The median effective dose of ropivacaine required for producing an effective costoclavicular block has not yet been determined. The authors conducted this dose-finding study with the objective of determining the median effective dose of 0.5% ropivacaine required to produce a successful costoclavicular block for surgical anesthesia in 50% of the patients (ED50) as well as the calculated dose required for effective blockade in 95% of the patients (ED95).
Methods

This single-armed prospective study was conducted on 40 American Society of Anesthesiologists physical status I or II patients, aged 18 to 60 yr, with a body mass index of 18 to 30 kg/m2, scheduled to undergo forearm and hand surgeries under ultrasound-guided costoclavicular block. A volume of 0.5% ropivacaine administered in the costoclavicular space was determined using the sample up-and-down sequential allocation study design of binary response variables. The first patient received a volume of 26 ml of 0.5% ropivacaine. After a successful or unsuccessful block, the volume of local anesthetic was decreased or increased, respectively, by 2 ml in the next patient. Evaluation of sensory and motor block was performed every 5 min for 30 min and graded using a 3-point scale. Surgical anesthesia was considered to be successful if a minimum score of 14 was achieved and the surgeon was able to proceed with surgery without needing to supplement anesthesia.

Results

The volume of local anesthetic administered ranged from 8 to 26 ml. Centered isotonic regression with a bias-corrected Morris 95% CI derived by bootstrapping showed ED50 of 13.5 ml (95% CI, 11.5 to 15.4 ml) and ED95 of 18.9 ml (95% CI, 17.9 to 27.5 ml).

Conclusions

A 19-ml dose of 0.5% ropivacaine is likely to produce an effective ultrasound-guided costoclavicular block for providing adequate surgical anesthesia to 95% of the patients.

Editor’s Perspective
What We Already Know about This Topic
  • The costoclavicular block is an approach to brachial plexus anesthesia featuring rapid onset
  • The optimal volume for ultrasound-guided costoclavicular blockade has not been defined
What This Article Tells Us That Is New
  • Forty patients were enrolled in a dose-finding study using 0.5% ropivacaine and an up-and-down sequential allocation study design
  • It was determined that 19 ml of 0.5% ropivacaine is likely to produce adequate surgical anesthesia for 95% of patients using this block technique