Arterial oxygenation during laryngoscopy and intubation.

Arterial oxygenation during laryngoscopy and tracheal intubation was studied in 37 patients, 22 taking four maximally deep breaths of O2 within 30 seconds, and 15 breathing air immediately before anesthetic induction. In both groups of patients induction was followed by ventilation with 100% O2 by face mask before laryngoscopy, which was followed by intubation. Both mean arterial O2 tension (PaO2) and mean arterial O2 content (CaO2) increased significantly after four breaths of O2 in 30 seconds (339 +/- 34 (SD) vs 77 +/- 5, p less than 0.05, and 19.6 +/- 2.1 vs 18.8 +/0 2.1, respectively, p less than 0.05). At the end of laryngoscopy, mean PaO2 remained significantly greater in preoxygenated patients than in air-breathing patients (353 +/- 33 torr vs 319 +/- 26 torr, respectively, p less than 0.05). After intubation, mean PaO2 in preoxygenated patients remained higher than in air-breathing patients (332 +/- 34 vs 289 +/- 23 torr, p less than 0.05). Calculated mean CaO2 was not significantly different for the two groups during either maneuver. We conclude that four breaths of O2 in 30 seconds before anesthetic induction elevates PaO2 but provides insignificant improvement in CaO2 during laryngoscopy and intubation when the anesthetic routine includes ventilation of the patient with O2 by face mask after induction and before laryngoscopy.