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The different approaches to the brachial plexus have clinical implications and all these approaches have clinical limitations. Combining different approaches helps to reduce these limitations. Can a combination of two different methods of brachial plexus block give a better anaesthetic outcome?
To compare the effect of combining axillary plexus block with interscalene as opposed to axillary plexus block with supraclavicular blocks.
Prospective observational study.
University of Benin Teaching Hospital, Benin city. Edo state. Nigeria.
A total of 182 patients who met the inclusion criteria were observed and were divided into 5 groups. Group I (interscalene) n=33, Group S (supraclavicular) n=39, Group A (axillary) n=35. Group IA (interscalene and axillary) n=34, Group SA (supraclavicular and axillary) n=41. The brachial plexus was identified using a nerve stimulator and 40ml of 2% lidocaine with 1:200,000 adrenaline and 0.5% bupivacaine, were deposited in each single approach or divided into two equal portions in the combined approach .The time of onset, duration of analgesia, level of satisfaction and complications were compared.
There were no differences with regard to the time of onset (p= 0.74), duration of analgesia (p= 0.82), patients’ satisfaction between the groups. Horner’s syndrome was a commonest complication in the interscalene group consisting (15.15%) cases.
There was no difference in terms of time of onset, duration of sensory block and level of patients’ satisfaction between the combined brachial plexus approaches and single approach.
There are multiple sites at which the brachial plexus can be blocked in selecting regional anaesthesia for upper extremity surgical patients; these include the interscalene, supraclavicular, infraclavicular and axillary. Selection of the preferred approach is determined by the innervations of the surgical site, risk of regional anaesthesia-related complications, as well as the preference and experience of the anaesthesiologist1. Success of these anaesthetic blocks requires the identification and block of the appropriate roots, trunks, cords and peripheral nerves for the proposed surgery.
Good understanding of the brachial plexus anatomy is necessary for the effective application of these blocks and the different clinical implications between the blocks. The interscalene brachial plexus block anaesthetizes the shoulder, but not always the ulnar parts of the lower forearm and hand2, because it rarely reaches the caudal segments of the brachial plexus. Distal to this, anaesthesia of the arm excluding the shoulder is achieved using supraclavicular brachial plexus blocks; this approach also misses the lower trunk in 5% of blocks3. The axillary plexus blocks provides good surgical anaesthesia for the elbow, forearm and hand and also provides sensory anaesthesia of the inner upper arm, including the medial cutaneous nerve of the arm and intercostobrachial areas4; however there is still an anatomical gap present in the region of the musculocutaneous nerves which is given off before the neurovascular bundle enters the axilla. The axillary approach to the brachial plexus is considered the safest of the four approaches because of reduced risk to surrounding structures such as the risk of phrenic nerve blockade and/or pneumothorax, but the general risks of accidental intravascular and intraneural injection still exist.
Since the different approaches to the brachial plexus have limitations, combination of these approaches may be necessary in other to improve their anaesthetic outcome. These combinations will also enable surgical operations to be carried out in any part of the upper limb similar to what is obtainable with the use of central neural blockade for lower limb procedures.
Due to the limitation of individual brachial plexus block and extent of surgery, a combination of more than one brachial plexus block is sometimes carried out in our centre. We therefore want to find out if combination of two different approaches of brachial plexus block gives a better anaesthetic outcome. Thus, this study presents our observation on the effect of combining axillary plexus block with either interscalene or supraclavicular blocks because axillary block is a more distal approach located below the clavicle unlike the interscalene and supraclavicular that are located in the interscalene groove which are both above the clavicle. The combination of axillary with either interscalene or supraclavicular is regarded to give a wider area of block unlike when interscalene is combined with a supraclavicular approach.
