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This is probably the most famous medical device in the world. Thanks to the films, many believe that with the help of a defibrillator, you can bring back to life after a cardiac arrest. Do you remember the shots where the patient lies lifeless on the couch, a straight line is visible on medical monitors, and the doctor yells: “Defibrillator!”? Then, according to the classics of the genre, the doctor must shout “Discharge!” several times, pressing the device to the patient’s chest, and – lo and behold! – the patient again had a pulse, and the straight line returned to the “live” curvature. Everything seems to be correct, no fantasy: the heart stopped and it was stimulated by an electric discharge. The heroes of the film rejoice – the patient will live, the audience calms down after the happy denouement of the climactic scene, and only those who work with the same defibrillator in real life watch such shots with a smirk. Well, this device cannot resurrect from the dead and start a stopped heart! Then why is it needed and in what cases do real doctors use a defibrillator? In principle, the answer to this question is already in the very name of the device, but for everyone who does not have a medical education, we will try to explain in a more accessible way what a defibrillator is.
What does the heart need to beat?
On average, the human heart beats 60 to 100 times per minute. This is due to the work of special stimulating cells in the upper wall of the right atrium (the so-called sinoatrial node). Thanks to them, an electrical differential is created between the outer and inner side of the cell membrane. At some point, they send an impulse through the entire heart muscle to its lower part, causing the muscle to contract. It would seem that since the heart works from the impulses sent, then what is wrong with electrical stimulation from the outside? To understand this, let’s move on.
The electrical differential in the sinoatrial node is created for a reason, but due to the presence of potassium, sodium and calcium electrolytes. The electric charge from them passes through the cell walls through special channels (each has its own). A moment before the contraction of the heart muscle, potassium is contained inside the cells, and calcium and sodium are outside. When sodium enters the cell, it begins to squeeze potassium out, thereby creating an electrical potential. Then the channels for calcium open and it also breaks inward. This creates the charge necessary for the impulse. Then the impulse from the sinoatrial node goes to the atrium, and then the pulse originates in another node (atrioventricular). Through this complex circuit, blood is pumped from the upper heart to the lower, and the impulse spreads to other parts of the heart muscle. And only the correct operation of this whole mechanism can create a heartbeat.
If the system fails, different consequences are possible. But we are now interested in the state of fibrillation. This happens if the sinoatrial node does not produce the impulse necessary for the heart. Then the cells of the heart muscle try for some time to create the necessary impulse themselves, but in this case, the contraction of different parts of the heart goes out of order (fibrillation begins) and the muscle loses its ability to pump blood. It is clear that it will not be able to continue for so long and soon cardiac arrest occurs. But while the muscle is still in a state of fibrillation, there is hope for a defibrillator.
When to Use a Defibrillator
A defibrillator is a device used in medicine to eliminate the state of fibrillation, that is, uneven, rapid, arrhythmic and unproductive contraction of the heart muscle, atria or ventricles.
The state of fibrillation on the cardiogram will look like a curved line with many small jumps up and down (and not like a straight line from the movies). Such a graph indicates that different parts of the heart contract with different strengths and with their own rhythm. And just the electric discharge gives a chance to restore the correct rhythm of contractions. The impact of an electric current, more powerful than the contraction of the heart muscle, allows you to align this process and make different parts of the heart work in unison again.
The “miracle” of the defibrillator is that the electric current activates the electrolytes and they again begin to pass through the channels in their “schedule”. But that same straight line on the heart monitors is asystole. She says that the electrolytes necessary to create an impulse are absent in the cells. The task of doctors is to apply defibrillation before the patient begins asystole. Later, all the defibrillator can do is burn the heart with the heat of the discharge.
Medical indications for defibrillation:
- ventricular fibrillation (chaotic contraction at a speed of 200-300 beats per minute);
- ventricular flutter (rhythmic contraction, but at a speed of about 300 beats per minute);
- atrial flutter (rhythmic but rapid contraction up to 240 beats per minute);
- atrial fibrillation (chaotic contraction, 300 beats per minute).
With ventricular fibrillation, the so-called emergency defibrillation is carried out (what, in fact, is shown in the films).
In case of atrial rhythm disturbances, the procedure can be done as planned. In such cases, they speak of cardioversion.
When the procedure is not done
The only contraindication to the use of a defibrillator is cardiac arrest. In such cases, the procedure using electric current will be simply useless. It is more correct to spend this time on other methods of resuscitation that are more effective in such a situation.
In cardiac arrest, doctors usually try to save the patient with chest compressions and mechanical ventilation, the patient is given epinephrine, adrenaline, atropine, sodium bicarbonate.
