Mepivacaine versus Bupivacaine Spinal Anesthesia for Early Postoperative Ambulation.

BACKGROUND: Early ambulation after total hip arthroplasty predicts early discharge. Spinal anesthesia is preferred by many practices but can delay ambulation, especially with bupivacaine. Mepivacaine, an intermediate-acting local anesthetic, could enable earlier ambulation than bupivacaine. This study was designed to test the hypothesis that patients who received mepivacaine would ambulate earlier than those who received hyperbaric or isobaric bupivacaine for primary total hip arthroplasty. METHODS: This randomized controlled trial included American Society of Anesthesiologists Physical Status I to III patients undergoing primary total hip arthroplasty. The patients were randomized 1:1:1 to 52.5 mg of mepivacaine, 11.25 mg of hyperbaric bupivacaine, or 12.5 mg of isobaric bupivacaine for spinal anesthesia. The primary outcome was ambulation between 3 and 3.5 h. Secondary outcomes included return of motor and sensory function, postoperative pain, opioid consumption, transient neurologic symptoms, urinary retention, intraoperative hypotension, intraoperative muscle tension, same-day discharge, length of stay, and 30-day readmissions. RESULTS: Of 154 patients, 50 received mepivacaine, 53 received hyperbaric bupivacaine, and 51 received isobaric bupivacaine. Patient characteristics were similar among groups. For ambulation at 3 to 3.5 h, 35 of 50 (70.0%) of patients met this endpoint in the mepivacaine group, followed by 20 of 53 (37.7%) in the hyperbaric bupivacaine group, and 9 of 51 (17.6%) in the isobaric bupivacaine group (P < 0.001). Return of motor function occurred earlier with mepivacaine. Pain and opioid consumption were higher for mepivacaine patients in the early postoperative period only. For ambulatory status, 23 of 50 (46.0%) of mepivacaine, 13 of 53 (24.5%) of hyperbaric bupivacaine, and 11 of 51 (21.5%) of isobaric bupivacaine patients had same-day discharge (P = 0.014). Length of stay was shortest in mepivacaine patients. There were no differences in transient neurologic symptoms, urinary retention, hypotension, muscle tension, or dizziness. CONCLUSIONS: Mepivacaine patients ambulated earlier and were more likely to be discharged the same day than both hyperbaric bupivacaine and isobaric bupivacaine patients. Mepivacaine could be beneficial for outpatient total hip arthroplasty candidates if spinal is the preferred anesthesia type.

An engineered methanogenic pathway derived from the domains Bacteria and Archaea.

A plasmid-based expression system wherein mekB was fused to a constitutive Methanosarcina acetivorans promoter was used to express MekB, a broad-specificity esterase from Pseudomonas veronii, in M. acetivorans. The engineered strain had 80-fold greater esterase activity than wild-type M. acetivorans. Methyl acetate and methyl propionate esters served as the sole carbon and energy sources, resulting in robust growth and methane formation, with consumption of >97% of the substrates. Methanol was undetectable at the end of growth with methyl acetate, whereas acetate accumulated, a result consistent with methanol as the more favorable substrate. Acetate was consumed, and growth continued after a period of adaptation. Similar results were obtained with methyl propionate, except propionate was not metabolized.