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Original Article
1 (
1
); 25-32
doi:
10.25259/JTARCC_6_2024

Comparison of Ultrasound-guided Corner Pocket and Two Aliquots Injection Techniques for Supraclavicular Block in Upper-limb Orthopedic Surgeries: A Prospective Randomized Study

Department of Anaesthesiology, Pain Medicine and Critical Care, All India Institute of Medical Sciences, New Delhi, India.
Department of Orthopaedic, All India Institute of Medical Sciences, New Delhi, India.

*Corresponding author: Abhishek Singh, Department of Anaesthesiology, Pain Medicine and Critical Care, Jai Prakash Narayan Apex Trauma Center, All India Institute of Medical Sciences, New Delhi, India. bikunrs77@gmail.com

Licence
This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, transform, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.

How to cite this article: Yadav P, Gupta B, Sharma V, Trikha V, Farooque K, Rewari V, et al. Comparison of Ultrasound-guided Corner Pocket and Two Aliquots Injection Techniques for Supraclavicular Block in Upper-limb Orthopedic Surgeries: A Prospective Randomized Study. J Trauma Anaesth Resusc Crit Care. 2025;1:25-32. doi: 10.25259/JTARCC_6_2024

Abstract

Objectives:

The two approaches described for ultrasound-guided supraclavicular brachial plexus block are single injection (SI) at corner pocket technique and drug injection in two or more aliquots. A prospective, randomized, controlled study was conducted to compare the SI at the corner pocket with the double-injection (DI) ultrasound-guided supraclavicular brachial plexus block. Our study hypothesis was that the DI technique results in a faster onset time of the block and a lower failure rate as compared to the SI, corner pocket technique. The primary objective of the study was to compare the anesthesia onset time in SI versus DI technique in ultrasound-guided supraclavicular brachial plexus block for orthopedic surgeries of the upper limb.

Materials and Methods:

Fifty adult patients of the American Society of Anesthesiologists physical status I and II scheduled for hand, wrist, forearm, and elbow orthopedic surgeries were randomized into two groups, SI at corner pocket (n = 25) and DI (n = 25). The drug used in both groups was 20 mL of 0.5% bupivacaine with 1 mcg/kg clonidine solution. The performance time, anesthesia onset time, surgical anesthesia, failed block, and any complications were noted by a blinded observer.

Results:

The mean anesthesia onset time was longer in SI (17.7 min [Standard deviation (SD) = 4.55 min]) as compared to DI (12.8 min [SD = 3.93 min]). The DI group had a quicker onset of sensory anesthesia as well as motor blockade of all 4 nerves, i.e., musculocutaneous, radial, and median nerves at 15 min and ulnar nerve at 20 min. The time to first rescue analgesic dose was earlier in the SI group (11.18 h [SD = 1.56]) than in the DI group (12.89 h [SD = 1.87]). Prolonged duration of anesthesia (12.79 [SD = 1.7] vs. 9.76 [SD = 3.96] h, P < 0.001) was observed in the DI group as compared to the SI group.

Conclusion:

DI ultrasound-guided supraclavicular block had a faster onset time, provided prolonged postoperative analgesia, and thus, a delayed demand for rescue analgesics than SI technique.

Keywords

Brachial plexus block
Orthopedic surgeries
Regional anesthesia
Technique
Ultrasound

INTRODUCTION

Regional anesthesia for upper-limb orthopedic surgeries has several advantages over general anesthesia, the most important being good postoperative analgesia, decreased post-operative opioid requirement, and reduced recovery time.1 Ultrasound-guided technique for performing brachial plexus blockade not only decreases the risk of the complications but also enhances the success of the blockade along with a reduction in local anesthetic (LA) dose.1 The brachial plexus is formed by the convergence of the anterior rami of the lower cervical nerves (C5, C6, C7, C8) and the significant part of the anterior division of the first thoracic nerve.2 These rami form three trunks and split into anterior and posterior divisions and arrange compactly, lateral to the subclavian artery. The supraclavicular brachial plexus block provides excellent anesthesia for all branches of the brachial plexus as they pass through this confined area. Thus, it is popularly known as “spinal anesthesia of the upper extremity,” making it the most suitable approach for brachial plexus block for forearm and hand surgeries.3

