Effect of Training in the Loss-of-Resistance Syringe Technique on Optimizing Endotracheal Tube Cuff Pressure: A Prospective Before-and-After Study

This is a prospective, single-center observational before-and-after study in the operating rooms of Kayseri City Hospital. Consecutive eligible adult patients undergoing general anesthesia with endotracheal intubation will be observed in two temporal cohorts: a two-week pre-training cohort and a two-week post-training cohort. Only the first surgical procedure for each patient will be included.

Between the observation periods, anesthesia physicians and anesthesia technicians will receive standardized theoretical and practical education on cuff pressure management and the loss-of-resistance syringe technique. The education covers the target pressure range, the consequences of excessive or insufficient pressure, the syringe's low-friction plunger mechanism, and practical application. With this technique, the cuff is inflated through the pilot balloon valve using a loss-of-resistance syringe. Force on the plunger is then released, allowing it to move backward passively as air returns from the cuff. The syringe is disconnected when spontaneous plunger movement stops.

The clinical team independently decides whether and how to use a cuff inflation technique in routine clinical care. The research protocol does not assign patients to a technique. Researchers independent of the clinical team measure cuff pressure with a manometer after initial cuff inflation and before any corrective adjustment. The researcher measuring cuff pressure is unaware of the inflation technique until after the pressure has been measured and recorded. The initial value, rather than the value after safety correction, is used for the primary outcome. Pressures outside 20-30 cmH2O are corrected promptly for patient safety.

Cuff leakage and the need for additional air are recorded. Postoperative sore throat is assessed after extubation during postoperative recovery, once the patient is awake and able to answer questions. Demographic characteristics, surgical procedure, intubation attempts, tube characteristics and procedure durations are also recorded.

The primary analysis compares the proportion of patients with initial cuff pressure within 20-30 cmH2O between the pre-training and post-training cohorts, using the chi-square test or Fisher's exact test when appropriate. Cohorts are defined by observation period, not by the cuff inflation technique actually used. Continuous cuff pressure values will be compared using an independent-samples t test or the Mann-Whitney U test according to distribution. Secondary categorical outcomes will be compared using the chi-square test or Fisher's exact test. If appropriate, multivariable logistic regression will explore factors associated with postoperative sore throat. All tests will be two-sided with a significance level of 0.05.