The study aims to examine the effect on intracranial pressure by calculating the optic nerve sheath diameter (ONSD) using ultrasound in patients who underwent suspension direct laryngoscopy.

Thirty-three patients who underwent suspension direct laryngoscopy were included in this prospective observational study. ONSD measurement was performed using a high-frequency linear probe. The ONSD basal (T0) value was determined using ultrasound in the supine position before the induction. Ultrasonography was used to record ONSD in the Boyce Jackson position (T1) just before inserting the laryngeal blade, in the Boyce Jackson position just before removing the laryngeal blade (T2), and in the supine position (T3) just before extubation.

A statistically significant rise (p < 0.001) was seen between the patients' baseline ONSD values and the values at T1, T2, and T3. The optic nerve sheat diameter level recorded prior to withdrawing the laryngeal blade (T2) was considerably greater than the ONSD level calculated instantly before insertion of the laryngeal blade (T1) (p < 0.001). The ONSD value prior to extubation (T3) following the removal of the laryngeal blade was considerably smaller than the ONSD value prior removing the laryngeal blade (T2) (p < 0.001).

This study found that when the laryngeal blade is mounted during the suspension direct laryngoscopy surgery, there is a significant increase in ultrasonographically measured ONSD and increased the ONSD even further during the time the mouth gag was remained in situ. This is the first research to indicate that measuring ONSD with ultrasonography during suspension direct laryngoscopy raises intracranial pressure.