Changes in Gastric volume during sedative flexible bronchoscopy with supraglottic jet oxygenation and ventilation: A randomized, double-blind study

Background: Increasing gastric volume is one of the main risk factors associated with pulmonary aspiration. Supraglottic jet oxygenation and ventilation (SJOV) using the WEI Nasal Jet Tube (WEI Nasal JET, WNJ) is a developing technique, and is increasingly used to promote oxygenation and ventilation during moderate to deep sedation and difficult airway management. However, its potential to increase gastric volume has not been investigated. Methods: This is a prospective, randomized, double-blind clinical study. Patients were randomized to three groups according to the driving pressures of SJOV (15, 20, or 25 psi), corresponding to P15, P20, or P25 groups, respectively. All patients were sedated with remifentanil and propofol, the longitudinal (D1) and anteroposterior (D2) of the gastric antrum were measured by ultrasonography. The primary outcome, gastric volume, was recorded at the initation of SJOV (T ₀ ), and after using SJOV for 1minute (T ₁ ), 5 minutes (T ₂ ), and at the end of the procedure (T ₃ ). The secondary outcomes included end-tidal CO ₂ (P _ET CO ₂ ) at T ₀ , T ₁ , T ₂ and T ₃ . Adverse events related to SJOV (gastric insufflations, hypoxemia, barotrauma, pharyngalgia and xerostomia) were also recorded. Results: 222 patients were randomized and recruited to the study. An ANOCVA showed no significant Group*Time interaction for gastric volume and P _ET CO ₂ (F _Group*Time =0.069, P=0.991 and F _Group*Time =0.165, P=0.956). The main effect analysis showed there were no significant differences in the effects of 3 driving pressure on gastric volume and P _ET CO ₂ (F _Group =0.034, P=0.966 and F _Group =0.602, P=0.549) and the changes in gastric volume and P _ET CO ₂ at different time points were similar (F _Time =8.760, P=0.350 and F _Time =1.876, P=0.154). However, there was more pharyngalgia and xerostomia in the P25 group than in the P15 group at 30 min and 1h after the procedure, but there was no significant difference among the three groups at 24h after the procedure. Gastric insufflations and barotrauma were absent in all patients. Conclusions: During fiberoptic bronchoscopy, SJOV using WNJ with driving pressure of 15 psi, 20 psi, and 25 psi had the same effect on gastric volume, and had a higher incidence of xerostomia and pharyngalgia at driving pressure of 25 psi than 15 psi Date of registration: 1/06/2019 Date of enrolment of the first research participant：04/01/2020