Effect of facemask oxygenation with and without positive pressure ventilation on gastric volume during anesthesia induction in patients undergoing laparoscopic cholecystectomy or partial hepatectomy: a randomized controlled trial.

Background: Studies focusing on the relationship between gastric volume and facemask oxygenation without ventilation during apnea in anesthesia induction are scarce. This study compared the change in gastric volume during apnea in anesthesia induction using facemask ventilation and facemask oxygenation without ventilation in adults undergoing laparoscopic surgery.

Methods: In this prospective, randomized, double-blinded trial, 70 adults undergoing laparoscopic surgery under general anesthesia were divided into two groups to receive facemask oxygenation with and without ventilation for 60 seconds after loss of consciousness. Before anesthesia induction and after endotracheal intubation, the gastric antral cross-sectional area was measured with ultrasound imaging. Arterial blood gases were tested at baseline (T1), after preoxygenation (T2), after loss of consciousness (T3), and before and after endotracheal intubation (T4 and T5, respectively).

Results: Sixty patients were included (ventilation n = 30; non ventilation n = 30, 10 patients were excluded). The median [IQR] change of gastric antral cross-sectional area in ventilation group was significantly higher than in non ventilation group (0.83 [0.20 to 1.54] vs. 0.10 [- 0.11 to 0.56] cm, P = 0.001). At T4 and T5, the PaO in ventilation group was significantly higher than in non ventilation group (T4: 391.83 ± 61.53 vs. 336.23 ± 74.99 mmHg, P < 0.01; T5: 364.00 ± 58.65 vs. 297.13 ± 86.95 mmHg, P < 0.01), while the PaCO in non ventilation group was significantly higher (T4: 46.57 ± 5.78 vs. 37.27 ± 6.10 mmHg, P < 0.01; T5: 48.77 ± 6.59 vs. 42.63 ± 6.03 mmHg, P < 0.01) and the pH value in non ventilation group was significantly lower (T4: 7.35 ± 0.029 vs 7.42 ± 0.047, P < 0.01; T5: 7.34 ± 0.033 vs 7.39 ± 0.044, P < 0.01). At T4, the HCO in non ventilation group was significantly higher (25.79 ± 2.36 vs. 23.98 ± 2.18 mmol l, P < 0.01).

Conclusions: During apnoea, the increase in gastric volume was milder in patients undergoing facemask oxygenation without ventilation than with positive pressure ventilation.

Trial Registration: ChiCTR2100054193, 10/12/2021, Title: "Effect of positive pressure and non-positive pressure ventilation on gastric volume during induction of general anesthesia in laparoscopic surgery: a randomized controlled trial". Website: https://www.chictr.ogr.cn .