There are two approaches described for ultrasound-guided supraclavicular brachial plexus block. In one of the approaches, the total volume of LA is injected at the intersection of the subclavian artery and first rib (i.e., the ‘corner pocket’ technique). Some authors suggest that when the LA bathes the inferior-most portion of the brachial plexus divisions, a dense and complete block of the entire upper extremity results within minutes.4 However, other authors believe that the double or multiple aliquot injection techniques for the brachial plexus block are better as they decrease the block onset time and decreases the LA volume.5 We conducted a prospective, randomized, controlled study to compare the efficacy of a single injection (SI) at the corner pocket and the double-injection (DI) ultrasound-guided supraclavicular brachial plexus block. Our research hypothesis was that the DI technique results in a quicker block onset time and a lower failure rate as compared to the SI, corner pocket technique. The primary objective of the study was to compare the anesthesia onset time in SI versus DI in ultrasound-guided supraclavicular brachial plexus block for orthopedic surgeries of the upper limb. The secondary objectives were to compare both techniques in terms of the success rate of surgical anesthesia, the incidence of adverse events during the study period from the time of brachial plexus block till the end of the follow-up period (5 days postoperatively), duration of anesthesia, and time to first rescue analgesia.

MATERIALS AND METHODS

After obtaining the institutional ethics committee approval (IECPG-3627.11.2015), this prospective open-label, two-group parallel randomized control study was conducted at a level 1 trauma center from February 2016 to January 2018. The study was prospectively registered with the Clinical Trials Registry of India (Ref/2015/12/010271). All adults aged 18–65 years scheduled for elbow, hand, and wrist surgeries with the American Society of Anesthesiologists (ASA) physical status I or II with a body mass index of 20–35 kg/m2 were assessed for eligibility. Patients with known neuropathy of the upper-limb undergoing surgery, allergy to LA drugs, abnormal neck and shoulder anatomy, pre-existing nerve injury, infection at the injection site, patients refusing to give consent, and pregnant patients were excluded from the study.

Patients meeting the inclusion criteria were assigned to two different supraclavicular brachial plexus technique groups by computer-generated randomization. The Visual Analog Scale (VAS) scoring for pain was explained to them during pre-anesthetic evaluation. On the day of surgery, patients were shifted to the procedure/block room, and standard ASA monitoring was applied. Intravenous access was secured in the upper limb contralateral to the surgical site, and intravenous premedication (1 mg midazolam) was administered to all patients. All the brachial plexus blocks were administered by an experienced anesthesiologist who had performed at least 50 ultrasound-guided supraclavicular brachial plexus blocks. All the procedural data were recorded by an independent investigator blinded to the approach of the procedure. The same investigator evaluated the sensory and motor block and followed up with the patients postoperatively for 24 h and thereafter on the 5th postoperative day.

All the brachial plexus block procedures were performed using the S Nerve Sonosite® ultrasound machine with a 6–13 MHz linear array transducer. The patients were lying supine with a 30° head-up position, and their necks turned toward the opposite side; the procedure site was disinfected, and the transducer was placed in the transverse plane just above the clavicle approximately at its midpoint to obtain a cross-sectional view of the subclavian artery and the divisions of the brachial plexus compactly arranged laterally to the subclavian artery. The skin infiltration was done with 2–3 mL xylocaine 2%. In the SI group, a 22-gauge, 5 cm echogenic needle was advanced using an in-plane technique from the lateral to medial direction until the tip was located at the junction of the subclavian artery and first rib, i.e., the corner pocket [Figure 1], and 20 mL of 0.5% bupivacaine with 1 mcg/kg clonidine solution was injected after negative aspiration. For the DI supraclavicular block, a similar mixture of LA with clonidine was used; half of the volume (10 mL) was injected in the corner pocket, and the remaining half (10 mL) was injected by directing the needle 10 mm further toward the cluster formed by the trunks and divisions of brachial plexus superolateral to the subclavian artery [Figure 2a and b].

