Reference values for strong ion difference--a novel tool for fetal metabolic assessment.
OBJECTIVE
The aim of this pilot study was to establish reference values for strong ion difference (SID) in umbilical cord blood and investigate the feasibility of evaluating fetal metabolism according to the comprehensive approach to acid-base abnormalities, based on Stewart's physiochemical theory.


METHODS
A prospective observational study. Women who underwent an elective cesarean section at term (n=40) were compared to women who completed a normal spontaneous delivery at term (n=40). The primary outcome was the establishment of normal values for SID in the umbilical cord vein. We also compared acid-base variables in the umbilical vein between the groups.


RESULTS
The apparent SID in the umbilical vein was 34.61+/-3.92 mequiv./L after normal delivery and 35.98+/-2.56 mequiv./L after elective cesarean section (the effective SID is 37.43+/-1.93 and 38.29+/-2.38 mequiv./L, respectively). The pH values were similar in both groups, but the pCO(2) was significantly higher and the plasma principal weak acids (albumin and phosphate) were significantly lower after cesarean sections.


CONCLUSIONS
SID enables a comprehensive approach to acid-base abnormalities in the neonate, making it a potential additional tool for evaluating fetal acid-base status.
Cohen
Yoni
Y
Lis Maternity Hospital, Tel Aviv Sourasky Medical Center, Affiliated to The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
Nimord
Adi
A
Ascher-Landsberg
Jessica
J
Kupferminc
Michael J
MJ
Lessing
Joseph B
JB
Many
Ariel
A
D000136:Acid-Base Equilibrium; D000137:Acid-Base Imbalance / Q000097:blood* / Q000175:diagnosis; D000838:Anions / Q000097:blood; D002245:Carbon Dioxide / Q000097:blood; D002412:Cations / Q000097:blood; D002585:Cesarean Section; D036861:Delivery, Obstetric; D005260:Female; D005333:Fetus / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010865:Pilot Projects; D011247:Pregnancy; D011446:Prospective Studies; D012016:Reference Values
D000838:Anions; D002412:Cations; D002245:Carbon Dioxide