Background and Goal of Study: Hydroxyethyl starch (HES) is widely used to prevent and treat spinal anesthesia-induced hypotension during cesarean section. However, the use of saline-based HES might lead to hyperchloremia. This study aimed to clarify the effects of saline-based HES on umbilical cord chloride level at delivery. 
Materials and Methods: The study participants were 93 consecutive single-pregnancy patients who underwent cesarean section with combined spinal-epidural anesthesia, at no sooner than 37 weeks of gestation, from January 2014 through March 2016. We divided the patients into two groups, depending on the use of saline-based 6% HES 130/0.4. Patients in group A received saline-based HES, and those in group B did not receive saline-based HES. The other solutions used in both groups were acetate Ringer’s solution, bicarbonate Ringer’s solution, and saline to dissolve the antibiotic. Data on the intraoperative volume of infusion were collected from the anesthesia records, and patient data were collected from the medical records. The major outcome was chloride levels in the umbilical cord at delivery. We defined the difference of 2.5 mmol/l or more as clinically significant considering 15% of the normal range. We also evaluated the following additional outcomes: levels of other electrolytes (Na+, K+), pH, base excess (BE), and Apgar score (at 1 and 5 min).
Results and Discussion: There were 43 patients in group A and 50 patients in group B. Age, body mass index, gestational week, time to delivery from operating room admission, the total amount of infusion, blood loss, and urine volume were not significantly different between groups. The volume infused from admission to the operating room to the point of delivery was also not significantly different between groups; 461 ± 167 ml of saline-based HES was administered in group A. The umbilical cord chloride level at delivery was significantly higher in group A than in group B (108 ± 2 vs 107 ± 2 mmol/l, P = 0.02). No differences were observed in the Apgar score and other umbilical cord laboratory data at delivery (Na+, K+, pH, BE). In terms of the riskbenefit balance, anesthesiologists may consider 500 ml of saline-based HES as the upper limit for routine use.
Conclusion: We suggest that although the use of up to 500 ml of saline-based HES during cesarean section influences umbilical cord blood electrolytes, the effect is not of a clinically significant magnitude.

Influence of saline based hydroxyethyl starch on umbilical cord blood electrolytes