The purpose of this study is to investigate the time-related intracuff pressure and volume change (which reflects the pharyngeal pressure) of the LT during anesthesia with N2O.

Background : The laryngeal tube airway (LT) is an extraglottic airway device with a proximal and distal conical cuff designed to secure a patient's airway during either spontaneous breathing or controlled ventilation. Application of this device with the use of N2O may be related to the ischemic change of the oropharyngeal mucosa. The objective of this study was to investigate the time-related intracuff pressure and volume change (which reflects the pharyngeal pressure) of the LT during anesthesia with N2O.

Methods : Seventy-five patients were studied with the use of LT size 4. N2O (66%) and isoflurane were used to maintain anesthesia. Initial intracuff pressure and volume were recorded for airway sealing during ventilation. Time-course changes of the intracuff pressure followed by recording every 10 min. If the intracuff pressure reached 100 cmH2O, the cuff was deflated to the initial intracuff pressure and the volume of deflated air and postoperative airway complications were recorded.

Inclusion Criteria:

• American Society of Anesthesiologist physical status I or II
• Undergoing elective orthopedic surgery and surgery of breast under general anesthesia with an expected duration of 60 min or more

Exclusion Criteria:

• Height was < 155 or >180 cm (for the use of laryngeal tube size 4)
• Body mass index ≥35 kg/m2
• Preexisting laryngotracheal disease
• Risk of pulmonary aspiration of gastric contents.

patients with general anesthesia