Difficult airway management during anesthesia remains a major contributor to perioperative morbidity and mortality, with potential preventable consequences such as airway trauma, hypoxic brain injury, and even death (Joffe et al., 2019). Many patients requiring endotracheal intubation (ETI) present with borderline respiratory and circulatory reserve, hemodynamic instability, and limited oxygen stores. These factors constrain the dosage of general anesthetics and the allowable duration for intubation, making ETI particularly high-risk in this population. In elderly patients, age-related degenerative changes in the cardiovascular system reduce their tolerance to hemodynamic fluctuations, while altered pharmacokinetics influence drug distribution, half-life, and clearance (Uysa et al., 2012). Consequently, controlling induction and maintenance of general anesthesia is challenging, with increased susceptibility to severe blood pressure fluctuations, peri-induction complications, respiratory depression, and delayed emergence due to incomplete postoperative drug metabolism.

Clinically, for patients with predicted difficult airways, anesthesiologists often adopt a slow-induction strategy with amnesic analgesia while preserving spontaneous respiration. In such cases, surface anesthesia with local anesthetics via cricothyroid membrane puncture (CMP) is widely employed (Andruszkiewicz et al., 2010). CMP anesthesia can effectively attenuate airway reflexes and blunt hemodynamic surges caused by tracheal intubation, thereby improving ETI safety in difficult airway scenarios (Chen et al., 2018). Anatomically, the cricothyroid membrane is the thinnest portion between the laryngeal cavity and trachea, with a superficial location and absence of major vessels, nerves, and rigid structures, making it a reliable and safe access point for percutaneous subglottic airway interventions (Kristensen et al., 2016). However, most CMP anesthesia procedures are performed in awake patients, and there is limited evidence on its application after anesthesia induction in elderly individuals. The potential benefits of combining CMP surface anesthesia with ETI under deep sedation—particularly in improving peri-induction hemodynamic stability and reducing emergence-phase airway complications—have not been fully elucidated. This study aimed to evaluate the clinical effects and safety of CMP anesthesia followed by ETI in elderly patients after induction, thereby addressing a current evidence gap and offering insights into optimizing airway management in high-risk populations.

During ETI, induction agents such as midazolam, propofol, etomidate, and fentanyl are commonly used (Allen et al., 2023). Most cases are induced while retaining spontaneous breathing; however, even with appropriate anesthetic dosing, elderly patients often experience hypotension after induction due to frailty and comorbidities (Sudfeld et al., 2017). Large hemodynamic fluctuations during intubation further increase perioperative risk (Ranjbar et al., 2018). Previous studies have shown that CMP anesthesia during awake fiberoptic intubation yields superior intubation conditions, shorter intubation times, and higher patient and operator satisfaction than conventional topical anesthesia (Wang et al., 2021). Moreover, CMP injection provides more effective airway anesthesia than nebulized lidocaine during diagnostic bronchoscopy (Isaac et al., 1990). Building on these findings, we applied CMP surface anesthesia after anesthesia induction, a less-reported approach, to explore its value in elderly patients.

In this study, both groups achieved a 100% first-attempt intubation success rate, confirming that CMP anesthesia does not compromise technical feasibility even in elderly patients. Notably, the CMP group had lower rates of hypotension and reduced vasoactive drug use, indicating better peri-intubation hemodynamic stability. This aligns with the pharmacological profile of lidocaine—rapid onset, wide dispersion, strong mucosal permeability, and the ability to block peripheral cough receptors and vagal reflexes, relax airway smooth muscle, and suppress arrhythmias (Rahimi et al., 2018). Modern studies also show that lidocaine can attenuate airway hyperreactivity induced by kinins, reduce forced expiratory volume decline, and blunt cardiovascular responses to airway manipulation (Sun et al., 2021). While some studies report no significant association between lidocaine use and hypotension or heart rate changes (Kim et al., 2025), our findings suggest that CMP delivery may enhance its hemodynamic benefits by ensuring rapid, concentrated mucosal exposure.

Compared with other surface anesthesia methods, CMP offers the advantage of delivering a larger volume of lidocaine directly to the subglottic area in a short time, resulting in faster onset and more complete airway anesthesia. This targeted delivery may explain its superiority over nebulized or sprayed lidocaine in suppressing airway reflexes and stabilizing hemodynamics. Clinically, this could be particularly advantageous in elderly patients with limited tolerance for sympathetic surges during ETI.

