Aim: The optimal dose of low-dose intrathecal epinephrine in the absence of intrathecal opioids is unknown. Materials & methods: Prospective, randomized, double blind clinical trial of patients undergoing lower limb arthroplasties. The primary end point was spinal block duration measured via motor and sensory block duration. Results: 30 patients undergoing lower limb arthroplasty were randomized into one of six groups with varying intrathecal epinephrine doses 0-100 mcg. There was a direct linear effect between motor block duration and intrathecal epinephrine dose with higher doses being associated with longer block duration (p = 0.011). Mean motor block duration was 3.74 ± 1.13, 3.36 ± 0.47, 3.39 ± 0.60, 4.06 ± 0.98 and 5.20 ± 1.41 h for the EPI0, EPI25, EPI50, EPI75 and EPI100 groups respectively. Conclusion: This study reveals that low-dose intrathecal epinephrine (75-100 mcg) in the absence of intrathecal opioids can be reliably used to prolong motor block duration in lower limb arthroplasty. Clinical Trial Registration: NCT02619409 (ClinicalTrials.gov).
Keywords: anesthesia adjuvants; epinephrine; intrathecal injections; spinal anesthesia; total hip arthroplasty; total knee arthroplasty.
What is this summary about? Here, we summarize the results of the addition of a medicine called epinephrine to a type of anesthesia called spinal anesthesia which involves injection of medication into the fluid surrounding the spinal cord. The study was to determine the optimal amount of epinephrine needed to prolong the effect of spinal anesthesia for patients undergoing replacements of their hips and/or knees. What were the results? The study showed that the addition of low-dose epinephrine to spinal anesthesia prolongs the motor block – or inability to move the leg – in a linear fashion with higher doses of epinephrine associated with longer motor block. Our results did not show a significant difference in sensory block, or the inability to feel the leg. What do the results mean? The study shows that the addition of low-dose epinephrine to spinal anesthesia can reliably prolong the effect of the anesthesia which may be needed in more complicated hip or knee surgeries.