<prompt> Inner diameter of adult male endotracheal tube is:4 nun6 mm9 mm2 mm  <response>: Ans: c 9 mm Ref: Ajay Yadav, 2nd ed, p. 33Sizes of endotracheal tubesNormal healthy males usually need No: 9 means inner diameter 9 mmNormal healthy female -No: 8 means inner diameter 8 mmIn childrenPremature: 2.5 mm i.d Inner diameter0-6 months: 3-3.5 mm i.d6 months to 1 year: 3.5-4 mm i.dFor children aged 1 -6 years is calculated by formulaAge in years3.5 mm i.d3 For children aged 6 yearsAge in years- 4.5 mm i.d4 Smallest size of tube available is 2.5 mm and largest size is 10.5 mm 