Objective To evaluate the efficacy of four-way pipe fitting with laryngeal mask airway (LMA) for airway management during tracheal stent implantation.Methods Thirty-six patients of both sexes,aged 18-64 yr,of American Society of Anesthesiology physical status Ⅱ or Ⅲ,scheduled for elective tracheal stent implantation,were allocated into 2 groups (n =18 each) using a random number table method:four-way pipe fitting with LMA group (FWP-LMA group) and rigid bronchoscope group.LMA was inserted after anesthesia induction,and the four-way pipe fitting and anesthesia machine were connected to perform intermittent positive pressure ventilation in FWP-LMA group.A rigid bronchoscope was implanted,and jet ventilator was used to assist ventilation in rigid bronchoscope group.The development of intraoperative hyoxemia,hypertension and tachycardia was recorded.Blood gas analysis was performed before operation and at the end of operation to record pH value,the partial pressure of arterial oxygen and partial pressure of arterial carbon dioxide.The success rate of tracheal stent implantation at first attempt and development of postoperative pharyngeal complications were also recorded.Results Operation was canceled due to rigid bronchoscope implantation in one patient in rigid bronchoscope group.Compared with rigid bronchoscope group,the pH value and partial pressure of arterial oxygen were significantly increased,and the partial pressure of arterial carbon dioxide was decreased at the end of operation,the incidence of intraoperative hyoxemia,hypertension and tachycardia was decreased,the incidence of postoperative sore throat and hoarseness was markedly decreased,operation time was prolonged,and the success rate of tracheal stent implantation at first attempt was decreased in FWP-LMA group (P＜ 0.05).Conclusion The four-way pipe fitting with LMA produces better ventilation effect,induces slighter stress responses with fewer complications and can be safely used for airway management during tracheal stent implantation.

Objective:To determine the oxygen concentration threshold for explosion induced by high-frequency electric knife or argon knife at different energies.Methods:① In vivo experiment The smooth muscle tissue or adipose-rich tissue in 10 pairs of isolated porcine lungs and trachea was electrocauterized at 30 and 50 W with high-frequency electroknife or argon knife at different oxygen concentrations.The initial oxygen concentration was 20%, the oxygen concentration was gradually increased in increments of 5% until the oxygen concentration reached 80%.Each sample was electrocauterized 10 times at each concentration, and the number of explosion was recorded.As long as one explosion occurred, it could be considered that the concentration could induce explosion, and the minimum oxygen concentration inducing explosion was considered as the threshold.② Measurement of oxygen concentration in the airway of patients received bronchoscopic intervention Thirty patients scheduled for elective bronchoscopy with cryotherapy were selected, the oxygen concentration inhaled was reduced from 100% until 50% in decrements of 10%, and the oxygen concentration in airway was measured with the AIRVO 2 transnasal high-flow oxygen inhalation device.ICC consistency analysis was performed between the oxygen concentration in airway and oxygen concentration inhaled. Results:In adipose-rich tissues, the threshold of the oxygen concentration for explosion was 70% at 30 W and 65% at 50 W when using the high-frequency electric knife; the threshold of the oxygen concentration for explosion was 35% at 30 W and 30% at 50 W when using the high-frequency argon knife.In smooth muscle tissues, no explosion occurred at each oxygen concentration when using the high-frequency electric knife and argon knife at 30 or 50 W, and the threshold value was above 80%.There was moderate consistency (ICC value 0.722, 95% CI 0.537-0.850, P<0.001) between the oxygen concentration in airway and oxygen concentration inhaled. Conclusions:In smooth muscle tissues, explosion is not easy to occur at oxygen concentrations below 80% when using the high-frequency electric knife or argon knife.In adipose-rich tissues, explosion is not easy to occur at oxygen concentrations less than 70% at 30 W and at oxygen concentrations less than 65% at 50 W when using the high-frequency electric knife; explosion is not easy to occur at oxygen concentrations less than 35% at 30 W and at oxygen concentrations less than 30% at 50 W when using the high-frequency argon knife.The threshold of oxygen concentrations in airway can be determined using the oxygen concentration inhaled.