The effects of 21 or 30% O2 plus umbilical cord occlusion on fetal breathing and behavior.
We have shown previously that continuous fetal breathing can be induced by 100% O2 alone or combined with umbilical cord occlusion (Baier, Hasan, Cates, Hooper, Nowaczyk & Rigatto, 1990). To know whether it could also be induced by lower O2 concentrations plus cord occlusion, we studied 9 chronically instrumented fetal sheep (16 experiments) using our window model. After a baseline cycle [1 low voltage + 1 high voltage electrocortical activity (ECoG) epoch] the fetal lung was distended via an endotracheal tube to about 30 cm H2O. Inspired N2 (control) and 21 or 30% O2 were given for one cycle each. While on 21% or 30% O2 the umbilical cord was occluded (balloon cuff). In 10 out of 16 experiments breathing output (% maximum of integral of EMGdi x f) increased after cord occlusion from 80 +/- 48 (N2) to 2871 +/- 641 (SEM; P < 0.01); in 7 of them breathing became continuous. Arterial PO2 increased from 14 +/- 1 (N2) to 33.5 +/- 5 Torr (occlusion; P < 0.01). In the other 6 experiments breathing output decreased from 319 +/- 116 (N2) to 86 +/- 38 (occlusion; P < 0.01) and arterial PO2 changed from 18 +/- 1 (N2) to 22 +/- 5 Torr (occlusion; P = 0.4). Arterial PCO2 increased similarly after occlusion in both groups, those which did respond with increased breathing (to 46 +/- 2 Torr) and those which did not respond (to 48 +/- 3 Torr; P = 0.6). The percent low voltage ECoG and the behavioral score increased after occlusion in the responder group only.(ABSTRACT TRUNCATED AT 250 WORDS)
Alvaro
R
R
Department of Pediatrics, University of Manitoba, Winnipeg, Canada.
Weintraub
Z
Z
Alvarez
J
J
Baier
J
J
Cates
D
D
Nowaczyk
B
B
Martino
C
C
Rigatto
H
H
D000818:Animals; D005260:Female; D005333:Fetus / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D007743:Labor, Obstetric / Q000502:physiology*; D008026:Ligation; D009359:Neonatology; D010100:Oxygen / Q000008:administration & dosage*; D011247:Pregnancy; D012039:Regional Blood Flow; D012119:Respiration / Q000187:drug effects*; D012756:Sheep; D014470:Umbilical Cord / Q000601:surgery
D010100:Oxygen