How does a defibrillator work?
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<h2>Defibrillator? I’ve seen one of those!</h2>
<p>No TV medical drama show is complete without a doctor at some point shouting, “Clear!” as he or she applies a <strong>defibrillator</strong> to a dying patient. More often than not, with a massive convulsion, the patient is shocked with hundreds of joules of <a rel="noopener" href="https://en.wikipedia.org/wiki/Electricity" target="_blank">electricity</a> and miraculously brought back to life.</p>
<p>In the real world, defibrillators are a little less dramatic, but they do save countless lives.</p>
<h3>How does a defibrillator work?</h3>
<p>As the name suggests, the defibrillator is a device that stops <em>fibrillation</em> – the condition where the heart starts to beat erratically, usually during <a href="https://cosmosmagazine.com/health/hearts-stopped-young/">cardiac arrest</a>.</p>
<p>It does this by generating a powerful electrical current – about 300 joules of electrical energy – which is passed through the heart. This has the effect of stopping the uncontrolled trembling and resetting the beating to normal.</p>
<p>There is a common misconception – thanks to those medical dramas – that a defibrillator is used when the heart stops beating entirely, or ‘flat lines’.</p>
<p>Unfortunately, this exaggerates the capabilities of the device.</p>
<p>Rather than restart the heart, the device works to reset the natural pacemaker in our bodies to return the heart to normal function and rhythm.</p>
<p>If the heart has stopped,<strong> a defibrillator will do little to restart it</strong>, so other techniques such as CPR are applied.</p>
<p>It is even possible to have an automatic defibrillator placed inside the body for patients who have a disorder of the heart known as <a href="https://cosmosmagazine.com/health/hearts-stopped-young/">arrhythmia</a>. These devices, about the size of a pocket watch, administer the appropriate electrical shock if they sense the heart going into fibrillation.</p>
<p>They differ from a <a href="https://cosmosmagazine.com/health/bionic-heart-beats-like-the-real-thing/">pacemaker</a>, however, as they do not assist the heart in maintaining a pace. Rather, they deliver an electrical shock when they sense that the heart is approaching a dangerous heartbeat.</p>
<p>The shock produced by the defibrillator is generated via a built-in battery, which releases a massive pulse of energy. This electrical energy is directed down two wires, each ending at a pad, known as a paddle.</p>
<p>With a defibrillator in a hospital, a doctor applies a conductive gel to maximise the flow of electricity to the patient. The paddles have insulated, plastic handles to prevent the user being shocked along with the patient.</p>
<p>Automatic defibrillators, such as those you might see at a shopping centre, use an adhesive pad, which can be quickly and easily applied by anyone and avoid the need to hold the pads during use.</p>
<p>They can also electronically guide a user through the defibrillation process without the need for a medical professional.</p>
<p>Where the pads are placed is crucial.</p>
<p>There are two correct positions – the first with the pads above and to the left, and below and to the right of the heart; the second with the paddles placed in front of and behind the heart.</p>
<p>These positions ensure that the electrical current moves around and through the heart.</p>
<em>Image credit: Shutterstock</em></div>
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<p><em>This article was originally published on <a rel="noopener" href="https://cosmosmagazine.com/technology/how-does-a-defibrillator-work/" target="_blank">cosmosmagazine.com</a> and was written by Jake Port. </em></p>
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