Amnioinfusion: does the choice of solution adversely affect neonatal electrolyte balance?

To determine whether various solutions commonly used in amnioinfusion during labor affect neonatal electrolyte and blood gas values.

Amnioinfusion for thick meconium or severe variable fetal heart rate decelerations is used at our institution according to a standardized protocol. During alternating 3-week periods, the only solution made available for amnioinfusion was either normal saline or Ringer's lactate. Bolus volume, rate, and duration of infusion were determined by the individual physicians. At delivery, cord blood was collected for electrolyte and blood gas determination. These values were compared between the two solution groups and to a non-infused control group.

Complete data on neonatal electrolytes and blood gas values were available on 53 infusion patients (20 Ringer's lactate, 33 normal saline) and 39 non-infusion patients. Comparing infusion to non-infusion patients and those infused with Ringer's lactate to those with normal saline, we found no significant difference in demographics, neonatal outcome variables, duration of labor, neonatal electrolytes, and cord blood gas values. Infusion variables (bolus volume, infusion rate, hours infused, and total volume infused) did not differ between solutions. Total volume and hours of infusion were closely correlated with each other (r = 0.93, P < .001); both were correlated with neonatal chloride (r = 0.38 and r = 0.36, respectively; P < .005). No cases of hypernatremia or hyperchloremia were found in any of the groups. The type of solution used had no effect on the neonatal chloride trend.

The use of both normal saline and Ringer's lactate for indicated amnioinfusion in labor appears to have no clinically significant effect on neonatal electrolytes.