Deposition of drug in the corner pocket, SA: Subclavian artery. P: Pleura, L: Lateral.
Figure 1:
Deposition of drug in the corner pocket, SA: Subclavian artery. P: Pleura, L: Lateral.
(a) First injection of drug in the corner pocket. (b) Second injection above the nerve bundle. P: Pleura, L: Lateral.
Figure 2:
(a) First injection of drug in the corner pocket. (b) Second injection above the nerve bundle. P: Pleura, L: Lateral.

Evaluation of the block

Imaging time (time interval between contact of the ultrasound probe with the patient and obtaining a satisfactory picture), needling time (start of insertion of block needle to the end of the entire volume of LA) injection through the block needle, and the performance time (sum of imaging time and needling time) were recorded during the performance of the block. Subsequently, the extent of sensory and motor blockade was assessed every minute, starting at 5 min after injection until 30 min by an independent investigator. The extent of sensory and motor blockade of the musculocutaneous, median, radial, and ulnar nerve distribution was graded by a pre-validated three-point scale [Table 1a and b].6,7

Table 1 (a and b): The three-point scale (a) and the nerve distribution area for sensory and motor block (b).
a
Threepoint scale Sensory block (Response to cold test) Motor block
0 No block No block
1 Analgesia (patient can feel touch, not cold) Paresis
2 Anesthesia (patient cannot feel touch or cold) Paralysis
b
Nerve tested Sensory block Motor block
Musculocutaneous Lateral aspect of forearm Elbow flexion in supination and pronation
Median Volar aspect of the thumb umb opposition
Radial Lateral aspect of the dorsum of hand umb abduction

Overall, the maximal composite score (sensory and motor block) was 16 points. The time taken from the injection of LA till achieving a minimum composite score of 14, with a sensory block score equal to or more than 7 of 8 points, was the anesthesia onset time. The patient was considered ready for surgery when a minimum sensorimotor composite score of 14 points was achieved, provided the sensory block score was equal to or superior to 7 of 8 points. Surgical anesthesia success was defined as surgery without the requirement for any supplementation of the block, general anesthesia (required for incomplete blockade), or surgical site infiltration. Intraoperative sedation was provided by intravenous midazolam. Subsequently, the block onset time, success rate, and the incidence of adverse events (vascular puncture, Horner’s syndrome, pneumothorax, hematoma formation, and LA toxicity) were also recorded. In case the composite sensorimotor score did not achieve a composite score ≥14 points 30 min after the brachial plexus block, it was considered a failed block, and general anesthesia was administered using a standard technique. The requirement for any supplementation of the block, LA infiltration of the surgical site, and general anesthesia was also recorded.

Post-operative period

In the post-anesthesia care unit, VAS scores for pain at rest and on movement were recorded at 2, 4, 6, 12, and 24 h. Fentanyl 0.5 mcg/kg was administered rescue analgesia as a rescue analgesic if VAS ≥3, and the time to the first analgesic requirement was recorded. Total episodes of post-operative nausea and vomiting were recorded; 4 mg ondansetron was given for nausea and vomiting. All patients were contacted telephonically by the blinded investigator on postoperative day 5 to inquire about new neurological symptoms. Patients who would report new neurological symptoms were planned to follow until the resolution of the symptoms.

Statistical analysis

The sample size was calculated to compare the mean time taken for the supraclavicular brachial plexus block between SI and DI ultrasound-guided supraclavicular block with the following assumptions based on previous studies: Mean ± standard deviation (SD) time taken in minutes in SI group = 18.5 ± 8.3, mean ± SD time taken in DI group = 10.1 ± 6.4, confidence level (CI) = 95%, and power = 90%. Hence, the number of evaluable patients required in each of the two groups was 17. Considering that around 80% of patients may have a successful block, i.e., a composite score >14 points within 30 min, and a loss to follow-up in 10% of patients, we enrolled 25 patients in each of the two groups. Data for continuous variables were presented as the mean ± SD, and the categorical and ordinal variables data were presented as a percentage. Data that did not follow a normal distribution were presented as the median and range. Student’s t-test and categorical variables analyzed data for continuous variables that followed normal distribution were analyzed by Fisher’s exact test. The data that did not follow normal distribution were analyzed by the Mann– Whitney U-test. Statistical analysis was performed using Strata Version 14.1. A P < 0.05 was considered statistically significant.

