Prolongation of spinal duration by escalating doses of intrathecal epinephrine in lower limb arthroplasty.

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).