title: Preoxygenation of pregnant and nonpregnant women in the head-up versus supine position.
abstract: The influence of preoxygenation in the supine (n = 10) versus the 45 degrees head-up (n = 10) position on the duration of apnea leading to a decrease in arterial oxygen saturation to 95%, as monitored by pulse oximetry, was investigated in 20 women undergoing elective cesarean section at term of pregnancy. The results were compared with those obtained in a control group of 20 nonpregnant women. In the supine position, the average time to desaturation to 95% was significantly shorter in the pregnant group (173 +/- 4.8 s [mean +/- SD]) than in the control group of nonpregnant women (243 +/- 7.4 s). Using the head-up position resulted in an increase in the desaturation time in the nonpregnant group (331 +/- 7.2 s) but had no significant effect in the pregnant group (156 +/- 2.8 s). We conclude that pregnant women desaturate their arterial blood of oxygen more rapidly than do nonpregnant women. Furthermore, the head-up position extends the duration of apnea that can take place before desaturation occurs in nonpregnant patients.
authors.affiliation: Department of Anesthesiology, American University of Beirut, Lebanon.
authors.forename: A S
authors.initials: AS
authors.lastname: Baraka
authors.forename: M T
authors.initials: MT
authors.lastname: Hanna
authors.forename: S I
authors.initials: SI
authors.lastname: Jabbour
authors.forename: M F
authors.initials: MF
authors.lastname: Nawfal
authors.forename: A A
authors.initials: AA
authors.lastname: Sibai
authors.forename: V G
authors.initials: VG
authors.lastname: Yazbeck
authors.forename: N I
authors.initials: NI
authors.lastname: Khoury
authors.forename: K S
authors.initials: KS
authors.lastname: Karam
mesh_terms: D000328:Adult; D001049:Apnea / Q000378:metabolism; D005260:Female; D006801:Humans; D010100:Oxygen / Q000378:metabolism*; D011187:Posture; D011247:Pregnancy / Q000378:metabolism*; D016683:Supine Position; D013997:Time Factors
chemical_list: D010100:Oxygen