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ETT Types — Cuffed, RAE, Double-Lumen, Microlaryngeal
TEXTAirway II · 9 min read
The standard PVC HVLP tube covers most cases. The specialty tubes solve specific problems.
After this lesson you can
4 min read9 sections- Choose ETT type for the case (standard, RAE, DLT, reinforced, microlaryngeal).
- Size ETT by patient age/sex.
- Monitor cuff pressure correctly.
- Anticipate ETT-specific complications.
Standard PVC HVLP cuff — pressure + N₂O caveat
Target cuff pressure: 20-30 cmH₂O — measured by a cuff manometer (finger 'feel' overestimates by 30-50%).
Above 30 cmH₂O exceeds capillary perfusion pressure ischemia, ulceration, post-extubation tracheal stenosis, fistula.
Below 20 leak + microaspiration risk.
N₂O diffuses INTO the cuff during anesthesia (air-filled cuff gains volume + pressure over 30-60 min) — recheck pressure periodically or fill cuff with saline if long N₂O case.
Inflation technique: minimum-occlusive-volume (inflate until leak just stops at peak airway pressure) OR target manometer pressure directly.
Sizing + depth
Larger ID less airway resistance, easier bronchoscopy passage, but more cord trauma + post-op hoarseness.
Depth at lip: women ~21 cm, men ~23 cm — confirm with chest auscultation + capnography + CXR if held in long-term.
Pediatric uncuffed: age/4 + 4. Pediatric cuffed: age/4 + 3.5.
Pediatric depth: ETT size × 3 = cm at lip.
Right mainstem intubation is the most common malposition — pull back if breath sounds asymmetric.
RAE (Ring-Adair-Elwyn) preformed tubes
Oral RAE: bend curves OUT over the chin tube exits inferiorly (ENT, ophthalmic, oral/maxillofacial, anterior neck cases).
Nasal RAE: bend curves UP over the forehead — used for intraoral procedures where oral tube interferes.
Bite block ESSENTIAL — a bite at the preformed bend kinks the tube permanently.
Single-use disposable.
Tube depth is fixed by the bend's design — verify position carefully because you can't pull it back without unraveling the bend.
Double-lumen tubes (DLT) — one-lung ventilation
Permits selective lung ventilation for thoracic surgery (lobectomy, pneumonectomy, lung volume reduction, thoracoscopy).
LEFT DLT preferred for almost all cases — left mainstem is longer (~5 cm vs right ~2.5 cm) and has more margin for positioning.
RIGHT DLT only when left mainstem is precluded (left main tumor, left lung transplant, left pneumonectomy) — and you MUST verify right upper lobe ventilation through the side slot / Murphy eye fiberoptically (RUL takes off ~2 cm from right main carina).
Sizes 35, 37, 39, 41 Fr (Fr ÷ 4 = approx OD in mm).
Confirm placement with fiberoptic scope — clinical signs alone miss 30-50% of malpositions.
Bronchial blocker — alternative to DLT
- standard ETT placement (no second intubation)
- can isolate lobes (not just whole lungs)
- useful in difficult airway
- pediatric thoracic (DLT not made small enough)
- less reliable lung deflation
- can migrate during positioning
- requires bronchoscopic guidance
Useful in trauma + difficult airway where DLT exchange is hazardous, and in awake fiberoptic situations.
Microlaryngeal tubes (MLT)
Used in ENT laryngeal microsurgery (vocal cord biopsy, laser cordectomy, papilloma removal) — small tube occupies less of the laryngeal aperture for surgical access while still permitting controlled ventilation.
Standard length, normal HVLP cuff.
Smaller lumen means higher airway resistance — generally ventilator-controlled with pressure-targeted mode, not spontaneous breathing.
Reinforced (armored, wire-wound) tubes
- prone position
- sitting
- lateral
- head-and-neck surgery where standard tubes would kink under retractor or position
ALWAYS use a bite block (oropharyngeal airway or soft bite block) during the case AND through emergence.
If bite occurs and tube is crushed: exchange the tube.
Some surgeons request reinforced even for routine ENT under retractor.
Specialty tubes — laser, MR-safe, contour
Used in airway laser surgery (CO₂, KTP, Nd-YAG) — pair with FiO₂ ≤30%, no N₂O, and an OR fire plan.
MR-safe (some labeled MR-conditional at specific Tesla ratings): ferromagnetic components removed; check pilot-balloon spring and 15 mm connector since these can contain metal.
Microcuff (Kimberly-Clark): polyurethane cuff with thinner wall + better seal at lower pressures — better aspiration prevention.
Contour Plus / Hi-Lo Evac: subglottic suction port above cuff for ventilator-associated pneumonia prevention in ICU intubations.
Tube exchange + extubation considerations
Airway exchange catheter (AEC, Cook): rigid hollow catheter passed through ETT before deflating the cuff ETT removed AEC remains in trachea as a conduit for reintubation if needed.
Useful after difficult airway, after long intubation with edema risk.
Patient can be awake + oxygenated through the AEC (15 L/min via Luer-lock).
Reintubation: railroad new ETT over AEC.
AEC sizing must match ETT internal diameter.
Hazards: barotrauma if high-pressure jet ventilation used through AEC, bronchial perforation if advanced past 25 cm.
⚠ Common pitfalls
- Cuff pressure 'just enough to stop the leak' — measure with manometer; 20-30 cmH₂O is the target.
- Right-sided DLT in routine thoracic — RUL takeoff variability; left preferred.
- Standard PVC tube in a prone or head/neck case — kinking risk; use a reinforced/wire-armored.
- Adult RAE in pediatric — these have specific size ranges; check the chart.
💎 Clinical pearls
- Cuff manometer q-30min — pressure climbs with N₂O diffusion and warming.
- Cuffed tubes are the modern peds standard; size = (age/4) + 3.5 cuffed.
- DLT confirmation: auscultate sequential clamping + fiberoptic verification — the answer is both.
- Microlaryngeal: small ID, long enough — needed for laryngology cases.
Recap
- Cuff manometer q-30min — pressure climbs with N₂O diffusion and warming.
- Cuffed tubes are the modern peds standard; size = (age/4) + 3.5 cuffed.
- DLT confirmation: auscultate sequential clamping + fiberoptic verification — the answer is both.
- Microlaryngeal: small ID, long enough — needed for laryngology cases.
Mark each section done to complete the module.