Preserved oxygenation in obese patients receiving protective ventilation during laparoscopic surgery: a randomized...

Area of Science:

• Anesthesiology
• Respiratory Physiology

Background:

• Venous admixture from atelectasis and airway closure can impair oxygenation during general anesthesia.
• Obesity presents unique challenges to maintaining adequate oxygenation during surgical procedures.

Purpose of the Study:

• To test if continuous positive airway pressure (CPAP) during pre-oxygenation and a reduced fraction of inspired oxygen (FIO2) during emergence can improve oxygenation in obese patients undergoing laparoscopic surgery.

Main Methods:

• Two groups of patients (n=40) with obesity undergoing laparoscopic surgery were studied.
• The intervention group received CPAP (10 cmH2O) during pre-oxygenation and induction; the control group did not.
• Oxygenation was assessed using estimated venous admixture (EVA) perioperatively, with varying FIO2 levels during emergence in the intervention group.

Main Results:

• CPAP during pre-oxygenation and induction significantly reduced median EVA during anesthesia (8.2% vs. 13.2%, P=0.048).
• EVA after CO2 pneumoperitoneum was similar between groups (8.4% vs. 9.9%).
• Post-operative oxygenation one hour after surgery deteriorated in patients given a high FIO2 (1.0) during emergence, but not in those given a reduced FIO2 (0.31).

Conclusions:

• CPAP of 10 cmH2O during pre-oxygenation and induction, followed by PEEP after intubation, appears to preserve oxygenation during anesthesia in obese patients.
• Post-operative oxygenation is influenced by the fraction of inspired oxygen used during the emergence from anesthesia.