ABSTRACT : Preoxygenation with tidal volume breathing for 3 min is the commonly used technique. Deep breathing with 8 deep breaths (vital capacity breaths) within 60 seconds is a promising alternative. An end tidal oxygen concentration (etO2) of 90% or more is considered to be adequate for maximal preoxygenation. This study compares tidal volume preoxygenation for 3 minutes with deep breathing technique for 60 seconds.

METHODS : Sixty patients from ASA class I or II who were scheduled for elective surgery under general anaesthesia in Gauhati Medical College, Guwahati were randomly divided into a tidal volume group and an 8 deep breaths group. Patients were instructed in the technique of preoxygenation. Preoxygenation was accomplished with the predetermined technique with an appropriately sized face mask connected to a circle absorber system with 100% oxygen with a preset flow rate for each group. Inspired and end tidal O2, end tidal CO2 and oxygen saturation were recorded throughout the period.

RESULTS : The 8 deep breaths group showed significantly lower end tidal oxygen concentration (84.03%) than the tidal volume group (91.26%) at the end of preoxygenation (P < 0.05). Oxygen saturations were comparable in both the groups.

CONCLUSIONS : Preoxygenation with 8 deep breaths within 1 minute failed to achieve the target of maximal preoxygenation (etO2 ≥ 90%).