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109-517: There are multiple factors during cardiopulmonary resuscitation (CPR) and defibrillation that are associated with success of achieving return of spontaneous circulation. One of the factors in CPR is the chest compression fraction, which is a measure of how much time during cardiac arrest are chest compressions performed. A study measured the effects of chest compression fraction on return of spontaneous circulation in out-of-hospital cardiac arrest patients with

218-470: A thoracotomy and possess pacing , cardioversion, and defibrillation capabilities. The invention of implantable units is invaluable to some people with regular heart problems, although they are generally only given to those people who have already had a cardiac episode. People can live long normal lives with the devices. Many patients have multiple implants. A patient in Houston, Texas had an implant at

327-420: A device to externally jump start the heart. He invented the defibrillator and tested it on a dog, like Prévost and Batelli. The first use on a human was in 1947 by Claude Beck , professor of surgery at Case Western Reserve University . Beck's theory was that ventricular fibrillation often occurred in hearts that were fundamentally healthy, in his terms "Hearts that are too good to die", and that there must be

436-515: A federal program in the National Institute of Health in physiology and medicine, telling Congress: "Let's compete with U.S.S.R. in research on reversibility of death". In 1959 Bernard Lown commenced research in his animal laboratory in collaboration with engineer Barouh Berkovits into a technique which involved charging of a bank of capacitors to approximately 1000 volts with an energy content of 100–200 joules then delivering

545-469: A healthcare professional. They are used in conjunction with an electrocardiogram , which can be separate or built-in. A healthcare provider first diagnoses the cardiac rhythm and then manually determine the voltage and timing for the electrical shock. These units are primarily found in hospitals and on some ambulances . For instance, every NHS ambulance in the United Kingdom is equipped with

654-667: A heart attack and, purely by chance, the ambulance that responded to the call carried a defibrillator. After recovering, Kerry Packer donated a large sum to the Ambulance Service of New South Wales in order that all ambulances in New South Wales should be fitted with a personal defibrillator, which is why defibrillators in Australia are sometimes colloquially called "Packer Whackers". Cardiopulmonary resuscitation Cardiopulmonary resuscitation ( CPR )

763-414: A mainly uniphasic characteristic. Biphasic defibrillation alternates the direction of the pulses, completing one cycle in approximately 12 milliseconds. Biphasic defibrillation was originally developed and used for implantable cardioverter-defibrillators. When applied to external defibrillators, biphasic defibrillation significantly decreases the energy level necessary for successful defibrillation, decreasing

872-544: A manual defibrillator for use by the attending paramedics and technicians. In the United States , many advanced EMTs and all paramedics are trained to recognize lethal arrhythmias and deliver appropriate electrical therapy with a manual defibrillator when appropriate. An internal defibrillator is often used to defibrillate the heart during or after cardiac surgery such as a heart bypass . The electrodes consist of round metal plates that come in direct contact with

981-531: A nearby AED defibrillator should be used on the patient as soon as possible. As a general reference, defibrillation is preferred to performing CPR, but only if the AED can be retrieved in a short period of time. All these tasks (calling by phone, getting an AED, and the chest compressions and rescue breaths maneuvers of CPR) can be distributed between many rescuers who make them simultaneously. The defibrillator itself would indicate if more CPR maneuvers are required. As

1090-400: A non-ventricular fibrillation arrhythmia and it showed a trend to achieving return of spontaneous circulation with an increased chest compression fraction. Another study highlighted the benefits of minimizing chest compression intervals before and after shocking a patient's rhythm, which would in turn increase chest compression fraction. A coronary perfusion pressure of 15 mmHg is thought to be

1199-412: A perfusing cardiac rhythm. These early defibrillators used the alternating current from a power socket, transformed from the 110–240 volts available in the line, up to between 300 and 1000 volts, to the exposed heart by way of "paddle" type electrodes. The technique was often ineffective in reverting VF while morphological studies showed damage to the cells of the heart muscle post-mortem. The nature of

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1308-465: A plausible and practical application." The problems to be overcome were the design of a system which would allow detection of ventricular fibrillation or ventricular tachycardia. Despite the lack of financial backing and grants, they persisted and the first device was implanted in February 1980 at Johns Hopkins Hospital by Dr. Levi Watkins Jr. assisted by Vivien Thomas . Modern ICDs do not require

1417-572: A portable machine that can be used with no previous training. That is possible because the machine produces pre-recorded voice instructions that guide the user. The device automatically checks the patient's condition and applies the correct electric shocks. There also exist written instructions that explain the procedure step-by-step. Survival rates for out-of-hospital cardiac arrests in North America are poor, often less than 10%. Outcome for in-hospital cardiac arrests are higher at 20%. Within

1526-464: A pulse), if the victim is a child. It can be difficult to determine the presence or absence of a pulse, so the pulse check has been removed for common providers and should not be performed for more than 10 seconds by healthcare providers. For untrained rescuers helping adult victims of cardiac arrest, it is recommended to perform compression-only CPR (chest compressions hands-only or cardiocerebral resuscitation, without artificial ventilation ), as it

