The Impact of Transnasal Humidified Rapid Insufflation Ventilatory Exchange (THRIVE) on Intragastric Pressure During Anaesthesia Induction in Overweight Patients: A Randomized Controlled Trial

Background: Although many studies have shown that transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) can be used in anaesthesia induction, its specific effects on obese patients remain unknown. Methods: We recruited 135 patients (BMI ≥25 kg/m²) who were randomly assigned to three groups: the facemask ventilation group (M group), the THRIVE group (T group), and the facemask with no ventilation combined THRIVE group (M+T group). Before induction, all patients underwent preoxygenation with a facemask until the partial pressure of end-tidal oxygen (PEtO ₂ ) exceeded 90%. After induction, a gastric intraluminal pressure catheter was inserted, and the catheter was connected to a disposable pressure transducer (in central venous pressure mode) via a three-way stopcock, with the calibration point located at the mid-axillary line. Subsequently, each group underwent different ventilation methods for 2 minutes before tracheal intubation and mechanical ventilation. Results: There were no significant differences in initial intragastric pressure among the three groups. However, the peak intragastric pressure in the T and M+T groups was significantly lower than that in the M group ( P < 0.05). Within-group comparisons indicated no statistically significant differences between initial and peak intragastric pressures in the T and M+T groups. In contrast, the peak intragastric pressure during ventilation in the M group was significantly higher than its initial value ( P < 0.05). Fewer patients in the T and M+T groups demonstrated notable changes in gastric antral area on ultrasound compared with the M group ( P < 0.05). Additionally, the lowest SpO ₂ and PEtO ₂ in the T and M+T groups were significantly higher than those in the M group ( P < 0.05). However, the first complete respiratory waveform of PEtCO ₂ after mechanical ventilation and the lowest PEtCO ₂ within 2 minutes of mechanical ventilation were higher in the T and M+T groups than in the M group ( P < 0.05). Conclusion: The use of THRIVE during the induction of anaesthesia in overweight patients, compared with conventional facemask preoxygenation, can improve oxygen saturation while ensuring minimal alterations in intragastric pressure. Trial registration: Chinese Clinical Trial Registry ChiCTR2300075652. Registered date: 12/09/2023