[Effects of maternal hyperventilation and oxygen inhalation during labor on fetal blood-gas status].
The effects of maternal hyperventilation and oxygen inhalation on fetal blood-gas status were studied in 54 fetuses, vaginally delivered of mothers without medical and obstetrical complications. The cases were divided into four groups according to MA (maternal arterial) pH and PCO2 values and by respiring either oxygen or room-air as follows. Group N: pH less than 7.5, PCO2 greater than 23 mmHg (normoventilation), without maternal oxygen inhalation, group H: pH greater than 7.5, PCO2 less than 23 mmHg (hyperventilation), without oxygen inhalation, group NO: pH less than 7.5, PCO2 greater than 23 mmHg, with oxygen inhalation and group HO: pH greater than 7.5, PCO2 less than 23 mmHg, with oxygen inhalation. Umbilical venous (UV) PO2 (27.8 mmHg: mean), SO2 (60.8%) and CO2 (oxygen content, 12.4 ml/dl), and umbilical arterial (UA) PO2 (17.9 mmHg), SO2 (35.6%) and CO2 (7.3 ml/dl) values in group H were significantly lower than those in group N. The fetal oxygenation in group HO was similar to that in group N, and the fetal oxygen values in group NO were significantly higher than those in the other groups. The fetuses in groups H and HO tended to respiratory alkalosis. The UV oxygen values had negative correlations with MA pH and positive correlations with the MA PCO2 value in both oxygen and no-oxygen groups. There was no significant correlation between maternal and fetal PCO2 values, and higher fetal oxygen extraction (41%: mean) in group H. These facts suggest that severe maternal respiratory alkalosis due to hyperventilation may lead to a disorder in placental circulation.(ABSTRACT TRUNCATED AT 250 WORDS)
D000136:Acid-Base Equilibrium; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D005333:Fetus / Q000378:metabolism*; D006801:Humans; D006985:Hyperventilation / Q000503:physiopathology*; D007743:Labor, Obstetric; D008431:Maternal-Fetal Exchange; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D010102:Oxygen Inhalation Therapy; D011247:Pregnancy
D002245:Carbon Dioxide; D010100:Oxygen