What Are the Different Types of Defibrillator Pads?

A defibrillator is a medical device that uses strong pulse current to pass through the heart to eliminate arrhythmia and restore sinus rhythm. It is a necessary first-aid device in the operating room. Defibrillation is one of the important steps for CPR.

Chinese name: Defibrillators
Foreign name: Defibrillation

Category Name: External defibrillation equipment
Management category: Class III

Defibrillator basic structure

The defibrillator is mainly composed of a monitoring part, an electric cardioversion machine, an electrode plate, and a battery. Electric cardioversion machines, also called defibrillators, are the main equipment for performing cardioversion. Equipped with electrode plates, most of which have two pairs of size, large for adults, small for children ^[1] .

use

How defibrillators work

What is acting on the heart during cardioversion is a transient high-energy pulse, which generally lasts 4 to 10 ms, and has an electrical energy of 40 to 400 J (joules). The device used to defibrillate the heart is called a defibrillator, which can complete the cardioversion, that is, defibrillation. When patients with severe tachyarrhythmias, such as atrial flutter, atrial fibrillation, supraventricular or ventricular tachycardia, etc., often cause different degrees of hemodynamic disorders. Especially when the patient has ventricular fibrillation, because the ventricle has no overall contraction ability, the cardiac ejection and blood circulation are terminated. If the patient is not rescued in time, it often causes the patient to die because of hypoxic brain time. If a defibrillator is used, controlling a certain amount of current through the heart can eliminate some arrhythmias and restore the heart rhythm to normal, so that the above-mentioned patients with heart disease can be rescued and treated ^[1] .

The original defibrillator used industrial AC power to defibrillate directly. This type of defibrillator often suffered injuries due to electric shock. At present, in addition to AC defibrillation (ventricular fibrillation), it is generally used DC defibrillation.

How to use defibrillator

Blind defibrillation steps ^[1] :

First, adjust the patient's posture to avoid contact with metal objects to avoid electric shock.
Exposing the chest and applying conductive lotion;
Turn on the defibrillator and charge according to the defibrillation energy selected by the patient;
After charging, place one electrode plate on the upper right side of the sternum below the clavicle, and the center of the other electrode on the left axillary midline of the nipple;
The defibrillator operator should press the electrode pad in his hand tightly and instruct the medical staff not to touch the patient. The operator presses the button to discharge the defibrillator. Repeat as necessary.

Synchronous defibrillation or synchronous cardioversion steps:

First connect the ECG monitoring on the defibrillator to display the patient's ECG;
The previous steps are the same as blind defibrillation, except that the defibrillator recognizes and selects the discharge time based on the patient's ECG.

Defibrillator indications

Ventricular fibrillation is an absolute indication of cardioversion.
Chronic atrial fibrillation (with a history of atrial fibrillation within 1 to 2 years), persistent atrial flutter.
Paroxysmal supraventricular tachycardia, conventional treatment is ineffective and patients with significant hemodynamic disorders or preexcitation syndrome complicated by supraventricular tachycardia and medication difficulties.
Atrial flutter was 1: 1.

Defibrillator contraindications

Bradyarrhythmias, including sick sinus syndrome.
Arrhythmias caused by digitalis overdose (except ventricular fibrillation).
Atrial fibrillation, atrial flutter, atrial tachycardia with high or complete conduction block.
Severe hypokalemia should not be used for cardioversion.
The left atrium is huge, the atrial fibrillation lasts for more than one year, and the chronic ventricular rate is unpleasant.

