¹Assistant Professor, Department of Anaesthesia, MGM Medical College, Aurangabad, Maharashtra, INDIA.

{²Professor, Department of Anaesthesia} {³Professor, Department of OBGY} Pacific Institute of Medical Sciences, Udaipur, Rajasthan, INDIA.

⁴Associate Professor, Department of Anaesthesia, IQ City Medical College, Durgapur, West Bengal, INDIA.

Email: vrajput214@gmail.com  , shalinikarad787@gmail.com , shashikant.dahifalkar@rediffmail.com

RESULTS

Total 80 pregnant women were enrolled & 40 pregnant women each were allotted to group B ( 10 mg bupivacaine) and group BM (10 mg bupivacaine combined with 2 mg of preservative-free midazolam) Baseline maternal characteristics such as age, weight, height, pulse rate, systolic BP, diastolic BP were comparable in both groups.

Table 1: Baseline Information & Vitals of Study Groups

Early onset time of sensory block, reduced time to achieve complete sensory block & prolonged duration of effective analgesia was noted in group BM as compared to group B, and the difference was statistically significant.

Table 2: Comparison of sensory parameters in two groups

Complications such as bradycardia, hypotension, nausea and vomiting were noted in present study. Group B had increased number of complications than group BM, difference was not statistically significant.

Table 3: Complication

DISCUSSION

The dose of the local anaesthetic (LA) decides the extent and duration of the block - too little dose will cause untimely wearing away of the block, visceral pain on exteriorization of uterus & handling of other abdominal contents, whereas too large a dose might result in an intensive block with the resultant hypotension, bradycardia and sometimes even cardiac arrest. The use of subarachnoid additives in spinal anaesthesia for cesarean section has two main objectives: to enhance spinal block and to produce effective and prolonged postoperative analgesia.

Midazolam is categorized under the benzodiazepine group of drugs, is used as a preoperative sedative or as a sleep medication during operations, and as a sedative drug during delivery, with analgesic effects.^7,8 Midazolam exerts its analgesic activity through benzodiazepine receptors, which are distributed in the gray matter of the cervical, thoracic, lumbar, and sacral regions of the spinal cord; the highest densities of receptors were localized within lamina II of the dorsal horn. The segmental analgesia produced by intrathecal midazolam is mediated by the benzodiazepine GABA receptor complex, which is also involved in other benzodiazepine actions .

Karbasfrushan et al.,⁹ compared intrathecal midazolam 2 mg added to bupivacaine 10 mg versus plain bupivacaine in women undergoing elective cesarean. Patients treated with midazolam had significant pain relieve at 15 and 120 min after surgery, but there were no significant differences between the groups regarding the intensity of pain 5, 30, 60 and 240 min after the surgery. Request for first analgesic was 178.06±77.33 versus 142.18±55.19 min. Duration of analgesia and regression for sensory analgesia was similar in both groups, but nausea and vomiting were higher in the midazolam group.

In a study by Sharifi et al.¹⁰ it was shown that adding midazolam to bupivacaine reduced the time required for spinal anesthesia, reduced the time required for motor block & increased the time of spinal anesthesia. Various studies have found that adding midazolam to bupivacaine significantly increases the duration of postoperative analgesia.¹¹ Similar findings were noted in present study.

In present study, episodes of hypotension and the associated vasopressor requirement, which were significantly high in the group B compared to the group. Sanwal et al. reported that this relationship may be due to the bupivacaine-sparing effect of midazolam and concluded that intrathecal midazolam may allow the dose of bupivacaine to be reduced while still providing the same surgical anaesthesia with fewer episodes of bradycardia and hypotension. They concluded that, with intrathecal midazolam 2 mg, it is possible to reduce the dose of bupivacaine from 2.2 mg to 1.5 mg to provide the same surgical anesthesia but with fewer incidence of hypotension and other side effects.

Further, the incidence of nausea and vomiting was also found to be low in the midazolam group. It has been postulated that a possible mechanism for the anti-emetic effect of benzodiazepines could be an action at the chemoreceptor trigger zone, which reduce the synthesis, release, and postsynaptic effect of dopamine.¹³                

Ravichandra D et al.,¹⁴ noted that intrathecal midazolam provides significant and effective postoperative analgesia along with stable intraoperative hemodynamics without affecting the level of sensory and motor blocks. Adequate postoperative analgesia can be achieved with minimal side effects using intrathecal midazolam in PIH patients. In the same study, duration of postoperative analgesia was significantly prolonged in the midazolam group compared to the control group (BC: 201.5 ± 1.83 vs. BM: 357.6 ± 9.74, P < 0.01); The duration of analgesia was also significantly prolonged in the midazolam group compared to the control group (260.6 ± 22.45 minutes. vs. 170.8±21.17 minutes). However, the duration of the motor block & sedation score were comparable in both groups.

Midazolam produces spinally mediated analgesia that is different in quality from that produced by the μ-opioid agonist fentanyl. The analgesic effects of intrathecal midazolam have been proposed to be due to its intrathecal spinal receptor interactions affecting the type A gamma-aminobutyric acid receptors.

Ho KM in a meta-analysis concluded that, adding intrathecal midazolam to other spinal medications improves perioperative or peripartum analgesia and reduces nausea and vomiting during caesarean delivery. A small diluted dose of intrathecal midazolam (1 to 2.5 mg) does not appear to increase the duration of motor blockade, the risk of respiratory depression or of short-term neurologic deficit.¹⁵

A large cohort study investigating the adverse neurological effects of intrathecal midazolam has also found no association between intrathecal midazolam and neurologic symptoms.¹⁶

CONCLUSION

Intrathecal bupivacaine plus midazolam for caesarean section reduces the onset time of sensory block,  prolongs the duration of analgesia with no increase in the incidence of complications. Intrathecal bupivacaine plus midazolam should be promoted for elective caesarean section.

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