Impact of interval between induction of spinal anesthesia to delivery on umbilical arterial cord ph of neonates delivered by elective cesarean section.

BACKGROUND

To evaluate the impact of interval between induction of spinal anesthesia to delivery of the fetus by elective cesarean section on umbilical arterial pH and neonatal outcome.

PATIENTS AND METHODS

Two hundred and twenty pregnant women who were planned for elective cesarean section at term under spinal anesthesia were recruited. Minimum systolic, diastolic and mean arterial blood pressures (SBP, DBP, MAP) and largest pressure decrease (SBP, DBP, MPA) were also recorded. Induction of spinal anesthesia to delivery interval was measured. Following delivery, umbilical arterial cord analysis for pH and base deficit were done. Apgar scores at 1 min and at 5 min, neonatal intensive care unit (NICU) admission, need for mechanical ventilation and incidence of hypoxemic-ischemic encephalopathy were recorded.

RESULTS

Induction of spinal anesthesia to delivery interval was 25.7 ± 5.6 min. Lowest SBP and MAP reached during cesarean delivery were 88.9 ± 7.3 mmHg and 60.4 ± 5.6 mmHg, respectively. MAP < 65 mmHg was reached in 136 (62%) patients with a decrease of MAP of > 20% in 149 (68%) patients. Duration of the longest hypotension episode was 3.3 ± 2.2 min. All patients required ephedrine administration for hypotensive episodes with an average dosage of 11.4 ± 3.2 mg. Umbilical pH of 7.3 ± 0.1 and base deficit of 8.3 ± 4.4 mmol/l were recorded. Apgar scores at 5 min were 8.5 ± 1.2. Eight (3.6%) neonates were admitted in the NICU. One neonate needed mechanical ventilation. There were no cases of hypoxemic-ischemic encephalopathy. There were inverse correlations between induction of spinal anesthesia to delivery interval, body mass index (BMI) and duration of longest hypotension episode in relation to umbilical pH (r = -0.817, -0.395 and -0.268, respectively). Cut off value for induction of spinal anesthesia to delivery interval greater than 27 min predicted an umbilical pH of < 7.2. Cut off value for the duration of the longest hypotension episode greater than 5 min predicted an umbilical pH of < 7.2. Cut off value for BMI greater than 35 kg/m predicted an umbilical pH of < 7.2.

CONCLUSION

Prolonged interval between induction of spinal anesthesia to delivery could be associated with neonatal acidosis. This could be aggravated by maternal obesity and prolonged duration of hypotension episodes during cesarean delivery.