RSI vs DSI: Paramedic Airway Decisions Under Pressure

Rapid sequence intubation trades the patient's protective reflexes and spontaneous breathing for a single, controlled attempt. Delayed sequence intubation buys oxygenation first. Both are protocol-dependent — know yours.

The 7 P's of RSI

1. Preparation — suction, two working laryngoscopes, SGA rescue, capnography, monitor, IV access.
2. Preoxygenation — 3 minutes of high-flow, ideally with a nasal cannula left in place for apneic oxygenation.
3. Pretreatment — situational and protocol-specific; fluids or push-dose pressor for the hypotensive patient.
4. Paralysis with induction — sedative then paralytic in rapid succession.
5. Positioning — ear-to-sternal-notch, ramp obese patients.
6. Placement with proof — waveform capnography confirms; nothing else does.
7. Post-intubation management — sedation, analgesia, ventilator or bagging targets, secure the tube.

Typical drugs

• Induction: etomidate (hemodynamically stable) or ketamine (favored when hypotensive or bronchospastic).
• Paralysis: rocuronium (longer duration, no hyperkalemia risk) or succinylcholine (fast on and off; avoid with hyperkalemia, crush injury, burns over 24 hours old, or known myopathy).
• Post-intubation sedation must be planned before you paralyze — an awake, paralyzed patient is a preventable harm.

When DSI is the better call

Use delayed sequence intubation when the patient is too agitated to tolerate preoxygenation but is not yet crashing. Give a dissociative dose of ketamine, apply a NRB or CPAP and preoxygenate properly, then paralyze once saturations are maximized. It is a procedural sedation for preoxygenation, not a shortcut.

Avoid peri-intubation collapse

Hypotension, hypoxia, and acidosis before the tube predict arrest after it. Resuscitate first: fix the pressure, load oxygen, and correct pH where you can. A saturation in the 80s is not the moment to induce apnea.

Exam pattern

If the stem highlights a systolic in the 80s, ketamine and fluid loading beat etomidate alone. If it highlights a crush injury or dialysis patient, avoid succinylcholine. If it highlights agitation with an unsafe saturation, the answer is DSI.