Ultrasonography may offer significant advantages in regional anaesthesia of the upper and lower limbs. It is not known if the same advantages demonstrated in adults also apply to children. We therefore performed a prospective, randomised study comparing ultrasound visualisation to conventional nerve stimulation for infraclavicular brachial plexus anasesthesia in children. Forty children scheduled for arm and forearm surgery underwent infraclavicular brachial plexus blocks with ropivacaine 0.5 ml.kg)1 guided by either nerve stimulation or ultrasound visualisation.
Evaluated parameters included sensory block quality, sensory block distribution and motor block. All surgical procedures were performed under brachial plexus anaesthesia alone. Direct ultrasound visualisation was successful in all cases and was associated with significant improvements when compared with the use of nerve stimulation: lower visual analogue scores during puncture (p = 0.03), shorter mean (median) sensory onset times (9 (5–15) min vs. 15 (5–25) min, p < 0.001), longer sensory block durations (384 (280–480) min vs. 310 (210–420) min, p < 0.001), and better sensory and motor block scores 10 min after block insertion. Ultrasound visualisation offers faster sensory and motor responses and a longer duration of sensory blockade than nerve stimulation in children undergoing infraclavicular brachial plexus blocks. In addition, the pain associated with nerve stimulation due to muscle contractions at the time of insertion is eliminated.
Ultrasonography has become an important tool for identifying nerves in the practice of regional anaesthesia [1-4]. Our study group has demonstrated that approaches to both brachial and lumbar plexus anaesthesia are facilitated with the use of ultrasound [5-9]. The benefits of directly visualising the target nerves and monitoring the distribution of the local anaesthetic are potentially significant. In addition, ultrasound monitoring allows repositioning of the needle in the event of maldistribution of the local anaesthetic and helps to avoid complications such as inadvertent intravascular or intrafascicular injection. The published data also suggest that ultrasound may improve the quality of nerve blockade . So far, all published reports on ultrasound guidance in regional anaesthesia have addressed its use in adults, although regional anaesthesia is being increasingly used in children, for whom most blocks are performed under sedation or anaesthesia. Thus, the use of ultrasound has important potential for paediatric anaesthesia.
In recent years, brachial plexus anaesthesia has become a valuable option in the management of upper limb surgery in children. This is particularly true in paediatric trauma surgery, where general anaesthesia may prove dangerous because of the high risk of gastric aspiration [10, 11]. The axillary route, due to its safety and simplicity, has become the most commonly used approach for brachial plexus blockade in children . However, a major drawback of this technique is that it not uncommonly produces poor analgesia [13, 14]. Furthermore, the axillary approach is unsuited to children who are unable to abduct their arm. It was for these reasons that our group investigated an infraclavicular approach to the brachial plexus with a lateral puncture site. Our results demonstrated that this technique offers better sensory and motor blockade than the axillary approach . The infraclavicular approach to the brachial plexus uses the coracoid process as a landmark and a nerve stimulator to locate the brachial plexus. However, this type of nerve stimulation provokes muscle contraction and therefore generates pain in the presence of fractures. In addition, multiple punctures are often necessary in order to optimise the position of the stimulation needle, thus increasing the overall burden of pain.
A potential solution to this dilemma is to combine the superior sensory and motor blockade offered by infraclavicular brachial plexus anaesthesia with the comfort of directly visualising the plexus by ultrasonography, thereby obviating the need for nerve stimulation. We therefore designed a prospective, randomised, blinded study in children undergoing surgical treatment of hand and forearm injuries to compare the quality and distribution of lateral infraclavicular anaesthesia guided by ultrasound visualisation and the same block produced with the guidance of a nerve stimulator.
After Local Research Ethics Committee approval and written, informed parental consent, 40 children (ASA physical status I or II, aged 1–10 years) scheduled for forearm and hand surgery for traumatic conditions were randomised to one of two study groups by sealed envelope. The subjects underwent lateral infraclavicular brachial plexus anaesthesia using either ultrasound visualisation or nerve stimulation to identify the plexus. Exclusion criteria included: coagulopathy; cardiac, hepatic, renal or neurological disease; malformations of the upper limb; surgical contra‐indications to regional anaesthesia.