1635-445: A rate of 1 breath every 6 to 8 seconds (8–10 ventilations per minute). In all victims, the compression speed is of at least 100 compressions per minute. Recommended compression depth in adults and children is of 5 cm (2 inches), and in infants it is 4 cm (1.6 inches). In adults, rescuers should use two hands for the chest compressions (one on the top of the other), while in children one hand could be enough (or two, adapting

1744-441: A rate of at least 100 to 120 per minute. The rescuer may also provide artificial ventilation by either exhaling air into the subject's mouth or nose ( mouth-to-mouth resuscitation ) or using a device that pushes air into the subject's lungs ( mechanical ventilation ). Current recommendations place emphasis on early and high-quality chest compressions over artificial ventilation; a simplified CPR method involving only chest compressions

1853-467: A result, it does not require a trained health provider to determine whether or not a rhythm is shockable. By making these units publicly available, AEDs have improved outcomes for sudden out-of-hospital cardiac arrests. Trained health professionals have more limited use for AEDs than manual external defibrillators. Recent studies show that AEDs does not improve outcome in patients with in-hospital cardiac arrests. AEDs have set voltages and does not allow

1962-412: A ring magnet to place over the device, which effectively disables the shock function of the device while still allowing the pacemaker to function (if the device is so equipped). If the device is shocking frequently, but appropriately, EMS personnel may administer sedation. A wearable cardioverter defibrillator is a portable external defibrillator that can be worn by at-risk patients. The unit monitors

2071-451: A slight variation for that sequence, if the rescuer is completely alone with a victim of drowning, or with a child who was already unconscious when the rescuer arrived, the rescuer would do the CPR maneuvers during 2 minutes (approximately 5 cycles of ventilations and compressions); after that, the rescuer would call to emergency medical services, and then it could be tried a search for a defibrillator nearby (the CPR maneuvers are supposed to be

2180-431: A software modeling system capable of mapping an individual's chest and determining the best position for an external or internal cardiac defibrillator. Defibrillation halts chaotic cardiac activity by forcibly depolarizing heart cells, disrupting re-entrant circuits, and allowing for the heart's natural pacemaker to take over. Cardiac cells require a strong electrical stimulus to raise their transmembrane potential to

2289-416: A sort of arrhythmia that will stop the heart immediately), it is recommended that someone asks for a defibrillator (because they are quite common in the present time), for trying with it a defibrillation on the already unconscious victim, in case it is successful. Order of defibrillation in a first aid sequence It is recommended calling for emergency medical services before a defibrillation. Afterwards,

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2398-511: A sufficient speed and depth of compressions, completely relaxing pressure between compressions, and not ventilating too much. It is unclear if a few minutes of CPR before defibrillation results in different outcomes than immediate defibrillation. A normal CPR procedure uses chest compressions and ventilations (rescue breaths, usually mouth-to-mouth) for any victim of cardiac arrest, who would be unresponsive (usually unconscious or approximately unconscious), not breathing or only gasping because of

2507-482: A way of saving them. Beck first used the technique successfully on a 14-year-old boy who was having his breastbone separated from his ribs because of a congenital growth disorder, causing breathing problems. The boy's chest was surgically opened, and manual cardiac massage was undertaken for 45 minutes until the arrival of the defibrillator. Beck used internal paddles on either side of the heart, along with procainamide , an antiarrhythmic drug, and achieved return of

2616-432: Is a treatment for life-threatening cardiac arrhythmias , specifically ventricular fibrillation (V-Fib) and non-perfusing ventricular tachycardia (V-Tach). A defibrillator delivers a dose of electric current (often called a counter-shock ) to the heart . Although not fully understood, this process depolarizes a large amount of the heart muscle , ending the arrhythmia. Subsequently, the body's natural pacemaker in

2725-554: Is an emergency procedure consisting of chest compressions often combined with artificial ventilation , or mouth to mouth in an effort to manually preserve intact brain function until further measures are taken to restore spontaneous blood circulation and breathing in a person who is in cardiac arrest . It is recommended for those who are unresponsive with no breathing or abnormal breathing, for example, agonal respirations . CPR involves chest compressions for adults between 5 cm (2.0 in) and 6 cm (2.4 in) deep and at

2834-476: Is an electrical shock delivered in synchrony to the cardiac cycle . Although the person may still be critically ill , cardioversion normally aims to end poorly perfusing cardiac arrhythmias , such as supraventricular tachycardia . Defibrillators can be external, transvenous, or implanted ( implantable cardioverter-defibrillator ), depending on the type of device used or needed. Some external units, known as automated external defibrillators (AEDs), automate

2943-419: Is associated with a worse presentation of PCAS. Lazarus phenomenon is the rare spontaneous return of circulation after cardiopulmonary resuscitation attempts have stopped in someone with cardiac arrest. This phenomenon most frequently occurs within 10 minutes of cessation of resuscitation, thus passive monitoring is recommended for 10 minutes following CPR cessation. Defibrillation Defibrillation

