Recent trends in obstetric anaesthesia show increased popularity of regional anaesthesia among obstetric anaesthetists. General anaesthesia in caesarean section is associated with high morbidity and mortality rate when compared with regional anaesthesia. Regional anaesthesia has its own demerits which are primarily related to excessively high spinal blocks and toxicity of local anaesthetics. Reduction in doses and improvement in technique to avoid high level blocks and increased awareness of toxicity of local anaesthetics have contributed to reduction in complications related to regional anaesthesia. The challenges presented by a parturient requiring anaesthesia or analgesia, or both, make the role of obstetric anaesthesiologist both challenging and rewarding. Spinal anesthesia is a popular technique for caesarean delivery. Hyperbaric Bupivacaine in 8% glucose is often used. Plain or glucose-free, Bupivacaine has been frequently referred to as “Isobaric” in the literature, even after Blomqvist and Nilsson demonstrated its hypobaricity. More recently, several studies have confirmed that plain Bupivacaine is indeed hypobaric in comparison with human CSF. Although hyperbaric local anesthetic solutions have a remarkable record of safety, their use is not totally without risk. To prevent unilateral or saddle blocks, patients should move from the lateral or sitting position rapidly to supine position. Hyperbaric solutions may cause sudden cardiac arrest after spinal anesthesia because of the extension of the sympathetic block. The use of truly isobaric solutions may prove less sensitive to position issues. Hyperbaric solutions may cause hypotension or bradycardia after mobilization. Isobaric solutions are favored with respect to their less sensitivity to postural changes.
MATERIALS AND METHODS
60 full term parturients of ASA Grade 1 and 2 posted for elective caesarean section under spinal anaesthesia were divided in to two groups.
GROUP LF (n = 30) – Received 1.8 ml (9 mg) Levobupivacaine 0.5% + Fentanyl 10 mcg (0.2 ml).
GROUP BF (n = 30) – Received 1.8 ml (9 mg) hyperbaric Bupivacaine 0.5% + Fentanyl 10 mcg (0.2 ml). The parameters measured in the two groups included haemodynamic measurements (Pulse rate, systolic blood pressure, diastolic blood pressure), respiratory parameters (Respiratory rate, oxygen saturation) characteristics of sensory block, characteristics of motor block, intra operative and post-operative complications like nausea, vomiting, shivering, visceral pain, sedation. In the neonate, Apgar score was measured to assess any effects of drugs the neonate.
Hypotension and bradycardia was more in hyperbaric Bupivacaine group (BF). Time for Onset of sensory block and maximum dermatome level reached were similar in both groups. Time for maximum sensory level reached, two segment regression time, T12 regression time and time for first analgesic requirement were early in LF group. Onset of motor block was delayed in LF group. Maximum degree of motor block was same in both groups (Bromage 3). Complete regression of motor block was significantly lower in Levobupivacaine group (LF). Intra operative incidence of nausea and vomiting were comparatively lower in LF group. Complications like respiratory depression, headache, back ache, and pruritus were not seen in both groups. Neonatal Apgar score was similar in all neonates. We recorded APGAR scores of 7 - 10 at 1 and 5 minutes in both groups. No significant postoperative complications were seen both the groups.
From present study findings and correlating it to the previous studies and literature plain Levobupivacaine 0.5% which is pure s - enantiomer of Bupivacaine is a good alternative for caesarean section in spinal anesthesia as it is less CVS and CNS toxic, early recovery of motor blockade leading to early mobilization of the mother, analgesia almost similar to racemic hyperbaric Bupivacaine. Addition of low dose Fentanyl 10 mcg with Levobupivacaine has dose sparing effect of opioids on local anesthetics, better postoperative analgesia and early recovery from motor block. However if using low dose Levobupivacaine +along with Fentanyl, it is advised to go for combined spinal epidural technique. Action of isobaric Levobupivacaine is independent on gravity in spinal anesthesia.