from BMET Library

  Paddles Position Owain Davies (2012), Defib electrode placement, retrieved from https://commons.wikimedia.org/wiki/File:Defib_electrode_placement.png

Schematics Openstax College. “Cardiac Muscle and Electrical Activity.” From the publication: Biology. Rice University: 2013.

Internal (Implantable) Defibrillator BruceBlaus (2013), Implantable Cardioverter Defibrilator [diagram]. Retrieved from https://commons.wikimedia.org/wiki/File:Blausen_0543_ImplantableCardioverterDefibrillator_InsideLeads.png

Commercial Examples External Defibrillator Openstax College. “Cardiac Muscle and Electrical Activity.” From the publication: Biology. Rice University: 2013.

Commercial Examples Internal Defibrillator Steven Rodriquez (2007), Defibrillator [photograph], retrieved from https://www.flickr.com/photos/n28ive1/431939091 Gregory Marcus (2008) Implantable cardioverter defibrillator chest X-ray [photograph] retrieved from https://commons.wikimedia.org/wiki/File:Implantable_cardioverter_defibrillator_chest_X-ray.jpg

Commercial Examples AED Wikipedia. “Automated External Defibrillator.” Wikipedia, p. 1-5. Retrieved from: https://en.wikipedia.org/wiki/Automated_external_defibrillator

Safety Avoid conducting mattress (spring), bedstead or metal table Wear surgeon’s rubber gloves with high-voltage insulation CAUTION: high current and voltage associated with the circuitry. Use GEL A completely different approach to measuring blood pressure is to invasively introduce a catheter into an artery. This is most common in surgery and intensive care units. The blood pressure device is connected to the catheter via a rigid wall plastic tube filled with a saline solution. The tube is connected to a transducer, which may be connected to bag of saline or “flush.” Figure 2.7.3 illustrates the set up. The transducer is hung at the level of the heart. The output from the transducer is amplified and displayed as numbers, waveform or both. Since the skin has been breached the patients first line of defense for both infection and electrical shock have been bypassed. Extreme care must be taken to assure the safety of the patient. Werneuchen (2008) Surgical Gloves [photograph]. Retrieved from https://commons.wikimedia.org/wiki/File:Surgical_gloves_26.JPG

Preventive Maintenance Replaced battery every 24 months Defibrillators offer a selftest option which should be done at least once a month

Common Problems Old Batteries Paddles and cables contact The gel build up on the paddles and have to be cleaned with alcohol

Test Procedures Paddles should be inspected for pit marks They could leave burns on the chest

NEVER TEST THE PADDLES AGAINST EACH OTHER! Test Procedures Defribillator Selftest Use a fresh meat (normally pig) NEVER TEST THE PADDLES AGAINST EACH OTHER!

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Troubleshooting