A prospective study evaluating the effectiveness of epidural volume extension with normal saline in combined spinal epidural anesthesia for lower limb orthopedic surgeries using low dose intrathecal hyperbaric bupivacaine

Background: Combined spinal-epidural anesthesia technique for providing pain relief for orthopedic procedures has gained popularity. It combines the advantages of rapid onset and the reliability of blockade obtained spinally along with the flexibility given by epidural catheter avoiding the disadvantages of either technique used alone. Spinal anesthesia provides dense neural blockade of finite duration while epidural is more titratable producing less hemodynamic swings and postoperative analgesia. The epidural volume extension adds color to combined spinal-epidural anesthesia technique where the onset and the level of blockade obtained spinally are enhanced by administering saline or local anesthetic via the epidural catheter. The ideology behind this is the volume effect accomplished by injecting saline epidurally which would result in intrathecal compression and cephalad migration of spinal local anesthetic. Aim of the study: To identify the effectiveness of block profile provided by extending the epidural volume with normal saline for lower limb orthopedic surgeries using a low dose intrathecal hyperbaric bupivacaine without causing hemodynamic changes. Materials and methods: A prospective randomised controlled study involving 80 patients posted for elective lower limb orthopedic surgeries were divided into two groups of 40 each. Group A received combined spinal-epidural anesthesia with 10 mg of 0.5% bupivacaine with epidural volume extension of 10 ml normal saline. Group B received combined spinal-epidural anesthesia alone. The blood pressure and heart rate changes were observed at the 5th, 10th, 15th, 20th min and then every fifteen minutes. Results: Low dose of intrathecal hyperbaric bupivacaine (10 mg) with 25 micrograms of fentanyl with epidural volume extension (10ml normal saline) is associated with early onset of sensory and motor blockade, high level of sensory block, shorter time of two segment regression. Conclusion: In this study we can safely conclude that combination of spinal epidural with epidural volume extension with normal saline achieves an effective and shorter block time as evident by significantly lower maximum motor block time providing prolonged analgesia by requiring less top-up dose of bupivacaine with higher level of sensory block at the tenth minute with shorter mean maximum sensory block time.