Sequential intrathecal injection of fentanyl and hyperbaric bupivacaine at different rates: does it make a difference? A randomized controlled study.

Background: The results of previous studies have shown that using sequential intrathecal injection of fentanyl and hyperbaric bupivacaine for cesarean section (CS) anesthesia provides better quality anesthesia and prolongs postoperative analgesia. The aim of this study was to determine whether rapid intrathecal injection of fentanyl followed by slow injection of hyperbaric bupivacaine affects the duration of postoperative analgesia, the quality of anesthesia and hemodynamic status.

Methods: Fifty-six American Society of Anesthesiologists physical status I and II parturients aged 18-40 years old who underwent elective CS were randomly assigned to two groups of 28 patients each. The normal sequential group received sequential intrathecal injections of fentanyl and hyperbaric bupivacaine administered at the same rate, each through a 5 ml syringe. The rapid sequential group received a rapid intrathecal injection of fentanyl through an insulin syringe followed by a slow injection of hyperbaric bupivacaine through a 5 ml syringe. The onset of sensory block, the time of the first rescue analgesia, the doses of rescue analgesics, the degree of postoperative pain, the onset and duration of motor block, the incidence and duration of hypotension, and spinal anesthesia-related complications were recorded.

Results: While both approaches had comparable spinal-related complications, incidences, durations of hypotension and doses of ephedrine, the rapid sequential group exhibited a more rapid onset of sensory block, a higher sensory level, and more prolonged postoperative analgesia.

Conclusions: Rapid sequential injection of fentanyl and hyperbaric bupivacaine produced a better quality of anesthesia and prolonged postoperative analgesia.