Visual rigid laryngoscope versus Macintosh laryngoscope using low-dose relaxants in thyroid surgery

This study evaluated the safety and efficacy of the Macintosh laryngoscope versus the visual rigid laryngoscope (VRL) for tracheal intubation under a low-dose muscle relaxant protocol in thyroid surgery, to provide clinical evidence for the selection of optimal intubation tools for this setting.

In this single-center, randomized controlled trial, two experienced anesthesiologists performed tracheal intubation using either the Macintosh laryngoscope (Mac group, n = 47) or VRL (VRL group, n = 45) in patients undergoing elective thyroid surgery with Intraoperative neuromonitoring (IONM). The primary outcome was intubation time. Secondary outcomes included first-attempt intubation success rate, hemodynamic changes during the peri-intubation period, laryngoscopic view graded by the Cormack-Lehane classification, and intubation-related complications.

The intubation time was significantly shorter in the VRL group (mean ± SD, 33.27 ± 8.36 s) than in the Mac group (52.19 ± 9.83 s) (P < 0.001). The intubation success rate and heart rates did not differ between groups (P > 0.05). The mean arterial pressure (MAP) at intubation and the amplitude of MAP increase during intubation was lower in Group VRL than in Group Mac (P < 0.005). No statistically significant differences were observed between the two groups in peripheral oxygen saturation (SpO₂), Cormack-Lehane classification, or intubation-related complications (P > 0.05).

For thyroid surgery using a low-dose muscle relaxant protocol to enable IONM, the VRL provides significantly shorter intubation time and better hemodynamic stability at intubation compared with the Macintosh laryngoscope. No significant differences were observed between the two devices in intubation success rate, laryngoscopic view, or intubation-related complications.