RESULTS

The consolidated standards of reporting trials (CONSORT) flow chart is depicted in Figure 3. No difference in the demographic profile and the surgical characteristics was observed between the two groups [Table 2]. Faster block onset time (12.83 [SD = 3.93] min vs. 17.73 [SD = 4.55] min, P < 0.001) and prolonged duration of anesthesia (12.79 [SD = 1.7] vs. 9.76 [SD = 3.96] h, P < 0.001) were observed in the DI group as compared to the SI group [Table 3]. The minimum sensorimotor composite score of 14 points was higher in the DI group at 15 and 20 min [Table 4]. The DI group had a faster onset of sensory anesthesia as well as motor blockade of all 4 nerves, i.e., musculocutaneous, radial, and median nerves at 15 min and ulnar nerve at 20 min [Figure 4a and b]. However, there was no difference in sensory and motor blockade in both groups at 30 min. The incidence of adverse events was comparable in both groups [Table 3]. The time to first postoperative analgesia was earlier in the SI group than in the DI group (11.18 ± 1.56 h vs. 13.89±1.83, P = 0.002). None of the patients sustained any neurologic sequelae on follow-up for 5 days.

CONSORT diagram of patient flow through the study. SCB: Supraclavicular block, CONSORT: Consolidated standards of reporting trials.
Figure 3:
CONSORT diagram of patient flow through the study. SCB: Supraclavicular block, CONSORT: Consolidated standards of reporting trials.
Table 2: Demographic profile and surgical characteristics.
Parameters SI group (n=25) DI group (n=25) P-value
Age (years)* 38.88±10.69 36.72±14.83 0.558
Gender# (%)
   Male 19 (76) 17 (68) 0.377
   Females 6 (24) 8 (32)
   BMI* 23.46±3.34 22.7±2.79 0.394
ASA physical status# (%)
   1 24 (96) 22 (88) 0.305
   2 1 (4) 3 (12)
Comorbidities# (%)
   None 24 (96) 22 (88) 0.352
   Diabetes 1 (4) 1 (4)
   Hypertension 0 (0) 2 (8)
Type of surgery# (%)
   Hand 11 (44) 8 (32) 0.349
   Wrist 6 (24) 10 (40)
   Forearm 7 (28) 4 (16)
   Elbow 1 (4) 3 (12)
: Parametric variables are presented as mean±SD, #: Nonparametric variablespercentage Significant P<0.05, SI: Single injection, DI: Double injection, ASA: American Society of Anesthesiologists, BMI: Body mass index, n: Number of patients, SD: Standard deviation
Table 3: Block performance parameters.
Parameters SI group (n=25) DI group (n=25) P-value
Imaging time (seconds) 13.80±2.958 18.88±5.652 0.00*
Needling time (seconds) 153.20±38.82 149.60±28.938 0.712
Performance time (seconds) 172.08±36.39 163.40±30.325 0.364
Anesthesia onset time in minutes±SD 17.73±4.55 12.83±3.93 0.000*
Total duration of anesthesia in hours±SD 9.76±3.96 12.79±1.70 0.001*
Patients with a composite score ≥14 at the end of 30 minutes after block; n(%) 22 (88) 24 (96) 0.609
Horner syndrome (%) 5 (20) 4 (16) 0.713
Vascular puncture, pneumothorax, hematoma, local anesthetic systemic toxicity 0 0
Significant P<0.05, n: Number of patients, SI: Single injection, DI: Double injection, SD: Standard deviation
(a and b) Distribution of patients with onset of sensory and motor blockade among two groups. SI: Single injection, DI: Double injection. *Significant P value.
Figure 4:
(a and b) Distribution of patients with onset of sensory and motor blockade among two groups. SI: Single injection, DI: Double injection. *Significant P value.
Table 4: Number of patients with a minimum composite score of >14 points at various time intervals.
Patients with a composite score ≥14 at various time intervals SI group (n=25) DI group (n=25) P-value
5 min (n) % 0.0 0.0
10 min (n) % 0.0 (1) 4.0 1.00
15 min (n) % (3) 13.6 (13) 52 0.005*
20 min (n) % (10) 40 (21) 84 0.003*
25 min (n) % (19) 76 (24) 96 0.098
30 min (n) % (22) 88 (24) 96 0.609
Significant P<0.05. SI: Single injection, DI: Double injection

