Airway & Ventilation

RAPID SEQUENCE INTUBATION

Enter weight above for calculated drug doses · Evidence: UpToDate RSI, ACEP 2020, Weingart Push-Dose Pressors

🔍 Difficult Airway Assessment — LEMON Before Every RSI

Assess ALL 5 criteria before intubation. Any positive predictor = plan for backup airway (VL, LMA, surgical).

Look Externally

Small jaw, large tongue, short neck, obesity, facial trauma, beard, blood/vomit in airway, trismus, prior neck surgery/radiation

Evaluate 3-3-2 Rule

3 finger breadths mouth opening · 3 finger breadths hyoid-to-chin · 2 finger breadths thyroid notch-to-hyoid. Any <3 fingers = difficult

Mallampati Score

Class I (uvula visible) = easy · Class II (partial) = some difficulty · Class III (soft palate only) = difficult · Class IV (hard palate only) = very difficult

Obstruction

Angioedema, abscess, epiglottitis, haematoma, Ludwig's angina, foreign body, tumour, tracheal deviation

Neck Mobility

Cervical spine injury, arthritis, collar, halo, prior cervical surgery. Reduced extension = reduced laryngeal view

⚡ RSI Protocol — Step by Step

Pre-oxygenation (3+ minutes)

Goal: SpO2 100% — denitrogenate lungs to maximise apnoea safe time (3–8 min normoxic, vs 1 min without pre-ox).

• Flush-rate O2: NRB at 15 L/min + nasal cannula 15 L/min beneath mask
• Upright position 20–30° head-up (increases FRC by 15–30%)
• BVM with PEEP valve 5–10 cmH2O if obtunded
• Apnoeic oxygenation: leave NC at 15 L/min during laryngoscopy

Preparation — "STOP MAID"

Suction on · Team roles assigned · O2 flush rate · Position optimal · Monitoring (ECG/SpO2/EtCO2) · Airway equipment laid out · IV access confirmed · Drugs drawn up

Push-dose pressor ready: Ephedrine 5 mg/mL (1 mL ephedrine 50 mg/mL + 9 mL NS) OR Epinephrine 10 mcg/mL (1 mL 1:10,000 + 9 mL NS)

Pre-treatment (optional, 3 min before induction)

Blunts haemodynamic response to laryngoscopy. Indicated in TBI (prevents ICP spike), cardiovascular disease, reactive airway.

Fentanyl: — (1–3 mcg/kg, max 200 mcg) IV over 1–2 min · 3 min before induction

Induction Agent — choose one

Give rapidly IV. Onset 30–60 sec. Patient loses consciousness.

Ketamine: — (1.5 mg/kg) — preferred in haemodynamic instability, bronchospasm
Etomidate: — (0.3 mg/kg) — haemodynamically stable; avoid in sepsis (adrenal suppression)
Propofol: — (1.5 mg/kg) — only if haemodynamically stable; significant hypotension risk

Neuromuscular Blockade — give immediately after induction

Succinylcholine: — (1.5 mg/kg, max 200 mg) — fastest offset; avoid in hyperkalaemia/burns/crush >48h
Rocuronium: — (1.2 mg/kg) — preferred if succinylcholine contraindicated; reverse with sugammadex 16 mg/kg

⚠ Succinylcholine contraindicated: K+ >5.5, burns >24–48h, crush >72h, denervation/UMN injury, muscular dystrophy, personal/family history MH, pseudocholinesterase deficiency

Laryngoscopy & Intubation (60–90 sec after NMB)

Optimise with: BURP manoeuvre (Backwards-Upwards-Right-Pressure on thyroid cartilage) · External laryngeal manipulation · Ramped position for obese patients (ear-to-sternal-notch alignment).