This is an observational study carried out at the University of Benin Teaching Hospital, Benin City, Nigeria. After obtaining approval from the Institutional Research and Ethics Committee, written informed consent from the patients was obtained. Patients scheduled for upper limb surgery between January 2013 and January 2016 were recruited consecutively for this study if they met the inclusion criteria. The criteria were patients aged 18 years and above and classified as American Society of Anesthesiologists physical status 1 or 2. A total of one hundred and eighty two (182) patients met these criteria during this period. The exclusion criteria included failed blocks, previous clavicle fractures, patient’s refusal, sensitivity to the local anaesthetics, patients on anticoagulation drugs and the presence of skin infection at needle insertion points. Others included Body Mass Index (BMI) exceeding 40kg/m2, pre-existing neurological deficits, severe obstructive pulmonary disease, and existence of implanted electrical devices, such as pacemakers. The 182 patients were observed and divided into 5 groups (brachial plexus approaches) used for upper limb surgeries, either singly or in combination as they present themselves for surgery. Group I (interscalene block only) had 33 patients, Group S (supraclavicular block only) 39 patients, Group A (axillary block only) 35 patients, Group IA (interscalene combined with axillary block) 34 patients and Group SA (supraclavicular combined with axillary block) 41 patients.
All blocks were performed by the same anaesthesiologist after a detailed preoperative assessment. The functionality and availability of the anaesthetic equipment and drugs (resuscitation and routine) were ascertained. Standard monitoring (non-invasive blood pressure, pulse oximetry and ECG) was commenced on arrival to the preoperative area; baseline values were obtained and recorded. Intravenous line established using 18 G cannula, which was connected to intravenous fluid. A 22-gauge, 50-mm insulated stimulation short bevel needle (Stimuplex® A, B/Braun Medical, Germany) connected to a nerve stimulator (Stimuplex®-DIG, B/Braun, Germany) was used for all blocks. The initial nerve stimulator settings was 1.0 mA with impulse duration of 0.1 ms, after getting the desired motor response, the current was tailed down to 0.4 mA. Desired motor response in the interscalene group was either a triceps, biceps or pectoralis contraction. Deltoid contraction was excluded because of the difficulty of differentiating it from trapezius stimulation. Finger flexion was taken as the correct location for the supraclavicular block. Multiple stimulations of the nerves in the axillary approach (radial, median, ulna and musculocutaneous) were desirable. Radial nerve was demonstrated by extension of the forearm or wrist and finger, median nerve by flexion of the wrist/ finger with pronation, ulna nerve by flexion of the fourth and fifth finger with adduction of the wrist or opposition of the first finger while musculocutaneous nerve by elbow flexion but in some cases it was not possible to locate all the individual nerves, this was probably due to the local anaesthetic effect of previously deposited local anaesthesia.
Patients in groups I (Interscalene), S (Supraclavicular) and A (Axillary) received 40mls of a combination of 20mls of 0.5% plain bupivacaine (100mg) and 20mls of 2% lidocaine with adrenaline (1:200,000), while those in the combined groups IA(Interscalene and Axillary) and SA( Supraclavicular and Axillary) had 20mls of a mixture of 10mls of 0.5% bupivacaine (50mg) and 10mls of 2% lidocaine with adrenaline(1:200,000) for each approach in the combination group, making a total of 40mls, with intermittent aspiration. After establishing the brachial plexus block, patient was sedated with 10mg of IV diazepam and monitoring of the patient’s vital signs continued till the end of surgery.
An assessor different from the anaesthesiologist who performed the block took note of the block characteristics, which was the onset time, duration of sensory block and intraoperative satisfaction to the surgical stimulus. Complications following these blocks such as blood vessel puncture, intravascular injection, overdose, dyspnoea, Horner's syndrome , (ptosis, myosis and enopthalmia) and pneumothorax were noted. The onset time of the sensory block was defined as the time between the last injection and the total abolition of the pinprick response (painful stimulus). The duration of sensory block is the time interval between the administration of the local anaesthetic and the first postoperative pain sensation experienced by the patient. Patient’s satisfaction was either satisfactory or unsatisfactory depending on patient’s intraoperative account of any painful stimulus in the operative site. The patients’ demographics, clinical features and outcome measures were documented on a data sheet. The data collected were analyzed with statistical Package for Social Sciences (SPSS) Version 16.T-test was used for data represented as the mean ±SD and ANOVA used for comparing the 5 different groups. The null hypothesis was rejected at P< 0.05 and rational deductions derived.
Out of the 182 patients in this study, there were 33(18.1%) in the interscalene group, 39(21.4%) in the supraclavicular group, 35(19.2%) in the axillary group, 34(18.7%) in the combined interscalene and axillary group, while 41(22.5%) were in the supraclavicular and axillary group.
