Which Local Anesthetic at what Dose is Recommended for Parturients Undergoing Cesarean Delivery Under Spinal Anesthesia?

Abstract

Spinal anesthesia is the most popular regional anesthesia technique for cesarean delivery as it is easily performed and provides rapid onset of block followed by dense surgical anesthesia. Although bupivacaine seems to be widely and routinely used long acting amide type local anesthetic drug for spinal anesthesia, ropivacaine and levobupivacaine may occasionally be chosen. However, it is difficult to make decision of the best local anesthetic for intrathecal use with optimal dose selection. Therefore, either hyperbaric or isobaric long-acting local anesthetic (bupivacaine, ropivacaine and levobupivacaine) option associated with pharmacological or clinical dose recommendations are reviewed.Keywords: Spinal anesthesia; Cesarean delivery; Local anesthetics; Dose response Short CommunicationAnesthesia choices for cesarean delivery include general, epidural, spinal or combined spinal epidural (CSE) anesthesia. According to ASA practice guidelines for obstetric anesthesia, induction to delivery times for general anesthesia are lower when compared to epidural or spinal anesthesia and rate of maternal hypotension due to epidural or spinal techniques are greater than general anesthesia. Results of metaanalysis demonstrate that Apgar scores at 1 and 5 minutes are lower with general anesthesia when compared to epidural and spinal anesthesia. As expected, time to skin incision with general anesthesia is shorter than either epidural or spinal anesthesia. But general anesthesia has increased risk of maternal complications associated with difficult airway and/or aspiration. When spinal and epidural anesthesia are compared, induction to delivery times are shorter for spinal anesthesia. However, epidural anesthesia does not result in increased risk of maternal complications like general anesthesia does [1]. Currently, single shot spinal anesthesia using local anesthetics with or without opioids has been the world wide preferred anesthetic technique for most of the elective cesarean section (CS) operations.Bupivacaine is mostly a routine option for cesarean deliveries under spinal anesthesia. When hyperbaric and isobaric forms of bupivacaine were compared, rate of conversion to general anesthesia was significantly less and time to achieve sensory block at T4 was significantly faster with hyperbaric bupivacaine than that of isobaric bupivacaine [2]. Different dose selections are made based on either dose response studies (ED95 or ED50) or clinical experiences. Of note, rational dose for intrathecal use of local anesthetics are ED95 or ED50. ED50 is called as median effective dose and regarded as minimum local anesthetic dose (MLAD). ED95 dose is recommended to achieve surgical anesthesia with a 5 % failure rate for surgical anesthesia [3,4]. According to dose response studies, ED95 of intrathecal dose of hyperbaric and isobaric bupivacaine when used with fentanyl (10 µg) and morphine (200 µg) to provide successful surgical anesthesia for cesarean delivery was found to be 11.2 mg and 13 mg, respectively [4,5]. There are two...

Comparative study of efficacy of intrathecal bupivacaine-ketamine with bupivacaine-fentanyl for caesarean section

“…Bupivacaine a long acting amide is the most popular local anaesthetic agent used for spinal anaesthesia in parturient undergoing LSCS. Commonly used dose of bupivacaine (10-15mg) is associated with hypotension and longer duration of motor block [2,3] . Decreasing the dose of bupivacaine in spinal anaesthesia helps to minimize these adverse effects but simultaneously may result in anaesthetic failure.…”

“…Decreasing the dose of bupivacaine in spinal anaesthesia helps to minimize these adverse effects but simultaneously may result in anaesthetic failure. To avoid such instances many drugs such as opioids (morphine, fentanyl), midazolam, clonidine, ketamine have been used as adjuvant to bupivacaine [3] . In parturient most commonly used adjuvant is fentanyl.…”