Comparison of ultrasound-guided supraclavicular nerve block combined with clavipectoral fascial plane block versus supraclavicular nerve block along with the upper trunk of brachial plexus “The SCUT block” in clavicle surgery: A single-centre, double-blind, randomised controlled trial

Abstract

Background and Aims:

Regional anaesthesia for clavicle surgery focuses on site-specific nerve blocks to minimise the drug volume, prevent unnecessary nerve block, and reduce complications. This study aimed to compare the effectiveness and dynamics of selectively blocking supraclavicular (SC) nerves and upper trunk (UT) of the brachial plexus (SCUT block) with clavipectoral fascial plane (CPF) block as a site-specific regional anaesthesia strategy for clavicle surgery.

Methods:

In this single-centre, double-blinded, randomised study, 50 patients undergoing clavicle surgeries were given either SCUT block or CPF block with SC nerve block under ultrasound guidance with 20 mL of 0.5% ropivacaine. The primary outcome was the total duration of analgesia. The secondary outcomes were onset of sensory blockade, motor impairment, degree of diaphragmatic excursion, visual analogue scale (VAS) score, and patient satisfaction score. Statistical analysis included Student’s t-test, Chi-square test, and Mann–Whitney U-test as appropriate, with statistical significance set at P < 0.05.

Results:

The mean duration of postoperative analgesia was 10.34 [standard deviation (SD): 1.20] h in the SCUT group and 8.45 (SD: 0.67) h in the CPF group (P < 0.001) [mean difference: 1.89 (95% CI: 1.15, 1.29)]. The SCUT group exhibited lower VAS scores but higher motor impairment and reduced diaphragmatic excursion than the CPF group. However, the differences in the onset of sensory block and patient satisfaction scores were not statistically significant.

Conclusion:

The SCUT block and CPF block with SC nerve block are effective site-specific regional anaesthesia strategies for clavicle surgery.

INTRODUCTION

Regional anaesthesia yields superior patient-reported outcomes compared to general anaesthesia for clavicle surgery.[1] Current literature comprises several regional anaesthetic approaches, including cervical plexus, selective supraclavicular (SC) nerve, upper trunk (UT), and interscalene blocks, but these are not site-specific.[2] The widespread availability of ultrasound-guided regional anaesthesia has led to newer blocks, such as the UT block, and interfascial techniques, such as the clavipectoral fascial plane (CPF) block.[3]

A ‘SCUT block’ in clavicle surgery refers to an ultrasound-guided regional anaesthetic technique that combines SC nerve (SCN) block with the UT of brachial plexus block (C5, C6), providing targeted anaesthesia for procedures in the clavicle area.[4] The SCN arises from the superficial cervical plexus, originating from the ventral rami of C2-C4, giving sensation to the area over the clavicle. Selective SCN block can be achieved using a reduced anaesthetic volume of 3–5 mL.[5] The CPF block refers to depositing local anaesthetic drug in the CPF to aim at the sensory nerves penetrating the clavipectoral fascia before supplying the clavicle, except for the SCN, which innervates the skin above the clavicle; thus, the additional SCN must be supplemented.[6]

In this study, we performed ultrasound-guided SCN block with CPF block or SCUT block for clavicle surgery to evaluate the clinical effectiveness and block quality between the two blocks. The primary objective was to compare the duration of analgesia in patients undergoing unilateral clavicle surgery under these blocks. The secondary objectives were the time of onset of sensory block, motor impairment, ipsilateral diaphragmatic excursion, visual analogue scale (VAS) score, and satisfaction level of the patient. We hypothesised that the SCUT and CPF block with the SCN block would provide a similar duration of analgesia in patients undergoing clavicle fracture surgery.

METHODS

After receiving approval from the Institutional Ethics Committee (approval number: GIMS/IEC/HR/2023/33, dated 21/10/2023), this study was registered with the Clinical Trials Registry-India (registration number: CTRI/2024/05/068199, accessible at https://ctri.nic.in/Clinicaltrials/login.php). It was a randomised, double-blinded interventional study, adhering to the Declaration of Helsinki (2013) and Consolidated Standards of Reporting Trials (CONSORT) and Good Clinical Practice guidelines. The study was conducted at a tertiary care hospital from May 2024 to December 2024. Fifty-two patients aged 18–60 years, having American Society of Anesthesiologists (ASA) physical status I/II, planned for unilateral clavicular procedures, were recruited. Written informed consent was obtained for participation in the study and use of the patient data for research and educational purposes.

