Dimensions of the neonatal cricothyroid membrane - how feasible is a surgical cricothyroidotomy?

BACKGROUND: Airway management of the neonate remains a cornerstone in neonatal resuscitation which in most cases involves tracheal intubation. However, difficult intubations do occur. Cricothyroidotomy is recognized as an entry point below the vocal cords. This procedure becomes increasingly difficult in young children and is not recommended in children under the age of 5 years. Little is known about the anatomy of the neonatal airway, especially the size of the cricothyroid membrane. The aim of the study was to determine the dimensions of the cricothyroid membrane in neonates.

METHODS: Twenty-seven neonatal cadavers (mean height of 44.89 cm and a mean weight of 2.05 kg) were carefully dissected and the dimensions of the cricothyroid membrane recorded with a digital caliper (accuracy 0.01 mm) by two independent observers.

RESULTS: The cricothyroid membrane has a mean height of 2.61 mm (sd: 0.71) and width of 3.03 mm (sd: 0.63).

CONCLUSIONS: Results of this study indicate that the dimensions of the cricothyroid membrane are too small for passing a tracheal tube as the dimensions of the tube exceeds that of the cricothyroid membrane. This could fracture the cartilages of the larynx. The performance of a surgical cricothyroidotomy with passing of a tracheal tube is therefore strongly discouraged in neonatal patients.