Department of Anaesthetics, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK*Corresponding author
Accepted for publication: July 19, 2000
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Br J Anaesth 2001; 86: 803
Keywords: brachial plexus, axillary approach; technique, nerve stimulation
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The purpose of this study was to examine the extent of local anaesthetic blockade within all the nerves of the plexus using two different nerve stimulator techniques by the axillary approach.
![]() |
Patients and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
All patients were visited before surgery and were given a full explanation; informed consent was obtained. On a patients arrival in the anaesthetic room, a 20G intravenous cannula was inserted in the hand not being operated upon and full non-invasive monitoring commenced (NIBP, ECG, SpO2). A small dose of midazolam (12 mg) was administered and oxygen 2 litres min1 was delivered through a nasal cannula. With the patient lying supine, with their head placed on a pillow, the arm was abducted to 90° and the axillary artery palpated. The skin was cleaned and then anaesthetized with 12 ml of plain lidocaine 10 mg ml1. Neural blockade was facilitated using a 22G insulated short-bevelled needle and peripheral nerve stimulator (Stimuplex; B. Braun Medical). All patients received a total of 30 ml of lidocaine 15 mg ml1 with epinephrine 5 µg ml1.
With both techniques, the musculocutaneous nerve was first located by eliciting maximal biceps contraction with a current of 0.5 mA and 5 ml of the local anaesthetic solution was injected. Then, from the same injection site in the distal axilla, 1520 mm distal to the pectoralis major tendon, further injections were carried as follows (Figure 1). In group 1 (single-injection technique), the median nerve was located by eliciting the maximal flexor response in the fingers of the hand with a current of 0.5 mA and a total of 25 ml of lidocaine 15 mg ml1 with epinephrine was then injected. In group 2 (double-injection technique), the median nerve was located as above and 15 ml lidocaine 15 mg ml1 with epinephrine was injected. The radial nerve was then located by eliciting the maximal extensor response in the fingers and wrist with a current of 0.5 mA. A further 10 ml of lidocaine 15 mg ml1 with epinephrine was then injected.
|
Duration of surgery, tourniquet discomfort or any additional problems, such as vascular puncture, were noted. All brachial plexus blocks were carried out by one operator (D.C.) and assessed by one blinded assessor (M.T.). Assuming a success rate of 60% with one technique against 90% for the second, 29 patients in each group would be required to show a significant difference at 80% power. Statistical comparisons were made using the Fischer exact test.
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The trans-arterial approach appears to be both unnecessary and undesirable. Axillary block complicated by haematoma and nerve injury4 or by false aneurysm formation5 has been reported using this method and, as our study demonstrates; other methods avoiding this risk can be very effective. Another issue is whether large-volume single injections are as reliable as multiple-injection techniques. The failure rate remains significant for the single-shot, high volume techniques often described in textbooks,6 even when specific blocking of the musculocutaneous nerve is included, and this is reinforced by the findings in our single-injection patients, even when performed with a peripheral nerve stimulator.
CT studies by Thompson and Rorie7 attributed this failure to anatomical variability in the septae within the neurovascular sheath creating a multi-compartmental structure which limits circumferential spread; they advocated the use of a multiple-injection approach. Vester-Anderson and colleagues8 showed, using a catheter technique, that even volumes of 80 ml of local anaesthetic cannot reliably block the musculocutaneous nerve, which is essential for complete sensory analgesia of the limb and to prevent tourniquet discomfort and unwanted arm movement during surgery.
Some investigators have shown a favourable success rate with single-shot techniques with an end-point of readiness for surgery, but in these studies there may have been a predominance of palmar surgery. Lavoie and colleagues9 compared single and multiple injections using a nerve stimulator and demonstrated the benefit of considering the musculocutaneous nerve as a separate, preliminary part of any axillary brachial plexus block. However, despite correctly determining the sensory block of each nerve 30 min after injection, they failed to detail those findings, confining themselves to recording adequacy for surgery as the study end point, rather than completeness of brachial plexus anaesthesia. Only 48% of the surgery in this study was restricted to the palmar surfaces of the hand, leaving radial nerve blockade desirable in 34% and essential in 18%.
