Electrodes for defibrillation: types and principles of operation
The principle of action of a generally recognized remedy for a number of life-threatening arrhythmias, as well as the features of electrodes for a defibrillator are considered
Defibrillation is an aspect of medical care for a person who has a heart rhythm that requires a shock. Using direct current, a short-term electrical impulse with a high degree of intensity is supplied to the heart muscle.
The procedure can be performed using two types of electrodes:
- disposable electrodes for defibrillation;
- reusable defibrillator electrodes.
Features of a reusable product
Repeated application of defibrillator electrodes has one important drawback - the need to lubricate the skin with gel each time to reduce the degree of transthoracic impedance.
The second important point is that the gel must be applied in such a way as to prevent the formation of a so-called bridge between the electrodes. If you do not adhere to this rule, the result will be a banal short circuit and a decrease in the actual discharge. As a result, the effectiveness of the procedure will significantly decrease.
Also, electrodes for a defibrillator, which many manufacturers of medical equipment offer today, must be coated exclusively with a special gel. An unsuitable gel can cause a spark, which, together with oxygen respirators, will create a completely unfavorable situation.
Other disadvantages of this gel include:
- they contain a lot of salts;
- sticky;
- greasy to the touch;
- difficult to remove;
- To get a good effect, you will need to press very hard on the Defi-monitor defibrillator electrodes.
One of the best, time-tested and practice-tested, are the reusable electrodes of the Metrax defibrillator.
[edit] History
By the end of the 1950s, treatment for cardiac fibrillation was carried out only with medications.
Paul Zoll was the first to propose in 1956 the use of electric current to influence the heart muscle in case of fibrillation, demonstrated the first successful experience in open heart surgery and using 110 Volt alternating current directly to the heart muscle.
In 1959, based on his publication, Bernard Lown set out to achieve a more effective and less traumatic effect of electric current, for which he began conducting experiments on animals. The result of his research is a single pulse waveform, in the following known as the " Lown waveform"
"—a single sinusoidal pulse lasting about 5 milliseconds.
In the serial device, the pulse was generated by discharging capacitors precharged to 1000 Volts through inductance and electrodes. Continuing his research, Laun brought in the cooperation of engineer Berkavich Barro, who, according to the specifications presented by Laun, developed the first prototype of a defibrillator called a “cardioverter ”
. This first device, weighing 27 kilograms, provided a pulse of 100 Joules of energy for use on the open heart and a controlled pulse of 200-400 Joules for use through a closed chest.
Disposable AED Electrodes
Adhesive disposable products are lubricated with gel at the production stage. Therefore, resuscitators can quickly apply them to the patient’s chest.
Among their other advantages:
- there is no need to remove residual gel from the instrument;
- huge surface area.
Options such as Primedic disposable defibrillator electrodes have recently become increasingly popular.
Electrodes for external defibrillation: buy at the best price
Such defibrillators can be fully automated or equipped with manual controls.
The advantages of the first type are small dimensions, ease of transportation and storage, and the absence of the need to be a professional doctor to use them.
Disadvantages include the high price of disposable electrodes and the lack of several important functions, for example, monitoring, synchronization.
A professional defibrillator with a manual control system has the following advantages:
- Use of reusable electrodes of the HeartSave defibrillator and other models.
- More affordable price.
- The best option for doctors, as it allows them to independently monitor the patient’s condition thanks to a wide range of functions.
Among the disadvantages is that use requires serious skills and knowledge. The mechanism is also quite large in size and weight.
Terms of use
When using a defibrillator, you need to know a few basic points:
- The patient's chest must first be completely cleared of clothing, jewelry, and jewelry.
- Only specially selected gels can be used.
- If possible, it is better to use gels in solid form. They will not need to be removed from the surface of the device later.
- Although wet electrodes distribute the current more evenly, they are safe for the doctor.
The choice of this medical equipment on the market is represented by a fairly wide range. All types have both their advantages and significant disadvantages.
Published 09/03/2016 by admin. Category: Uncategorized.
Batteries for defibrillators Metrax, HeartSave, AkuPak
Patient cable for ECG
Characteristics of modern defibrillators
A defibrillator is a medical device designed for electrical pulse therapy for cardiac arrhythmias. The main indications for its use are arrhythmia and ventricular fibrillation.
