Evaluating the Sealing Capacities of Different Endotracheal Tube Cuff Designs

Background: Endotracheal tube (ETT) cuffs prevent over-the-cuff secretions from flowing into the lower airways. However, they may not completely prevent fluid leakage around ETTs. To validate a cuff design with high sealing capacity, we compared ETTs with varying cuff materials and structural properties. Methods: We used 7 ETTs with different cuff materials (polyvinyl chloride [PVC], polyurethane [PU]), shapes (conical, tapered, or cylindrical), wall thickness, and cuff sizes (contact area with the trachea). Wall thickness was measured after cutting the cuff using a micrometer. The contact area was calculated based on the long diameter of the cuff when expanded within a clear acrylic tube. The sealing capacity was defined as the time taken for 10 mL of distilled water to leak past the cuff. The sealing capacities of the cuffs were compared by inserting them into the simulated trachea (silicone corrugated tube). Results: The wall thicknesses were 29-29.3 µm for PU and 45.6-285 µm for PVC cuffs. The contact areas with the trachea were 18.7-27.1 and 12.5-22.3 cm for PU and PVC cuffs, respectively. The mean (SD) sealing capacities were 2,381 (484), 437 (177), 56 (12), and 24 (4) s for the cylindrical PU, conical PU, tapered PVC, and conical PVC cuffs, respectively. For the 3 cylindrical PVC cuffs (A, B, and C, respectively), the mean (SD) sealing capacities were 53 (11), 15 (2), and 9 (2) s. Conclusions: The PU cuff had a higher sealing capacity than the PVC cuff, and the cylindrical cuff had a higher sealing capacity than the conical cuff. For the PVC cuff, thinner materials had higher sealing capacities. Furthermore, the contact area between the cuff and model trachea significantly affected the sealing capacity.