Non shockable rhythms
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Understanding Cardiac Arrest: Causes, Rhythms, and Initial Response
Non-Shockable Rhythms in Cardiac Arrest
In some cardiac arrest cases, the heart enters a non-shockable rhythm. During the initial stages, the primary treatment involves high-quality chest compressions and ventilations. It's crucial to note that the chances of reverting asystole (flatline) back into a life-supporting rhythm are less than 6%. In contrast, for ventricular fibrillation, the success rate is approximately 40%.
Understanding the Causes
Cardiac arrest can be attributed to various factors, and a helpful mnemonic to remember these causes is the four H's and four T's. Recognizing these reversible causes is essential during a cardiac arrest scenario:
The Four H's
- Hypoxia: Inadequate oxygen supply
- Hypothermia: Dangerously low body temperature
- Hypovolemia: Low blood volume
- Metabolic Imbalances: Includes hypo/hypercalcemia, hyponatremia, hyperkalemia, and metabolic acidosis
The Four T's
- Cardiac Tamponade: Compression of the heart due to fluid accumulation
- Tension Pneumothorax: Build-up of air in the chest, causing pressure on the heart
- Toxins: Poisoning or exposure to harmful substances
- Thromboembolic: Blood clots or embolisms, often following a heart attack or stroke
In the pre-hospital setting, thromboembolic events, such as those occurring after a myocardial infarction (heart attack) or a significant cerebrovascular accident (CVA or stroke), are among the more frequently encountered causes of cardiac arrest.