Comparing the minimum local anesthetic dose of ropivacaine in real-time ultrasound-guided spinal anesthesia and traditional landmark-guided spinal anesthesia: a randomized controlled trial of knee surgery patients

Abstract

Background: Through previous studies and clinical practice, we have found that real-time ultrasoundguided (UG) spinal anesthesia (SA) and traditional landmark-guided (LG) SA each require a different minimum local anesthetic dose (MLAD) of ropivacaine. For this study, we used Dixon's up-and-down sequential method to analyze and compare the MLAD of different ropivacaine concentrations required for the UG and LG SA methods.Methods: A total of 120 patients undergoing knee surgery were consecutively recruited and randomly divided into four groups (30 patients per group). These groups were categorized as follows: Group I: high ropivacaine ultrasound-guided (HRUG), Group II: low ropivacaine ultrasound-guided (LRUG), Group III: high ropivacaine landmark-guided (HRLG), and Group IV: low ropivacaine landmark-guided (LRLG). SA was established by a bolus administration of up-and-down doses of 0.75% or 0.5% plain ropivacaine. Initial doses of 16, 18, 12, and 14 mg were administered to groups I-IV, and after that, increased or decreased by 1.5 mg according to dose effectiveness. Upon identifying the intervertebral puncture level, a lumbar X-ray was performed with metal markers, and actual radiographic findings were identified and compared to the initial markings.Results: For UG groups, the MLAD in the LRUG group was significantly higher than in the HRUG

Dural Puncture Epidural with 25-G Spinal Needles versus Conventional Epidural Technique in Conjunction with PIEB for Labor Analgesia: A Randomized Trial

“…Besides, a lower concentration of ropivacaine exhibits a more pronounced motorsensory separation block than other local anesthetics. 13 So, it seems greatly useful in labor analgesia, given the undesirability of motor blockade. Additionally, dural conduit played a proportionally more important role in transmeningeal medication transfer, when local anesthetics with a low concentration were used.…”

“…[9][10][11][12] Lower concentrations of ropivacaine can lead to sensory-motor dissociation block, which is associated with a decreased risk of motor block. 12,13 In theory, DPE technique combined with PIEB infusion of low-concentration local ropivacaine for initial and maintenance analgesia may provide additional benefits for women in labor. However, limited data exist on this specific pain management strategy.…”

Letter to the editor: ‘Comparative dose-response study on the infusion of norepinephrine combined with intravenous ondansetron versus placebo for preventing hypotension during spinal anesthesia for cesarean section – a randomised controlled trial’

“…Secondly, the combined spinal-epidural anesthesia was administered at the L2-L3 or L3-L4 interspace, where 16 mg of hyperbaric ropivacaine was infused at a rate of 0.2 ml/s, following the anesthesiologist’s verification of a clear, free-flowing cerebrospinal fluid utilizing a needle-through-needle technique, with the patients in a left lateral position. The uniform dosage of ropivacaine across all patients may result in divergent hypotension rates due to individual variations in spinal anesthesia depth, potentially influencing the study’s outcomes 5 . Moreover, interspace selection variability for the puncture could cause different hypotension rates.…”