3052-418: Is easier to perform and instructions are easier to give over a phone. In adults with out-of-hospital cardiac arrest , compression-only CPR by the average person has an equal or higher success rate than standard CPR. The CPR 'compressions only' procedure consists only of chest compressions that push on the lower half of the bone that is in the middle of the chest (the sternum ). Compression-only CPR

3161-416: Is effective only for certain heart rhythms, namely ventricular fibrillation or pulseless ventricular tachycardia , rather than asystole or pulseless electrical activity , which usually requires the treatment of underlying conditions to restore cardiac function. Early shock, when appropriate, is recommended. CPR may succeed in inducing a heart rhythm that may be shockable. In general, CPR is continued until

3270-468: Is effective only if performed within seven minutes of the stoppage of blood flow. The heart also rapidly loses the ability to maintain a normal rhythm. Low body temperatures, as sometimes seen in near-drownings, prolong the time the brain survives. Following cardiac arrest, effective CPR enables enough oxygen to reach the brain to delay brain stem death , and allows the heart to remain responsive to defibrillation attempts. If an incorrect compression rate

3379-464: Is likely to occur (but has not yet), self-adhesive pads may be placed prophylactically. Pads also offer an advantage to the untrained user, and to medics working in the sub-optimal conditions of the field. Pads do not require extra leads to be attached for monitoring, and they do not require any force to be applied as the shock is delivered. Thus, adhesive electrodes minimize the risk of the operator coming into physical (and thus electrical) contact with

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3488-416: Is manual squeezing of the exposed heart itself carried out through a surgical incision into the chest cavity , usually when the chest is already open for cardiac surgery. Active compression-decompression methods using mechanical decompression of the chest have not been shown to improve outcome in cardiac arrest. A defibrillator is a machine that produces a defibrillation: electric shocks that can restore

3597-529: Is necessary for survival, it is not, itself, a predictor of a favorable medium- or long-term outcome. Patients have died not long after their circulation has returned. One study showed that those who had had an out-of-hospital cardiac arrest and had achieved return of spontaneous circulation, 38% of those people had a cardiac re-arrest before arriving at the hospital with an average time of 3 minutes to re-arrest. Patients with sustained ROSC generally present with post-cardiac arrest syndrome (PCAS). Longer time-to-ROSC

3706-406: Is necessary for the ventilations, because of the size of the baby's neck. In CPR, the chest compressions push on the lower half of the sternum —the bone that is along the middle of the chest from the neck to the belly— and leave it rise up until recovering its normal position. The rescue breaths are made by pinching the victim's nose and blowing air mouth-to-mouth. This fills the lungs, which makes

3815-612: Is not as good for children who are more likely to have cardiac arrest from respiratory causes. Two reviews have found that compression-only CPR had no more success than no CPR whatsoever. Rescue breaths for children and especially for babies should be relatively gentle. Either a ratio of compressions to breaths of 30:2 or 15:2 was found to have better results for children. Both children and adults should receive 100 chest compressions per minute. Other exceptions besides children include cases of drownings and drug overdose ; in both these cases, compressions and rescue breaths are recommended if

3924-442: Is not indicated if the patient has a normal pulse or is still conscious. Also, it is not indicated in asystole or pulseless electrical activity (PEA) , in those cases a normal CPR would be used to oxygenate the brain until the heart function can be restored. Improperly given electrical shocks can cause dangerous arrhythmias , such as the ventricular fibrillation (VF) . When a patient does not have heart beatings (or they present

4033-400: Is not normal medical practice, as the heart cannot be restarted by the defibrillator itself. Only the cardiac arrest rhythms ventricular fibrillation and pulseless ventricular tachycardia are normally defibrillated. The purpose of defibrillation is to depolarize the entire heart all at once so that it is synchronized, effectively inducing temporary asystole, in the hope that in the absence of

4142-415: Is recommended for untrained rescuers. With children, however, 2015 American Heart Association guidelines indicate that doing only compressions may actually result in worse outcomes, because such problems in children normally arise from respiratory issues rather than from cardiac ones, given their young age. Chest compression to breathing ratios is set at 30 to 2 in adults. CPR alone is unlikely to restart

4251-488: Is required, the machine is charged, and the shock is delivered, without any need to apply any additional gel or to retrieve and place any paddles. Most adhesive electrodes are designed to be used not only for defibrillation, but also for transcutaneous pacing and synchronized electrical cardioversion . These adhesive pads are found on most automated and semi-automated units and are replacing paddles entirely in non-hospital settings. In hospital, for cases where cardiac arrest

4360-473: Is superior to compression-only CPR. Standard CPR is performed with the victim in supine position . Prone CPR, or reverse CPR, is performed on a victim in prone position , lying on the chest. This is achieved by turning the head to the side and compressing the back. Due to the head being turned, the risk of vomiting and complications caused by aspiration pneumonia may be reduced. The American Heart Association's current guidelines recommend performing CPR in

4469-546: Is that the CPR ventilations (rescue breaths) are considered the most important action for those victims. Cardiac arrest in drowning victims originates from a lack of oxygen, and a child would probably not suffer from cardiac diseases. The reason is that the phone call is considered urgent. In 2010, the AHA and International Liaison Committee on Resuscitation updated their CPR guidelines. The importance of high quality CPR (sufficient rate and depth without excessively ventilating)

