Surface ultrastructure and pressure dynamics of tracheal tube cuffs

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Abstract
The outer and inner surfaces of six commercial endotracheal tube cuffs were characterized using scanning electron microscopy (SEM) and energy dispersive x‐ray analysis. Lateral tracheal wall pressure (LWP) was measured at various steps of cuff inflation using a mock‐trachea system. The surface characteristics of the cuffs were found to vary widely. The surface of the Lanz cuff was relatively smooth but showed a regular array of circular depressions 0.8 μm in diameter. Uniform spheres also 0.8 μm in diameter were distributed through the thickness of the membrane. The American Hi‐Lo cuff surface was also relatively smooth but was covered widely with flakes of material which x‐ray showed to be a clay‐like substance containing aluminum, silica, and potassium. The Harlake cuff was covered widely with roughly spherical, 5‐μm‐diam particles, probably starch granules. The membrane itself was smooth even at 3,000X. The Foregger cuff had a rough surface and was covered with the same clay‐like particles seen on the American cuff. The inner surface with irregular, uneven areas were surrounded by fissures. The Rusch Armored tube cuff was completely covered by a continuous 2‐μm‐thick chlorinated coating. The surface was highly convoluted and irregular. The three cuff membranes showing relatively smooth surfaces, Lanz, American and Harlake, also produced relatively low LWP at various points of cuff inflation. While we have no data to indicate that cuff surface smoothness correlates with tracheal morbidity, it would seem prudent to select cuffs that produce low LWP's with smooth surfaces for clinical use.