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Background and Aims: It is a common practice to add intrathecal lipophilic opioids to local anesthetics to improve the quality of subarachnoid block. This study was designed to find a dose of intrathecal fentanyl, which can improve the quality of surgical anesthesia with minimal side effects in parturients undergoing cesarean section under spinal anesthesia with intrathecal bupivacaine. Material and Methods: In a prospective randomized double‑blind study, 243 parturients undergoing cesarean section under spinal anesthesia were randomly allocated to receive 10, 15, or 25 μg of intrathecal fentanyl with 10 mg of 0.5% hyperbaric bupivacaine. Patients were assessed for clinical efficacy by measuring pain score, need for rescue analgesia, conversion to general anesthesia, and complaints of inadequacy of surgical anesthesia by the surgeon. The side effects assessed were pruritus, nausea, vomiting, dizziness, and decrease in saturation and respiratory rate. In addition, neonatal APGAR score, patients' hemodynamics, need for vasopressors, onset and duration of sensory, and motor block were measured. Results: Patients receiving 25 μg of fentanyl had a significantly higher incidence of pruritus, nausea, and dizziness in addition to a significantly prolonged sensory and motor block (P < 0.001). All patients in three groups had adequate surgical anesthesia with no statistically significant difference in the onset of block, quality of surgical anesthesia, pain scores, neonatal APGAR score, hemodynamic variables, and need for vasopressor. Conclusion: For patients undergoing cesarean section, 10 or 15 μg of intrathecal fentanyl with 10 mg of bupivacaine provided adequate surgical anesthesia and analgesia with minimal side effects. [ABSTRACT FROM AUTHOR]

Background: Spinal anesthesia with bupivacaine, typically used for elective and emergency cesarean section, is associated with a significant incidence of hypotension resulting from sympathetic blockade. A variety of dosing regimens have been used to administer spinal anesthesia for cesarean section. The objective of this study was to compare the incidence of hypotension following two different fixed dosing regimens. Methods: This was a randomized double-blind clinical trial with a two-sided design, 5% significance level and 80% power. After approval of the hospital ethics review committee, 60 patients were divided randomly into two groups. In one group, the local anesthetic dose was adjusted according to height and weight, and in the other, the dose was adjusted according to height only. Results: Sixty women with a singleton pregnancy were included. Of the factors that could affect dose and blood pressure, including age, weight, height, and dose, only height differed between the groups. Mean heart rate was similar between the groups. Hypotension was significantly more frequent with dosage based on height alone than with two-factor dose calculation (56.7% vs. 26.7%; P = 0.018). Conclusions: Adjusting the dose of isobaric bupivacaine to a patient's height and weight provides adequate anesthesia for elective cesarean section and is associated with a decreased incidence and severity of maternal hypotension and less use of ephedrine. [ABSTRACT FROM AUTHOR]