DEFIBRILLATOR - PART 1

Sunday, May 31, 2020

DEFIBRILLATOR - PART 1

Hi friends!!!

Defibrillator is a important life saving device, therefore it is important for every healthcare professionals to know in details about the defibrillator machine.

Let’s get into the topic with a defibrillator definition.

WHY DEFIBRILLATOR?

Defibrillator is an electronic device used to deliver electric shock to the patients to restore the rhythm of the heart.

The basic function of the heart is to pump the blood and there is a term called VENTRICULAR FIBRILLATION which means abnormal heart rhythm where the ventricles of the heart quiver instead of pumping the blood normally. So to avoid this issue electric shock is given using defibrillator machine.

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WHAT IS THE CONCEPT OF DEFIBRILLATOR?

The defibrillator machine works based on the principle of charging and discharging of the capacitor. There are two modules in defibrillator machine, charging module and discharging module.

Charging module consists of Battery, DC to AC converter, Step up transformer, AC to DC convertor, Switches A & B and a Capacitor as shown in the image below.

Battery is used because a defibrillator machine needs to be a portable device and in order to have a charge large enough for fibrillation capacitor needs to be charged with a very high voltage. So a step up transformer is used.

Since a step up transformer will accept only AC Current as input, a DC to AC converter is used between battery and transformer. Capacitor accepts only DC input, so AC to DC converter is used Switches A and B are used to provide a path for charging the capacitor.

Let’s see how capacitor charges. Capacitor consists of two metal plates close to each other. When these plates contain equal amount of positive and negative charged couples, they are said to have NO CHARGE.

When the terminals of capacitor are connected to a battery, negative charge from Plate B moves towards Plate A. Now plate A has excess of single negative charges and plate B has excess of single positive charges. So there is a attraction between the excess positive and negative charges.

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This process of making one plate positively charged and other plate negatively charged is called charging the capacitor. During this entire process switches A & B are turned ON to provide path for charges to flow.

Discharging module is connected to heart through switches 1, 2, 3, 4 to support the discharging function in both forward direction & reverse direction as shown in the image below.

During discharge of defibrillator machine both switches A & B are turned OFF. The terminals of capacitor are connected to the heart with the use of Conductive Pads.

In Forward Direction switches 1 and 4 of defibrillator machine are turned ON to provide the path for charges to flow as shown in the image below.