Effects of Continuous Monitoring and Progressive Regulation of Inflatable Laryngeal Mask Airway Cuff Pressure on Postoperative Pharyngolaryngeal Complications in Elderly Patients

The laryngeal mask airway (LMA) is a supraglottic ventilation device designed based on human anatomy, developed by Dr. Archie Brain from the United Kingdom in 1981, aiming to overcome the limitations of tracheal intubation and mask ventilation. Due to its advantages of easy operation, minimal airway stimulation, and stable hemodynamics, LMA has been widely used in clinical practice. In the past, tracheal intubation was the standard method for airway control during general anesthesia. Nowadays, in China, Europe, and the United States, the proportion of general anesthesia using LMA for ventilation has increased significantly over the past decade. By 2022, as an emergency airway device, the utilization rate of LMA in China had risen to 95.96% . With continuous improvement and development, LMA can also establish safe airway management in special positions such as lateral and prone positions, as well as in long-duration and special-site surgeries.

However, the widespread application has also exposed critical issues. Malposition, airway obstruction, laryngospasm, regurgitation, and aspiration may occur during LMA use, leading to a series of pulmonary and extrapulmonary complications. Studies have shown that many adverse events during LMA insertion may be related to cuff pressure monitoring. The lack of pressure monitoring results in pressure imbalance; inappropriate pressure management may lead to poor fitting between the LMA and the pharyngeal mucosa. Combined with intraoperative position changes and postoperative transportation, the risks of postoperative sore throat and LMA displacement are increased. Therefore, there is an urgent need for dynamic pressure monitoring during LMA use.

In terms of LMA pressure management, first, precise control of cuff pressure is the core. Cuff pressure refers to the pressure inside the LMA cuff after inflation, which is related to the inflation volume, LMA size, temperature, and other factors. For inflatable LMAs, clinicians usually inflate the pilot balloon and valve via a syringe empirically, judging cuff distension by the appearance of the pilot balloon, with the goal of achieving an airtight seal, adequate tidal volume, and normal peak airway pressure.

Insufficient cuff pressure may lead to inadequate ventilation, while excessive pressure compresses the pharyngeal mucosa and causes postoperative pharyngolaryngeal complications. In addition, nitrous oxide (N₂O) inhalation during clinical anesthesia can increase cuff pressure; thus, regular monitoring of cuff pressure is of great significance. Previous clinical studies used homemade cuff pressure gauges to monitor LMA cuff pressure and set cuff pressure according to peak airway pressure, showing that appropriate inflation volume under cuff pressure monitoring and setting LMA cuff pressure at Ppeak + 0-5 cmH₂O during general anesthesia with LMA ventilation can achieve a satisfactory seal and reduce the incidence of postoperative pharyngolaryngeal complications. Studies exploring appropriate inflation volumes for LMA cuffs have suggested that low cuff pressure is conducive to enhanced postoperative recovery.

Second, the sealing pressure of the LMA refers to the pressure required to form an effective seal between the LMA and the surrounding laryngeal tissues, formed by matching and compression between the cuff and the periglottic structures. It reflects LMA positioning and pharyngeal fitting, and is related to LMA type and patient laryngeal anatomy. Leak pressure is defined as the pressure at which gas escapes from the edge of the LMA as airway pressure gradually increases. Oropharyngeal leak pressure (OPLP) is commonly used clinically to evaluate the reliability of LMA sealing during ventilation. Some studies have suggested that it is the most accurate description of peripharyngeal gas leak pressure, which is affected by upper airway anatomy, anesthetic agents, LMA size, surgical position, and other factors.