Cardiopulmonary Resuscitation Cycle and Algorithm

Basic algorithm of actions during cardiac arrest

The success of resuscitation measures directly depends on a clear sequence of actions. If assistance is provided by a single rescuer, the initial algorithm includes the following stages:

1. Diagnosis: Determination of signs of clinical death (cardiac arrest).
2. Airway clearance: Thorough cleansing of the victim's oral cavity.
3. Initial ventilation: Delivery of 4 initial rescue breaths into the lungs. Classical methods "mouth-to-mouth" or "mouth-to-nose" are used.
4. Basic CPR cycle: Immediate transition to circulatory support. A strict alternation of 15 chest compressions with 2 rescue breaths is performed.

In the case of sudden cardiac arrest, the algorithm has its own features. First, 3–4 initial rescue breaths ("mouth-to-mouth") must be performed, followed by a precordial thump—a short and sharp strike with the ulnar edge of the palm against the sternum. After this, the rescuer waits 5 seconds to evaluate the effect. If spontaneous heartbeat does not recover, closed-chest cardiac massage should be started immediately alongside ongoing ventilation.

Pathophysiology and technique of cardiac massage

The circulation restoration stage (Circulation) is performed strictly in parallel with artificial ventilation—this is the absolute basis for reviving from clinical death. In addition to closed-chest massage, methods include ventricular defibrillation and intracardiac drug administration (the choice depends on available equipment).

The hemodynamic mechanism of closed-chest massage is based on two main factors:

• Artificial systole: Mechanical compression of the myocardium occurs between the sternum and the spine, which forces blood into the vessels.
• Artificial diastole: When compression ceases, passive expansion of the ventricles occurs, ensuring their filling with blood.
• Additional factor: Fluctuations in intrathoracic pressure during compression and decompression cycles play a significant role.

Indications for initiating compressions are complete asystole (cessation of cardiac activity) and hemodynamic inefficiency (a condition in which the electrical activity of the heart is preserved, but the pulse on major arteries, such as the carotid, is not palpable).

Execution technique: The patient is placed on a flat, hard surface (floor, backboard, ground). The rescuer is positioned on the right. The heel of one hand is placed on the lower third of the sternum, and the second hand is placed on top (parallel or interlocked). The arms must be fully straightened at the elbows. Pressure is exerted strictly perpendicular to the chest exclusively using the rescuer's body weight.

Features of CPR and ventilation in children

Resuscitation in pediatric patients requires adaptation of the technique depending on the child's age.

Age-specific compression features:

• Infants of the first months of life: The encircling technique is used. The rescuer encircles the infant's chest with both hands. The thumbs are placed on the lower third of the sternum, and the remaining fingers are positioned under the back.
• Children aged 5–7 years: Compressions are performed with the proximal part (heel) of the palm of only one hand. The point of force application remains the same—the lower third of the sternum.

Specifics of artificial lung ventilation: The volume of the delivered respiratory mixture is strictly dosed: the younger the child, the smaller the volume required. The main criterion for breathing effectiveness is adequate chest excursion (it should rise just as during a deep physiological breath). The expiration mechanics occur completely passively due to the elastic recoil of the lung tissue and chest wall. Important to remember: to ensure full expiration, the rescuer must clear the patient's mouth.

In newborns and infants, due to the anatomical features of the face, air is blown simultaneously through the patient's mouth and nose.

Ventilation parameters for children:

• Respiratory rate (RR): from 24 to 40 per minute (adjusted for age).
• Phase ratio: active inspiration time to passive expiration time should be 1:2.
• Complications: Excessive forced inspiration by the rescuer can lead to barotrauma and provoke the development of pneumothorax.

Class and exam questions

What else to study on this topic

• Indications and technique of ventricular defibrillation during CPR
• Choice and dosages of pharmacological agents for intracardiac administration
• Differential diagnosis of hemodynamic inefficiency states
• Prevention of barotrauma and pneumothorax during artificial ventilation

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.