The use of the peripheral nerve stimulator for brachial plexus block can improve success rates for both the regular practitioner of regional anaesthesia10 and the occasional user,11 combined with a reduced theoretical risk of nerve damage.12 We designed our study to start with the identification and blocking of the musculocutaneous nerve in both groups, as that nerve lies within the body of coracobrachialis muscle at the distal axillary level and is outwith the connective tissue sheath. Thereafter, we compared a single intra-sheath injection (by identifying the median nerve), with a more specific localization of the median and radial nerves. The order in which each nerve is localized and blocked is important to minimize the theoretical risk of nerve injury. In this we disagree with Gaertner and colleagues,13 who suggested a sequence of nerve blockade as follows: median, ulnar, radial, musculocutaneous and medial (brachial and antebrachial) cutaneous nerves. This implies that whilst seeking the musculocutaneous nerve, the area of the median nerve may be recrossed some time after it has had local anaesthetic applied and risks transfixion of that nerve. In our study, the musculocutaneous nerve, outside the sheath, above and posterior to the artery, was blocked first. The needle was then withdrawn to and directed towards the artery to find the median nerve, and finally the needle was directed inferior to the artery to define the radial nerve (Figure 1). Following this sequence removes the risk of transfixing a nerve already partially blocked by a previous injection. Our experience with this double-injection technique is that there is little interference with localization of each nerve, even with the use of the more rapid onset local anaesthetic agents such as lidocaine.
This study revealed that the double-injection technique can have significant advantages over the single-injection technique in both speed of onset and pattern of block. Ninety per cent of blocks in the double-injection group and 23% in the single-injection group were deemed complete at 20 min. The pattern of sensory block showed the radial nerve to be incompletely blocked in 40% of patients having the single-injection technique, even after 30 min, compared with none in the double-injection group. It is also interesting to note that the ulnar nerve was blocked in 100% of the double-injection group despite no attempt to localize it. Motor blockade testing also showed significant advantage in the double-injection technique, 83% having complete motor blockade compared with 30% in the single-injection group. The double-injection technique in which the radial nerve is specifically identified has a faster onset and more complete sensory block.
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
2 Vester-Anderson T, Christiansen C, Sørensen M, Eriksen C. Perivascular axillary block. I: Blockade following 40 ml 1% mepivacaine with adrenaline. Acta Anaesthesiol Scand 1982; 26: 51923[ISI][Medline]
3 Brockway MS, Wildsmith JAW. Axillary brachial plexus block: method of choice? Br J Anaesth 1990; 64: 22431[ISI][Medline]
4 Ben-David B, Stahl S. Axillary block complicated by haematoma and radial nerve injury. Reg Anesth Pain Med 1999; 24: 2646[ISI]
5 Zipkin M, Backus WW, Scott B, Poppers PJ. False aneurysm of the axillary artery following brachial plexus block. J Clin Anesth 1991; 3: 1435[Medline]
6 Hughes TJ, Desgrand DA. Upper limb blocks. In: Wildsmith JAW, Armitage EN, eds. Principles and Practice of Regional Anaesthesia. Edinburgh: Churchill Livingstone, 1993; 16988
7 Thompson GE, Rorie DH. Functional anatomy of the brachial plexus sheath. Anaesthesiology 1983; 59: 11722[ISI][Medline]
8 Vester-Anderson T, Christiansen C, Sørensen M, Kaalund-Jorgensen HO, Saugbjerg P, Schultz-Moller K. Perivascular axillary block. II: Influence of injected volume of local anaesthetic on neural blockade. Acta Anaesthesiol Scand 1983; 27: 958[Medline]
9 Lavoie J, Martin R, Tetrault JP, Cote DJ, Colas MJ. Axillary plexus block using a peripheral nerve stimulator: single or multiple injections. Can J Anaesth 1992; 39: 5836[Abstract]
10 Tuominen MK, Pitkanen MT, Numminen MK, Rosenberg PH. Quality of axillary brachial plexus block. Comparison of success rate using perivascular and nerve stimulator techniques. Anaesthesia 1987; 42: 2022[ISI][Medline]
11 Eifert B, Hahnel J, Kustermann J. Axillary blockade of the brachial plexus. A prospective study of blockade using electrical nerve stimulation. Anaesthesist 1994; 43: 78085[ISI][Medline]
12 Salander D. Axillary plexus block: paresthetic or perivascular. Anesthesiology 1987; 66: 610.
13 Gaertner E, Kern O, Mahoudeau G, Freys G, Golfetto T, Calon B. Block of the brachial plexus branches by the humeral route. A prospective study in 503 ambulatory patients. Proposal of a nerve-blocking sequence. Acta Anaesthesiol Scand 1999; 43: 60913[ISI][Medline]