Ultrasound-guided superior laryngeal nerve block reduces the cardiovascular response during bronchoscopy in awake patients: a randomised controlled trial

In bronchoscopy, conscious patients often have excessive sympathetic stimulation due to the high intensity of stimulation and strong discomfort, causing an increase in heart rate and blood pressure during the procedure. Superior laryngeal nerve block can reduce the sensation of the larynx, glottis and subglottic tracheal mucosa. Whether this can reduce cardiovascular response during bronchoscopy has not been reported. The purpose of this study was to explore whether superior laryngeal nerve block can reduce cardiovascular response in patients during bronchoscopy. This randomised controlled trial included 80 patients that were randomly assigned to two groups of 40 patients each in Fourth Hospital of Hebei Medical University (1 July to 20 December 2022). Group L was anaesthetised with a superior laryngeal nerve block + direct injection of 2% lidocaine into the upper trachea through the cricothyroid membrane. Group C received direct injection of local anaesthetic through the cricothyroid membrane. Heart rate (HR), mean arterial pressure (MAP) and blood oxygen saturation were measured before (T0) and after (T1) the block, immediately after bronchoscope entry into the glottis (T2) and during bronchoscopic biopsy (T3). Repeated‑measures ANOVA revealed significant group × time interactions for both heart rate (HR) and mean arterial pressure (MAP) (all p < 0.01), indicating that the temporal trajectories of haemodynamic changes during bronchoscopy differed significantly between the two groups. No significant between‑group differences were observed in HR or MAP at baseline (T0) or after nerve block completion (T1) (all p > 0.05). Compared with Group C, Group L had significantly lower HR at T2 and T3 (92.72 ± 13.76 vs. 101.38 ± 12.04 beats/min, p = 0.004; 90.10 ± 14.72 vs. 100.45 ± 11.46 beats/min, p < 0.001), as well as significantly lower MAP at both T2 and T3 (108.92 ± 11.71 vs. 117.31 ± 9.49 mmHg, p < 0.001; 105.61 ± 13.01 vs. 113.87 ± 9.93 mmHg, p = 0.003).Urapidil use in group L was significantly less than that in group C (2 [5%] vs. 12 [30%]; p = 0.006). The coughing score was significantly lower in group L than C (1 [0–1] vs. 2 [1–2]; p < 0.001). Significantly more patients had open vocal cords in group L than C (22 [55%] vs. 7 [17.5%]; p <0.001). Ultrasound-guided superior laryngeal nerve block can effectively reduce cardiovascular response and maintain stable haemodynamics in conscious patients during bronchoscopy. The study was registered with the China Clinical Trial Registration Center on 12/06/2022 ( http://www.chictr.org.cn ; registration number: ChiCTR2200060843).