Confirm: Bilateral breath sounds · EtCO2 waveform (gold standard) · Chest rise · SpO2 improving · CXR for depth

Post-intubation Management

Sedation: Propofol 5–50 mcg/kg/min OR Midazolam 0.03–0.1 mg/kg/hr
Analgesia: Fentanyl — (1–2 mcg/kg q1h or 25–100 mcg/hr infusion)
Ongoing NMB (if needed): Rocuronium — (10–12 mcg/kg/min infusion)

Initiate ventilator: start with lung-protective settings (see Ventilator tab). Target SpO2 92–98%, EtCO2 35–45 mmHg. Head of bed 30–45°.

🚨Cannot Intubate / Cannot Oxygenate (CICO)Emergency

CICO = Immediately life-threatening. Do NOT attempt more than 3 laryngoscopy attempts. Call for help early. Declare CICO loudly.

Attempt LMA / Supraglottic Airway

Size 3 (30–50 kg), 4 (50–70 kg), 5 (70–100 kg). Insert, ventilate. May be bridge to surgical airway.

Reverse NMB (if rocuronium used)

Sugammadex: — (16 mg/kg IV) — full reversal within 3 min. Only works for rocuronium/vecuronium.

Emergency Surgical Airway — Scalpel-Bougie-Tube

Preferred technique: 1) Vertical 3 cm skin incision over cricothyroid membrane · 2) Horizontal stab incision through membrane · 3) Tracheal hook caudally · 4) Bougie inserted · 5) 6.0 ETT railroaded over bougie · 6) Inflate cuff, ventilate, confirm EtCO2

VENTILATOR SETTINGS

Enter height + sex above for IBW-based tidal volume · Evidence: ARDSNet NEJM 2000, GOLD 2024, ATS/ESICM Guidelines

💡 Tidal volume is based on Ideal Body Weight (IBW), not actual weight — obese patients have the same lung size as their height-matched non-obese counterparts. Using actual weight causes volutrauma.

📊 Live Calculated Settings

Enter weight + height + sex above to generate calculated vent settings

IBW

—

Tidal Volume (6 mL/kg)

—

ARDSNet / lung-protective

Tidal Volume (8 mL/kg)

—

Normal lungs / post-op

Min Ventilation (6×14)

—

TV × RR target range

Min Ventilation (6×20)

—

Upper end for ARDS

Min TV (4 mL/kg)

—

Absolute minimum (ARDS refractory)

ARDSNet Protocol (NEJM 2000): 6 mL/kg IBW reduces mortality vs 12 mL/kg. Plateau pressure <30 cmH2O. Driving pressure <15 cmH2O. Accept permissive hypercapnia (pH >7.20). SpO2 target 88–95%.

Mode

AC/VC

Volume-controlled. Guarantees tidal volume delivery.

Tidal Volume

— mL

6 mL/kg IBW (range 4–8). Calculated from height/sex above.

Resp Rate

14–20

Start 14–16. Increase to compensate for low TV if needed. Max 35.

PEEP

Start 5. Use ARDSNet PEEP/FiO2 table below to titrate.

FiO2

0.60

Titrate to SpO2 88–95%. Use PEEP/FiO2 table — increase together.

I:E Ratio

1:2

Standard. Avoid inverse ratio (risk of auto-PEEP).

Plateau Limit

<30

Check q4h. If >30: reduce TV by 1 mL/kg to minimum 4 mL/kg. Accept lower pH.

Driving Pressure

<15

Plateau − PEEP. Independent mortality predictor. Reduce TV or PEEP if >15.

📊ARDSNet PEEP / FiO2 Table (Lower PEEP Strategy)

FiO2	0.30	0.40	0.50	0.60	0.70	0.80	0.90	1.00
PEEP	5	5–8	8–10	10	10–12	14	14–18	18–24

Auto-PEEP risk: Obstructive physiology traps air → dynamic hyperinflation → haemodynamic collapse. Prioritise full exhalation: low RR, low I:E, high flow rate. Permissive hypercapnia acceptable (pH >7.20).

Mode

AC/VC

Volume control ensures delivered volume despite high airway resistance.

