Comparison of Hydroxyethyl Starch and Crystalloid Coload Combined With Norepinephrine Infusion for Hypotension

Post-spinal anesthesia hypotension is a frequent complication during spinal anesthesia for cesarean section. The incidence of post-spinal anesthesia hypotension is as high as 62.1-89.7% if prophylactic measures are not taken. Colloid fluid coload has been highly demonstrated for prevention and/or treatment of post-spinal anesthesia hypotension. In addition, there's some evidence that prophylactic infusion of norepinephrine could effectively reduce the incidence of post-spinal anesthesia hypotension in parturients undergoing cesarean section. However, the ED50 and ED90 for an effective 6% Hydroxyethyl starch (130/0.4) or crystalloid coload combined with prophylactic norepinephrine infusion dose for postspinal anesthesia hypotension is still unknown. The purpose of this study is to investigate the ED50 and ED90 for an effective 6% Hydroxyethyl starch (130/0.4) or crystalloid coload combined with prophylactic norepinephrine infusion dose for postspinal anesthesia hypotension in patients undergoing cesarean section.

Inclusion criteria

• 18-40 years
• Primipara or multipara
• Singleton pregnancy ≥ 37 weeks
• American Society of Anesthesiologists physical status classification I to II
• Scheduled for elective cesarean section under spinal anesthesia

Exclusion criteria

• Body height < 150 cm
• Body weight > 100 kg or body mass index (BMI) ≥ 40 kg/m2
• Eclampsia or chronic hypertension or baseline blood pressure ≥ 160mmHg
• Hemoglobin < 7g/dl
• Coagulation or renal function disorders
• Known allergy to hydroxyethyl starch
• Fetal distress, or known fetal developmental anomaly