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4578-534: Is the basis for modern defibrillators. A major breakthrough was the introduction of portable defibrillators used out of the hospital. Already Peleška's Prema defibrillator was designed to be more portable than original Gurvich's model. In Soviet Union, a portable version of Gurvich's defibrillator, model ДПА-3 (DPA-3), was reported in 1959. In the west this was pioneered in the early 1960s by Prof. Frank Pantridge in Belfast . Today portable defibrillators are among

4687-482: Is the traditional metal "hard" paddle with an insulated (usually plastic) handle. This type must be held in place on the patient's skin with approximately 25 lbs (11.3 kg) of force while a shock or a series of shocks is delivered. Paddles offer a few advantages over self-adhesive pads. Many hospitals in the United States continue the use of paddles, with disposable gel pads attached in most cases, due to

4796-417: Is used during CPR, going against standing American Heart Association (AHA) guidelines of 100–120 compressions per minute, this can cause a net decrease in venous return of blood, for what is required, to fill the heart. For example, if a compression rate of above 120 compressions per minute is used consistently throughout the entire CPR process, this error could adversely affect survival rates and outcomes for

4905-402: The sinoatrial node of the heart is able to re-establish normal sinus rhythm . A heart which is in asystole (flatline) cannot be restarted by a defibrillator; it would be treated only by cardiopulmonary resuscitation (CPR) and medication, and then by cardioversion or defibrillation if it converts into a shockable rhythm. In contrast to defibrillation, synchronized electrical cardioversion

5014-465: The supine position , and limits prone CPR to situations where the patient cannot be turned. During pregnancy when a woman is lying on her back, the uterus may compress the inferior vena cava and thus decrease venous return. It is therefore recommended that the uterus be pushed to the woman's left. This can be done by placing a pillow or towel under her right hip so that she is on an angle of 15–30 degrees, and making sure their shoulders are flat to

5123-495: The AC machine with a large transformer also made these units very hard to transport, and they tended to be large units on wheels. Until the early 1950s, defibrillation of the heart was possible only when the chest cavity was open during surgery. The technique used an alternating voltage from a 300 or greater volt source derived from standard AC power, delivered to the sides of the exposed heart by "paddle" electrodes where each electrode

5232-572: The Beth Davis Hospital of New York City and C. Henry Hyman, an electrical engineer, looking for an alternative to injecting powerful drugs directly into the heart, came up with an invention that used an electrical shock in place of drug injection. This invention was called the Hyman Otor where a hollow needle is used to pass an insulated wire to the heart area to deliver the electrical shock. The hollow steel needle acted as one end of

5341-473: The DC discharge) which would burn the patient. Gel may be either wet (similar in consistency to surgical lubricant ) or solid (similar to gummi candy ). Solid-gel is more convenient, because there is no need to clean the used gel off the person's skin after defibrillation. However, the use of solid-gel presents a higher risk of burns during defibrillation, since wet-gel electrodes more evenly conduct electricity into

5450-547: The activation threshold. Only a small amount of electrical current enters the cell due to high membrane impedance. The intracellular voltage of the cell remains uniform, while the extracellular voltage rapidly increases or decreases depending on proximity to the electrodes. This creates a voltage gradient that alters the transmembrane potential of cells, potentially resetting irregular electrical activity to restore normal cardiac rhythm. Irregular rhythms often result from re-entrant circuits, where electrical impulses circle within

5559-418: The age of 18 in 1994 by the recent Dr. Antonio Pacifico. He was awarded "Youngest Patient with Defibrillator" in 1996. Today these devices are implanted into small babies shortly after birth. As devices that can quickly produce dramatic improvements in patient health, defibrillators are often depicted in movies, television, video games and other fictional media. Their function, however, is often exaggerated with

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5668-400: The age of 8 or those under 55 lbs. (22 kg). Resuscitation electrodes are placed according to one of two schemes. The anterior-posterior scheme is the preferred scheme for long-term electrode placement. One electrode is placed over the left precordium (the lower part of the chest, in front of the heart). The other electrode is placed on the back, behind the heart in the region between

5777-430: The algorithm for basic life support (BLS). Many first responders , such as firefighters, police officers, and security guards, are equipped with them. AEDs can be fully automatic or semi-automatic. A semi-automatic AED automatically diagnoses heart rhythms and determines if a shock is necessary. If a shock is advised, the user must then push a button to administer the shock. A fully automated AED automatically diagnoses

5886-430: The availability of Automated External Defibrillators. These devices can analyse the heart rhythm by themselves, diagnose the shockable rhythms, and charge to treat. This means that no clinical skill is required in their use, allowing lay people to respond to emergencies effectively. Until the mid 1990s, external defibrillators delivered a Lown type waveform (see Bernard Lown ), a heavily damped sinusoidal impulse having

5995-558: The blood and maintain a cardiac output to keep vital organs alive. Blood circulation and oxygenation are required to transport oxygen to the tissues. The physiology of CPR involves generating a pressure gradient between the arterial and venous vascular beds; CPR achieves this via multiple mechanisms. The brain may sustain damage after blood flow has been stopped for about four minutes and irreversible damage after about seven minutes. Typically if blood flow ceases for one to two hours, then body cells die . Therefore, in general CPR