Tidal Volume

— mL

6–8 mL/kg IBW. Small volumes reduce hyperinflation risk.

Resp Rate

10–14

Low RR = more time for exhalation. Start 10–12. Permissive hypercapnia.

PEEP

3–5

Low extrinsic PEEP (3–5 cmH2O). Must measure intrinsic/auto-PEEP. Extrinsic PEEP <80% of auto-PEEP.

FiO2

Titrate

COPD: target SpO2 88–92% (avoid hypoxic drive suppression). Asthma: 92–98%.

I:E Ratio

1:3 – 1:5

Prolonged expiratory phase — essential. Use highest flow rate to shorten inspiratory time.

Flow Rate

60–80 L/min

High inspiratory flow shortens Ti, maximises expiratory time.

PaCO2 Target

45–60+

Permissive hypercapnia acceptable if pH >7.20. Do NOT hyperventilate — causes severe auto-PEEP.

Lung-protective ventilation for all intubated patients — not just ARDS. Even normal lungs develop VILI with high tidal volumes. Start conservative; wean FiO2 and PEEP as tolerated.

Mode

AC/VC or PRVC

Volume or pressure-regulated. PRVC adapts to compliance changes.

Tidal Volume

— mL

6–8 mL/kg IBW. Even normal lungs: avoid >8 mL/kg.

Resp Rate

12–16

Targeting normocapnia (PaCO2 35–45 mmHg).

PEEP

Standard physiological PEEP. Prevents alveolar derecruitment at end-expiration.

FiO2

Titrate

Start 0.60, wean to <0.60 to avoid O2 toxicity. Target SpO2 92–98%.

I:E Ratio

1:2

Standard 1:2. Adjust if patient-ventilator dyssynchrony noted.

Plateau

<30

Monitor plateau. In normal lungs plateau usually <25 with these settings.

PaCO2 Target

35–45

Normocapnia unless underlying condition warrants otherwise.

TBI/Neuro: Hypoxia (SpO2 <90%) and hypocapnia (PaCO2 <35) are BOTH harmful — cause secondary brain injury. Normocapnia mandatory. Hyperventilation only for impending herniation (brief, bridge to intervention).

Mode

AC/VC

Tidal Volume

— mL

6 mL/kg IBW. Lung-protective even in TBI.

Resp Rate

14–16

Titrate to PaCO2 35–40 mmHg. Serial ABG essential. EtCO2 correlation variable in TBI.

PEEP

Standard PEEP 5. Higher PEEP reduces cerebral venous drainage — balance with oxygenation needs.

FiO2

Target 94–98%

SpO2 >94% mandatory. Avoid hyperoxia (PaO2 >300 — associated with worse outcomes).

PaCO2 Target

35–40

Normocapnia. Prophylactic hyperventilation is HARMFUL (cerebral vasoconstriction → ischaemia).

Herniation Protocol

PaCO2 30–35

Brief hyperventilation for acute herniation ONLY — bridge to mannitol/hypertonic saline/surgery. Not sustained.

Head Position

HOB 30°

Head of bed 30–45°, neutral alignment. Reduces ICP, improves CPP.

Cardiogenic pulmonary oedema: high PEEP recruits flooded alveoli, reduces preload (beneficial in LV failure), and offloads work of breathing. Higher FiO2 requirements initially.

Mode

AC/VC or PRVC

Tidal Volume

— mL

6–8 mL/kg IBW.

Resp Rate

14–18

Targeting normocapnia. High RR compensates for low TV if needed.

PEEP

8–12

Higher PEEP recruits flooded alveoli. Reduces preload (good in LV failure). Monitor for RV afterload increase.

FiO2

High initially

Start 0.80–1.0. Wean as oedema clears. Target SpO2 92–98%.

I:E Ratio

1:2

Plateau

<30

Note

High PEEP reduces RV preload too — monitor for RV failure in acute RV dysfunction/massive PE.