DISCUSSION

In this randomized controlled trial, we compared the SI at the corner pocket with the DI technique for a supraclavicular ultrasound-guided block in upper-limb orthopedic surgery. The study results showed that the DI group exhibited significantly faster anesthesia onset time (P < 0.01), and the effect was more prolonged as compared to the SI group. Our study results are in concordance with the previous study conducted by Tran et al., wherein 92 subjects were included in the study, both SI and DI groups comprising 46 patients each.8 The study showed a faster onset of the block with the DI technique, i.e., 17.5 min, as compared to 21.7 min in the SI technique (p = 0.021). Interestingly, although the study conducted by Tran et al. used a different drug composition (lidocaine 1.5% with epinephrine, 5 mcg/mL) and higher LA volume than our study, the anesthesia onset time of the DI group was slightly slower (17.5 ± 8.4 vs. 12.83 ± 3.93 min) than our DI group results. The probable reason may be the different injection techniques used in both studies. We used a 22 G nerve block needle for block administration, as opposed to Tran et al.,8 wherein the Tuohy needle might have led to the rapid spread of LA, separating the division of compactly arranged brachial plexus, thus countering the benefit of compact topography of brachial plexus at the supraclavicular level. Although the onset time was faster in the DI group by a few minutes, it is of significance in a hospital treating a high volume of orthopedic trauma patients as the cumulative gain translates into an increased number of surgeries and better utilization of operating room time.

The number of patients with a composite score ≥14 points qualified as successful supraclavicular brachial plexus blocks. The difference between the two groups was statistically significant at 15 min and 20 min; however, at 30 min, both groups had similar success rates. The results are consistent with a previous study by Tran et al.8 wherein the authors observed a success rate of 95.7% of the surgical anesthesia in both groups, which is almost similar to our study, i.e., 88% and 96% in the SI and DI groups, respectively. Another important observation in the present study was the duration of anesthesia, which was observed to be more prolonged in the DI group (12.79 ± 1.7 h) as compared to the SI group (9.76 ± 3.96 h). None of the previous studies comparing SI at the corner pocket versus DI or triple injection techniques have compared the total duration of anesthesia between both groups. The prolonged duration of anesthesia can be attributed to the increased area of contact of LA with the brachial plexus. Another probable explanation is that since we used the intraplexus technique of injection, there was less systemic uptake of the LA drug due to more anesthetic solution within the brachial plexus sheath, which eventually increased the reservoir volume of the LA solution.9

The performance time in both groups was comparable. However, the difference in the imaging time between the two groups was statistically significant. The probable reason for the longer duration in the DI group was due to the time required for focused scanning to achieve an optimal image of the corner pocket and the cluster of plexus in the same ultrasound image view. However, as compared to previous studies, the imaging time in our study was lesser than that of the other authors, wherein the mean imaging time was 31.6 s (Techasuk et al.)10 and 31.9 s (Arnuntasupakul et al.).11 Ultrasound scanning is a skill that is operator-dependent, and hence, this difference in the two different studies may exist. The needling time recorded in our study was lesser than that recorded in other studies, wherein the needling time was 8–10 min.4,12 The reason for this difference is due to the variation in the definition used for ‘needling time’. Other authors have included local skin infiltration as well as injection of LA in the ‘needling time’. However, we have recorded the time required for injecting LA through a block needle.