Patients were randomly assigned to one of two groups, SCUT or CPF, in a 1:1 ratio through simple randomisation utilising a computer-generated randomisation table through an online software (Open Epi software version 3.01, Atlanta, GA, USA), with 25 participants per group. Allocation concealment was done using the sequentially numbered opaque-sealed envelope method by the technician not involved in the study. An independent observer did the data collection. The enroled participants and the independent data-collecting person were unaware of the patient’s group allocation and the block given. Those who refused to participate, had bilateral clavicle fractures or rib fractures, cardio-cerebrovascular diseases, respiratory insufficiency, abnormal blood coagulation, puncture site infection or hematoma, continuous use of analgesics for the past 3 months, and allergy to local anaesthetics were excluded.

After pre-anaesthetic assessment, the block procedure and VAS scale were explained to them. Patients were shifted to the preoperative room on the day of surgery, an 18-G intravenous (IV) access was secured, and standard monitoring was initiated. IV midazolam 1 mg, ondansetron 4 mg, and fentanyl 1 µg/kg were administered before giving block. The blocks were administered as per the randomised group:

SCN block: The patient was supine with the head turned to the contralateral side. Under all aseptic precautions, a linear high-frequency ultrasound probe (4–12 MHz, Philips Innosight, Philips Ultrasound Inc., Bothell, WA, USA) was placed at the lateral side of the neck over the midpoint of the sternocleidomastoid muscle at the level of the cricoid cartilage.[5] After giving 1 mL of lignocaine 1% at the skin, a 22-G, 50-mm insulated needle (Stimuplex D, B Braun, United States) was introduced from lateral to medial using the posterior-in-plane technique until its tip was placed near the SCN above the prevertebral fascia, and 5 mL of 0.5% ropivacaine was deposited [Figure 1a].

Figure 1.

Ultrasound images during the performance of the (a) supraclavicular nerve block, (b) upper trunk block, (c) CPF block. PVF = prevertebral fascia; ASM = anterior scalene muscle; MSM = middle scalene muscle; SCN = supraclavicular nerve; C5 = fifth cervical nerve root; C6 = sixth cervical nerve root; ASM = anterior scalene muscle; CPF = clavipectoral fascia; PM = pectoralis major muscle; SC = subclavius muscle

Selective blockade of the UT of brachial plexus (UT block): After giving the SCN block, the ultrasound probe was subsequently moved medially to scan the scalene muscles and C5 and C6 nerve roots, which were followed distally until their union from the UT down to the SC area. The needle was directed from lateral to medial, and 15 mL of 0.5% ropivacaine plain was given [Figure 1b].[4,7]

CPF block: After performing the SCN block, the needle was again inserted to inject 15 mL of 0.5% ropivacaine plain beneath the clavipectoral fascia to separate it from the periosteum of the clavicle.[8,9,10] The injection was administered on both sides of the fractured ends of the clavicle, with 7.5 mL injected on each side [Figure 1c].

The effect of the block was measured after 20 minutes of block administration in three areas: the sternoclavicular joint, midclavicular, and acromioclavicular joint. Four levels were established: 0 for no decreased sensation, 1 for decreased sensitivity to puncture, 2 for no sensitivity to puncture, and 3 for no tactile sensitivity. Modified Bromage scale (MBS) scores assessed upper limb movement function.[11] A score of 4 indicated full muscle strength in relevant muscle groups, 3 indicated reduced strength but the ability to move against resistance, 2 indicated the ability to move against gravity but not against resistance, 1 indicated discrete movements of muscle groups, and 0 indicated lack of movement. The VAS scores of the patients were noted hourly till 4 hours and then at 6, 8,10, 12,18, 20, and 24 hours post-surgery. The diaphragmatic movement was evaluated by real-time M-mode ultrasonography of the hemidiaphragm. Patients were assessed in an upright seated position for the range of diaphragmatic movement from a resting expiratory position to deep inspiration (sigh test). It was recorded before and 30 minutes after the block. Diaphragmatic movement reduction of more than 75%, no movement, or paradoxical movement was considered complete paresis. Reduction between 25% and 75% was considered partial paresis, and movement less than 25% was considered no paresis.[12] The block-related adverse effects were recorded, including local anaesthetic systemic toxicity, nerve injury, Horner’s syndrome, pneumothorax, and haemothorax. Assessments were done at 20 minutes or until grade 2 sensory-motor blockade, considered complete conduction blockade (CCB). Patients not registering for CCB at the end of 30 minutes were excluded from the study, assuming block failure.