There was no difference in the patient’s demographics and duration of surgery between the groups (Table 1).
Interscalene block type had the fastest onset time (16.00±8.08 min) and longest duration of analgesia was 440.0±116.86min, while axillary block had the slowest onset time 21.25±2.50min. Interscalene and axillary group (IA) had the shortest duration of analgesia (336.75±120min). Statistically there was no difference between the groups (Table 2).
All patients were satisfied intraoperatively irrespective of the type of approach used except one patient in the interscalene group and another 2 patients in the supraclavicular and axillary combination group (Table 3).
The commonest complication was Horner’s syndrome which occurred in (15.15%) patients in the interscalene group and (2.56%) patients in the supraclavicular group. One patient (3.03%) had hoarseness of voice in the interscalene group while another had seizure in the supraclavicular group. Two patients (5.71%) had blood vessel puncture in the axillary group A and one patient (2.27%) in the combined axillary and supraclavicular group. No incidence of pneumothorax was recorded in all the groups (Table 4).
This study showed that there was no difference in the onset time and duration of sensory block when axillary plexus block was either combined with interscalene or supraclavicular block. This finding is in contradistinction to the works of Jamal et al5 which is one of the few studies that evaluated the effect of combining different approaches to the brachial plexus (infraclavicular and axillary block anaesthesia) which demonstrated an extensive sensory and motor block in comparison to performing same block individually. The outcome of their study could be explained by the fact that distal pressure was applied during injection of the local anaesthetic when axillary block was performed thus encouraging cephalad spread and also by the fact that infraclavicular and axillary brachial plexus blockade both blocks the brachial plexus at the level of the cords6. However, combining infraclavicular and axillary plexus anaesthesia with application of distal pressure during axillary block could have resulted in ‘double dose’ (increased concentration) of local anaesthetic agent at the level of the cords and consequently better outcome. However, in this index study interscalene and axillary blocks the roots and the cords of the brachial plexus while a combination of supraclavicular and axillary blocks the trunks and cords of the brachial plexus which are some distance apart and cephalad spread was not enhanced by distal pressure application.
Although there was no difference in the outcomes measured (onset time of sensory block, duration of analgesia and the level of patient’s satisfaction) in this study between the different study groups. Nonetheless, it has some clinical relevance. Firstly, the surgeries that would have been performed as a two stage procedure because of block limitation associated with a single technique can be effectively performed by combining two approaches to the brachial plexus. General anaesthesia which is an alternative choice may be avoided because of its associated disadvantages (difficult intubation, pressor response to laryngoscopy, delayed recovery, post operative cognitive disorder etc) compared to a plexus block. Secondly, block combination eliminates the need for multiple stimulation techniques during the axillary approach. For instance, the musculocutaneous nerve that is outside the neurovascular bundle is not sought after when combination of approaches is used because it would have been anaesthetised by either the interscalene or supraclavicular technique. Multiple stimulations may sometimes become difficult because the first injection of the LA may partially anaesthetise other nerves in the vicinity of the axilla. So, combining brachial plexus blocks above the clavicle (interscalene or supraclavicular) can be done with the use of only single stimulation technique of the axillary plexus. Moreover triple injection axillary block is said to be probably the fastest and the most efficient technique for axillary plexus blockade 7,8.
There was no difference in the onset time of sensory block between the five study groups. This implies that when brachial plexus blocks are carried out singly or in combination, irrespective of the time it took to establish the block. It does not have any effect on their onset times and therefore no effect on commencement of surgery. The reason for the similar onset time could be due to the rapid onset time of 2% lidocaine. Clinically, interscalene block had the fastest onset time and longest duration of sensory block compared to others, though not statistically significant, as the nerve roots have less fibrous covering in this region, allowing for enhanced local anaesthetic permeation of this groups of nerves9.
The use of nerve stimulation is a better method of locating peripheral nerves compared to that of the paraesthesia technique, in which there is a deliberate attempt to prick the nerve in order to locate it, unlike the use of nerve stimulation which uses current as an indirect method of nerve location. Contemporary method of locating nerves is by the use of a dual mode, which is a combination of ultrasound and nerve stimulation to locate nerves.
