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Updated: Sep 28, 2026
Preoxygenation Techniques for Tracheal Intubation in Critically Ill Adults Utilizing Oxygen Mask and Noninvasive Ventilation
Published on: December 5, 2025
Oxygen in air (FiO2 0.4) improves gas exchange in young healthy patients during general anesthesia
Anil Agarwal1, Prabhat K Singh, Sanjay Dhiraj
1Department of Anesthesia, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, India. aagarwal@sgpgi.ac.in
Purpose:
One hundred percent O(2) is used routinely for preoxygenation and induction of anesthesia. The higher the O(2) concentration the faster is the development of atelectasis, an important cause of impaired pulmonary gas exchange during general anesthesia (GA). We evaluated the effect of ventilation with 0.4 FiO(2) in air, 0.4 FiO(2) in N(2)O and 100% O(2) following intubation on the development of impaired gas exchange.
Methods:
Twenty-seven patients aged 18-40 yr, undergoing elective laparoscopic cholecystectomy were administered 100% O(2) for preoxygenation (three minutes) and ventilation by mask (two minutes). Following intubation these patients were randomly divided into three groups of nine each and ventilated either with 0.4 FiO(2) in air, 0.4 FiO(2) in N(2)O or 100% O(2). Arterial blood gases were obtained before preoxygenation and 30 min following intubation for PaO(2) analysis. Subsequently PaO(2)/FiO(2) ratios were calculated. Results were analyzed with Student's t test and one-way ANOVA. P value of < or = 0.05 was considered significant.
Results:
Ventilation of the lungs with O(2) in air (FiO(2) 0.4) significantly improved the PaO(2)/FiO(2) ratio from baseline, while 0.4 FiO(2) in N(2)O or 100% O(2) worsened the ratio (558 +/- 47 vs 472 +/- 28, 365 +/- 34 vs 472 +/- 22 and 351 +/- 23 vs 477 +/- 28 respectively; P < 0.05).
Conclusion:
Ventilation of lungs with O(2) in air (FiO(2) 0.4) improves gas exchange in young healthy patients during GA.
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