Study: NCT02961842

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: 500 mL Colloid Preload
Description: 6% hydroxyethyl starch 130/0.4 in 0.9% sodium chloride (voluven®) 500 mL will be rapidly infused before spinal anesthesia

Intervention type: PROCEDURE
Group type: ACTIVE_COMPARATOR
Intervention: Spinal Anesthesia
Description: Performed at the L3-L4 or L4-L5 interspace using 27- or 25-gauge spinal needle

Intervention type: PROCEDURE
Group type: EXPERIMENTAL
Intervention: Spinal Anesthesia
Description: Performed at the L3-L4 or L4-L5 interspace using 27- or 25-gauge spinal needle

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: Intrathecal Bupivacaine
Description: Bupivacaine 12.5 mg (2.5 mL 0.5%) will be administered in the subarachnoid space

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Intrathecal Bupivacaine
Description: Bupivacaine 12.5 mg (2.5 mL 0.5%) will be administered in the subarachnoid space

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: Intrathecal Fentanyl
Description: Fentanyl 15 µg will be administered in the subarachnoid space

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Intrathecal Fentanyl
Description: Fentanyl 15 µg will be administered in the subarachnoid space

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: 500 mL Crystalloid Coload
Description: Ringer acetate 500 mL will be rapidly infused immediately after intrathecal injection

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: 1000 mL Crystalloid Coload
Description: Ringer acetate 1000 mL will be rapidly infused immediately after intrathecal injection

Intervention type: PROCEDURE
Group type: ACTIVE_COMPARATOR
Intervention: Cesarean Delivery
Description: Lower segment cesarean section using the Pfannenstiel incision

Intervention type: PROCEDURE
Group type: EXPERIMENTAL
Intervention: Cesarean Delivery
Description: Lower segment cesarean section using the Pfannenstiel incision

Intervention type: RADIATION
Group type: ACTIVE_COMPARATOR
Intervention: Ultrasound Assessment of the Inferior Vena Cava
Description: 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

Intervention type: RADIATION
Group type: EXPERIMENTAL
Intervention: Ultrasound Assessment of the Inferior Vena Cava
Description: 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

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: Intravenous Ephedrine
Description: Intravenous ephedrine 3, 5, and 10 mg will be administered when Systolic blood pressure decreases below 90%, 80%, and 70% of baseline, respectively.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Intravenous Ephedrine
Description: Intravenous ephedrine 3, 5, and 10 mg will be administered when Systolic blood pressure decreases below 90%, 80%, and 70% of baseline, respectively.