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On-line version ISSN 1806-907X
Rev. Bras. Anestesiol. vol.55 no.1 Campinas Jan./Feb. 2005
Comparison of transarterial and multiple nerve stimulation techniques for axillary block using lidocaine with epinephrine*
Comparación de las técnicas transarterial y de estimulación de múltiples nervios para bloqueo del plexo braquial por vía axilar usando lidocaína con epinefrina
Luiz Eduardo Imbelloni, TSA, M.D.I; Lúcia Beato, TSA, M.D.II; José Antônio Cordeiro, M.D.III
IDiretor do Instituto de Anestesia
Regional do Hospital de Base de São José do Rio Preto, SP; Anestesiologista
da Clínica São Bernardo e Casa de Saúde Santa Maria. Rio de Janeiro,
IIAnestesiologista da Clínica São Bernardo e Casa de Saúde Santa Maria. Rio de Janeiro
IIIProfessor na Faculdade de Medicina de São José do Rio Preto, FAMERP, São José do Rio Preto, SP
BACKGROUND AND OBJECTIVES: High-dose transarterial
technique results in highly effective axillary block. The multiple nerve stimulation
technique (MNS) requires more time and experience. This prospective study aimed
at comparing onset and success rate of multiple-injection axillary brachial
plexus block using two methods of nerve location: transarterial or multiple
nerve stimulation technique.
METHODS: Axillary block was initially induced with 800 mg lidocaine with epinephrine. The transarterial group received deeply injected 30 mL of 1.6% lidocaine with epinephrine, and 20 mL superficially to the axillary artery. For the multiple nerve stimulation group, three terminal motor nerves were electrolocated and blocked with 20 mL, 20 mL and 10 mL. Blockade was considered effective when analgesia was present in all sensory nerves distal to the elbow.
RESULTS: Onset (8.8 ± 2.3 min versus 10.2 ± 2.4 min; p-value = 0.010) was significantly shorter in the transarterial group. Complete sensory block of all four nerves (median, ulnar, radial and musculocutaneus) was achieved in 92.5% versus 83.3% for multiple nerve stimulation group and transarterial group, respectively, without significant difference (p = 0.68). Musculocutaneous nerve was significantly easier to be blocked with the aid of peripheral nerve stimulator (p = 0.034).
CONCLUSIONS: Both MNS technique for axillary block with nerve stimulator (3 injections) and transarterial technique (2 injections) promote similar results. Musculocutaneous nerve is more easily blocked with the aid of peripheral nerve stimulator. MNS technique has required less supplementary blocks and has delayed beginning of surgery.
Key words: ANESTHETIC, Local: epinephrine, lidocaine; ANESTHETIC TECHNIQUES, Regional: axillary block, brachial plexus
JUSTIFICATIVA Y OBJETIVOS: La técnica
transarterial con grandes dosis de anestésico local resulta en alta efectividad
para el bloqueo axilar del plexo braquial. La técnica de utilizar múltiples
estímulos exige más tiempo y mayor experiencia. Este estudio prospectivo
compara la latencia y el índice de éxito del bloqueo del plexo braquial
usando dos técnicas de localización: transarterial o múltipla
estimulación de los nervios.
MÉTODO: La lidocaína con epinefrina, 800 mg, fue usada inicialmente para el bloqueo axilar. En el grupo transarterial, 30 mL de lidocaína a 1,6% con epinefrina fueron inyectados profundamente y 20 mL superficialmente a la arteria axilar. En el grupo de múltipla estimulación, tres nervios fueron localizados eléctricamente y bloqueados con volúmenes 20 mL, 20 mL y 10 mL de la solución. El bloqueo fue considerado efectivo cuando la analgesia estaba presente en todos los nervios en la área distal al codo.
RESULTADOS: El tiempo de latencia (8,8 ± 2,3 min versus 10,2 ± 2,4 min; p-valor = 0,010) fue significativamente menor en el grupo transarterial. Bloqueos sensitivos completos en los cuatro nervios (mediano, ulnar, radial y musculocutáneo) fueron logrados en un 92,5% versus 83,3% en el grupo de múltipla estimulación y acceso transarterial, respectivamente sin diferencia significativa (p-valor = 0,68). El nervio musculocutáneo fue significativamente más fácil de bloquear con el estimulador de nervio periférico (p = 0,034).
CONCLUSIONES: La técnica de múltipla estimulación para el bloqueo axilar usando estimulador de nervios (3 inyecciones) y la técnica transarterial (2 inyecciones) producen resultados semejantes en la calidad del bloqueo. El nervio musculocutáneo es más facilmente bloqueado con el uso del estimulador del nervio periférico. La técnica de múltipla estimulación necesitó menor suplementación del bloqueo y aumentó el tiempo para el inicio de la cirugía.