6104-683: The body. Paddle electrodes, which were the first type developed, come without gel, and must have the gel applied in a separate step. Self-adhesive electrodes come prefitted with gel. There is a general division of opinion over which type of electrode is superior in hospital settings; the American Heart Association favors neither, and all modern manual defibrillators used in hospitals allow for swift switching between self-adhesive pads and traditional paddles. Each type of electrode has its merits and demerits. The most well-known type of electrode (widely depicted in films and television)

6213-582: The bystander is trained and is willing to do so. As per the AHA, the beat of the Bee Gees song " Stayin' Alive " provides an ideal rhythm in terms of beats per minute to use for hands-only CPR, which is 104 beats-per-minute. One can also hum Queen 's " Another One Bites the Dust ", which is 110 beats-per-minute and contains a repeating drum pattern. For those in cardiac arrest due to non-heart related causes and in people less than 20 years of age, standard CPR

6322-404: The case of babies. Water and metals transmit the electric current. This depends on the amount of water, but it is convenient to avoid starting the defibrillation on a floor with puddles, and to dry the wet areas of the patient before (fast, even with any cloth, if that could be enough). It is not necessary to remove the patient's jewels or piercings, but it should be avoided placing the patches of

6431-417: The charge through an inductance such as to produce a heavily damped sinusoidal wave of finite duration (~5 milliseconds ) to the heart by way of paddle electrodes. This team further developed an understanding of the optimal timing of shock delivery in the cardiac cycle, enabling the application of the device to arrhythmias such as atrial fibrillation , atrial flutter , and supraventricular tachycardias in

6540-436: The chest and the other on the back (no matter which of them). There are several devices for improving CPR, but only defibrillators (as of 2010) have been found better than standard CPR for an out-of-hospital cardiac arrest. When a defibrillator has been used, it should remain attached to the patient until emergency services arrive. Timing devices can feature a metronome (an item carried by many ambulance crews) to assist

6649-571: The chest to rise up, and increases the pressure into the thoracic cavity. If the victim is a baby, the rescuer would compress the chest with only 2 fingers and would make the ventilations using their own mouth to cover the baby's mouth and nose at the same time. The recommended compression-to-ventilation ratio, for all victims of any age, is 30:2 (a cycle that alternates continually 30 rhythmic chest compressions series and 2 rescue breaths series). Victims of drowning receive an initial series of 2 rescue breaths before that cycle begins. As an exception for

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6758-433: The circuit and the tip of the insulated wire the other end. Whether the Hyman Otor was a success is unknown. The external defibrillator, as it is known today, was invented by electrical engineer William Kouwenhoven in 1930. Kouwenhoven studied the relationship between electric shocks and their effects on the human heart when he was a student at Johns Hopkins University School of Engineering. His studies helped him invent

6867-474: The compressions to the child's constitution), and with babies the rescuer must use only two fingers. There exist some plastic shields and respirators that can be used in the rescue breaths between the mouths of the rescuer and the victim, with the purposes of sealing a better vacuum and avoiding infections. In some cases, the problem is one of the failures in the rhythm of the heart (ventricular fibrillation and ventricular tachycardia) that can be corrected with

6976-476: The correct shocks if they are needed. The time in which a cardiopulmonary resuscitation can still work is not clear, and it depends on many factors. Many official guides recommend continuing a cardiopulmonary resuscitation until emergency medical services arrive (for trying to keep the patient alive, at least). The same guides also indicate asking for any emergency defibrillator (AED) near, to try an automatic defibrillation as soon as possible before considering that

7085-413: The defibrillator are considered urgent when the problem has a cardiac origin). Defibrillation The standard defibrillation device, prepared for a fast use out of the medical centres, is the automated external defibrillator (AED), a portable machine of small size (similar to a briefcase) that can be used by any user with no previous training. That machine produces recorded voice instructions that guide to

7194-441: The defibrillator directly on top of them. The patches with electrodes are put on the positions that appear at the right. In very small bodies: children between 1 and 8 years, and, in general, similar bodies up to 25 kg approximately, it is recommended the use of children's size patches with reduced electric doses. If that is not possible, sizes and doses for adults would be used, and, if the patches were too big, one would be placed on

7303-414: The defibrillator inducing a sudden, violent jerk or convulsion by the patient. The pad placement is also shown wrong, along with sudden rising of patient to large height when shock is given. In reality, while the muscles may contract, such dramatic patient presentation is rare. Similarly, medical providers are often depicted defibrillating patients with a "flat-line" ECG rhythm (also known as asystole ). This

7412-485: The diagnosis of treatable rhythms, meaning that lay responders or bystanders are able to use them successfully with little or no training. Defibrillation is often an important step in cardiopulmonary resuscitation (CPR). CPR is an algorithm-based intervention aimed to restore cardiac and pulmonary function. Defibrillation is indicated only in certain types of cardiac dysrhythmias , specifically ventricular fibrillation (VF) and pulseless ventricular tachycardia . If

