Characterization of Endotracheal Tube Cuff Pressure-Volume in Simulated and Cadaveric Tracheas

To characterize the pressure-volume (P-V) behavior of two common endotracheal tube (ETT) cuffs across three airway models of increasing anatomic realism: rigid, elastic, and cadaveric, and to quantify the narrow volume threshold separating safe from potentially injurious cuff pressures.

We tested TaperGuard and Sheridan reinforced ETTs (sizes 6.0-8.0 mm) in a rigid manikin, elastic synthetic, and cadaveric tracheas. Cuff pressure was recorded after 0.2 mL incremental inflation up to 120 cmH₂O. Polynomial and power-law models were fitted to the P-V curves. Key metrics included ΔV from 20 to 30 cmH₂O, curve slope, and model fit accuracy.

All cuffs demonstrated nonlinear P-V behavior. Cadaveric tracheas exhibited the steepest pressure escalation, with ΔV (20 → 30 cmH₂O) as small as 0.25 mL. Elastic models showed delayed pressure rise, while rigid models escalated rapidly once wall contact was reached. Polynomial models (R² ≥ 0.93-0.99) better captured high-pressure transitions than power-law fits. Tapered cuffs achieved effective seals with lower volumes than cylindrical cuffs but demonstrated similarly steep pressure increases when overinflated.

ETT cuff behavior is highly sensitive to airway compliance. Cadaveric airways showed a narrower inflation margin than synthetic models, underscoring the limitations of manikin-based training. Across designs, small additional volumes can precipitate unsafe pressures, highlighting the need for precise pressure-guided cuff management over volume estimation.

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