The absence of significant differences in adverse reactions (e.g., local anesthetic allergy, bleeding, or oropharyngeal pain) between groups further supports the safety profile of CMP anesthesia. Topically applied agents with analgesic properties primarily act on peripheral pain pathways, thereby reducing systemic absorption and minimizing the risk of widespread adverse effects (Gudin and Nalamachu, 2020). Lidocaine is a local anesthetic, which can block the Na⁺ channel and produce local anesthetic effect (Hermanns et al., 2019). In the CMP anesthesia approach, a relatively large amount of lidocaine comes into direct contact with the airway surface within a short time, resulting in rapid anesthetic onset. The cricothyroid administration route has been shown to be both safe and effective for topical anesthesia during endobronchial ultrasound-guided transbronchial needle aspiration (Mittal et al., 2021). Moreover, at low concentrations, lidocaine poses minimal toxicity risk while maintaining respiratory and hemodynamic stability (Liu et al., 2020). Yang et al. reported that the low incidence of throat pain associated with lidocaine use may be attributable to its stabilizing effects on both central and peripheral nervous systems, further supporting its potential role in mitigating anesthesia-related adverse effects (Han et al., 2024).

In this study, the increases in HR, SBP, and MAP in the observation group were lower than those in the control group at T1, T2, and T3, indicating that CMP anesthesia contributed to greater circulatory stability and more effective attenuation of intubation-related irritation. This finding is clinically relevant, as airway manipulation often triggers pronounced sympathetic reflex activation, leading to significant hemodynamic changes. With reduced vagal stimulation during ETI, the incidence of tachycardia rises correspondingly (Mendonca et al., 2022). Such hemodynamic instability can diminish cardiac output, impair tissue perfusion and oxygen delivery, and promote anaerobic metabolism, resulting in lactic acidosis, progressive organ dysfunction, and potentially death (Kumar et al., 2021). Therefore, achieving adequate airway surface anesthesia before ETI is crucial for minimizing airway stimulation, preventing cardiovascular adverse reactions during intubation, and maintaining hemodynamic stability (Tung et al., 2020).

Choking during emergence from anesthesia is a common and potentially dangerous event that can induce laryngospasm, hypoxia, or hypercapnia (Tang et al., 2023). Previous studies have demonstrated that intravenous administration of lidocaine during surgery can reduce respiratory complications such as coughing (Yang et al., 2020). Similarly, administering lidocaine intravenously before anesthesia in premedicated dogs effectively alleviates the coughing response associated with ETI (Panti et al., 2016). In line with these observations, our study found that CMP anesthesia with lidocaine significantly reduced the incidence of choking cough during the recovery period in elderly patients, thereby enhancing airway safety and patient comfort.

This study has several limitations. First, the sample size was relatively small (n = 80) and conducted at a single center; further subgroup analyses would markedly reduce statistical power, potentially affecting the stability and reliability of the findings. Future multi-center studies with larger and more diverse patient populations are needed to enhance external validity and allow for more precise subgroup analyses. Second, due to the invasiveness of CMP and the specific drug administration method, a single-blind design was used, and blinding of operators was not feasible. Although standardized scoring scales and independent, trained evaluators were employed to minimize bias in subjective outcomes such as the cough score, the influence of assessor experience cannot be completely excluded. Third, patients with essential hypertension were not included, which may limit the generalizability of the results to this population. Finally, the study focused on the immediate safety of tracheal intubation after CMP, with only short-term adverse events recorded; future research should incorporate longer follow-up periods to assess long-term safety and outcomes.

In conclusion, this study provides evidence that CMP anesthesia, when performed after induction in elderly patients, enhances the safety of ETI by stabilizing hemodynamics and reducing recovery-related adverse events. Given the high perioperative risks in elderly individuals—such as age-related cardiovascular changes, reduced physiological reserve, and multiple comorbidities—our findings offer a practical and targeted strategy to optimize airway management in this population. By attenuating the sympathetic response to tracheal tube stimulation, CMP anesthesia helps to minimize hemodynamic fluctuations and reduce the incidence of choking during emergence, ultimately contributing to improved perioperative stability and patient outcomes.

To our knowledge, this is the first controlled clinical study to evaluate CMP anesthesia performed after induction—rather than in the traditional awake setting—in elderly surgical patients requiring ETI. The results demonstrate that this approach not only maintains procedural safety but also confers measurable benefits in hemodynamic stability and recovery quality without increasing overall adverse event rates. This expands the potential application of CMP anesthesia from difficult airway cases to routine airway management in high-risk elderly patients, offering a new option that is both feasible and effective in the intraoperative setting. Anesthesiologists can consider incorporating CMP anesthesia after induction into the airway management protocol for elderly patients at risk of peri-intubation hemodynamic instability, particularly those with limited tolerance for blood pressure fluctuations or prone to severe choking during emergence. Successful implementation requires standardized operator training, strict adherence to aseptic technique, careful patient selection, and close perioperative monitoring. Integrating this method into routine practice could enhance patient safety, improve comfort during recovery, and potentially reduce the need for vasoactive support in elderly surgical populations.