CPR manually oxygenates the blood and pushes it through the body so that we can try to stop brain death for as long as we can. Essentially you are mimiking a heart beat through chest thrusts. But the heart is still not beating right, just beating on the chest won’t fix that. Thats where the defibrillator comes in – it shocks the heart in a way that makes it spontaneously beat again.
They are used when the heart is in an arrhythmia (incorrect rhythm). What it does is delivers a shock to the heart which stops it and then it hopefully starts back up with the correct rhythm.
An incorrectly beating heart can result in no blood flow so even though the heart is still beating it’s possible to have no pulse due to the lack of blood flow.
But I think you meant flatline which means a stopped heart. In this case a defib will do nothing because the heart is already stopped.
Defibrillation is only indicated in two lethal rhythms: ventricular fibrillation and pulseless ventricular tachycardia. The goal is for the electrical current to reorganize these electrical activities into a normal rhythm that would be compatible with perfusion.
There are other heart rhythms that can cause or coincide with cardiac arrest, like asystole, but these are not responsive to defibrillation. They are exclusively treated with chest compressions, rescue breaths, and medications like epinephrine.
Sometimes electrical therapies are used in patients who are not in cardiac arrest. Synchronized cardioversion and transcutaneous pacing are used in the treatments of certain hemodynamically unstable tachycardias and bradycardias, respectively.
No idea how TV and movie scenes are researched or scripted. My wife hates watching anything that has a medical emergency because I usually lol too much at how ridiculous it is compared to reality. Side note: Scrubs does a great job with its medical accuracy as well as its portrayal of resident life.
Source: am Advanced Cardiac Life Support (ACLS) qualified and instruct courses as well
All a defibrillator does is to stop fibrillation. Fibrillation is a chaotic situation where each bit of heart muscle is contracting to its own rhythm, not in step with the rest to produce an effective pumping action. The shock halts those contractions and hopefully the signal coming from the internal pacemaker cells takes over the rhythm.
Think of it like an orchestra. In fibrillation, the conductor may be on the podium waving their baton but player is doing their own thing, playing different sections of the score at different speeds. The outcome is a cacophony of sound. The defib shock sort of shouts “STOP!” and stuns everyone to silence for amoment and then they all pick up their cue from the conductor, resulting in proper music again.
Lets look at the word “defibrillator”.
“De” means to stop
“Fibrillation” – this is a condition where the heart isn’t beating correctly. Your heart has 4 chambers, and if the heart muscle doesn’t contract in a very precise order you aren’t going to get any blood flow around the body. The blood will just be pushed back and forth between the chambers.
So a “defibrillator” stops fibrillation.
It is a common misconception that a defibrillator starts a heart beating. It doesn’t. It stops it from beating incorrectly.
The hope is that after stopping the heart your brain gets its act together and kinda “reboots” the heart and it starts beating properly.
It also allows for CPR to be more effective. CPR doesn’t really help if the heart beat is wrong and working against the CPR. So even if the heart doesn’t start on its own after a defibrillator, a defibrillator followed by CPR still increases the odds a person will survive long enough to make it to a hospital where other techniques could save their life.
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