Combined Colloid Preload And Crystalloid Coload Versus Crystalloid Coload During Spinal Anesthesia for Cesarean Delivery

6% hydroxyethyl starch 130/0.4 in 0.9% sodium chloride (voluven®) 500 mL will be rapidly infused before spinal anesthesia

Performed at the L3-L4 or L4-L5 interspace using 27- or 25-gauge spinal needle

Bupivacaine 12.5 mg (2.5 mL 0.5%) will be administered in the subarachnoid space

Fentanyl 15 µg will be administered in the subarachnoid space

Ringer acetate 500 mL will be rapidly infused immediately after intrathecal injection

Ringer acetate 1000 mL will be rapidly infused immediately after intrathecal injection

Lower segment cesarean section using the Pfannenstiel incision

The inferior vena cava largest and smallest diameters will be measured proximal to the opening of the hepatic veins in the longitudinal axis with the M-mode using a 5-2 MHz curved array ultrasound probe placed longitudinally in the subxiphoid region

Intravenous ephedrine 3, 5, and 10 mg will be administered when Systolic blood pressure decreases below 90%, 80%, and 70% of baseline, respectively.