Contraindications for elective defibrillation:
- the presence of blood clots in the atria;
- sinus or polytopic atrial tachycardia;
- electrolyte disturbances;
- contraindications to anesthesia;
- glycoside poisoning.
What is a defibrillator
A defibrillator is a medical device designed to apply electrical current to the heart muscle in order to restore and synchronize its rhythm. For the procedure, high voltage (about 1000 volts) is used. During “shock therapy”, the patient’s heart receives approximately 300 J of electricity (approximately the same amount uses a 100-watt lamp in 3 seconds).
The defibrillation method was first used in 1899. It was a scientific study on animals. Two physiologists from the University of Geneva found that applying a small electric shock to the heart can cause ventricular fibrillation, while a more powerful current, on the contrary, eliminates this process.
The first person to experience the effect of an electrical discharge procedure was a 14-year-old boy. In 1947, professor of surgical sciences Claude Beck managed to restore a normal heart rhythm in a child with the help of an electric current. In the Soviet Union, electric current treatment was initiated by V. Eskin and A. Klimov. In 1959, Bernard Lown and Baruch Berkowitz determined the optimal procedure time for different cases of arrhythmias.
The first portable defibrillator was created in 1965. The device was invented by a professor from Northern Ireland, Frank Pantridge.
The fact that in the 1960s the defibrillator could only be used in medical facilities, but many patients with heart disease died on the way to the hospital, prompted the creation of the doctor’s apparatus. Pantridge’s invention was very different from today’s portable machines. The device weighed about 70 kilograms, and huge lead plates served as “irons” in it. But even such a device could already be transported in ambulances, and this was its huge plus.
What are the
Defibrillators of the new generation are, as a rule, multifunctional devices that also take on the functions of a pacemaker and a cardioscope. But not all heart stimulation devices are equally sophisticated.
Today, there are 4 types of devices on the medical equipment market:
- professional;
- automatic;
- universal (combined);
- implantable.
A professional defibrillator is a multifunctional device commonly used in intensive care units and emergency departments. This is the same device known from films, consisting of two electrodes – “ironing pads” applied to the patient’s chest.
Only specially trained doctors can work with such a device, since the resuscitator has to determine the power of the discharge and the duration of the procedure on an individual basis.
In addition, during defibrillation, it is important to correctly place the paddles. For the procedure, the patient is laid on a flat hard surface, freed from clothing, and the “irons” are treated with a special current conductor gel.
The electrodes are pressed against the chest with a force of 8-10 kg. During exposure to the discharge to the body of the patient, as well as the surface on which he lies, it is forbidden to touch.
Devices of this type are usually equipped with a monitor and a built-in printer. The advantage of a professional defibrillator is the possibility of reusable electrodes, which ultimately affects the cost of consumables. But he also has disadvantages.
In particular, a device of this type is very large and more suitable for stationary use. It is quite capricious in care, requires special maintenance. In addition, not every doctor will be able to work with such a device.
An automatic defibrillator requires minimal involvement of the resuscitator. Such devices independently recognize heart rhythm disturbances and give a signal when to perform a shock.
Unlike professional devices, automatic devices are not equipped with “irons”, but with disposable Velcro electrodes that are fixed on the patient’s chest. These devices can only be operated by people with basic medical training.
Devices are popular among rescuers, volunteers, sports trainers. This type of defibrillator can be found in hotels, on board aircraft and on trains.
The list of advantages of automatic models includes compactness, ease of storage and transportation, as well as the ability to use the device without special skills and knowledge. The main disadvantages of the device are the high cost and the lack of some functions inherent in professional models.
The combined defibrillation device is a versatile model that combines the functions of a professional and automatic device. More precisely, this is an automatic device, complemented by a display, a printer and elements for manual control.
An implantable defibrillator is a miniature device designed to be sewn in. Often used in conjunction with a pacemaker. In addition, there are mini-defibrillators that are fixed on the patient’s body. Such devices constantly monitor the heart rate and, if necessary, act on the muscle with an electrical discharge.
According to the type of pulses generated, implantable devices are monophasic (less commonly used) and bipolar (more effective, more often used in modern medical practice).
The human body is made up of a huge number of different muscles. But there is one among them, on which absolutely everything depends. This is the heart. It rarely stops instantly.
Before the heart muscle finally stops pumping blood, it will still make weak attempts to contract for some time.
It is at this time that there is still a chance to save a person. Of course, if there is a defibrillator and a qualified doctor nearby.