Endotracheal tube seal and suction performance in a novel biorealistic tracheal model

Abstract

BACKGROUND: Endotracheal tube (ETT) cuffs create a seal to protect against secretion entry to the lungs. Cuff inflation currently is recommended at 20–30 cm H2O pressure. ETT designs have variable seal performance in bench studies using rigid tracheal models lacking the dynamic characteristics of the human trachea. We compared ETT designs within a new, biorealistic tracheal model to assess cuff and suction performance in the setting of a compliant trachea. METHODS: Three ETT designs (Mallinckrodt Hi-Lo, KimVent Microcuff, and Sheridan/HVT) were tested for performance by simulant leakage below the cuff and air leakage (measured as return tidal volume ≥ 80% delivered) over a range of cuff (5–25 cm H2O) and end-expiratory pressure (PEEP 0–15 cm H2O). Subglottic suction channel performance was tested in 2 ETTs (TaperGuard Evac [Covidien] and ISIS HVT [Teleflex]) as time to evacuate the simulant. RESULTS: All ETT cuffs provided effective seals at an inflation pressure of 12 cm H2O when PEEP was ≤5 cm H2O. The Microcuff ETT sealed at the lowest pressure of 6 cm H2O, whereas the Sheridan/HVT cuff sealed at 12 cm H2O (P =01). With a PEEP of 15 cm H2O, a reciprocal increase in air leak occurred, requiring a cuff inflation up to 22 cm H2O to maintain a return tidal volume at ≥ 80% delivered. Suction channel performance improved in the lateral position compared with supine for both ETT designs during continuous 15 mm Hg suction pressure (P=001). CONCLUSIONS: Within a novel model with normal trachea compliance, we found all ETT designs tested to seal at lower than current recommended cuff pressures.