Obese patients: use IBW (not actual weight) for tidal volume. Higher PEEP needed to overcome chest wall weight and recruit dependent atelectasis. Ramped position for intubation and ventilation.

Mode

AC/VC or PRVC

Tidal Volume

— mL

6–8 mL/kg IBW — critical. Using actual weight causes severe volutrauma.

Resp Rate

14–18

Higher RR may be needed due to reduced FRC and increased O2 consumption.

PEEP

8–12

Higher PEEP needed to overcome chest wall weight and recruit dependent atelectasis. Titrate to oxygenation.

FiO2

Titrate

Often need higher FiO2 initially. Target SpO2 92–98%.

Position

HOB 30–45°

Reduces diaphragmatic compression, improves FRC.

Recruitment

Consider

PEEP trial or recruitment manoeuvre (sustained inflation 30–40 cmH2O × 30 sec) for refractory hypoxia.

IBW Formula

Enter height above

BiPAP / NIV / CPAP

Non-invasive ventilation — avoids intubation in appropriate patients · Evidence: NICE NG38, BTS NIV Guidelines 2016, AHA/ACC CPE Guidelines

NIV Absolute Contraindications: Respiratory arrest / Apnoea · Unable to protect airway · Facial trauma/burns/anatomy precluding mask fit · Uncooperative/agitated patient (relative) · Vomiting/high aspiration risk · Haemodynamic instability not responsive to fluids · Recent upper GI/oesophageal surgery

😷 Live NIV / BiPAP Quick Reference

Select condition below — settings shown. Enter weight for any weight-related context.

IPAP Start

12–16

cmH2O — titrate up by 2 q15 min

EPAP Start

4–6

cmH2O

Pressure Support

8–12

cmH2O (IPAP − EPAP)

Backup RR

14–16

/min

SpO2 Target

88–92%

Controlled O2

Reassess ABG

1–2 hours

If pH not improving → intubate

COPD + acute hypercapnic RF: NIV reduces intubation rate by 65%, mortality by 50% (Brochard 1995, Plant 2000). First-line treatment. Target pH >7.25 on NIV; if <7.25 after 1h → intubate.

Mode

BiPAP (S/T)

IPAP Start

12–16 cmH2O

Increase by 2 cmH2O q15 min to max 20–30. Target: ↓RR, ↑TV, ↓accessory muscle use.

EPAP Start

4–6 cmH2O

Low EPAP (3–5) for COPD — avoid dynamic hyperinflation. Higher EPAP (6–8) if significant secretions or OSA component.

Pressure Support

8–14 cmH2O

PS = IPAP − EPAP. Aim 8–14 cmH2O. Drives ventilation.

Backup RR

14–16 /min

FiO2 Target

SpO2 88–92%

Controlled O2 — avoid suppressing hypoxic drive. Titrate.

Reassess

ABG at 1–2h

If pH not improving >7.25 → escalate to intubation. Do not delay.

Evidence

Brochard 1995, Plant 2000, BTS NIV 2016

Cardiogenic pulmonary oedema: CPAP equivalent to BiPAP for most patients (3CPO trial). Both superior to O2 alone — reduces intubation rate ~50%. CPAP is simpler. Use BiPAP if hypercapnia.

Mode (1st choice)

CPAP

If normocapnic — equivalent to BiPAP (3CPO trial). Simpler, better tolerated.

CPAP Level

5–10 cmH2O

Start 5 cmH2O. Increase by 2 cmH2O every 5–10 min to max 10–12. Reduces preload and afterload.

Mode (if hypercapnia)

BiPAP (S/T)

BiPAP IPAP

10–16 cmH2O

BiPAP EPAP

5–8 cmH2O

FiO2

High — SpO2 >94%

Reassess

15–30 min

If not improving → reassess diagnosis. Add GTN infusion, furosemide. Early escalation if deteriorating.

