title: End-tidal oxygen measurement compared with patient factor assessment for determining preoxygenation time.
abstract: Time to adequate preoxygenation was assessed in 200 elective surgical patients, using measurement of end-tidal oxygen concentration. A variety of patient factors were assessed as to their ability to predict the time required to preoxygenate a patient. Of the 200 patients, 23 (11.5%) were unable to be adequately preoxygenated; most of these cases were due to a poor mask fit. The average time for preoxygenation was 154 seconds (range 43-364 seconds). Of those patients who could be preoxygenated, 46 (23%) required more than three minutes. Although a regression equation could be constructed to calculate time required for preoxygenation, the wide standard errors of the coefficients preclude a clinically useful predictive equation. We thus found that we could not accurately predict time required for preoxygenation and that a routine three minutes preoxygenation may not be sufficient for many patients. However, the measurement of end-tidal oxygen concentration is a very useful method of determining the end-point for preoxygenation.
authors.affiliation: Department of Anaesthesia, Alfred Hospital, Melbourne, Victoria.
authors.forename: H A
authors.initials: HA
authors.lastname: Machlin
authors.forename: P S
authors.initials: PS
authors.lastname: Myles
authors.forename: C B
authors.initials: CB
authors.lastname: Berry
authors.forename: P J
authors.initials: PJ
authors.lastname: Butler
authors.forename: D A
authors.initials: DA
authors.lastname: Story
authors.forename: B J
authors.initials: BJ
authors.lastname: Heath
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure / Q000502:physiology; D001827:Body Height / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D017558:Elective Surgical Procedures; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000008:administration & dosage* / Q000097:blood*; D011229:Preanesthetic Medication; D012737:Sex Factors; D012907:Smoking / Q000503:physiopathology; D013997:Time Factors
chemical_list: D010100:Oxygen