Free
Correspondence  |   February 2006
Preoxygenation during Pregnancy in the Head-up versus  the Supine Position
Author Notes
  • American University of Beirut, Beirut, Lebanon.
Article Information
Correspondence
Correspondence   |   February 2006
Preoxygenation during Pregnancy in the Head-up versus  the Supine Position
Anesthesiology 2 2006, Vol.104, 380. doi:
Anesthesiology 2 2006, Vol.104, 380. doi:
To the Editor:—
I read with interest the article of Dixon et al.  1 The results show in the class III obese patients that preoxygenation in the 25° head-up position achieves 23% higher oxygen tensions, allowing a clinical increase in the desaturation safety period. The report postulated that preoxygenation in the head-up position may be advantageous in many other clinical circumstances in which respiratory function may be impaired in the supine position, e.g.  , advanced pregnancy, ascites, bowel obstruction.
Baraka et al.  2 (1992) reported about “Preoxygenation of Pregnant and Nonpregnant Women in the Head-up versus Supine Position.” The results showed that after 3 min of preoxygenation, desaturation to 95% during subsequent apnea, as monitored by pulse oximetry, was more rapid in pregnant than in nonpregnant patients. Also, changing from the supine to the 45° head-up position prolonged the desaturation time in the nonpregnant women but had no significant effect in the pregnant women (table 1). These results were unanticipated because a change from the supine to the sitting position has been shown to increase the functional residual capacity in both pregnant3 and nonpregnant patients.4 Baraka et al.  postulated that adopting the 45° head-up position rather than the sitting position may not significantly increase the functional residual capacity in the pregnant woman at term, because the gravid uterus at term may not allow a significant descent of the diaphragm in the head-up position.
Table 1. Preoperative Oxygen Saturation (So2%) and Times to So295% in Nonpregnant  versus  Pregnant Patients in the Supine and Head-up Positions 
Image not available
Table 1. Preoperative Oxygen Saturation (So2%) and Times to So295% in Nonpregnant  versus  Pregnant Patients in the Supine and Head-up Positions 
×
American University of Beirut, Beirut, Lebanon.
References
Dixon BJ, Dixon JB, Carden JR, Bum AJ, Schachter LM, Playfair JM, Laurie CP, O’Brien PE: Preoxygenation is more effective in the 25° head-up position than in the supine position in severely obese patients. Anesthesiology 2005; 102:1110–5Dixon, BJ Dixon, JB Carden, JR Bum, AJ Schachter, LM Playfair, JM Laurie, CP O’Brien, PE
Baraka AS, Hanna MT, Jabbour SI, Nawfal MF, Siba A, Yazbeck VG, Khoury NI, Karam KS: Preoxygenation of pregnant and nonpregnant women in the head-up versus supine position. Anesth Analg 1992; 75:757–9Baraka, AS Hanna, MT Jabbour, SI Nawfal, MF Siba, A Yazbeck, VG Khoury, NI Karam, KS
Russel IF, Chambers WA: Closing volume in normal pregnancy. Br J Anaesth 1981; 53:1043–7Russel, IF Chambers, WA
Nunn JF: Elastic forces and lung volumes, Applied Respiratory Physiology, 3rd edition. Edited by Nunn JF. London, Butterworths, 1987, pp 39–40Nunn, JF Nunn JF London Butterworths
Table 1. Preoperative Oxygen Saturation (So2%) and Times to So295% in Nonpregnant  versus  Pregnant Patients in the Supine and Head-up Positions 
Image not available
Table 1. Preoperative Oxygen Saturation (So2%) and Times to So295% in Nonpregnant  versus  Pregnant Patients in the Supine and Head-up Positions 
×