Defibrillator Precautions

Choice of electric energy
Defibrillation requires energy, and appropriate energy is selected during defibrillation to generate sufficient transmyocardial current. If the energy and current are too low, the shock cannot stop the arrhythmia. If energy and current are too high, functional and morphological damage can result. There is no clear relationship between body size and the energy required for defibrillation in adults, and transthoracic impedance does not play an important role. The recommended energy for the first defibrillation is 200J, and the energy level for the second shock should be 200 ~ 300J. Defibrillation is possible with any energy given, so an energy range of 50 ~ 360J can be specified. Since transthoracic impedance decreases with repeated electric shocks, subsequent electric shocks will produce a higher current even if the energy is the same. For this reason, if the first shock does not stop the ventricular fibrillation, it is best to repeatedly apply the same amount of energy as the first shock. If the first two shocks fail to defibrillate, a third shock to 360J should be given immediately. If the electric shock VF has terminated, but then appears again, an electric shock should be performed again, and the energy given should be the level given by the previous successful defibrillation. Shock energy should only be increased if the shock cannot stop defibrillation ^[1] .
The electrical energy used for cardioversion is indicated by "J". Charge as needed, ventricular fibrillation is 250 ~ 300J asynchronous cardioversion. Ventricular tachycardia is 150 ~ 200J, atrial fibrillation is 150 ~ 200J, atrial flutter is 80 ~ 100J, supraventricular tachycardia is 100J, all are synchronous cardioversion.
Electrode position
There are two positions where the electrode plates are placed during extracorporeal cardioversion. One is called the anterior and posterior position, that is, one electrode plate is placed on the lower subscapular region of the back; the other is placed on the left margin of the sternum between 3 and 4 intercostal levels. Some people think that this way passes more current through the heart, so that less electricity is required, and potential complications can be reduced. This method should be used for selective cardioversion. The other is an electrode plate placed on the right margin of the sternum between 2 and 3 intercostal spaces (the bottom of the heart). The other was placed in the 5th intercostal space (apical portion) within the front line of the left axilla. This method is quick and convenient, and is suitable for emergency shock defibrillation. The distance between the two electrode plates should not be <10 cm. The electrode plate should be pressed against the patient's skin and slightly pressurized. There should be no gaps and the edges should not be lifted. The skin on which the electrodes are placed should be coated with conductive paste, or saline gauze can be used, and even water can be used in emergency, but alcohol is absolutely prohibited, otherwise it can cause skin burns. Those who are thin and the intercostal space is significantly depressed, which causes poor contact between the electrodes and the skin, should use saline gauze, and can use more layers, which can improve the contact between the skin and the electrodes. Keep the two electrode plates dry to avoid short circuits caused by conductive paste or salt water. The electrode plate handle should also be kept dry. It must not be contaminated by conductive paste or salt water, so as not to hurt the operator. When cardiac surgery or open-heart cardiac massage requires direct electric shock defibrillation of the heart, a proprietary small electrode plate is required, one is placed on the right ventricle surface; the other is placed on the apex, and the surface of the heart is sprinkled with physiological saline and the electrode plate Close to the ventricular wall.
Cardiac pacing or defibrillation in patients with a permanent pacemaker
Care should be taken not to place the electrode near the pacemaker, as defibrillation can cause the pacemaker to malfunction. After defibrillation or reinstatement in patients with permanent pacemakers, the pacing threshold should be checked after an electric shock. Transthoracic impedance defibrillation is the passage of sufficient current (amps) to the heart. The amount of current depends on the selected energy (Joules) and transthoracic impedance (ohms) or resistance to the current. Factors that determine transthoracic impedance include selected energy, electrode size, plate-skin coupling material, previous shock times and pause times, distance between electrodes (chest size), and electrode plate pressure. The average adult impedance is 70 ~ 80. If the transthoracic impedance is high, a low-energy shock cannot produce enough current to achieve defibrillation. To reduce transthoracic impedance, the defibrillator operator should compress the electrode pad in his hand, and apply a gel float or saline gauze pad between the pre-held electrode pad and the chest. If the electrode plate is directly attached to the chest wall, there is no binding substance between the electrode and the chest wall, which will make the transthoracic impedance very high ^[1] .
Equipment inspection
Before use, check whether the defibrillator's various functions are intact, whether the power supply is faulty, whether the charging is sufficient, whether the various wires are broken, and whether there is poor contact. Emergency shock defibrillation can be performed at any time in an emergency.

Defibrillator postoperative care

Continue to observe heart rate, heart rate, breathing, blood pressure, complexion, physical condition, and the presence of embolism, and keep records at any time. Return to the ward when the condition is stable. Anticoagulant treatment before surgery. Postoperative medication is still required and anticoagulant monitoring is performed.
Rest in bed for 1 to 2 days, give high calories, high vitamins, easy to digest diet, and keep the stool smooth.
After cardioversion of atrial fibrillation, continue to take medication to maintain, and observe the efficacy and adverse reactions.
Health guidance, explain the predisposing factors to the patient, such as overwork, emotional excitement, etc., to prevent recurrence.

Defibrillator related reports

On March 23, 2013, the U.S. Food and Drug Administration (FDA) said that after receiving reports of approximately 45,000 equipment failures in the past seven years, it plans to propose new regulatory rules to improve the reliability of emergency defibrillators. The agency said that its proposal would require manufacturers to provide clinical data or other evidence that their equipment is safe and effective and can be approved or left on the market. The FDA proposal will also require manufacturers to provide inspection reports and submit details about any changes to the equipment. The agency said that most of the reported problems were "preventable and correctable." "The most common problems related to the design and production of equipment and poor control over parts purchased from other suppliers." ^{[2 ]}

Many public places in the United States are equipped with self-service defibrillators, including airports, stadiums, schools, shopping malls, and office buildings. After simple training, whether it is an on-site bystander, or emergency responders or the police, you can operate this instrument correctly and win precious rescue time for patients with heart attack. According to statistics, the survival rate of cardiac arrest cases occurring outside the hospital is only about 5%, and if an automatic defibrillator is used within 5 minutes of the onset, the survival rate can be increased to 75%. ^[2]