Brachial plexus may be located in different ways, including paresthesia, transarterial puncture, loss of nervous sheath resistance and neurostimulation. Axillary route has been indicated for forearm, arm and hand procedures 1-3. The multiple stimulation technique during axillary block, in which each nerve is located with stimulator and injections are performed separately, provides high success rates and decreases installation time 4-7.
The axilla is a region at low risk of vital structures damage, being the axillary artery an excellent guide for axillary block. The transarterial technique is performed by injecting local anesthetics in two different areas separated by the axillary artery and has low incidence of failures1,5. Neurostimulation allows the easy identification of each of the four possible motor responses: median, ulnar and radial nerves stimulated within the nervous sheath, and musculocutaneous nerve in the upper axilla or close to coracobrachial muscle. This way, neurostimulation allows for fractional and directed local anesthetic injection and, differently from paresthesia search with a needle, has a low probability of direct nervous trauma.
Several studies on individualized brachial plexus block have shown that upper limb anesthetic extension and depth were better with location and blockade of the 4 terminal branches, notwithstanding the longer time for the procedure, which would be balanced by faster onset 4-8.
This prospective study aimed at comparing onset, duration, effectiveness and failures of brachial plexus block induced with two techniques to identify the presence of the needle in the axillary perivascular compartment: multiple stimulation and transarterial perivascular injection.
After the Publication and Disclosure Board of Directors approval, participated in this prospective study 70 patients aged 20 to 60 years, physical status ASA I and II, submitted to orthopedic forearm and hand surgeries who were randomly distributed in two groups (group MNS = 40 patients and group TA = 30 patients) according to the technique. All patients gave their informed consent after being informed in detail about the technique.
Patients were not premedicated. After venoclysis with 18G or 20G catheter, lactated Ringer's solution was slowly injected. Monitoring in the operating room consisted of continuous ECG at CM5, noninvasive blood pressure and pulse oximetry. The patients received 50 to 100 µg intravenous fentanyl associated to 10 mg metochlopramide and were only sedated with midazolam after blockade installation and beginning of surgery.
Multiple Stimulation Technique (MNS)
Patients were placed in the supine position with 90º arm abduction and forearm extended or flexed. Axillary artery was drawn in the biceps muscle sulcus, on the line connecting the umeral insertion of pectoral and greater dorsal muscles. A point was marked 3 cm below this, were infiltration was performed anterior and posterior to the artery for the entry of the needle connected to the stimulator.
After a skin wheal raised on the marked point, a B. Braun 22G 0.70 x 50 mm electrically isolated needle was connected to a peripheral nerve stimulator (Stimuplex®R, B. Braun Melsungen AG) adjusted to release a pulsatile square 1 mA current with intensity decreased to 0.5 mA and inserted in 30º angle with the skin posterior to the axillary artery. We tried to stimulate the ulnar nerve with responses of thenar and hypothenar eminence muscles and clamping of fifth finger and thumb, or the radial nerve with hand extension.
Recently prepared 20 mL of 1.6% lidocaine with 1:200,000 epinephrine were injected. Needle was then removed and reinserted anterior to the axillary artery, in an attempt to stimulate the median nerve and obtain muscle contractions of anterior forearm and hand flexion. At this point, additional 20 mL of the prepared solution were injected. After, needle was removed from the axillary bundle and musculocutaneous nerve was looked for by orienting the needle toward the coracoid apophysis at the insertion of the coracobrachial muscle. When biceps contraction and flexion of the forearm over the arm were reached, 10 mL of the prepared solution were injected.
Five randomly selected patients received 1 mL iohexol contrast (300 mg.mL-1) in each nerve before anesthetic injection for radiological evaluation.
Transarterial Technique (TA)
Patients were placed in the supine position with 90º arm abduction, flexed elbow and hand under the head. Axillary artery was palpated and marked. A 30 x 8 needle perpendicular to the artery was slowly introduced until blood reflux was obtained, when it was introduced slightly beyond until artery transfixation, confirmed by the lack of reflux. At this moment, recently prepared 30 mL of 1.6% lidocaine with 1:200000 epinephrine were slowly injected observing possible signs of vascular injection. Needle was then slowly backed, going once more through the artery lumen and being positioned anterior to it, when remaining 20 mL of the solution were injected. Needle was then removed and arm was positioned along the body with axillary compression. Five randomly selected patients received 1 mL iohexol contrast (300 mg.mL-1) in each side of the artery before anesthetic injection for radiological evaluation.