All children were premedicated with rectal midazolam 1 ml.kg−1 up to a maximum dose of 15 mg. After venous access was obtained, intravenous midazolam 0.05–0.1 ml.kg−1 was given, and, if necessary, propofol was given to produce sedation during brachial plexus anaesthesia. Spontaneous ventilation was maintained in all cases. Routine monitoring comprised ECG, non‐invasive blood pressure and pulse oximetry. The surgical procedures were started 30 min after induction of brachial plexus anaesthesia. The children’s lungs were auscultated before and after brachial plexus anaesthesia to detect clinical signs of a pneumothorax. If there was clinical suspicion of a pneumothorax, a chest X‐ray was taken. After the surgical procedure, the puncture site was checked for haematoma or swelling caused by inadvertent puncture of major blood vessels. The puncture site was checked for potential infections on the first postoperative day. Sensory and motor blockades were assessed by an anaesthetist who was not involved in the study.
The brachial plexus blocks in the nerve stimulation group were performed as described by Fleischmann et al. . With the patient in the supine position, the upper arm adducted to the trunk and the elbow flexed to 90° with the forearm placed on the abdomen, the coracoid process was identified. After aseptic preparation and infiltration of the puncture site with lidocaine 1% 1 ml, an insulated 24G 40 mm block needle with a ‘facet’ tip (Pajunk, Geisingen, Germany) was connected to the nerve stimulator (MultiStim Vario™, Pajunk, Geisingen, Germany) and was inserted 0.5 cm caudally to the coracoid process and was passed in a posterior direction. Once a distal motor response was obtained (current threshold > 0.3 mA, stimulation frequency = 2 Hz, pulse duration = 0.3 ms), the needle was aspirated to exclude vascular puncture and then ropivacaine 0.5% 0.5 ml.kg−1was injected.
The same position of the upper limb as described above was used for the ultrasound‐guided brachial plexus blocks. Firstly, the infraclavicular part of the brachial plexus was visualised using an HDI 3500 ultrasound device (ATL Ultrasound, Bothell, WA, USA) with a 5–12 MHz linear sector probe held in a transverse position (Fig. 1). After the brachial plexus had been identified (Fig. 2), the ultrasound probe was aseptically prepared by covering the surface with non‐sterile ultrasound jelly, slipping it into a sterile glove, and covering the glove with sterile ultrasound jelly. The puncture site was then disinfected and the brachial plexus was once again visualised in the above manner. After injection of lidocaine 1% 1 ml, the same make of needleFigure 1: Positions of the ultrasound probe and block needle during infraclavicular brachial plexus bloc used for the nerve stimulator guided brachial plexus block was inserted 1 cm caudal to the ultrasound probe with a slight cranial angulation such that the needle crossed the ultrasound beam. Under direct ultrasonographic control, the needle was advanced to the lateral border of the plexus. Ropivacaine 0.5% 0.5 ml.kg−1 was then injected and its distribution around the brachial plexus was confirmed (Fig. 3).
A visual analogue score (VAS) consisting of a ‘smiley scale’ ranging from 1 (no pain) to 5 (maximum pain) was recorded every 5 min to evaluate pain during and after the brachial plexus block in all children aged ≥ 3 years (n = 36). Sensory onset time was defined as the time from injection of the local anaesthetic to the first recording of VAS = 1. Sensory block quality was evaluated by comparing the VAS score 30 min after local anaesthetic injection to the baseline score before injection. After surgery, VAS scores were recorded every 15 min. Once postoperative VAS scores ≥ 3 were reached, or if the children showed other signs of pain, they were given rectal paracetamol 30 mg.kg−1. Sensory block durationwas defined as the time between the brachial plexus block and the first dose of paracetamol. Thirty minutes after injection, all children were evaluated according to Vester‐Andersen’s criteria , which require at least two of the four nerves (ulnar, radial, median and musculocutaneous) to be blocked effectively. Children who failed to meet these criteria or who showed pain responses to surgical stimulation were given general anaesthesia and were excluded from further statistical analysis.
