Scanning electron-microscopic evaluation of cuff shoulders in pediatric tracheal tubes

Technical and conceptual shortcomings of cuffed pediatric tracheal tubes have been pointed out in the past, all representing a potential risk for mucosal damage of the pediatric airway. In this study, cuffed pediatric tracheal tubes from different manufacturers were investigated with regard to the cuff shoulder design using scanning electron microscopy (SEM).

Cuffed pediatric tracheal tubes with the smallest internal diameter available were ordered from five manufacturers. SEM scans were performed from the tube shaft - cuff shoulder - tube cuff assembly and from the cuff shoulder alone. Each investigation was repeated in four samples of each tube brand. In addition, thickness of cuff membrane was measured.

Major differences were found among the cuff shoulders investigated ranging from smooth transitions, softened borders to very sharp steps. There was also considerable difference in the thickness among the cuff membranes between the different tube brands ranging from 18 microm in polyurethane cuffs up to 90 microm in polyvinylchloride cuffs.

Because the gap between the outer tracheal tube and the internal mucosal layer of the pediatric airway is often very narrow, some of the observed irregularities have the potential to injure the airway mucosa in pediatric patients, particularly during long-term use and firm fit of the tracheal tube in the airway. As cuffed tubes are increasingly used in small children, the observed irregularities in some tracheal tube brands may need to be improved and their safety should be proved by the manufacturers.