Background: The posterior quadratus lumborum block (pQLB) has been used in postoperative pain management after cesarean section (CS). However, clinicians have no data about pQLB safety in pregnants, at increased risk of local anesthetic systemic toxicity (LAST). The purpose of the present study was to explore the efficacy and the safety of adding epinephrine to ropivacaine for bilateral pQLB vs. bilateral pQLB performed with ropivacaine alone in CS.
Methods: In this prospective trial 52 pregnants, ASA 2 physiological status, were consecutively allocated to one of two groups, e-pQLB and pQLB; e-pQLB group received 0.375% ropivacaine+100 mcg epinephrine, 20 mL each side; pQLB received 0.375% ropivacaine alone, 20 mL each side. The primary and secondary outcomes were to evaluate if the adjunct of epinephrine to ropivacaine increases efficacy and safety of pQLB, respectively.
Results: Authors found in e-pQLB group vs. p-QLB group: a total mean morphine consumption statistically lower during the first 24 postoperative hours (5.08±3.12, vs. 9.11±4.67 SD mg, P=0.0002); NRS values statistically lower at six hours from block, both at rest (1.73±1.88 SD vs. 2.88±2.53, P=0.03) and with movement (3.03±1.98 SD vs. 4.23±2.87, P=0.04); a longer time between block and the first opioid request (5.92±2.48 vs. 3.78±2.68 SD hrs, P<0.003); venous ropivacaine concentrations significantly lower at any time of samples but at 120 minutes.
Conclusions: Adding epinephrine to ropivacaine increases efficacy and duration of pQLB. Moreover it increases block safety, reducing peak and mean venous ropivacaine concentration.