Neuromuscular Blocking Agents Reduce Intubation Complications, But Do Not Directly Prevent Vomiting
Paralytics (neuromuscular blocking agents) do not prevent vomiting during intubation, but they significantly improve intubation conditions and reduce airway trauma, which indirectly minimizes the risk of aspiration by facilitating rapid, successful intubation on the first attempt. The primary strategy to avoid vomiting and aspiration during intubation involves rapid sequence induction (RSI) techniques that minimize the time between loss of consciousness and securing the airway, combined with appropriate aspiration precautions 1.
How Paralytics Reduce Overall Intubation Risk
Neuromuscular blocking agents are strongly recommended to facilitate tracheal intubation and reduce complications 1:
Improved intubation conditions: Without a muscle relaxant, 24.6-25.9% of patients experience poor intubating conditions compared to only 4.1% with a muscle relaxant 1. This represents a six-fold reduction in difficult intubation scenarios.
Reduced airway trauma: Muscle relaxants significantly decrease pharyngeal and laryngeal injury during intubation attempts 1. Avoiding neuromuscular blocking agents is associated with increased difficulty and higher complication rates 1.
Faster successful intubation: By optimizing conditions for first-pass success, paralytics minimize the time the airway remains unprotected, thereby reducing the window for potential aspiration 1.
The Actual Mechanisms to Prevent Vomiting/Aspiration
The risk of pulmonary aspiration is reduced through a comprehensive RSI approach, not by paralytics alone 1:
- Discontinue enteral feeding before the procedure 1
- Remove gastric contents by suction via nasogastric or orogastric tube 1
- Apply cricoid force: 10 N (1 kg) while awake, increasing to 30 N (3 kg) after loss of consciousness 1
- Preoxygenation to maximize oxygen reserves 1
- Rapid-acting induction agents combined with fast-onset neuromuscular blockers to minimize time between unconsciousness and airway protection 1
Critical Caveat About Active Vomiting
If active vomiting occurs, cricoid force should be reduced or removed immediately 1. Maintaining cricoid pressure during active vomiting can cause esophageal rupture. The patient should be positioned in left lateral head-down position to minimize aspiration risk 1.
Choice of Paralytic Agent
For rapid sequence intubation, both succinylcholine (1 mg/kg) and rocuronium (0.9-1.2 mg/kg) provide rapid onset suitable for RSI 1:
Succinylcholine provides slightly superior intubating conditions (79.4% first-attempt success) compared to rocuronium (74.6% first-attempt success) 2, and creates excellent intubating conditions more frequently (RR 0.86,95% CI 0.81-0.92) 3
Rocuronium may be more rational in critically ill patients due to succinylcholine's numerous side effects including life-threatening hyperkalemia 1. Rocuronium at 1.2 mg/kg provides onset times similar to succinylcholine (55 seconds vs 50 seconds) 4
Avoiding neuromuscular blocking agents entirely is associated with increased intubation difficulty and was identified as an independent risk factor for difficult intubation in a cohort of 103,784 patients 1
Bottom Line
Paralytics facilitate rapid, successful intubation which minimizes aspiration risk by reducing the time the airway is unprotected, but they do not pharmacologically prevent vomiting. The comprehensive RSI technique—including gastric decompression, cricoid pressure, preoxygenation, and rapid-acting drugs—is what actually reduces aspiration risk 1.