Preoxygenation of Pregnant and Nonpregnant Women in the Head-Up Versus Supine Position

• Published in: Anesthesia and analgesia Vol. 75; no. 5; pp. 757 - 759
• Main Authors: Baraka, Anis S., Hanna, Myrna T., Jabbour, Samar I., Nawfal, Maud F., Sibai, Abla A. N., Yazbeck, Vanda G., Khoury, Nawal I., Karam, Karam S.
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD International Anesthesia Research Society 01-11-1992; Lippincott
• Subjects: Abdominal surgery. Urology. Gynecology. Obstetrics; Adult; Anesthesia; Anesthesia depending on type of surgery; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Apnea - metabolism; Biological and medical sciences; Female; Humans; Medical sciences; Oxygen - metabolism; Posture; Pregnancy - metabolism; Supine Position; Time Factors; Pregnancy; Human; Apnea; Surgery; General anesthesia; Female; Oxygenation; Patient position; Cesarean section
• DOI: 10.1213/00000539-199211000-00018
• EISSN: 1526-7598
• ISSN: 0003-2999

The influence of preoxygenation in the supine (n = 10) versus the 45° 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.