• R Jones and I Ueda.
• Department of Anesthesia, Primary Children's Hospital, Salt Lake City, Utah 84113-1103, USA. pcrjonel@ihc.com
• Can J Anaesth. 1996 May 1; 43 (5 Pt 1): 514-7.

PurposeTo investigate cuff types for potential use in late childhood and early adolescence for appropriate fit.MethodFormulae suggest the use of a tracheal tube having a 6.5 mm internal diameter at ages 8 to 10 years, so a model system was used to test the passage of cuffed and uncuffed tracheal tubes of 6.5 mm internal diameter through calibrated holes 8.1-16.6 mm diameter, in plastic plates.ResultsUncuffed tracheal tubes passed through 9.0 mm diameter holes. "High pressure" cuffed tubes passed through 10.5 to 11.3 mm holes. "Low pressure" cuffed tubes passed through 12.3 to 16.4 mm.ConclusionPatients aged 8 to 10 yr have a limiting internal diameter at the cricoid of 8 to 10 mm. Their unstretched tracheal diameter below the cricoid is only about 11 mm. The actual outside diameters of "low pressure" cuffs chosen by commonly used formulae considerably exceed the limiting diameters of eight to ten year old patients, even considering recommended compensation factors. Analysis of background data indicates that these problems are especially aggravated at this age by non-linear growth of the cricoid.

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