Maternal oxygen administration and fetal cerebral oxygenation: Studies on near-term fetal lambs at both low and high altitude

• Published in: American journal of obstetrics and gynecology 2006-08, Vol.195 (2), p.535-541
• Main Authors: Tomimatsu, Takuji, Pereyra Peňa, Jorge, Hatran, Douglas P., Longo, Lawrence D.
• Format: Article
• Language: English
• Subjects: Acclimatization - physiology; Altitude; Animals; Biological and medical sciences; Brain - metabolism; Cerebrovascular Circulation; Female; Fetal cerebral oxygenation; Fetus - physiology; Gynecology. Andrology. Obstetrics; High altitude; Hydrogen-Ion Concentration; Maternal oxygen administration; Medical sciences; Oxygen - administration & dosage; Oxygen - blood; Oxygen - metabolism; Pregnancy; Sheep
• ISSN: 0002-9378; 1097-6868
• DOI: 10.1016/j.ajog.2006.01.105

We tested the hypothesis that O 2 administration to the mother would increase arterial O 2 tension (PaO 2) and cortical tissue O 2 tension ( tPO 2) in both the normoxic control fetus and that acclimatized to high altitude, and that this effect might be greater in the high altitude fetus than that at sea level. Pregnant ewes were divided into either low-altitude group or high-altitude group (3820 m; maintained from day 30 of gestation to near-term, term = 145 days; n = 6 each). In near-term fetuses we instrumented the cerebral cortex with tissue PO 2-laser Doppler flow probes, and placed arterial catheters. With the ewe breathing either air or 50% O 2, we measured fetal arterial and brain tissue PO 2 and cerebral blood flow (CBF). In response to maternal O 2 administration, in both low- and high-altitude fetuses, PaO 2, O 2 content, and brain tissue PO 2 increased significantly. Nonetheless, the fetuses at high altitude showed significantly greater increase in both PaO 2 and cerebral tPO 2, than that seen in fetuses at low altitude. In neither group was there a change in CBF or cerebral metabolic rate for O 2. Maternal O 2 administration significantly increased PaO 2 and cerebral tPO 2 of the fetus both at low altitude and at high altitude, with this increase being greater in the high altitude animals. We suggest that maternal O 2 administration can have an important effect in ameliorating nonreassuring fetal status, and perhaps be of value in instances of mothers who smoke heavily or with cardiopulmonary disease.