The postoperative pain management protocol included the administration of IV paracetamol 1 g every 8 hours. IV tramadol 2 mg/kg was administered as rescue analgesia when the VAS was ≥4. Clavicular pain was evaluated at baseline and hourly for the first 4 hours, and then at 6, 8, 10, 12, 18, 20, and 24 hours post-surgery. The potential adverse effects, including hypoxia, dyspnoea, hoarseness, hiccups, and Horner’s syndrome, were assessed postoperatively within the first 24 hours. Patient satisfaction was evaluated using a 7-point Likert scale.[13] The patient was asked to express his satisfaction 24 hours post-procedure: 1 = extremely dissatisfied, 2 = dissatisfied, 3 = somewhat dissatisfied, 4 = unsatisfied, 5 = somewhat satisfied, 6 = satisfied, and 7 = extremely satisfied. The duration between the block time and the patient’s first complaint of pain was considered the duration of postoperative analgesia.

The primary outcome of this study was the total duration of postoperative analgesia. The secondary outcomes were the time of onset of sensory block, the degree of the relevant upper limb motor impairment using the MBS, changes in the ipsilateral diaphragmatic excursion, and the VAS scores within the first 24 hours. Lastly, satisfaction levels were assessed by the patient at the end of the first postoperative day.

The sample size was calculated using Epi Info Software (statistical software manufactured by the Centres for Disease Control and Prevention, Atlanta, Georgia, USA). The sample size of our study was calculated based on a previous study by Xu et al.,[8] which observed a mean difference of 7.0 [standard deviation (SD): 1.5] hours in the time to first analgesia after the block. The sample size was determined with a significance level of 0.05, a minimum of 20 cases in each group, and a power of 0.80. Taking dropouts and the difference in standard deviation into account, we took a sample size of 25 in each group.

All data were compiled and analysed using Statistical Package for the Social Sciences version 28 (International Business Machines Corporation, Armonk, NY, USA). The normality of continuous variables was assessed using the Shapiro–Wilk test. Normally distributed variables such as age, BMI, onset of sensory block, duration of surgery, duration of analgesia, and diaphragmatic excursion were compared using a paired Student’s t-test. A paired t-test was also used for within-group comparisons (e.g. pre- and post-block diaphragmatic excursion). Non-normally distributed variables (median and interquartile range) were VAS and patient satisfaction scores. For these, the Mann–Whitney U test was used. Categorical variables were gender (male/female), ASA physical status (I/II), MBS scores, number of patients with complete sensory block, rescue analgesia requirement, and incidence of diaphragmatic paresis. These were analysed using the Chi-square test or Fisher’s exact test, as appropriate. A two-tailed P value below 0.05 was considered significant.

RESULTS

Fifty-two patients were enroled in this study, out of which two were excluded; one patient was excluded due to the presence of a haematoma at the site of injection, and a second was excluded as he had sustained multiple rib fractures as well. The remaining 50 participants were equally randomised to receive either the SCUT block or the CPF block with the SCN block [Figure 2]. The physical characteristics, surgical procedures, and average surgical duration in the recruited patients are depicted in Table 1 and are almost comparable. No patient was converted to general anaesthesia during surgery.

Figure 2.

Consolidated Standards of Reporting Trials (CONSORT) flow diagram for participant enrolment. SCUT = Selective blockade of supraclavicular nerves and upper trunk of brachial plexus; CPF = clavipectoral fascial block; n = number of patients

Table 1.

