Cardiac arrest

Cardiac arrest, or sudden cardiac death, can occur suddenly (within 24 hours of the first signs of illness in physically active individuals), it occurs outside the hospital, in approximately 400,000 people per year (USA), in 90% of cases cardiac arrest is the cause of death.

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Causes of cardiac arrest

In adults, sudden cardiac arrest usually occurs in the presence of heart disease, and is often the first manifestation of this pathology. Other causes of cardiac arrest include pulmonary embolism, trauma, ventilation problems, and metabolic disorders (including drug overdose).

In children, the main causes are trauma, poisoning and various respiratory disorders (airway obstruction, smoke inhalation, drowning, infection, etc.).

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Pathophysiology of cardiac arrest

Cardiac arrest causes global ischemia, the main consequences of which are cell damage and edema formation. Edema is especially dangerous for the brain, since the rigidity of the skull bones leads to increased intracranial pressure and decreased perfusion of the brain. All successfully resuscitated patients experience short-term or long-term cerebral disorders.

A decrease in ATP production leads to an increase in the permeability of the cell membrane. Potassium leaves the cell, and sodium and calcium enter the cell. Excessive sodium intake causes cell swelling. Calcium causes damage to mitochondria (ATP production decreases), increases nitric oxide production (free radicals are formed), and in some cases activates proteases that cause cell damage.

In neurons, abnormal ion current causes depolarization and release of neurotransmitters. The neurotransmitter with the greatest damaging effect is glutamate, which activates specific calcium channels and increases the calcium content in cells.

The release of inflammation mediators leads to thrombosis of microvessels, increased permeability of the vascular wall and the formation of edema. With prolonged ischemia, apoptosis processes are activated.

Symptoms of cardiac arrest

In severely ill patients, cardiac arrest is usually preceded by deterioration of the condition, rapid shallow breathing, hypotension and impaired mental function.

In other cases, it is preceded by collapse with a short attack of convulsions (less than 5 s).

Treatment of cardiac arrest

Clinically, cardiac arrest is manifested by apnea, absence of pulse and consciousness. Blood pressure is not determined. The cardiac monitor may show ventricular fibrillation, ventricular tachycardia or asystole. In the case of electromechanical dissociation, the monitor may show sinus bradycardia against the background of absence of pulse.

In children, asystole is often preceded by bradyarrhythmia. Ventricular tachycardia or fibrillation is observed in 15-20% of children. Therefore, children need emergency defibrillation if sudden cardiac arrest is not preceded by respiratory distress.

Potentially treatable causes of cardiac arrest (hypoxia, cardiac tamponade, tension pneumothorax, massive hemorrhage, or pulmonary embolism) must be immediately excluded. However, not all causes can be identified during resuscitation. Clinical, radiographic, and ultrasound examinations help in identifying the cause of cardiac arrest. The most likely causes must be eliminated immediately. If the patient is in a state of severe shock and the cause of cardiac arrest cannot be determined, massive infusion therapy in combination with vasopressors must be started.

Further treatment continues during cardiopulmonary resuscitation.