THRIVE is previously shown feasible as sole mode of ventilation in selected patients during general anaesthesia for minor laryngeal surgery for a limited time up to 30 minutes, where direct laryngoscopy was required and applied throughout the procedure. A stable oxygenation and a degree of ventilation was observed. However, a slowly developed respiratory acidosis was also observed over time.
Existing physiologic studies on high flow humidified nasal oxygen suggest that closed mouth breathing enhance the effects of the high flows of oxygen levels applied by increasing the airway pressures and thereby enhance gas exchange in the lungs. Currently, it is unclear whether the efficiency of THRIVE depends on the particular circumstances of airway management. Physiologic characterization of THRIVE performance under standardized conditions of airway management and under close monitoring by systematic analysis of blood gas dynamics over time during general anesthesia is needed.
We plan to study the blood gas dynamics during THRIVE apnea ventilation during general anesthesia, where the airway is managed only by jaw-thrust for up to 60 minutes. The patients will be closely monitored by repetitive arterial blood gasses to evaluate blood gas dynamics and development of respiratory acidosis. Desaturation or respiratory acidosis with pH under 7.15 and/or PaCO2-rise \> 12 kPa will lead to cessation of THRIVE.
