Case Presentation
Compared with the female patient’s tracheal cross-sectional area in T3 vertebra,the endotracheal tube (ETT) cuff undersize was diagnosed in a 70-yr-old with 50kg body weight and 158cm height during the patient’s chest CT(X-ray computed tomography). Endotracheal tube was intubated through the mouth with reinforced endotracheal tubes CT showed tracheal area in T2 vertebra is 584.2 mm2(Fig1A), T3 vertebra is 646.2 mm2(Fig1B), T4 vertebra is 498.8mm2(Fig1C). Endotracheal intubation for patients. ID of endotracheal tube:7.0 (Guangzhou Weili Medical Equipment Co., Ltd., Guangzhou, China). Cuff diameter: 22mm, cross-sectional area of cuff:380.13 mm2 . The above results are greater than cross-sectional area of cuff:380.13 mm2(Fig2). Cuff pressure was maintained with the minimum leak technique (MLT) and measured with a cuff pressure gauge[6], Subsequent cuff manometer measurement demonstrated a pressure of 100cm H2O.
Yousef aljatlany et al demonstrated the formula for measuring cross-sectional area in tracheal, cross-sectional area = -171.834+ (0.5850×age)+ (86.8685×sex)+(2.3953×height in com) (Sex will be denoted by “1” for men and “0” for women)[7], The final calculated tracheal cross-sectional area of the patient is 247.5734 mm2. Height-based nomogram for endotracheal tubes (ETT) size selection derived from the Coordes et al CT imaging study[8], The final predicted ETT size of the patient is 6.5 or 7.0mm. According to the above two selection methods, theoretically, the cuff of endotracheal intubation can effectively seal the airway, When the intracuff pressure is 30 cmH2O. However, the true tracheal cross-sectional area of the patient is unusual.