Ultrasound-guided superior laryngeal nerve block: a randomized comparison between parasagittal and transverse...

Different approach ultrasound-guided superior laryngeal nerve block was used to aid awake intubation, but little is known which approach was superior. We aimed to compare the parasagittal and transverse approaches for ultrasound-guided superior laryngeal nerve block in adult patients undergoing awake intubation.

Fifty patients with awake orotracheal intubation were randomized to receive either a parasagittal or transverse ultrasound-guided superior laryngeal nerve block. The primary outcome was patient's quality of airway anesthesia grade during insertion of the tube into the trachea. The patients' tube tolerance score after intubation, total procedure time, mean arterial pressure, heart rate, Ramsay sedation score at each time point, incidence of sore throat both 1 h and 24 h after extubation, and hoarseness before intubation, 1 h and 24 h after extubation were documented.

Patients' quality of airway anesthesia was significantly better in the parasagittal group than in the transverse group (median grade[IQR], 0 [0-1] vs. 1 [0-1], P = 0.036). Patients in the parasagittal approach group had better tube tolerance scores (median score [IQR],1[1-1] vs. 1 [1-1.5], P = 0.042) and shorter total procedure time (median time [IQR], 113 s [98.5-125.5] vs. 188 s [149.5-260], P < 0.001) than those in the transverse approach group. The incidence of sore throat 24 h after extubation was lower in the parasagittal group (8% vs. 36%, P = 0.041). Hoarseness occurred in more than half of the patients in parasagittal group before intubation (72% vs. 40%, P = 0.023).

Compared to the transverse approach, the ultrasound-guided parasagittal approach showed improved efficacy in terms of the quality of airway topical anesthesia and shorter total procedure time for superior laryngeal nerve block.

This prospective, randomized controlled trial was approved by the Ethics Committee of Nanjing First Hospital (KY20220425-014) and registered in the Chinese Clinical Trial Registry (19/6/2022, ChiCTR2200061287) prior to patient enrollment. Written informed consent was obtained from all participants in this trial.