수술실에서의 저강도 기계 환기: 파일럿 연구 (VIOLET)

A guided standard of care protocol will be applied in the control group. This includes a PEEP of 5 cmH₂O, with adjustment by the anesthesia provider if SpO₂ falls below 96% or whenever deemed clinically necessary, a tidal volume of 6-10 mL/kg predicted body weight, and a respiratory rate adjusted to maintain end-tidal CO₂ between 35 and 45 mmHg throughout anesthesia. FiO₂ will be set to 100% during the washout phase at the end of surgery to limit resorption atelectasis.

A bundle of protective low-intensity mechanical ventilation strategies will be applied throughout the procedure. All interventions consist of modification of ventilator settings.

A bundle of protective low-intensity mechanical ventilation strategies will be applied throughout the procedure:

1. Recruitment maneuver
2. Tidal volume set to 8 ml/kg predicted body weight (PBW) and stepwise adjustment to achieve a driving pressure (Plateau pressure - PEEP) < 13 cmH2O with a minimum tidal volume of 5ml/kg PBW
3. Respiratory rate adjustment to maintain a target end-tidal carbon dioxide concentration (etCO₂) between 45 and 55 mmHg.
4. Reassessment and adaptation after Trendelenburg positioning and pneumoperitoneum.
5. Re-adjustment of Tidal Volume and PEEP ventilator settings to (2.) after exsufflation and return to the supine position. FiO₂ set to 70% during the washout phase of the inhalational anesthetic until extubation.

Change in end-expiratory lung volume (EELV), measured using electrical impedance tomography between baseline and after extubation before leaving the operating room.

Re-intubation, hypoxemia requiring oxygen therapy, pleural effusion, pneumonia, atelectasis or emergency non-invasive ventilation

Proportion of patients enrolled in the study-defined as those who provided acceptance and signed informed consent-relative to all patients approached.

proportion of patients in the intervention arm in whom the full bundle of protective low-intensity ventilation strategies is delivered as planned across all predefined intraoperative phases.

End-expiratory lung volume measured by Electrical Impedance Tomography in mL

Center of ventilation measured by Electrical Impedance Tomography in percentage

Regional ventilation delay inhomogeneity measured by Electrical Impedance Tomography (unitless)

Global inhomogeneity index measured by Electrical Impedance Tomography (unitless)

Maximum dorsal ratio of impedance measured by Electrical Impedance Tomography (unitless)

End-expiratory transpulmonary pressure, calculated as airway pressure minus esophageal pressure (cmH₂O)

End-inspiratory transpulmonary pressure, calculated as airway pressure minus esophageal pressure (cmH₂O)

Correlation between BMI (kg/m²) and the optimal positive end-expiratory pressure (PEEP, cmH₂O) determined after pneumoperitoneum insufflation and patient positioning for surgery.

Correlation between the degree of Trendelenburg inclination (in degree) and the optimal positive end-expiratory pressure (PEEP, cmH₂O) determined after pneumoperitoneum insufflation and patient positioning for surgery.

Correlation between the pneumoperitoneum (insufflation in cmH2O) and the optimal positive end-expiratory pressure (PEEP, cmH₂O) determined after pneumoperitoneum insufflation and patient positioning for surgery.

Intraoperative peripheral pulsed oxygen saturation (SpO2)

Postoperative peripheral pulsed oxygen saturation (SpO2)