Minimum Effective Volume of Lidocaine for Ultrasound-Guided Costoclavicular Block.

BACKGROUND AND OBJECTIVES: This dose-finding study aimed to determine the minimum effective volume in 90% of patients (MEV90) of lidocaine 1.5% with epinephrine 5 µg/mL for ultrasound-guided costoclavicular block. METHODS: Using an in-plane technique and a lateral-to-medial direction, the block needle was positioned in the middle of the 3 cords of the brachial plexus in the costoclavicular space. The entire volume of lidocaine was deposited in this location. Dose assignment was carried out using a biased-coin-design up-and-down sequential method, where the total volume of local anesthetic administered to each patient depended on the response of the previous one. In case of failure, the next subject received a higher volume (defined as the previous volume with an increment of 2.5 mL). If the previous patient had a successful block, the next subject was randomized to a lower volume (defined as the previous volume with a decrement of 2.5 mL), with a probability of b = 0.11, or the same volume, with a probability of 1 - b = 0.89. Success was defined, at 30 minutes, as a minimal score of 14 of 16 points using a sensorimotor composite scale. Patients undergoing surgery of the elbow, forearm, wrist, or hand were prospectively enrolled until 45 successful blocks were obtained. This clinical trial was registered with ClinicalTrials.gov (ID NCT02932670). RESULTS: Fifty-seven patients were included in the study. Using isotonic regression and bootstrap confidence interval, the MEV90 for ultrasound-guided costoclavicular block was estimated to be 34.0 mL (95% confidence interval, 33.4-34.4 mL). All patients with a minimal composite score of 14 points at 30 minutes achieved surgical anesthesia intraoperatively. CONCLUSIONS: For ultrasound-guided costoclavicular block, the MEV90 of lidocaine 1.5% with epinephrine 5 µg/mL is 34 mL. Further dose-finding studies are required for other concentrations of lidocaine, other local anesthetic agents, and multiple-injection techniques.

A randomized comparison between costoclavicular and paracoracoid ultrasound-guided infraclavicular block for upper limb surgery.

BACKGROUND: This two-centre randomized trial compared costoclavicular and paracoracoid ultrasound-guided infraclavicular brachial plexus block in patients undergoing upper limb surgery. We hypothesized that both techniques would result in similar onset times and designed the study as an equivalence trial. METHODS: Ninety patients undergoing upper limb surgery at or distal to the elbow were randomly allocated to receive a costoclavicular (n = 45) or paracoracoid (n = 45) ultrasound-guided infraclavicular brachial plexus block. Both groups received a 35-mL mixture of 1% lidocaine-0.25% bupivacaine with epinephrine 5 µg·mL-1. In the costoclavicular group, local anesthetic was injected into the costoclavicular space in the middle of the three cords of the brachial plexus. In the paracoracoid group, local anesthetic was deposited dorsal to the axillary artery in the lateral infraclavicular fossa. A blinded observer recorded the block onset time (primary endpoint), success rate (i.e., surgical anesthesia), block-related pain scores, as well as the incidence of hemidiaphragmatic paralysis. Performance time and the number of needle passes were also recorded during the performance of the block. The total anesthesia-related time was defined as the sum of the performance and onset times. RESULTS: The mean (SD) onset times were comparable between the costoclavicular and paracoracoid groups [16.0 (7.5) min vs 16.8 (6.2) min, respectively; mean difference, 0.8; 95% confidence interval, -2.3 to 3.8; P = 0.61]. Furthermore, no intergroup differences were found in terms of performance time (P = 0.09), total anesthesia-related time (P = 0.90), surgical anesthesia (P > 0.99), and hemidiaphragmatic paralysis (P > 0.99). The paracoracoid technique required marginally fewer median [interquartile range] needle passes than the costoclavicular technique (2 [1-4] vs 2 [1-6], respectively; P = 0.048); however, procedural pain was comparable between the two study groups. CONCLUSION: Costoclavicular and paracoracoid ultrasound-guided infraclavicular blocks resulted in similar onset times. Furthermore, no intergroup differences were found in terms of performance times and success rates. Future dose-finding trials are required to elucidate the minimum effective volume of local anesthetic for costoclavicular infraclavicular blocks. This trial was registered at www.clinicaltrials.in.th (Study ID: TCTR20160525001).

Cardiovascular effects of volatile induction and maintenance of anesthesia (VIMA) and total intravenous anesthesia (TIVA) for laryngeal mask airway (LMA) anesthesia: a comparison study.

OBJECTIVE: To compare changes of heart rate and blood pressure in patients that underwent LMA anesthesia with VIMA or TIVA technique. MATERIAL AND METHOD: A hundred healthy patients, age 16 to 60 years were enrolled. They were randomized into two groups. Patients in group V (VIMA) were induced with 8% sevoflurane until loss of eyelash reflexes then controlled ventilation for five minutes before LMA insertion. Group T (TIVA) patients were given propofol to reach the affected site concentration of eight mcg/mlfor the LMA insertion. Bloodpressure and heart rate were recorded before induction, immediately before and after LMA insertion then every two minutes until surgical incision. RESULTS: Decreased SBP from baseline in group T was significantly more than group V in each period of time (D1-D7). DBP in group T decreased more than group V significantly only at eight and ten minutes after LMA insertion. The incidence of decreasing SBP > 20% from baseline was more significant in group T than group V. No significant difference of changed HR was found. Coughing during LMA insertion occurred in eight patients (16%) in group T and in three patients (6%) in group V (p = 0.11). CONCLUSION: Induction with propofol by effective site concentration of eight mcg/ml significantly decreased SBP more than with 8% sevoflurane. Both techniques provided smooth LMA insertion without serious complication.