When the heart stops, sometimes minutes and even seconds count, and it is not always possible to quickly transport the patient to the hospital. Compact, lightweight and easy to use, modern models of defibrillators allow this device to be used outside of medical institutions, which saves the lives of a huge number of people.
Types of defibrillators
There are several types of modern devices that restore heart rhythm fibrillation. These include:
- professional defibrillator (manual control) - has the necessary set of functions and is controlled manually using buttons. The electrical discharge is transmitted by discharge electrodes in the form of irons, which are pressed tightly to the chest;
- automatic defibrillator - independently recognizes heart rhythm disturbances and signals the health worker to perform a shock, which is carried out through disposable sticky electrodes glued to the patient’s chest;
- An implantable defibrillator is an ultra-small device that is implanted into the human body during surgery. It is often combined with a pacemaker. Implantable devices are necessary for people with severe and dangerous heart rhythm disorders.
Features of the device
Experienced, appropriately trained doctors and paramedics are allowed to work with professional fibrillation devices. In emergency cases, devices operating in automatic mode can be used not only by medical workers, but also by persons without medical education - rescuers, flight attendants, sports trainers, etc.
Some models of professional defibrillators may have an automatic mode function. Such a device is called universal.
There are two types of defibrillating impulse in devices:
- monopolar (monophasic);
- bipolar (biphasic).
The most modern and effective is the biphasic pulse. Devices with a monophasic pulse today can only be purchased on the secondary market for medical equipment.
The latest generation devices operate not only from the electrical network, but also from a battery or batteries. A fully charged battery can keep the device operational for several hours.
Automatic defibrillators-monitors are more convenient to use and popular. They are equipped with a screen, a printer and have the ability to store received data in memory. Such devices minimize the probability of error to zero.
Therapy. AC defibrillators.
In cases where circulatory arrest is caused by ventricular fibrillation, attempts should be made, after resumption of blood circulation using external cardiac massage, to stop fibrillation and resume regular ventricular activity. This is done using electrical defibrillation.
Previously, AC defibrillators were used for this purpose. But over the past few years they have been completely replaced by DC defibrillators, with which an electrical shock is caused by discharging a capacitor that charges within tenths of a second. This type of defibrillator does not require special strong electrical fuses or grounding like the old defibrillator. The pulses from a DC defibrillator are strong and occur over a very short period of time (3 m/s). During this time, more clearly than when using impulses from an AC defibrillator, synchronization of the ventricular ECG complex is carried out during defibrillation of atrial fibrillation. Currently, the normalization of atrial contractions is carried out mainly by electrical defibrillation discharge, and not, as before, by the administration of quinidine. For electrical atrial defibrillation, the defibrillator must be combined with a mobile ECG recording machine and a synchronizing device. With the help of such a device, defibrillation is carried out in the appropriate phase of the ventricular ECG complex. If defibrillation is performed outside the appropriate phase of electrical activity of the heart, ventricular fibrillation may resume. It has recently been shown that the absence of a synchronizer is not a reason to refuse defibrillation when the patient's condition requires it. Since treatment of atrial fibrillation is not particularly urgently needed in most cases, it is probably appropriate that these devices are not included in the intensive care unit budget. They should be referred rather to a physical therapy laboratory or specialist clinic, although this procedure should be performed in an intensive care unit.
Treatment of patients in the intensive care unit requires fairly frequent x-ray examinations. Therefore, the department needs an X-ray machine. The inconvenience of X-ray examination is that when moving the device through the “air lock,” the insulation of the room is broken. Moreover, the device must be thoroughly disinfected between uses in different rooms. The inconvenience can, however, be somewhat compensated for if each room is equipped with a wall with an X-ray outlet with its own cable and protective apron. In this case, the insulation will be violated only when the device is imported and exported. For these purposes, you should choose a convenient, lightweight moving X-ray machine. In order to avoid excessive workload with various equipment that is not needed on a daily basis or which, for financial reasons, cannot be provided in every room, it is advisable that the department have a special room for equipment. It stores ventilators, a defibrillator, a pacemaker, a dialysis machine, cardioscopes, suction machines for lobectomy, anesthesia machines and operating lamps. Intensive therapy should include a certain amount of laboratory work. In large hospitals with a good laboratory in the department itself, you can limit yourself to only what is necessary for analyzing blood gases and acid-base status. Since central laboratories and special laboratories are busy, agreement should be reached on the procedure for conducting tests required for the intensive care unit.