Analgesia was evaluated in both groups by skin clamping and observing patients' pain manifestations, aiming at determining the extension of sensory block of musculocutaneous nerve in forearm radial border, radial nerve in dorsal face of hand, ulnar nerve in medial hand and fifth finger, and median nerve in the palm. The following parameters were evaluated: 1) anesthetic onset: time elapsed from beginning of puncture to loss of sensitivity in the four nerves; 2) sensory block duration: time elapsed between beginning of puncture and total sensory recovery; 3) motor block duration: time elapsed between beginning of puncture and total recovery of blocked limb; 4) tourniquet perception; and 5) complications and side effects.
Blockade was considered complete if all nerves were blocked with the preconized volume. If there was need for additional injection or anesthetic complementation, blockade was considered incomplete. In this case, additional anesthetic dose would only involve the nerve of the unblocked area. Blockade failure was defined as the need for general anesthesia.
Lidocaine toxicity signs were investigated during anesthetic injection, such as hum, metal taste, heat sensation, visual disorders, dizziness or muscle contractions.
Tenoxicam (40 mg) and dipirone (30 mg.kg-1) in 100 mL lactated Ringer's were administered at surgery completion and patients were transferred to the ward. All patients were followed up for 48 hours via telephone to check for complications on blockade site. If there were any signs, patient should return to the hospital to be evaluated by the authors. All patients were asked about their satisfaction with the technique.
Results were evaluated by t test with Welch correction for levels of freedom and by Fisher's exact test to compare two percentages, considering significant p < 0.05.
Continuous variables results are shown as mean ± standard deviation. Distribution by age, weight, height and gender is shown in table I; sensory and motor block onset and duration are shown in table II. Contrasted study of each nerve with the multiple stimulation technique is shown in figure 1, figure 2 and figure 3, and with the transarterial technique in figure 4 and figure 5.
Mean onset has been significantly shorter for the TA group. There has been no arterial or venous puncture with multiple stimulation technique.
Only two patients, both from the TA group, needed general anesthesia; remaining patients were operated with blockades. Artery was transfixed and anesthetic solution was deposited posterior and anterior to it in all TA group patients. Muscle contraction in the territories innervated by median, radial or ulnar and musculocutaneous nerves was obtained in all MNS group patients and in three TA group patients. Musculocutaneous nerve was significantly easier to be blocked with the aid of nerve stimulator (p = 0.034) (Table III).
Sensory and motor block duration was significantly longer for the MNS group as compared to the TA group.
Mean lidocaine dose was 13.5 mg.kg-1 for the MNS group being 16.6 mg.kg-1 the highest dose. Mean dose was 12.5 mg.kg-1 for the TA group, with maximum dose of 15.09 mg.kg-1. There has been no clinical signs of systemic local anesthetic toxicity in both groups.
No patient has referred pain at surgery site. However, four patients have referred tourniquet pain, being two from the TA group and two from the MNS group, without significant difference.
There were no nervous injuries in the MNS group or hematoma or anesthetic vascular injection in the TA group.
When several lidocaine plus epinephrine injections are axillary applied in the brachial plexus, the use of plexus stimulator (3 injections) results in a similar success rate to the transarterial technique (2 injections), however demanding longer time for surgery beginning. Several authors consider axillary block success when analgesia is present in all surgical areas. This definition is clinically similar success rates sufficient, but implies a false success rate as compared to different blockade techniques 5. We have considered the blockade complete when all forearm nerves were blocked with the first injection. Complementation was needed in three MNS group patients in different nerves: musculocutaneous, radial and ulnar. Complementation was needed in three TA group patients and blockade failure was seen in two other patients of this same group.
The brachial plexus block requires continuous concern with the injected volume. The ratio between injected anesthetic volume and extension of analgesia was firstly described in 1961 9. Although mean axillary neurovascular compartment volume is just 42 mL 9, single 60 to 80 mL perivascular injection may result in partial block 10,11. This was initially explained by insufficient proximal anesthetic spread to nervous branches and upper plexus divisions caused by the umeral head, but was not confirmed by the randomized controlled studies 12,13.
The two axillary block techniques improve anesthetic spread in the neurovascular sheath, as compared to single injection techniques: the transarterial with two injections and the multiple nerve stimulation with three or four injections. The transarterial technique with 800 mg of 1.6% lidocaine with epinephrine has resulted in 95% to 100% success rate without any adverse effect 1.
