Spinal anesthesia for elective cesarean section. Use of local anesthetic at different doses of Fentanyl. Randomized Clinical Trial

INTERVENTION: Anesthesia, Spinal Procedure/surgery The research subjects were randomly assigned (by lot) into 4 groups of 31 patients. The research subjects in group 4 corresponded to the placebo group (not treated with fentanyl). All 124 patients received combined spinal anesthesia for cesarean section: spinal anesthesia (containing the anesthetic solution for the group to which each patient belonged) and epidural catheter insertion to complement surgical anesthesia, when necessary (verbal number scale pain complaint greater than 3, not bypassed with 100 mcg injection of intravenous fentanyl and / or midazolam 1mg), with local anesthetic Lidocain 2% ‐ from 10 to 20ml). The anesthetic solution injected during spinal anesthesia contained, as studied group, the following composition: Group I: 0.5% hyperbaric bupivacaine (2.0mL = 10mg) + fentanyl (0.3mL = 15mcg) + 0.9% saline (0.7 mL); Group II: 0.5% hyperbaric bupivacaine (2.0mL = 10mg) + fentanyl (0.2mL = 10mcg) + 0.9% saline (0.8 mL); Group III: 0.5% hyperbaric bupivacaine (2.0mL = 10mg) + fentanyl (0.15mL = 7.5mcg) + 0.9% saline (0.85mL); Group IV (placebo): 0.5% hyperbaric bupivacaine (2.0mL = 10mg) + 0.9% saline (1.0 mL) In addition to enabling anesthetic complementation, the epidural catheter was also used for injection of 2mg morphine before anesthetic discharge for better control of late postoperative pain. The catheter was removed immediately before anesthetic discharge in all patients. The drugs used in the study were commercial products from a single manufacturer. CONDITION: Cesarean Section Cesarean Section ; Cesarean Section O00‐O99 PRIMARY OUTCOME: Evaluate the duration of analgesia, from the beginning of anesthesia to the first spontaneous complaint of pain reported by the patient over than 3, according to the numeric‐verbal scale. in that scale, 0 means no pain and 10 the worst pain in the world for the person. To evaluate the quality of the intraoperative anesthesia, using a qualitative scale proposed by Lee (excellent, good, fair and poor) SECONDARY OUTCOME: Assess the presence of maternal side effects: nausea, vomiting, and pruritus Evaluate the results of fetal vitality, using the Apgar index Quantify the duration of the motor block: time elapsed between the end of the anesthetic injection in the subarachnoid space until the free movement of lower limbs INCLUSION CRITERIA: ASA II or III; pregnant women; elective cesarean; age range from 18 to 65 years.