A simplified pinprick test was used to evaluate the distribution of sensory blockade in the areas supplied by the axillary, median, radial, ulnar, musculocutaneous, medial brachial cutaneous and medial antebrachial cutaneous nerves 10 min and 30 min after brachial plexus block. The following scale was used: 1 = no pain in the area supplied by the individual nerves; 2 = contralateral discrepancy in the area supplied by the individual nerves; 3 = pain in the area supplied by the individual nerves. The motor block quality of axillary, median, radial, ulnar and musculocutaneous nerves was evaluated 10 min and 30 min after puncture. The following scale was used: 1 = motor paralysis; 2 = decreased motor function; 3 = normal motor function.
All values are expressed as median [range]. Differences in duration of surgery, sensory onset time, and sensory block duration were evaluated using an independent t‐test. Intergroup differences in VAS, sensory block quality and motor block quality were evaluated using the Mann–Whitney U‐test. Intergroup differences in Vester‐Andersen’s criteria were evaluated using the Chi‐squared test (Stat View 4.51, Abacus Concepts, Berkley, CA). Statistical significance was set at p < 0.05.
Demographic and operation data are shown in Table 1. All brachial plexus blocks were successfully performed with the sedation regimen described above. All children were alert and fully able to communicate for evaluation purposes. In the ultrasound group, the children were given a median [range] dose of midazolam of 1.3 [0.7–2.1] mg.kg−1, and 11/20 children received a median [range] dose of propofol of 10.4 [0–14] mg. In the nerve stimulator group, the children were given midazolam 1.3 [0.8–2.1] mg.kg−1, and 13/20 children were given propofol 11.3 [0–14] mg. The relatively low doses of propofol result from the fact that only the younger children needed propofol. Ultrasound visualisation of the infraclavicular portion of the brachial plexus was successful in all subjects. All anaesthetic procedures were uneventful, with no clinical signs of pneumothorax, inadvertent puncture of major vessels, infection or haematoma.
Use of the VAS to evaluate sensory onset time, and sensory block quality and duration, was confined to 36 children aged ≥ 3 years (ultrasound group: n = 17, nerve stimulator group: n = 19). All children met Vester‐Andersen’s criteria 30 min after brachial plexus block. All brachial plexus blocks were successful; no subjects were given general anaesthesia. No further sedation was required during surgery.
The median [range] sensory onset time was 9 [5–15] min in the ultrasound group and 15 [5–25] min in the nerve stimulator group (p < 0.001). The median [range] sensory block duration was 384 [280–480] min in the ultrasound group and 310 [210–420] min in the nerve stimulator group (p < 0.001). The VAS scores during performance of the blocks were significantly lower in the ultrasound group than in the nerve stimulator group (3.00 [1–4] vs. 3.75 [3–5], p = 0.03). No differences in the VAS scores were observed before the block, 30 min after the block or during surgery. Ten minutes after the block, sensory blockade was more effective in the ultrasound group in five out of the seven nerves assessed (median [range] values for ultrasound group vs. nerve stimulator group: musculocutaneous nerve = 1.15 [1–2] vs. 1.8 [1–3], p < 0.01; medial brachial cutaneous nerve = 1.3 [1–2] vs. 1.7 [1–2], p = 0.03; medial antebrachial cutaneous nerve = 1.3 [1–2] vs. 1.7 [1–2], p = 0.03; median nerve = 1.15 [1–2] vs. 1.55[1–2], p = 0.03; ulnar nerve = 1.3 [1–2] vs. 1.7 [1–2], p = 0.03). The difference in the remaining two nerves (axillary and radial nerves) almost reached statistical significance (p = 0.1 and p = 0.14, respectively). Motor blockade 10 min after the puncture was more effective in three out of the five nerves assessed (median [range] values for ultrasound group vs. nerve stimulator group: axillary nerve = 1.9 [1–3] vs. 2.25 [1–3], p = 0.03; musculocutaneous nerve = 1.2 [1–2] vs. 1.85 [1–2], p < 0.001; ulnar nerve = 1.3 [1–2] vs. 1.7 [1–2], p = 0.03). The differences did not reach statistical significance for the radial and median nerves. After 30 min, the quality of motor block and quality of sensory block were similar in the two groups.