7521-470: The electric shock of a defibrillator . So, if a victim is suffering a cardiac arrest, it is important that someone asks for a defibrillator nearby, to try with it a defibrillation process when the victim is already unconscious. The common model of defibrillator (the AED) is an automatic portable machine that guides to the user with recorded voice instructions along the process, and analyzes the victim, and applies

7630-500: The ground. If this is not effective, healthcare professionals should consider emergency resuscitative hysterotomy . Evidence generally supports family being present during CPR. This includes in CPR for children. Interposed abdominal compressions may be beneficial in the hospital environment. There is no evidence of benefit pre-hospital or in children. Cooling during CPR is being studied as currently results are unclear whether or not it improves outcomes. Internal cardiac massage

7739-405: The group of people presenting with cardiac arrest, the specific cardiac rhythm can significantly impact survival rates. Compared to people presenting with a non-shockable rhythm (such as asystole or PEA), people with a shockable rhythm (such as VF or pulseless ventricular tachycardia) have improved survival rates, ranging between 21 and 50%. Manual external defibrillators require the expertise of

7848-434: The heart has completely stopped, as in asystole or pulseless electrical activity (PEA) , defibrillation is not indicated. Defibrillation is also not indicated if the patient is conscious or has a pulse. Improperly given electrical shocks can cause dangerous dysrhythmias, such as ventricular fibrillation. A defibrillation device that is often available outside of medical centers is the automated external defibrillator (AED),

7957-408: The heart rhythm and advises the user to stand back while the shock is automatically given. Some types of AEDs come with advanced features, such as a manual override or an ECG display. Implantable cardioverter-defibrillators , also known as automatic internal cardiac defibrillator (AICD), are implants similar to pacemakers (and many can also perform the pacemaking function). They constantly monitor

8066-452: The heart tissue due to areas of slow conduction or unidirectional block. The widespread depolarization from the shock interrupts these circuits, stopping the erratic propagation of electrical signals. After the cells depolarize, they enter a refractory period, during which they cannot be re-excited. This allows the heart's natural pacemaker, the sinoatrial node, to resume control of the rhythm. During this period, ion pumps actively restore

8175-443: The heart to stop heart fibrillation . In 1972, Lown stated in the journal Circulation – "The very rare patient who has frequent bouts of ventricular fibrillation is best treated in a coronary care unit and is better served by an effective antiarrhythmic program or surgical correction of inadequate coronary blood flow or ventricular malfunction. In fact, the implanted defibrillator system represents an imperfect solution in search of

8284-427: The heart. Its main purpose is to restore the partial flow of oxygenated blood to the brain and heart . The objective is to delay tissue death and to extend the brief window of opportunity for a successful resuscitation without permanent brain damage . Administration of an electric shock to the subject's heart, termed defibrillation , is usually needed to restore a viable, or "perfusing", heart rhythm. Defibrillation

8393-475: The inherent speed with which these electrodes can be placed and used. This is critical during cardiac arrest, as each second of nonperfusion means tissue loss. Modern paddles allow for monitoring ( electrocardiography ), though in hospital situations, separate monitoring leads are often already in place. Paddles are reusable, being cleaned after use and stored for the next patient. Gel is therefore not preapplied, and must be added before these paddles are used on

8502-435: The lack of heart beats. But the ventilations could be omitted for untrained rescuers aiding adults who suffer a cardiac arrest (if it is not an asphyxial cardiac arrest, as by drowning, which needs ventilations). The patient's head is commonly tilted back (a head-tilt and chin-lift position) for improving the air flow if ventilations can be used. However, in the case of babies, the head is left straight, looking forward, which

8611-495: The life-threatening arrhythmia is ventricular fibrillation, the device is programmed to proceed immediately to an unsynchronized shock. There are cases where the patient's ICD may fire constantly or inappropriately. This is considered a medical emergency , as it depletes the device's battery life, causes significant discomfort and anxiety to the patient, and in some cases may actually trigger life-threatening arrhythmias. Some emergency medical services personnel are now equipped with

8720-444: The many very important tools carried by ambulances. They are the only proven way to resuscitate a person who has had a cardiac arrest unwitnessed by Emergency Medical Services (EMS) who is still in persistent ventricular fibrillation or ventricular tachycardia at the arrival of pre-hospital providers. Gradual improvements in the design of defibrillators, partly based on the work developing implanted versions (see below), have led to

8829-577: The minimum necessary to achieve ROSC. Pertaining to defibrillation, the presence of a shockable rhythm ( ventricular fibrillation or pulseless ventricular tachycardia ) is associated with increased chances of return of spontaneous circulation. Although a shockable rhythm increases chances for return of spontaneous circulation, a cardiac arrest can present with pulseless electrical activity or asystole , which are non-shockable cardiac rhythms. Return of spontaneous circulation can be achieved through cardiopulmonary resuscitation and defibrillation. Though ROSC

