Optimizing nonintubated laryngeal microsurgery: The effectiveness and safety of superior laryngeal nerve block with high-flow nasal oxygen – A prospective cohort study

Abstract

Background: Laryngeal microsurgery (LMS) typically requires intubated general anaesthesia. Although nonintubated general anaesthesia (NIGA) with high-flow nasal oxygen (HFNO) can be applied with LMS, a muscle relaxant is required, which can cause apnoea and hypercapnia. This study evaluated the effectiveness of a superior laryngeal nerve block (SLNB) in improving safety during LMS. Methods: This prospective cohort study enrolled a cumulative total of 61 adult patients received LMS under intravenous general anesthesia and allocated to three groups: intubated general anesthesia (ITGA) group (n = 18), which patients performed intubation; neuromuscular blocking (NMB) group (n = 21), which patients administrated muscle relaxant without intubation and superior laryngeal nerve block (NB) group (n = 22), which patients performed SLNB without intubation or muscle relaxant. Results: The average (standard deviation) values of PaCO2 after surgery in ITGA, NMB and NB group were 50.8 (7.5), 97.5 (24.9) and 54.8 (8.8) mmHg, respectively. The mean postoperative pH values were 7.33 (0.04), 7.14 (0.07), and 7.33 (0.04), respectively. The results were all p<0.001, and the average pH value of the NMB group was lower than that of the ITGA and NB groups. During the LMS, the mean HR (93.9 [18.1] bpm) and NBPs (143.5 [28.2] mmHg) in the NMB group were higher than those in the ITGA group (HR 77.4 [13.5] bpm and NBPs 132.7 [20.8] mmHg) and NB group (HR 82.3 [17.4] bpm and NBPs 120.9 [25.0] mmHg). The results of p value by HR and NBPs are p<0.001. The PaCO2 and pH values are similar between ITGA group and NB group. Conclusion: Our approach of using HFNO with SLNB was successful for performing nonintubated LMS, enabling the patients to maintain spontaneous breathing and effectively eliminate CO2. This approach reduces the risks of hypercapnia and acidosis even when the duration of LMS exceeds 30 min.