Evidence

3CPO Trial (NEJM 2008)

Obesity Hypoventilation Syndrome (OHS): chronic hypercapnia + obesity (BMI >30). High EPAP needed to overcome chest wall mass. Often requires high IPAP. Treat as COPD exacerbation approach.

Mode

BiPAP (S/T)

IPAP Start

16–20 cmH2O

Higher IPAP required. Titrate to clinical response and PaCO2.

EPAP Start

8–12 cmH2O

Higher EPAP to overcome chest wall weight and upper airway obstruction.

Backup RR

14–16 /min

FiO2

SpO2 88–92%

Position

HOB 30–45°

Post-extubation NIV: prophylactic BiPAP in high-risk patients (hypercapnia, COPD, CHF, prolonged intubation) reduces re-intubation rate. Not effective once post-extubation respiratory failure is established — treat early or re-intubate.

Mode

BiPAP (S/T)

IPAP

12–16 cmH2O

EPAP

5–8 cmH2O

Schedule

q4h minimum

Prophylactic: scheduled sessions post-extubation × 24–48h. Rescue: apply immediately if deteriorating.

Caution

Early decision

Do not delay re-intubation. NIV should not be used to delay inevitable intubation once failure is established.

Hypoxic respiratory failure: NIV evidence weaker than for hypercapnic failure. HFNC often preferred first-line. NIV for immunocompromised (avoids intubation complications). High failure rate — monitor closely.

Mode

BiPAP or CPAP

IPAP

14–20 cmH2O

EPAP

8–10 cmH2O

Higher EPAP needed for oxygenation in diffuse lung disease.

FiO2

High — SpO2 >92%

ROX Index

Monitor q1–2h

Use ROX index (HFNC tab) as failure predictor. Escalate early.

Neuromuscular disease (MG, GBS, ALS, DMD): ventilatory failure from muscle weakness rather than lung disease. High IPAP needed to overcome weak respiratory muscles. Bulbar dysfunction = relative contraindication (aspiration risk).

Mode

BiPAP (S/T)

IPAP

18–25 cmH2O

High IPAP to compensate for weak inspiratory muscles. Titrate to tidal volume >7 mL/kg.

EPAP

4–6 cmH2O

Backup RR

14–18 /min

Higher backup rate if bulbar weakness — patient may be unable to trigger.

Escalation

VC <1 L or <20 mL/kg

Intubate early in GBS/MG crisis if VC declining rapidly, NIF worsening, or bulbar dysfunction progressing.

HIGH FLOW NASAL CANNULA

Evidence: FLORALI trial (NEJM 2015), ROX index (Intensive Care Med 2019)

FLORALI trial: HFNC superior to standard O2 and non-inferior to NIV in acute hypoxic respiratory failure. 90-day intubation rate significantly lower. First-line for non-hypercapnic hypoxic RF.

💨Starting Settings

Flow Rate

30–40 L/min

Start 30 L/min. Increase to 40–60 L/min for severe hypoxia. Max 60 L/min. Higher flow = better FiO2 delivery + PEEP effect (~1 cmH2O per 10 L/min).

FiO2

0.60–1.0

Start high (0.60–1.0 if severe). Titrate to SpO2 target 92–96%. Wean FiO2 first, then flow.

Temperature

37°C

Heated humidified gas. Improves tolerance and mucociliary clearance. 34°C if less tolerated.

Reassess

1–2 hours

Calculate ROX index at 2, 6, and 12h. Clinical reassessment at 30–60 min.

📐ROX Index CalculatorFailure Predictor

ROX = (SpO2/FiO2) ÷ RR. Predicts HFNC failure and need for intubation. Calculate at 2h, 6h, and 12h.

