Module 13
Reversible Causes (Hs & Ts)
The reversible causes of cardiac arrest — always consider these when ROSC is not achieved.
The Hs
| Cause | Consider |
|---|---|
| Hypovolemia | Blood loss, severe dehydration — volume bolus |
| Hypoxia | Inadequate oxygenation — optimize airway and ventilation |
| Hydrogen ion (Acidosis) | Severe acidemia — adequate ventilation, consider bicarbonate |
| Hypo / Hyperkalemia | Electrolyte imbalance — check labs, treat accordingly |
| Hypothermia | Core body temperature low — active warming |
The Ts
| Cause | Consider |
|---|---|
| Tension pneumothorax | Needle decompression, then chest tube |
| Tamponade (cardiac) | Pericardiocentesis |
| Toxins | Overdose, poisoning — identify agent, give antidote if available |
| Thrombosis (pulmonary) | Massive PE — consider thrombolytics |
| Thrombosis (coronary) | MI — consider PCI or thrombolytics |
Clinical Pearl
These should always be considered when ROSC is not achieved — run through the Hs and Ts systematically, not by memory recall alone.
Want to practice this with The Guide?
Request a scenario or ask clinical questions about this module.