The cricothyroid versus the spray-as-you-go method for topical anesthesia during flexible bronchoscopy: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND: Lignocaine can be administered during bronchoscopy using either a direct injection through the cricothyroid membrane (the cricothyroid method) or a spray of lignocaine solution through the bronchoscope working channel (the spray-as-you-go method). In this meta-analysis of randomized controlled trials (RCTs), we compared the efficacy of these two methods for topical anesthesia during flexible bronchoscopy. METHODS: We performed a systematic search to extract the relevant RCTs comparing the two techniques. RESULTS: Five RCTs meeting the inclusion criteria (747 subjects) were identified. The cricothyroid method was associated with significantly less cough (standardized mean difference [SMD] = −1.18, 95% confidence interval [CI] [−1.75, −0.62], P < 0.001, significant heterogeneity I(2) = 86%, P < 0.001). On analysis of secondary outcomes, the cricothyroid method was associated with a greater operator-rated procedure satisfaction (SMD = 1.00, 95% CI [0.74, 1.25], P < 0.001), less time for upper airway negotiation (mean difference, MD = −0.99, 95% CI [−1.37, −0.6], P < 0.001), and a significantly less cumulative dose of lignocaine administered (MD = −68.12, 95% CI [−130.18, −6.06], P = 0.03). The overall procedure duration (MD = 0.08, 95% CI [−0.09, 0.24], P = 0.36) and patient discomfort (MD = −0.08, 95% CI [−0.38, 0.22], P = 0.59) were not different between the two methods. There was no significant publication bias (P = 0.94). CONCLUSIONS: The cricothyroid method is associated with less cough during flexible bronchoscopy. Other advantages are a greater operator-rated procedure satisfaction at a less cumulative lignocaine dose. These findings highlight the superior performance characteristics of the cricothyroid method for lignocaine administration for flexible bronchoscopy.