Patient demographic profile and sensory block onset, duration of surgery, and duration of analgesia

Variables	SCUT group (n=25)	CPF group (n=25)	P
Age (year)	30.12 (5.12)	32.04 (6.01)	0.230
BMI (kg/m2)	22.90 (2.45)	22.50 (2.01)	0.530
Gender: Male/Female	22/3	21/4	0.683
ASA Grade: I/II	20/5	21/4	0.712
Onset of sensory block (min)	7.24 (1.05)	7.55 (0.88)	0.263
Duration of surgery (min)	62.35 (9.12)	60.24 (10.26)	0.446
Duration of analgesia (h)	10.34 (1.20)	8.45 (0.67)	0.0001

Data expressed as mean (SD) or frequency. SCUT=patients received supraclavicular nerves and upper trunk of the brachial plexus block; CPF=patients received clavipectoral fascial plane block; BMI=body mass index; ASA=American Society of Anesthesiologists (ASA) physical status; SD=standard deviation; n=number of patients

All 25 patients completed the surgery successfully under the SCUT block without any supplemental analgesic intervention, with the mean duration of analgesia being 10.34 (SD: 1.20) (95% CI: 9.87, 10.81) hours. Among the CPF group, the mean duration of analgesia was 8.45 (SD: 0.67) (95% CI: 8.18, 8.71) hours, with three patients experiencing pain during exposure to a lateral fragment of the clavicle, which subsided with supplemental subcutaneous infiltration performed by the surgeon. The time for the first rescue analgesic request was significantly longer in the SCUT group, with a mean difference of 1.89 hours (95% CI: 1.15, 1.29, P < 0.001).

All patients recovered complete sensory and motor function at 24 hours. The sensory block onset was comparable in both groups, with 7.24 (SD: 1.05) (95% CI: 6.82, 7.65) minutes in the SCUT group and 7.55 (SD: 0.88) (95% CI: 7.20, 7.89) minutes in the CPF group, with a mean difference of 0.31 minutes (95% CI: −0.86, 0.24; P = 0.263).

The CPF group exhibited no impairments in ipsilateral upper limb motor function, as evidenced by a MBS score of 4 for all patients’ deltoid and biceps muscles. In the SCUT group, there was a notable decline in the motor function of the deltoid or biceps muscles, with eight cases scoring 3, 15 cases scoring 2, and two cases scoring 1, which was statistically significant (P < 0.001) [Table 2]. The baseline diaphragm excursion before giving block was 6.08 (SD: 0.56) (95% CI: 5.86, 6.30) cm and 6.10 (SD: 0.28) (95% CI: 5.99, 6.21) cm in the SCUT group and CPF group, respectively, and the diaphragm excursion was 4.67 (SD: 0.27) (95% CI: 4.56, 4.77) cm and 6.02 (SD: 0.36) (95% CI: 5.87, 6.16) cm in the SCUT group and CPF group, respectively, after 30 minutes of block. The reduction in diaphragmatic movement in the SCUT group was significantly higher than that in the CPF group, with a mean difference of − 1.35 cm (95% CI: 1.17, 1.53; P < 0.001) [Table 3]. One patient in the SCUT group exhibited reductions exceeding 25% of their baseline values (28.3%). The remaining participants in the SCUT group demonstrated reductions of less than 25% in their baseline diaphragmatic excursion values. Despite the statistically significant difference, no patients showed symptoms of respiratory insufficiency or required oxygen therapy.

Table 2.

Modified Bromage score of ipsilateral upper limb and patient satisfaction score between the two groups

Variables	SCUT group (n=25)	CPF group (n=25)	P
Modified Bromage score 1/2/3/4	2/15/8/0	0/0/0/25	<0.001
Patient satisfaction score	6 (6–7)	6 (5–7)	0.543

Data expressed as median (interquartile range). SCUT=patients received supraclavicular nerves and upper trunk of the brachial plexus block; CPF=patients received clavipectoral fascial plane block; BMI=body mass index; SD=standard deviation; n=number of patients

Table 3.