The difference in the sensory and motor blockade of musculocutaneous, radial, and median nerves between the two groups was statistically significant at 15 min and for the ulnar nerve at 20 min. This is in accordance with a randomized controlled trial conducted by Choi et al.,13 wherein the SI technique was compared with the DI intracluster approach; the drug volume used was 30 mL. The rate of blockage of all 4 nerves was significantly higher in the DI intracluster group, although the proportion of patients with a complete sensory and motor block at 30 min was similar in the two groups. LA was better distributed within the brachial plexus sheath in the DI intracluster group than in the SI group. In another study by Techasuk et al., the DI technique was compared with the multiple aliquots intracluster technique.10 The authors concluded that a novel targeted intracluster injection approach provides rapid onset times and 100% success, but the detection of all satellite neural clusters requires a high level of skill in ultrasonography.10 The multiple aliquot groups displayed a higher proportion of patients with complete sensory and motor blockade of the median, radial, and ulnar nerves during the initial 15 and 20 min. However, at the end of 30 min, there was no difference in the overall sensorimotor composite score, as well as sensory and motor blockade of individual nerves, except musculocutaneous nerve, which had higher sensory and motor blockade rates at all-time points. The time of the first post-operative analgesic was 11.18 ± 1.56 h and 13.89 ± 1.83 h in SI and DI groups, respectively. The prolonged analgesic effect observed in both groups is due to the use of adjuvant (clonidine) in all the blocks.

Horner’s syndrome was the most common complication observed in our study, with an incidence of 20% and 16% in the SI and DI groups, respectively. This incidence is lower than seen in previous studies, with a reported incidence of 58–67% in the SI and DI groups, respectively.8 The most probable reason for decreased incidence may be less volume of LA used in our study. There was a 12% failure to achieve block in SI and 4% in the DI group. The difference was not significantly different between the two groups (P = 0.297) as compared to the previous study.14 The incidence of unintentional intraneural injection and post-operative neurological complications with ultrasound-guided interscalene and supraclavicular nerve blocks has been reported to be 17% in a previous study.15 Although no patient developed postoperative neurological complications, intraneural injection remains a concern despite the use of ultrasound.

Limitations of the study

The limitations of our study include a single-center study with a small sample size. The second limitation was that the sensory and motor block of the musculocutaneous, median, radial, and ulnar nerves were seen at intervals of 5 min, which could have decreased the accuracy of successful block time. Another limitation of our study is that we did not assess individual nerves for the duration of sensory and/or motor blockade in the postoperative period. The reason for that was that the subjects included in the study were orthopedic trauma patients necessitating plaster/cast application after surgery. Many correlations did not achieve statistically significant value due to the small sample size. Experienced anesthesiologists performed all the blocks in our study, and no patient had a neurologic deficit in either group. The study results may differ if novice operators had performed all the blocks.

CONCLUSION

We conclude that the double aliquots ultrasound-guided supraclavicular block technique is associated with a faster onset time than the single corner pocket injection technique. Despite a comparable success rate among the two groups at 30 min, the DI technique provided prolonged postoperative analgesia and thus a delayed demand for rescue analgesics. The complications associated with the supraclavicular block were comparable between the two groups.

Authors’ contributions:

PY, BG, VS, VT, AS, KF, VR and RP contributed to the conception, study design, and data collection and evaluation; PY, BG, VS, and VR contributed to the statistical analysis, and interpretation of data. PY, BG, VS, VT, AS, KF, VR, and RP drafted the manuscript; all authors have read and approved the final manuscript.

Ethical approval:

The research/study was approved by the Institutional Review Board at All India Institute of Medical Sciences, New Delhi, number IECPG-36/November 27, 2015, dated 6th January 2016.

Declaration of patient consent:

The authors certify that they have obtained all appropriate patient consent.

Conflict of interest:

Dr. Babita Gupta is on the editorial board of the Journal.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation:

The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.

Financial support and sponsorship: Nil.

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