8938-409: The myocardium. Manual internal defibrillators deliver the shock through paddles placed directly on the heart. They are mostly used in the operating room and, in rare circumstances, in the emergency room during an open heart procedure . Automated external defibrillators (AEDs) are designed for use by untrained or briefly trained laypersons. AEDs contain technology for analysis of heart rhythms. As

9047-467: The normal compression-to-ventilation ratio of 30:2, if at least two trained rescuers are present and the victim is a child, the preferred ratio is 15:2. Equally, in newborns, the ratio is 30:2 if one rescuer is present, and 15:2 if two rescuers are present (according to the AHA 2015 Guidelines). In an advanced airway treatment, such as an endotracheal tube or laryngeal mask airway , the artificial ventilation should occur without pauses in compressions at

9156-497: The normal distribution of ions, re-establishing the resting membrane potential. Defibrillators were first demonstrated in 1899 by Jean-Louis Prévost and Frédéric Batelli, two physiologists from the University of Geneva , Switzerland. They discovered that small electrical shocks could induce ventricular fibrillation in dogs, and that larger charges would reverse the condition. In 1933, Dr. Albert Hyman, heart specialist at

9265-429: The normal heart function of the victim. The common model of defibrillator out of an hospital is the automated external defibrillator (AED), a portable device that is especially easy to use because it produces recorded voice instructions. Defibrillation is only indicated for some arrhythmias (abnormal heart beatings), specifically ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT) . Defibrillation

9374-643: The operator to vary voltage according to need. AEDs may also delay delivery of effective CPR. For diagnosis of rhythm, AEDs often require the stopping of chest compressions and rescue breathing. For these reasons, certain bodies, such as the European Resuscitation Council, recommend using manual external defibrillators over AEDs if manual external defibrillators are readily available. As early defibrillation can significantly improve VF outcomes, AEDs have become publicly available in many easily accessible areas. AEDs have been incorporated into

9483-443: The patient 24 hours a day and can automatically deliver a biphasic shock if VF or VT is detected. This device is mainly indicated in patients who are not immediate candidates for ICDs. The connection between the defibrillator and the patient consists of a pair of electrodes, each provided with electrically conductive gel in order to ensure a good connection and to minimize electrical resistance , also called chest impedance (despite

9592-445: The patient as the shock is delivered by allowing the operator to be up to several feet away. (The risk of electrical shock to others remains unchanged, as does that of shock due to operator misuse.) Self-adhesive electrodes are single-use only. They may be used for multiple shocks in a single course of treatment, but are replaced if (or in case) the patient recovers then reenters cardiac arrest. Special pads are used for children under

9701-472: The patient has died. A normal cardiopulmonary resuscitation has a recommended order named 'CAB': first 'Chest' (chest compressions), followed by 'Airway' (attempt to open the airway by performing a head tilt and a chin lift), and 'Breathing' (rescue breaths). As of 2010, the Resuscitation Council (UK) was still recommending an 'ABC' order, with the 'C' standing for 'Circulation' (check for

9810-404: The patient is not in cardiac arrest, such as supraventricular tachycardia and ventricular tachycardia that produces a pulse ; this more-complicated procedure is known as cardioversion , not defibrillation. In Australia up until the 1990s it was relatively rare for ambulances to carry defibrillators. This changed in 1990 after Australian media mogul Kerry Packer had a cardiac arrest due to

9919-418: The patient's heart rhythm, and automatically administer shocks for various life-threatening arrhythmias, according to the device's programming. Many modern devices can distinguish between ventricular fibrillation , ventricular tachycardia , and more benign arrhythmias like supraventricular tachycardia and atrial fibrillation . Some devices may attempt overdrive pacing prior to synchronised cardioversion. When

10028-419: The patient. Paddles are generally only found on manual external units. Newer types of resuscitation electrodes are designed as an adhesive pad, which includes either solid or wet gel. These are peeled off their backing and applied to the patient's chest when deemed necessary, much the same as any other sticker. The electrodes are then connected to a defibrillator, much as the paddles would be. If defibrillation

10137-442: The person has a return of spontaneous circulation (ROSC) or is declared dead. CPR is indicated for any person unresponsive with no breathing or breathing only in occasional agonal gasps, as it is most likely that they are in cardiac arrest . If a person still has a pulse but is not breathing ( respiratory arrest ), artificial ventilations may be more appropriate, but due to the difficulty people have in accurately assessing

10246-444: The presence or absence of a pulse, CPR guidelines recommend that lay persons should not be instructed to check the pulse, while giving healthcare professionals the option to check a pulse. In those with cardiac arrest due to trauma , CPR is considered futile but still recommended. Correcting the underlying cause such as a tension pneumothorax or pericardial tamponade may help. CPR is used on people in cardiac arrest to oxygenate

10355-469: The previous abnormal electrical activity, the heart will spontaneously resume beating normally. Someone who is already in asystole cannot be helped by electrical means, and usually needs urgent CPR and intravenous medication (and even these are rarely successful in cases of asystole). A useful analogy to remember is to think of defibrillators as power-cycling, rather than jump-starting, the heart. There are also several heart rhythms that can be "shocked" when

