# Rapid sequence intubation

Source: saved session `01a154c5-d453-766c-a8c2-5196c1049ae4`, October 19, 2026.

This is the original session write-up, preserved verbatim below. Desktop paths and verification claims refer to that original session, not this import. Educational material only; not a clinical protocol. Clinical statements have not been independently reviewed during import.

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I built the RSI model as an interactive bench figure. Open `~/Desktop/02_projects/anatomy-rsi/rsi.html` (or `rsi-light.html` for the light theme). The line-end check passes at 0 in both themes and in the start, mid-sequence and desaturation poses, and the page logs no console errors.

## The model

| Part | What it stands for |
|---|---|
| Bellows (bright top plate) | The patient's oxygen store. It fills during preoxygenation and drains at the patient's oxygen use once apnoea starts. |
| Induction and paralytic syringes | The plungers go down at t = 0, induction first and the paralytic about 6 s later. The barrels are filled to the true dose volume. |
| Third syringe | Push-dose pressor, drawn up and waiting |
| SpO₂ dial (bright needle) | Reads about 20 s behind the blood, like a real finger probe |
| MAP dial | Dips with propofol, holds with etomidate or ketamine, and drops again from positive-pressure ventilation once the tube is in |
| 4 lamps | Train-of-four (TOF): four twitches from a nerve stimulator. They go out one by one as paralysis deepens. |
| Single lamp | Patient awake: it comes back on if the sedative wears off while the patient is still paralysed |
| Capnogram window | Small waves while breathing on their own, flat during apnoea, full waves only with the tube in the trachea |
| Caddy | Laryngoscope, cuffed tube, bougie |
| Carriage on the ruler | Time, from −3:00 to +9:00 |

Hover over the figure to scrub time, or let it loop. Clicking a syringe changes the drug, and the buttons under the card change the patient, the drugs, how long laryngoscopy takes, and whether nasal-cannula oxygen is on. One line under the buttons gives the dose math, when paralysis is complete, when the tube goes in, and when (if ever) SpO₂ drops below 90%.

Try obese patient + 180 s laryngoscopy + nasal O₂ off. SpO₂ crashes to about 55%, and the needle keeps falling after the tube is in because the probe lags.

## RSI: the 7 Ps

| Time | Step | What matters |
|---|---|---|
| −10 min | Preparation | Plan A/B/C said out loud. SOAP-ME: suction, oxygen, airway kit, drugs, monitoring, ETCO₂ (end-tidal CO₂). Treat low blood pressure, low oxygen and acidosis before you push. |
| −3 min | Preoxygenation | 3 min tidal breathing on 100% O₂, or 8 vital-capacity breaths. Head up 20–30°. Nasal cannula at 15 L/min stays on through apnoea. |
| −3 min | Pretreatment (optional) | Fentanyl 2–3 mcg/kg for raised ICP, aortic dissection or ACS (acute coronary syndrome). Lidocaine has no outcome benefit. |
| 0 | Paralysis with induction | Induction agent, flush, paralytic right after. No titrating. |
| 0–45 s | Positioning, protection | Ear to sternal notch. Cricoid pressure is optional. Gentle bag-mask with PEEP is fine if oxygen is low. |
| 45–60 s | Placement with proof | Start at TOF 0/4. Waveform ETCO₂ over 5 or more breaths is the proof. Tube about 21 cm at the teeth for women, 23 cm for men. Stop and bag at SpO₂ about 93%. |
| After | Post-intubation | Pain control first, then sedation within minutes. Ventilator: 6–8 mL/kg of ideal body weight, PEEP 5. Expect the blood pressure to drop. |

## Induction agents

| Drug | Dose | Onset / duration | Use / watch |
|---|---|---|---|
| Etomidate | 0.3 mg/kg | 30–60 s / 3–5 min | Keeps blood pressure steady. Can cause muscle jerks (myoclonus) and suppress the adrenal glands. |
| Ketamine | 1–2 mg/kg (0.5–1 in shock) | 45–60 s / 10–20 min | Good in shock and asthma. Can drop BP in catecholamine-depleted shock (stress hormones used up). |
| Propofol | 1–2.5 mg/kg | 15–45 s / 5–10 min | Drops blood pressure. Cut the dose hard or avoid it in shock. |
| Midazolam | 0.1–0.3 mg/kg | 60–120 s / 15–30 min | Slow onset. A poor RSI agent. |

## Paralytics

| Drug | Dose | Onset / duration | Key points |
|---|---|---|---|
| Succinylcholine | 1.5 mg/kg, total body weight | 45–60 s / 6–10 min | Raises potassium about 0.5 mEq/L. Don't use with high potassium, burns or crush injuries older than 24–72 h, nerve injury older than 72 h, muscle disease, or a history of malignant hyperthermia. It wears off too late to rescue a patient who is desaturating. |
| Rocuronium | 1.2 mg/kg (up to 1.6 in shock) | 45–60 s / 45–70 min | No potassium rise. Reversed by sugammadex 16 mg/kg. The block outlasts every induction agent, so sedate early. |

**Support drugs:**
- Push-dose epinephrine: 10 mcg/mL, give 0.5–2 mL.
- Push-dose phenylephrine: 100 mcg/mL, give 0.5–2 mL.

**Safe apnoea time** (time to SpO₂ 90% after full preoxygenation):

| Patient | Time |
|---|---|
| Healthy adult | about 8 min |
| Obese | about 3 min |
| Small child | about 3.5 min |
| Critically ill | 2–5 min, often less |
| No preoxygenation | about 1 min |

Below 90% the curve falls off a cliff.

## Limits

- The desaturation curves come from Benumof's apnoea model. Onset and offset times are textbook values.
- The nasal-cannula benefit is modelled as a flat 1.5× slower oxygen drain.
- It teaches timing, not dosing for a real patient.

The full reference tables are also on the page under the controls. Files are in `~/Desktop/02_projects/anatomy-rsi/`:
- `build.mjs`
- `rsi.mjs` (the model)
- `dynamic.js`
- `notes.html`
- `rsi.html` and `rsi-light.html`
- `preview-dark.png` and `preview-light.png`