Outcomes
The primary outcome was metabolic acidosis (MA) in cord blood defined as
pH < 7.05 and BDecf > 10mmol/L
and/or lactate > 10mmol/L (18). If arterial samples were
missing, venous samples were used with the same cut-offs as arterial.
Since venous pH values are usually less acidotic than arterial, venous
levels meeting cut-off criteria for arterial samples are evidently
pathological (19).
Secondary outcome measures included alternative combinations of the
blood gas parameters, Apgar scores (AS) and various clinical neonatal
outcomes: neonatal intensive care unit admission
(NICU), neonatal resuscitation
interventions, such as continuous positive airway pressure therapy
(CPAP), bilevel positive airway pressure (BiPAP) or ventilation. The
correlation between scalp blood lactate and umbilical artery blood
pH/lactate was determined in relation to the time interval 0-15 minutes,
0-25 minutes, 0-30 minutes and 0-60 minutes from FBS to delivery to
define the optimal time-limit for cases to be included in the
calculation of the suggested cut-off for intervention.