In 2020, a trial demonstrated that a 2-injection technique constitutes the optimal method for the costoclavicular block.
This study aims to determine the minimum amount of medication required to achieve a successful double-injection costoclavicular nerve.
Block dose assignment will be done using an up-and-down sequential method, called the Biased Coin Design (BCD).
The double-injection technique for US-guided costoclavicular block consists in depositing two thirds of the LA volume in the deep compartment (to anesthetize the posterior and medial cords), and one third of the injectate in the superficial compartment (to anesthetize the lateral cord).
The ED90 will be calculated using isotonic regression with a 95% confidence interval derived by bootstrapping.
Age between 18 and 70 years
American Society of Anesthesiologists classification 1-3
Body mass index between 20 and 30
Adults who are unable to give their own consent
Pre-existing neuropathy (assessed by history and physical examination)
Coagulopathy (assessed by history and physical examination and, if deemed clinically necessary, by blood work up i.e. platelets≤ 100, International Normalized Ratio≥ 1.4 or partial prothrombin time ≥ 50)
Renal failure (assessed by history and physical examination and, if deemed clinically necessary, by blood work up i.e. creatinine≥ 100)
Sequential
Ultrasound-guided double-injection costoclavicular nerve block with same previous volume
Procedure/Surgeryultrasound-guided double-injection costoclavicular nerve block with the same volume used in the previous successful block
Ultrasound-guided double-injection costoclavicular nerve block with lower volume
Procedure/SurgeryUltrasound-guided double-injection costoclavicular nerve block with lower volume than the previous successful block
Success rate
The primary outcome is success rate evaluated by the sensorimotor block which is defined as a minimal composite score of at least 14 points (out of a maximum of 16) is achieved at 30 minutes. The sensorimotor block will be assessed every 5 minutes until 30 minutes after the end of local anesthetic injection using a 16-point composite score evaluating sensory and motor block of musculocutaneous, median, radial, and ulnar nerves. Sensation will be assessed with ice in each nerve territory with a 0 to 2 point scale. 0= no block, patients can feel cold; 1= analgesic block, the patient can feel touch but not cold; 2= anesthetic block, the patient cannot feel cold or touch. The motor function will be assessed for each nerve with a 0 to 2 points scale where 0= no motor block; 1= paresis; 2= paralysis. Successful blocks at 30 minutes correlate with a final score ( sum of all individual sensory and motor scores) of at least 14 points out of 16.
Operator level of experience
expert vs. trainee
The number of needle passes
The number of times the needle had to be withdrawn by ≥1 cm before redirecting to achieve the final position for local anesthetic injection.
Block performance time
Sum of: 1- the acquisition time of the ultrasonographic image. and 2- the time to perform the block itself (from the skin anesthesia to the end of local anesthetic injection)
Block onset time
Time required to reach a minimal sensorimotor composite score of 14 points out of a maximum of 16 points. The sensorimotor score is described in primary outcome.
Incidence of nerve block side effects
The presence of Horner syndrome, paresthesia, vascular puncture, hematoma, pneumothorax, or local anesthetic systemic toxicity after the nerve block.
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