Determinants of the middle cerebral artery peak systolic velocity in the human fetus.
OBJECTIVE
The purpose of this study was to identify physiologic determinants of the peak systolic blood flow velocity (PSV) of the middle cerebral artery (MCA) in the human fetus.


METHODS
MCA PSV was measured with pulsed wave Doppler ultrasound in human fetuses who underwent cordocentesis. Hemoglobin, hematocrit, and blood gas values were analyzed from umbilical venous blood, and the data were normalized for gestational age. Total oxygen content of fetal venous blood was calculated from oxygen saturation, hemoglobin value, and pO2. Correlation and logistic regression analyses were performed to identify primary physiologic determinants of MCA PSV.


RESULTS
In 136 fetuses who underwent cordocentesis (predominantly for alloimmune disease), hematocrit, hemoglobin, and blood oxygen content correlated significantly with the MCA PSV (P < .01). Logistic regression modeling demonstrated that fetal hemoglobin content (odds ratio, 7.1; 95% CI, 3.71-13.7) and pCO2, but not pO2 or fetal blood oxygen content, accounted for increases in MCA PSV.


CONCLUSIONS
Under physiologic circumstances, fetal hemoglobin, and not fetal oxygenation, primarily determines the middle cerebral artery peak systolic velocity.
Picklesimer
Amy H
AH
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. Picklesimer@med.unc.edu
Oepkes
Dick
D
Moise
Kenneth J
KJ
Kush
Michelle L
ML
Weiner
Carl P
CP
Harman
Christopher R
CR
Baschat
Ahmet A
AA
D001783:Blood Flow Velocity; D001784:Blood Gas Analysis; D017218:Cordocentesis; D005260:Female; D005333:Fetus / Q000502:physiology*; D006400:Hematocrit; D006801:Humans; D016015:Logistic Models; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000196:embryology* / Q000502:physiology; D010100:Oxygen / Q000097:blood; D011247:Pregnancy; D012039:Regional Blood Flow; D018608:Ultrasonography, Doppler; D016216:Ultrasonography, Prenatal
D010100:Oxygen