The use of mixtures of local anaesthetic solution for regional anaesthesia has become relatively popular in recent years. The basis of this practice is to compensate for the short duration of action of certain rapidly acting agents, such as lidocaine which was used in this study and to reduce the toxicity potential of the longer acting agents such as tetracaine and bupivacaine. The use of lidocaine with adrenaline improved the onset time for the different approaches (12-21minutes) as compared to the use of agents with long latency period like bupivacaine alone with slow onset times in the range of 30 minutes10. Addition of adrenaline1:200,000 to short acting LA like lidocaine causes vasoconstriction of blood vessels which slows down LA reabsorption from the blood stream, this phenomenon prolongs the duration of LA.
Shorter duration of sensory block was observed in all the different groups in this study which was between 337min and 440min compared to 763min reported by Chun et al 1. This difference may be as a result of high doses of longer acting LA (30ml ropivacaine) used in their study, unlike the 20ml of bupivacaine used in our combination. Furthermore, the use 20ml bupivacaine in the Uikram et al11 study that compared axillary to infraclavicular approach, had similar duration of sensory block (336min).This outcome supports the known fact that the higher the concentration of local anaesthetic agent used, the longer the duration of action. When using admixture of short and long local anaesthetics, toxicity might be additive and it can result in shortened post-operative analgesic period10 due to the reduced amount of the long acting agent used in the mixture. This could be a disadvantage in acute pain management.
The higher incidence of Horner’s syndrome in the interscalene group (I) 15.15% compared to that observed in the supraclavicular group(S) with 2.56% and the interscalene axillary combination group (IA) with 0% could be due to the fact that a higher volume (40ml) of LA was used in the single interscalene group (I) compared to 20ml used in the interscalene and axillary combination group. This resulted in an increased diffusion rate to the sympathetic cervical ganglion chain including the stellate ganglion. The difference in the anatomical location of the insertion site may have accounted for the disparity observed in the incidence of Horner syndrome between interscalene and supraclavicular despite using same volume of 40mls of LA. The site of needle insertion for the interscalene is at the apex of the interscalene groove unlike the supraclavicular which is performed at the base. Occurrence of ipsilateral ptosis is dependent on the site of injection, (less common with the low interscalene approach) and total volume of local anaesthetic injected2. Horner syndrome is benign in nature, patient should be reassured that resolution is spontaneous in about 1-2hours
Seizure that occurred in the supraclavicular group is a known complication of intra-arterial deposition, it occurred at the end of performing the block. This was aborted with i/v 10mg diazepam. This complication occurred despite the precautionary measure of test aspiration (negative aspiration of blood) taken. It is said that aspirating the needle or catheter before each injection may fail to identify intravascular placement in up to 2% of patients12. It was later found out that the patient that developed seizure is a known epileptic. Could this seizure have resulted from intravascular deposition of LA or due to patient’s premorbid state? Assay of serum level of LA would have provided the answer but this was not available. Patients are not routinely premedicated with benzodiazepines for managing anxiolysis because they may displace bupivacaine from protein binding sites, this sharp increase in the free plasma fraction of bupivacaine may enhance the potential for CNS toxicity13.
Only one patient experienced blockade of the recurrent laryngeal nerve while communicating with the patient, hoarseness of the voice gradually increased to a stage of whispering. There was no associated breathing difficulty and all the vital signs and oxygen saturation were within normal limits, we decided to go ahead with the surgery, which was uneventful. Recurrent laryngeal nerve palsy is an occasional complication of interscalene block, it is said to occur more frequently on the right side. This effect receded as the block wears off by the 6th hour.
The study had some limitations, first it was a prospective observational cohort study there were no randomizations of the groups. Secondly, the time it took to establish the blocks (block performance time) were not assessed, this is an important factor when comparing single versus combined approaches to the brachial plexus.
The outcome of combining two different brachial plexus approaches in terms of its onset time, duration of sensory block and patients satisfaction though not different from single approach has some clinically relevance. In that, surgeries requiring two staged procedure due to block limitation associated with the use of a single technique can be effectively performed by combining approaches.
Competing Interests: The authors have declared that no competing interests exist.
Grant support: None