What is drug-assisted intubation?

What is Drug-Assisted Intubation?

Drug-assisted intubation, most commonly referred to as Rapid Sequence Intubation (RSI), is the rapid administration of a sedative-hypnotic agent followed immediately by a neuromuscular blocking agent (NMBA) to facilitate endotracheal intubation in critically ill patients. 1, 2, 3

Core Definition and Purpose

Drug-assisted intubation involves administering medications in a specific sequence to:

• Induce unconsciousness using a sedative-hypnotic agent (such as etomidate, ketamine, or propofol) 1, 2
• Produce complete muscle paralysis using an NMBA (succinylcholine or rocuronium) to optimize intubating conditions 1, 3
• Facilitate immediate endotracheal tube placement before assisted ventilation begins 1, 3

The primary goals are to reduce aspiration risk in patients with full stomachs and to optimize intubating conditions, thereby reducing the occurrence of difficult or failed airways, esophageal tube placement, and complications. 3

The Two-Drug Sequence

Step 1: Sedative-Hypnotic Agent (Induction)

A sedative-hypnotic agent must always be administered before the neuromuscular blocker to prevent awareness during paralysis. 1, 2 Common options include:

• Etomidate (0.2-0.3 mg/kg): Preferred for hemodynamically unstable patients due to minimal cardiovascular depression 1, 3
• Ketamine (1-2 mg/kg): Maintains respiratory drive and increases catecholamine release; useful for agitated patients requiring medication-assisted preoxygenation 1, 2
• Propofol (2 mg/kg): Suppresses airway reflexes effectively but can cause vasodilation and hypotension 2

The Society of Critical Care Medicine found no significant difference between etomidate and other induction agents with respect to mortality or hypotension. 2, 3

Step 2: Neuromuscular Blocking Agent (Paralytic)

The Society of Critical Care Medicine strongly recommends administering an NMBA when a sedative-hypnotic agent is used for intubation. 1, 2, 3 The two primary options are:

• Succinylcholine (1-1.5 mg/kg): Fastest onset and shortest duration; preferred for hemodynamically stable patients without contraindications 1, 2, 3
• Rocuronium (0.9-1.2 mg/kg): Non-depolarizing alternative with onset in approximately 1 minute; requires sugammadex to be immediately available for reversal in "cannot intubate/cannot oxygenate" scenarios 1, 2, 3

Critical Timing

The medications are administered in rapid succession with immediate endotracheal tube placement before assisted ventilation begins, distinguishing this from standard intubation techniques. 1, 3 This minimizes the time between loss of consciousness and airway protection, reducing aspiration risk. 3

Modified Approaches

Delayed Sequence Intubation (DSI)

For agitated, delirious, or combative patients who cannot tolerate preoxygenation devices, medication-assisted preoxygenation (also called delayed sequence intubation) is recommended. 2, 3 This involves:

1. Administering ketamine (typically 1-1.5 mg/kg) to achieve a dissociative state 2
2. Allowing 3 minutes of preoxygenation 2
3. Then administering the NMBA and proceeding with intubation 2

Studies show this approach increases mean oxygen saturation by 8.9% before NMBA administration. 2, 3

Target Patient Population

Drug-assisted intubation is indicated for critically ill adult patients in emergency departments, ICUs, or other locations outside the operating room requiring emergency airway management, particularly those at risk for aspiration or requiring optimization of intubating conditions. 2, 3

Essential Safety Considerations

Preoxygenation Strategies

• High-flow nasal oxygen (HFNO) is suggested when laryngoscopy is expected to be challenging 2, 3
• Noninvasive positive pressure ventilation (NIPPV) is recommended for patients with severe hypoxemia (PaO₂/FiO₂ < 150) 2, 3
• Semi-Fowler positioning (head and torso inclined) is suggested to reduce aspiration risk and potentially improve first-pass intubation success 2, 3

Common Pitfalls to Avoid

• Never administer the NMBA before the sedative-hypnotic agent, as this causes awareness during paralysis 1, 2
• Inadequate preoxygenation increases desaturation risk—ensure proper technique and consider medication-assisted preoxygenation for uncooperative patients 2, 3
• Failure to have sugammadex immediately available when using rocuronium can lead to catastrophic outcomes in "cannot intubate/cannot oxygenate" scenarios 1, 3
• Delayed post-intubation analgosedation when using rocuronium may increase awareness risk due to its longer duration (58-67 minutes) compared to succinylcholine 2, 3

Key Distinction from Other Intubation Methods

Drug-assisted intubation differs fundamentally from awake intubation, where topical anesthesia and sedation are used while the patient maintains spontaneous breathing and airway reflexes. 4 In drug-assisted intubation, complete unconsciousness and paralysis are induced before intubation, whereas awake intubation preserves the patient's ability to maintain their own airway. 4