The main objective of the trial is to complete a double-blinded randomized controlled trial of a lumbar plexus block with the Shamrock technique versus the Lumbar Ultrasound Trident technique by estimating the time of performance of lumbar plexus blocks in healthy volunteers. Secondary objectives include a) estimates of number and depth of needle injections, distance of injection site from the midline, minimal electric nerve stimulation to trigger muscular response and the type of response, and volunteer discomfort during block injection, b) measurements of plasma lidocaine and mean arterial blood pressure, c) examinations of sensory block of the dermatomes T8-S3 and motor block of the femoral nerve, the obturator nerve, the hip abductor muscles, and the hamstring muscles, d) success rate of lumbar plexus block, e) perineural and epidural distribution of local anesthetics added contrast visualized on magnetic resonance imaging (MRI) scanning, and f) cost-effectiveness for the Shamrock technique versus the Lumbar Ultrasound Trident Technique for lumbar plexus block in healthy volunteers. The hypothesis is that the Shamrock technique is faster to perform than the Lumbar Ultrasound technique, and that the success rate of the Shamrock technique is equal to or higher than the Lumbar Ultrasound Trident technique.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
20
Department of Aneshtesiology and Intensive Care Medicine; Aarhus University Hospital
Aarhus C, Denmark
Block performance time
Time for performance of lumbar plexus block in seconds from placement of the ultrasound transducer on the skin until the block needle is pulled out after injection of local anesthetics.
Time frame: Estimated 0 minutes after block placement. Presented 10 months after the last visit of the last volunteer.
Number of needle feeds
Needle feeds are defined as retraction of needle followed by new feed of the needle disregarding the number of skin punctures.
Time frame: Estimated 0 minutes after block placement. Presented 10 months after the last visit of the last volunteer.
Discomfort during block placement
Discomfort is measured with Numeric Rating Scale (NRS).
Time frame: Estimated 1 minute after block placement. Presented 10 months after the last visit of the last volunteer.
Plasma Lidocaine
Time frame: Blood samples are withdrawn 0, 5, 10, 20, 40, 60, and 90 minutes after block placement. Presented 10 months after the last visit of the last volunteer.
Mear arterial pressure
Time frame: Measured 5 minutes after block placement. Presented 10 months after the last visit of the last volunteer.
Cost-effectiveness
Cost-effectiveness estimated as extra expense per successful lumbar plexus block and calculated as incremental cost-effectiveness ratio (ICER).
Time frame: Calculated two weeks after the last visit of the last volunteer. Presented 10 months after the last visit of the last volunteer.
Sensor block
Sensor block (cold, warm, touch, and pain) of the dermatomes T8-S3 and of the femoral nerve and the lateral femoral cutaneous nerve.
Time frame: Tested 30 minutes after block placement. Presented 10 months after the last visit of the last volunteer.
Motor block
Motor block of the femoral nerve (knee extension), the obturator nerve (hip adduction), the superior gluteal nerve (hip abduction), and the sciatic nerve (knee flexion) estimated as active resistance against movement of the relevant joint and with sphygmomanometer of the relevant joint as maximal voluntary isometric contraction with dynamometer (mmHg).
Time frame: Tested 40 minutes after block placement. Presented 10 months after the last visit of the last volunteer.
Block success rate
Success rate defined as motor block of the femoral nerve (knee extension) and the obturator nerve (hip adduction) and reduced sensory of the lateral femoral cutaneous nerve (middle of the lateral side of the thigh).
Time frame: Tested 30 minutes after block placement. Presented 10 months after the last visit of the last volunteer.
Block success rate
Defined as above after lumbar plexus block with the Shamrock technique for motor response on electrical nerve stimulation above respectively below 0,5 milliampere (mA).
Time frame: Tested 30 minutes after block placement. Presented 10 months after the last visit of the last volunteer.
Epidural spread of local anesthetics with contrast
Estimated with T1- and T2-weighted and with diffusion weighted imaging (DWI) MR scanning.
Time frame: Estimated 10-30 minutes after block placement. Presented 10 months after the last visit of the last volunteer.
Perineural spread of local anesthetics with added contrast
Estimated with T1- and T2-weighted and with DWI MR scanning.
Time frame: Estimated 10-30 minutes after block placement. Presented 10 months after the last visit of the last volunteer.
Depth of block needle
The depth in cm from the injection site in the skin to the needle tips position during injection. of local anesthetics
Time frame: Estimated during block
Injection site
The distance in cm from the injection site of the block needle to the midline of the volunteer.
Time frame: Estimated immediately after block placement
Minimal electrical nerve stimulation
The estimated minimal electrical nerve stimulation in mA to trigger a muscular response.
Time frame: Estimated immediately before injection of local anesthetics during block placement
Type of response on electrical nerve stimulation
The type of response triggered by electrical nerve stimulation.
Time frame: Assessed immediately before injection of local anesthetics during block placement
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