The Preoperative Use of Ultrasound in Airway Assessment in Critically Ill Obstetrics with Pre-eclampsia; Comparison Between Two Ultrasound Techniques in Relation to the Standard Clinical Assessment

Unexpected difficult airway exposes the patient to serious morbidity and even mortality. Obstetrics airway carries the risk of complications due to physiological changes. The airway shows more restriction and changes in preeclamptic patients and peripartum periods. A study reported one incidence of difficult intubation in obstetrics in 20 cases. Inadequate airway management leads to failure in ventilation and oxygenation of the critically ill mother and her fetus.

the Practice Guidelines for Management of the Difficult Airway by the American Society of Anesthesiologists (ASA) define the difficult airway as difficult facemask ventilation of the upper airway, difficult tracheal intubation, or both. preoperative assessment of the airway avoids that risk; however, current clinical screening tests have low sensitivity and specificity with limited predictivity.

Ultrasound (US) provides a more precise assessment for tissues like epiglottis, vocal cords, and ring-shaped membranes; thus, it facilitates a bedside, non-invasive objective airway assessment. Moreover, ultrasound assessment can plan and guide airway interventions if needed. The airway in pregnancy goes through changes. a study concluded that The US airway assessment parameters differ significantly between pregnant and non-pregnant patients. Previous studies reported that the best predictors of difficult laryngoscopy and/or difficult intubation were the epiglottis midline-skin distance, hyoid bone-to-skin distance, thyroid cartilage-to-skin distance, thyrohyoid membrane-to-skin distance, and vocal cord anterior commissure-skin distance also predicted difficult airway. In Pregnancy, hyoid bone visibility, and Pre-E/E-VC ratio were independent predictors of the difficult airway.

Researchers suggested different techniques for airway ultrasound. Some suggested detailed technique that allows the determination of multiple parameters. Others suggested a more concise protocol to lessen the time of assessment and to avoid complexity.

This trial assesses the superiority of either 2 views or 5 views ultrasound assessment in predictivity of difficult airway (difficult ventilation, laryngoscopy, and intubation) and their comparison to traditional clinical examination by El-Ganzouri index (GREI) (9) in critically ill obstetric patients with pre-eclampsia.