10464-423: The priority for the drowned and most of the already collapsed children). As another possible variation, if a rescuer is completely alone and without a phone near, and is aiding to any other victim (not a victim of drowning, nor an already unconscious child), the rescuer would go to call by phone first. After the call, the rescuer would get a nearby defibrillator and use it, or continue the CPR (the phone call and

10573-450: The risk of burns and myocardial damage. Ventricular fibrillation (VF) could be returned to sinus rhythm in 60% of cardiac arrest patients treated with a single shock from a monophasic defibrillator. Most biphasic defibrillators have a first shock success rate of greater than 90%. A further development in defibrillation came with the invention of the implantable device, known as an implantable cardioverter-defibrillator (or ICD). This

10682-537: The scapula. This placement is preferred because it is best for non-invasive pacing. The anterior-apex scheme (anterior-lateral position) can be used when the anterior-posterior scheme is inconvenient or unnecessary. In this scheme, the anterior electrode is placed on the right, below the clavicle. The apex electrode is applied to the left side of the patient, just below and to the left of the pectoral muscle. This scheme works well for defibrillation and cardioversion, as well as for monitoring an ECG. Researchers have created

10791-421: The shock time, then continues to decay for some time after which the voltage is cut off, or truncated. The studies showed that the biphasic truncated waveform could be more efficacious while requiring the delivery of lower levels of energy to produce defibrillation. An added benefit was a significant reduction in weight of the machine. The BTE waveform, combined with automatic measurement of transthoracic impedance,

10900-473: The technique known as " cardioversion ". The Lown-Berkovits waveform, as it was known, was the standard for defibrillation until the late 1980s. Earlier in the 1980s, the "MU lab" at the University of Missouri had pioneered numerous studies introducing a new waveform called a biphasic truncated waveform (BTE). In this waveform an exponentially decaying DC voltage is reversed in polarity about halfway through

11009-438: The user along the defibrillation process. It also checks the victim's condition to automatically apply electric shocks at the correct level, if they are needed. Other models are semi-automatic and require the user to push a button before an electric shock. A defibrillator may ask for applying CPR maneuvers , so the patient would be placed lying in a face up position. Additionally, the patient's head would be tilted back, except in

11118-406: The victim. The best position for CPR maneuvers in the sequence of first aid reactions to a cardiac arrest is a question that has been long studied. As a general reference, the recommended order (according to the guidelines of many related associations as AHA and Red Cross) is: If there are multiple rescuers, these tasks can be distributed and performed simultaneously to save time. The reason

11227-477: Was a flat or slightly concave metal plate of about 40 mm diameter. The closed-chest defibrillator device which applied an alternating voltage of greater than 1000 volts, conducted by means of externally applied electrodes through the chest cage to the heart, was pioneered by Dr V. Eskin with assistance by A. Klimov in Frunze, USSR (today known as Bishkek , Kyrgyzstan ) in the mid-1950s. The duration of AC shocks

11336-470: Was awarded Grand Prix at Expo 58 . In 1958, US senator Hubert H. Humphrey visited Nikita Khrushchev and among other things he visited the Moscow Institute of Reanimatology, where, among others, he met with Gurvich. Humphrey immediately recognized importance of reanimation research and after that a number of American doctors visited Gurvich. At the same time, Humphrey worked on establishing

11445-417: Was carried out by Schuder and colleagues at the University of Missouri . The work was commenced, despite doubts amongst leading experts in the field of arrhythmias and sudden death. There was doubt that their ideas would ever become a clinical reality. In 1962 Bernard Lown introduced the external DC defibrillator. This device applied a direct current from a discharging capacitor through the chest wall into

11554-538: Was designated model ИД-1-ВЭИ ( Импульсный Дефибриллятор 1, Всесоюзный Электротехнический Институт , or in English, Pulse Defibrillator 1, All-Union Electrotechnical Institute ). It is described in detail in Gurvich's 1957 book, Heart Fibrillation and Defibrillation . The first Czechoslovak "universal defibrillator Prema" was manufactured in 1957 by the company Prema, designed by Dr. Bohumil Peleška. In 1958 his device

11663-411: Was emphasized. The order of interventions was changed for all age groups except newborns from airway, breathing, chest compressions (ABC) to chest compressions, airway, breathing (CAB). An exception to this recommendation is for those believed to be in a respiratory arrest (airway obstruction, drug overdose, etc.). The most important aspects of CPR are: few interruptions of chest compressions,

11772-484: Was pioneered at Sinai Hospital in Baltimore by a team that included Stephen Heilman, Alois Langer, Jack Lattuca, Morton Mower , Michel Mirowski , and Mir Imran , with the help of industrial collaborator Intec Systems of Pittsburgh. Mirowski teamed up with Mower and Staewen, and together they commenced their research in 1969. However, it was 11 years before they treated their first patient. Similar developmental work

11881-409: Was typically in the range of 100–150 milliseconds. Early successful experiments of successful defibrillation by the discharge of a capacitor performed on animals were reported by N. L. Gurvich and G. S. Yunyev in 1939. In 1947 their works were reported in western medical journals. Serial production of Gurvich's pulse defibrillator started in 1952 at the electromechanical plant of the institute, and

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