Comparison of Airway Ultrasound Measurements With Conventional Parameters in Predicting Difficult Intubation

Clinical screening tests, which have long been routinely used for airway assessment, do not have sufficient sensitivity and specificity to detect difficult laryngoscopy. The Cormack-Lehane laryngoscopy classification, which can be assessed during direct laryngoscopy, is an invasive procedure and is not suitable for routine preoperative airway assessment. Preoperative airway assessment using ultrasound can help to predict a difficult laryngoscopy and/or difficult intubation and is growing in popularity as a non-invasive diagnostic tool. Several recent studies have emphasised the importance of various ultrasound-mediated airway measurements in predicting difficult intubation, and have shown that measurements with different parameters and data obtained by ratioing some measurements to each other may have an important role. However, the parameters obtained by ultrasound-mediated airway measurement can help determine airway anatomy and guide airway interventions with dynamic real-time images.

In this study, investigators used hyoid bone visibility obtained through preoperative ultrasound evaluation of the upper airway, followed by measurements of the skin-hyoid distance, skin-cricothyroid membrane distance and length, and hyomental distance in two different positions-neutral and extension. The ratios of these measurements were analyzed to predict difficult intubation. Traditional parameters commonly used as indicators of difficult ventilation and/or intubation, such as the Mallampati-Samsoon classification, upper lip bite test, thyromental distance, sternomental distance, neck circumference, maximum mouth opening, Wilson difficult intubation score, and Han ventilation scale, were also included in the study.