This is the first study describing the use of ultrasound guidance in paediatric regional anaesthesia. Its results demonstrate that ultrasound visualisation of the lateral portion of the infraclavicular brachial plexus is highly effective in children. These observations are in keeping with our previous studies of regional anaesthesia in the upper  and lower  limbs of adults, and result from the fact that ultrasound visualisation optimises the proximity of the placement of the local anaesthetic to the targeted nerve structures.
The acute pain caused by brachial plexus puncture under nerve stimulator guidance due to muscle contractions is totally eliminated by ultrasound guidance, thus decreasing the pain felt at the time of block performance to a more comfortable level. Although we have not formally investigated patient and parental satisfaction, our experience with > 300 ultrasound‐guided brachial plexus blocks in children leaves us in no doubt that the technique described will make all parties involved feel better about the entire procedure. Compared to nerve stimulator guidance, ultrasound visualisation offers shorter sensory onset times, thus decreasing the period in which the children feel pain. Furthermore, more nerves are blocked more effectively with ultrasound guidance than with the nerve stimulator technique during the onset phase of the block. The longer duration of sensory blockade improves postoperative analgesia without increasing the incidence of side effects – a benefit unattainable with systemic analgesic drugs. The reason for the faster onset time and the longer duration of sensory block with ultrasound guidance is probably a more accurately targeted delivery of the local anaesthetic to the brachial plexus. Although lateral infraclavicular plexus anaesthesia has not been reported to be associated with complications, e.g. pleural puncture or inadvertent intravascular injection of the local anaesthetic, the safety implications of ultrasound visualisation are evident.
Often‐cited arguments against the use of ultrasound in regional anaesthesia are the associated costs and the space requirements for storage and use of the ultrasound equipment. Ultrasound systems have been decreased in size to the dimensions of a laptop computer in the past few years, while the cost of these miniaturised systems has decreased to one‐tenth the cost of conventional ultrasound systems. These facts will hopefully weaken the arguments relating to cost and space requirements, and enhance the use of ultrasound guidance, not only for infraclavicular brachial plexus anaesthesia in children, but also for other regional anaesthesia techniques in all age groups for which it has been shown to be effective .
This new technique requires specialist training. Nerve blocks no longer require anatomical landmarks, e.g. bones or blood vessels, or complex calculations, but they do demand that anaesthetists adopt a new perspective. We hope that this study contributes to the acceleration of this ‘paradigm shift’ in regional anaesthesia. During initial attempts at ultrasound‐guided plexus anaesthesia, the orientation of the tip of the needle in relation to the ultrasound picture feels unfamiliar. However, in our experience, it takes only 15–20 supervised attempts to obtain successful blocks.
In conclusion, ultrasound guidance allows direct visualisation of the lateral infraclavicular brachial plexus in paediatric anaesthesia. Due to the absence of muscle contractions, this method is less painful for the children than nerve stimulator guidance. Moreover, ultrasound guidance decreases sensory and motor onset times, and prolongs the duration of sensory blockade. Therefore, ultrasound visualisation offers advantages over nerve stimulation for the performance of infraclavicular brachial plexus anaesthesia in children and will hopefully become a standard technique for plexus anaesthesia in children as well as adults.
Marhofer P 1, Sitzwohl C, Greher M, Kapral S.
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