## Comparison: Succinylcholine vs Rocuronium in RSI **Key Point:** Succinylcholine remains the gold standard for RSI because of its rapid onset (30–60 seconds) and ultra-short duration (5–10 minutes), allowing rapid recovery if intubation fails. ### Mechanism & Pharmacokinetics | Feature | Succinylcholine | Rocuronium | |---------|-----------------|------------| | **Class** | Depolarizing agent | Non-depolarizing agent | | **Onset** | 30–60 sec | 60–90 sec | | **Duration** | 5–10 min | 30–40 min | | **Metabolism** | Plasma pseudocholinesterase | Hepatic (Hofmann elimination) | | **Fasciculations** | Present (risk of hyperkalemia, ICP rise) | Absent | | **Reversibility** | Spontaneous (metabolism) | Neostigmine or sugammadex | **High-Yield:** In RSI, succinylcholine's **speed of onset and offset** is the critical discriminator. If intubation fails and ventilation becomes impossible, succinylcholine wears off in 5–10 minutes, restoring spontaneous ventilation. Rocuronium requires reversal agents (sugammadex) or prolonged waiting. **Clinical Pearl:** Although rocuronium has gained popularity in some centers due to absence of hyperkalemia risk, succinylcholine remains preferred in true RSI scenarios where rapid recovery is essential. **Warning:** Do not confuse rocuronium's lack of fasciculations (an advantage in certain patients like those with spinal cord injury or burns) with superiority in RSI. Duration of action is the limiting factor. ## Why Succinylcholine Remains RSI Standard 1. **Rapid onset:** 30–60 seconds allows intubation within the safe apnea window. 2. **Ultra-short duration:** Spontaneous metabolism ensures airway recovery if intubation fails. 3. **No reversal agent needed:** Unlike rocuronium, which requires sugammadex (expensive, not always available in India). **Mnemonic:** **SUCK** = **S**uccinylcholine **U**ltra-short **C**hoice for **K**ey RSI moments.
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