Anatomic studies have shown that musculocutaneous and axillary nerves leave neurovascular sheath at the coracoid process, in line with the fact that 50 mL of 1.6% lidocaine have not blocked the musculocutaneous nerve in three patients of this series. There are few studies on the multiple stimulation technique with nerve stimulator. A comparison of three axillary block techniques (catheter, paresthesia and nervous stimulation) has shown higher success rate when more than one nerve is stimulated (50% for 1, 80% for 2 and 100% for 3 nervous stimulations) 14. Three stimulations technique, where only median, radial and ulnar nerves are located, has just 50% success rate 15. Our study has included isolated stimulation of musculocutaneous nerve, resulting in 92.5% success rate.
When anesthetic solution was injected close to 2 or 4 identified nerves, only 1 out of 15 patients needed complementation 15. The comparison between single injection and injection after locating 3 nerves has resulted in 43% effectiveness versus 90%, respectively 4. It has been recently shown that double stimulation results in 92% success rate while single injection results in just 52% 16. Our study comparing triple injection after locating three nerves with the neurostimulator and the transarterial technique with two injections has resulted in 92.5% success rate with triple injection as compared to 83.3% with double injection.
Success rate depends on surgery site and blockade extension 17 thus being hard to compare it among different studies. We were more concerned with analgesia spread than with motor block for surgical success. Initially we have not looked for the nerve innervating the surgical site, but rather for stimulation internal and external to the axillary artery. Median nerve is usually easier to be located with nerve stimulator and its investigation has become popular for the single injection method 17.
Incomplete musculocutaneous nerve blockade is a common axillary technique problem because it is not close to the axillary artery 18. In our study, double injection with the transarterial technique and the attempt to stimulate this nerve with the three stimulations technique has shown that this problem may be minimized with the latter approach.
Transarterial access is achieved with double injection, being one superficial and the other deep to the axillary artery. Success rate of 83.3% in our study was close to that observed in some studies (79% 19, 88.8% 20), however lower than 92% 16 and 95% 1 of other studies. Success rate of 92.5% obtained with multiple stimulations is similar to results obtained by other studies, which have varied from 88% to 93% 4,5,8.
Notwithstanding the increased risk of complications such as vasospasm, hematoma and/or pseudoaneurysm 21,22, transarterial is considered a safe technique, shown by a prospective analysis of 1000 patients 20. In our study, 48 hours follow up has not evidenced any complication. Major concern during multiple stimulation location is the possibility of puncture-induced neuropraxis. This possibility was minimized in our study by the nerve stimulator and by slow needle advance while current was decreased to 0.5 mA. In addition, analgesic complementation was never injected in the same site of the previous injection.
Maximum lidocaine plus epinephrine dose recommended for regional anesthesia in adults is 7 mg.kg-1 23. However, when lidocaine is diluted for infiltrative anesthesia, dose varies from 45 mg.kg-1 in slim patients to 50 mg.kg-1 in obese patients 24. Lidocaine dose to obtain 5 µg.mL-1 plasma concentration varies according to the administration site 25.
There have been no signs of intoxication in 346 patients receiving 900 mg lidocaine with epinephrine (30 mL of 2% and 30 mL at 1%) for transarterial brachial plexus block and success rate has been 100% 26. A different study has found mean plasma concentration of 2.9 µg.mL-1 after transarterial brachial plexus block with 900 mg lidocaine, with highest individual value of 5.6 µg.mL-1 representing a dose of 18 mg.kg-1
In this series, there has been no anxiety related to multiple injections technique because the method has been thoroughly explained, needle pathway has been anesthetized, stimulation was achieved with 0.5 to 1 mA and fentanyl has been previously administered.
In conclusion, when axillary brachial plexus block is achieved with the aid of peripheral nerve stimulator and when the musculocutaneous nerve is stimulated together with radial and/or median and/or ulnar nerve, the result is similar to double injection transarterial technique, but with more effective musculocutaneous nerve block. However, time to surgery beginning is longer with the use of neurostimulation.
Transarterial dose of 900 mg routinely used in more than 500 patients 27 is 12.5% higher than 800 mg used in this study. Highest dose has been 16.6 mg.kg-1, lower than 18 mg.kg-1 used in the above-mentioned study 27. Similarly, there have been no clinical manifestations of systemic toxicity with lidocaine plus epinephrine.
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Dr. Luiz Eduardo Imbelloni
Address: Av. Epitácio Pessoa, 2356/203 Lagoa
ZIP: 22471-000 City: Rio de Janeiro, Brazil
Submitted for publication June 23, 2004
Accepted for publication October 25, 2004
* Received from Instituto de Anestesia Regional, São José do Rio Preto, SP