Why cardiac arrest follows to respiratory arrest?

Cardiac arrest follows respiratory arrest due to the interruption of the oxygen supply to the heart and brain. Here's how respiratory arrest leads to cardiac arrest:

1. Hypoxia: When breathing stops, the oxygen supply to the lungs is cut off, and the blood oxygen levels start to drop. As a result, the tissues and organs in the body, including the heart, become deprived of oxygen.

2. Acidosis: The buildup of carbon dioxide in the blood, which occurs due to the lack of ventilation, leads to acidosis. Acidosis affects the heart's electrical system, making it more susceptible to abnormal heart rhythms.

3. Myocardial Ischemia: Oxygen deprivation and the accumulation of waste products in the heart muscle (myocardium) cause myocardial ischemia. Ischemia can damage the heart's electrical conduction system and weaken its contractions.

4. Dysrhythmias: The combination of hypoxia, acidosis, and ischemia can trigger abnormal heart rhythms, such as ventricular fibrillation (VF) or asystole. These dysrhythmias are often fatal if not treated promptly.

5. Loss of Perfusion: As the heart's contractions weaken and become disorganized due to the dysrhythmias, the heart is unable to effectively pump blood to the rest of the body. This leads to a loss of perfusion, which means the organs and tissues are not receiving enough oxygen and nutrients.

6. Cardiac Arrest: Ultimately, the heart's electrical activity can cease entirely, leading to cardiac arrest. Without immediate medical intervention, such as CPR and defibrillation, cardiac arrest can result in permanent brain damage and death.

The time it takes for respiratory arrest to progress to cardiac arrest depends on several factors, including the underlying medical conditions of the individual, the duration of the respiratory arrest, and the effectiveness of any interventions initiated to restore breathing and circulation.