Underdosing of Local Anesthetics Clinical Trial
Official title:
Minimum Effective Volume Of Local Anesthetic İn USG Guided Axillary Approach Brachial Plexus Block
Background Peripheral nerve blocks with use of USG allowed visualisation of the structures
and nerves and made the block administrations safe, quick and comfortable. However there are
few publications concerning the minimum local anesthetic volume capable of providing blocks.
In this study the investigastors aimed to find Minimum Effective Volume Of Local Anesthetic
For Ultrasound-Guided Axillary Brachial Plexus Block in hand, elbow and forehand operations.
Materials & Methods A total of 55 ASA I-II patients underwent hand surgery operation by
administering USG guided-axillary brachial plexus blockage were included in the study. Ulnar,
median and radial nerves were seen and the minimum effective local anesthetic volume was
investigated starting with total 21 ml of %0.5 bupivacain. After accomplishing the blockage,
volume was decreased by 0.5 for each nerves. Block administration time, block onset times,
anesthesia times and time to first analgesic requirement were recorded.
Matherials and Method This randomized, prospective, double-blinded, single-center study was
conducted in accordance with the most recent version of the Helsinki Declaration. Approval
for the study was granted by the Ankara Numune Research and Training Hospital Ethics
Committee. A total of 55 adult patients classified as American Society of Anesthesiologists
(ASA) physical status I-II, who were to undergo elective, forearm, wrist or hand surgery were
recruited in this trial. Written informed consent was obtained from each patient. Exclusion
criteria were patients with coagulopathy, local anesthetic allergy, local infection, any
significant neurological, pysychiatric or congnitive disorder, chronic analgesic use, known
neuropathies, infection in the injection site or unwillingness of the patient. After arrival
in the operating room, an 20-gauge intravenous catheter was placed in the contralateral
forearm. Standard monitoring was used throughout the procedure, including non-invasive
arterial blood pressure, heart rate, and pulse oximetry. Patients were divided into groups
according to their order of arrival and a five-person group was created. İnitial volume of 7
ml. Per nerve(ulnar, median, radial), totaly 21 ml local anesthetic administered in first
group(first five patient). İf the success rate of block is three or more in the group, volume
was reduced in the next group of 0.5 ml for each nerve. if the success rate is less than
three in the group, study is ended. And minimum effective volume was calculated to be
statistically.
Block prosedures All the brachial plexus blocks were performed by the same anesthesiologist.
The patient is made comfortable in supine position with the arm abducted and the elbow flexed
to 90 degrees. After skin and probe preparation, A linear US probe (HFL 38, 6-13MHz) was
placed in the transverse plane at the lateral border of pectoralis major muscle to obtain the
best view of the brachial plexus. Image quality is optimised with selection of appropriate
depth (within 2 cm), focus range (within 1cm) and gain. The structures of interest are very
superficial with the pulsating axillary artery localised within 1 cm . Surrounding the
axillary artery, one will find the three out of four terminal branches of the brachial
plexus: the median (superficial and lateral to the artery), the ulnar (superficial and medial
to the artery) and the radial (posterior and lateral or medial to the artery) nerves. A 5 cm
needle (21G, Locoplex, Vygon, Ecouen, France) is inserted parallel to the long axis of the
transducer from the lateral side. As the needle is in the same plane as an ultrasound beam,
the path of the advancement can be visualised in real time as the needle approaches the
target nerves. Ideally, the radial nerve should be targeted first, as it lies posterior to
artery, in order to prevent displacing the structures of interest to deeper and obscuring the
median and ulnar nerves. The musculocutaneous nerve was blocked separately outside the
neurovascular bundle with 3 ml %0.5 bupivacaine at all of the patient. We were also worried
about the nerve puncture or intraneural injection. In addition, we also confirmed that the
location of the needle tip was not in hypoechoic area before each injection. For further
safety, we injected 0.5 ml of local anesthetic as a test dose. If the patients complained of
paresthesia or pain, or the injection pressure was high, or the spread of local anesthetic
was not visualized, investigastors stopped injection, and withdrew the needles and tried
again. The investigastors regarded the paresthesia or pain, or high injection pressure as
intraneural injection.
The investigator who testing the block is don't know the dose. Sensory block was evaluated
for each nerve distribution using ice to test cold sensation, comparing the anaesthetized arm
with the contralateral arm, and graded on a three-point scale (0, no difference between
sides; 1, some difference between arms but cold still sensed in the blocked arm; 2, no cold
sensation in the blocked arm). Motor block for each nerve was evaluated by asking the patient
to extend the flexed arm and wrist (radial nerve), flex the wrist and oppose the second and
third fingers and thumb (median nerve), flex and oppose fifth finger towards the thumb (ulnar
nerve) and was graded as 0, no change; 1, reduced contraction; 2, no contraction. Data were
collected every 5 min for the first 60 min, and then 1,2,4,6,8,10,12,18,24 hours. motor and
sensory scale, the total value should be higher than 10, if not surgical anesthesia was
considered unsuccessful. sensitive block score must be at least five. VAS determination was
performed with a scale of numbers between 0 and 10 cm. 1mg/kg tramadol and 15 mg/kg
paracetamol IV infusion were administered to patients with a reequirement for additional
analgesia (VAS ≥ 4) . The total number of patients who required additional analgesic drugs
was noted. During the initial procedures, the operation and postoperatively, patient
satisfaction was evaluated as poor (1), moderate (2), good (3) or very good (4).
Statical Analysis Statistical analysis was applied using SPSS 19.0 statistical software.our
sample size calculation method is dixon and massey up and down method. According to this
account, n = 2 (SD / SEM) ²; n: sample size, SD (standard deviation): The standard deviation,
SEM (standard error of mean) is calculated as the standard error of the mean (SD = 5 mL, SEM
= 1.0 mL) n were found in 50 patients. For the aplicational errors we add 5 patient (%10 ). A
total of 55 patients were included in the study.
The sample size calculation, made by G * Power 3.0.10 statistical software package (effect
size (effect size) = 0.4, α = 0.05, degrees of freedom (df) = 48 and 0.85 power (power (1-
β)), the number of 50 patients were found to be adequate. However for practical magnification
error with a sample of 10% of 55 patients were included in the study.
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| Status | Clinical Trial | Phase | |
|---|---|---|---|
| Completed |
NCT03838120 -
Determination of Minimum Effective Volume of Local Anesthetic in Patients Undergoing Ultrasound-Guided Infraclavicular Approach for Brachial Plexus Blockade
|
Phase 4 |