Selecting an Appropriate Cuffed Endotracheal Tube Using Ultrasound of the Cricoid in a Child with Down Syndrome

A 7-year-old girl (height, 94 cm; weight, 15.1 kg) with Down syndrome was scheduled for right patellar dislocation repositioning. The ultrasonographically measured internal transverse width of the cricoid before intubation was 7.8 mm. Attempted insertion of a cuffed Mallinckrodt® endotracheal tube (ETT) (internal diameter, 5.0 mm; deflated cuff portion, 8.4 mm diameter) failed. In contrast, the insertion of a cuffed Microcuff® ETT (5.0 mm ID; deflated cuff portion, 7.3 mm diameter) was successful. Thicker folds in the deflated cuff of the Mallinckrodt ETT could have hindered passage through the vocal cord, including the cricoid region. It is becoming standard to use the ultrasonographically measured internal width of the cricoid when choosing cuffed paediatric ETTs, and this approach may be suitable for patients with Down syndrome as well. In these children, approximately 20% of uncuffed ETTs inserted were one or two sizes smaller in diameter than those predicted for the same age. We may choose the ETT size in reference to an ultrasonographically obtained internal transverse width of the cricoid, stated outer diameter (OD) by the producer, and the actual OD depending on the cuff bulk instead of a tube size calculation in patients with growth retardation.