SpO2 FiO2 RR

ROX ≥4.88 at 12h = low risk of intubation
ROX 3.85–4.88 = intermediate — close monitoring
ROX <3.85 = HIGH RISK — prepare for intubation

⚠️HFNC Failure Criteria — When to Escalate

Escalate to NIV or Intubation if:

ROX index <2.85 at any time or <3.85 at 12h

SpO2 <90% on FiO2 1.0 and flow 60 L/min

Rising PaCO2 or pH <7.30 (hypercapnia developing)

Increasing RR >35/min or worsening accessory muscle use

Haemodynamic instability

Altered mental status / inability to protect airway

HFNC Weaning Protocol

Wean FiO2 first to 0.40 while maintaining SpO2 >92%

Then reduce flow rate by 5 L/min increments q4–8h

Trial conventional O2 when flow <20 L/min and FiO2 ≤0.40

AIRWAY EQUIPMENT

ETT sizing, blade selection, LMA, surgical airway reference

🔬ETT Size & Insertion Depth

Adult Male

7.5–8.0

23–25 cm

Cuffed

Adult Female

7.0–7.5

21–23 cm

Cuffed

Newborn

3.0–3.5

9–10 cm

Uncuffed

6 months

3.5

11 cm

Uncuffed

1 year

4.0

12 cm

Uncuffed

2 years

4.5

13 cm

Uncuffed

4 years

5.0

14 cm

Uncuffed or cuffed −0.5

6 years

5.5

15 cm

Uncuffed or cuffed −0.5

8 years

6.0

16 cm

Consider cuffed −0.5

10 years

6.5

17 cm

Cuffed 6.0

12+ years

7.0

18–20 cm

Cuffed

Paediatric formula: Uncuffed: (age/4) + 4 · Cuffed: (age/4) + 3.5 · Depth: (age/2) + 12 cm
Confirm with: bilateral breath sounds + EtCO2 waveform + CXR (tip at carina level)

🫁LMA / Supraglottic Airway Sizing

<5 kg

4 mL

3.5

1.5

5–10 kg

7 mL

4.0

10–20 kg

10 mL

4.5–5.0

2.5

20–30 kg

14 mL

5.0–5.5

30–50 kg

20 mL

6.0

50–70 kg

30 mL

6.0–6.5

70–100 kg

40 mL

7.0

>100 kg

50 mL

7.0

🔦Laryngoscope Blade Selection

Mac 3

Curved

Average adult

Most common; sits in vallecula

Mac 4

Curved

Large adult / long neck

Larger mouth / longer blade

Miller 2

Straight

Average adult

Lifts epiglottis directly

Miller 3

Straight

Large adult / anterior airway

Anterior larynx, long epiglottis

Mac 1–2

Curved

Paediatric (toddler–child)

Mac 1 infant; Mac 2 small child

Miller 0–1

Straight

Neonate–infant

Miller 0 neonate; preferred in infants (anterior larynx)

VL (any)

Video

Difficult airway / anticipated difficult

First-line if LEMON positive. Glidescope/McGrath/C-MAC.

🔪Emergency Surgical Airway — Scalpel-Bougie-TubeCICO Protocol

Declare CICO loudly. Stop intubation attempts. Move directly to surgical airway. Hesitation kills. Perform within 2–3 minutes of decision.

Position & Identify

Neck extended. Palpate and identify cricothyroid membrane (between thyroid and cricoid cartilages). Stabilise larynx with non-dominant hand.

Skin Incision

Vertical 3–4 cm skin incision over CTM — vertical avoids vessels. Index finger palpates through skin to confirm CTM location.

Horizontal Stab Incision

Single horizontal stab through CTM with No.10 scalpel. Caudal traction on trachea with hook through incision.

Bougie Insertion

Bougie passed caudally through incision into trachea. Feel tracheal rings (clicks) and hold-up at carina to confirm tracheal placement.

ETT over Bougie

Cuffed 6.0 ETT railroaded over bougie. Rotate 90° anticlockwise if resistance at arytenoids. Advance to 8–9 cm at skin.

Confirm & Ventilate

Remove bougie. Inflate cuff. Ventilate. Confirm EtCO2 waveform + bilateral breath sounds. Secure tube. CXR.