The Effect of Adding Magnesium Sulfate, Neostigmine and Fentanyl to Ropivacaine on Sensory-Motor Block Properties in Lower Extremity Surgery under Spinal Anesthesia

Regional anesthesia with mild effects on vital organs is a common method of anesthesia that increases the competence of surgery. This study aimed to investigate the effects of adding magnesium, neostigmine, and fentanyl to ropivacaine alongside placebo on motor-sensory block properties in lower extremity surgeries under spinal anesthesia.

This current triple-blind clinical trial study was conducted on 100 patients who were candidates for lower limb surgery at Kashani Hospital in Isfahan during 2020-2021. These patients were randomly divided into four groups of 25 cases: Group1: ropivacaine plus fentanyl, Group2: ropivacaine plus magnesium sulfate, Group3: ropivacaine plus neostigmine and in the fourth group: ropivacaine plus 5% sugar solution that was injected into the cerebrospinal fluid space from L3-L4. The time of activity initiation and duration of sensory and motor block, and the maximal block height were recorded in all groups. Also, pain during recovery and the occurrence of common complications such as nausea, vomiting, hypotension) were evaluated and analyzed.

There is no significant difference between all groups in terms of the time interval between injection and motor block, sensory motor return, sensory block, and maximal block height and frequent distribution of nausea, vomiting, and hypotension. The shortest time interval between drug injection and sensory block occurred in ropivacaine plus fentanyl group. At the same time, the shortest length of stay in recovery was observed in the placebo group with ropivacaine. The lowest pain intensity was significantly recorded between 30 and 60 minutes of recovery in the fentanyl and neostigmine group compared to the other three groups.

Fentanyl, magnesium sulfate, neostigmine, along with ropivacaine, improved the onset of regional anesthesia with better anesthetic quality, but increased recovery time by reducing the consumption of analgesics compared to placebo. However, it seems that according to these data, a combination of ropivacaine with fentany in spinal anesthesia could be a better alternative for inducing a faster sensory block and controlling pain.