Ipsilateral diaphragmatic excursion before and after the block given

Diaphragmatic excursion	SCUT group	CPF group	Mean difference (95% CI)	P
Pre-block (cm)	6.08 (0.56)	6.10 (0.28)	-0.02 (-0.23-0.27)	0.874
Post-block (cm)	4.67 (0.27)	6.02 (0.36)	-1.35 (1.17-1.53)	<0.001
P	<0.001	0.385	-	-

Data expressed as mean (SD). SCUT=patients received supraclavicular nerves and upper trunk of the brachial plexus block; CPF=patients received clavipectoral fascial plane block; SD=standard deviation; CI=confidence interval

The VAS scores did not show statistically significant differences between the groups before and during the first 4 hours after surgery. However, the VAS score was significantly higher in the CPF group at 8, 10, 12, 16, and 24 hours after the operation. In contrast, it was significantly higher in the SCUT group at 10 hours post-surgery [Figure 3]. Patient satisfaction did not show a statistically significant difference between the two groups [Table 2]. No adverse events were observed within the first 24 hours postoperatively.

Figure 3.

VAS score over time after clavicular surgery in SCUT and CPF groups. SCUT = patients received supraclavicular nerves and upper trunk of the brachial plexus block; CPF = patients received clavipectoral fascial plane block; VAS = visual analogue scale

DISCUSSION

This randomised study compared SCUT block with CPF block and SCN block as the sole anaesthetic technique for clavicle surgery. The duration of postoperative analgesia was longer in the SCUT group than in the CPF group (P < 0.001).

A study by Mohamed et al.[14] also resulted in longer analgesic duration with SCUT block than clavipectoral fascial block, but their duration was prolonged: 18.76 (SD: 0.89) hours vs 15.34 (SD: 1.38) hours with a mean difference of 3.42 hours (P < 0.001). This can be explained using adjuvants, magnesium sulphate, and dexamethasone, along with the local anaesthetic. Another similar study also found the SCUT block effective for clavicle surgery.[4]

In the present study, the sensory block onset was comparable in both groups (P = 0.263), which is consistent with a study where the onset of sensory block was similar.[14]

A study by Xu et al.[8] found intact upper limb movement and higher MBS scores in the clavipectoral group, compared with the interscalene block for clavicle surgeries, consistent with our study. Jo et al.[15] found more incidences of hemi-diaphragmatic paresis when comparing the superior trunk and costoclavicular blocks for arthroscopic shoulder surgery, similar to the present study. However, Kim et al.[16] concluded that the superior trunk block preserved respiratory functions and significantly reduced hemi-diaphragmatic paralysis.

The VAS scores were higher in the CPF group than in the SCUT group in the present study, and patient satisfaction did not show a statistically significant difference between the two groups, which is consistent with the previous study.[14] SCUT block and CPF block are gaining popularity for being safe and adequate for clavicle surgery, thus avoiding the risk of general anaesthesia, especially in difficult airway situations or patients with various comorbidities.[17,18,19]

This study has a few limitations that need to be considered. First, it was single-centred and had a small sample size. Second, it did not consider the effects of different fracture sites and types. Third, more research needs to be done on geriatric and comorbid patients. Furthermore, the minimum drug amount required for these blocks, providing adequate anaesthesia, needs to be explored.

CONCLUSION

The supraclavicular nerves and upper trunk of the brachial plexus (SCUT) block and clavipectoral fascial plane block with supraclavicular nerve block effectively provide site-specific regional anaesthesia for clavicle surgeries and can be used as standalone anaesthetic techniques.

Author contributions

SG: Concept, design, definition of intellectual content, literature search, experimental studies, data acquisition, data analysis, statistical analysis, manuscript preparation, manuscript editing and manuscript review; AS, NN, SK, RS, VS: Experimental studies, data acquisition, data analysis, manuscript editing and manuscript review.

Study data availability

De-identified data may be requested with reasonable justification from the authors (email to the corresponding author) and will be shared after approval, as per the authors’ Institution’s policy.

Disclosure of use of artificial intelligence (AI)-assistive or generative tools

The AI tools or language models (LLM) have not been utilised in the manuscript, except that software has been used for grammar corrections and references.

Declaration of use of permitted tools

Nil.

Presentation at conferences/CMEs and abstract publication

None.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.