Comparison of a novel anterior out-of-plane approach with standard in-plane approach in ultrasound-guided supraclavicular subclavian vein cannulation: A randomised controlled trial

Abstract

Background and Aims:

Subclavian vein cannulation is a commonly performed procedure in the operating room. Ultrasound-guided supraclavicular subclavian vein cannulation can be done using either an in-plane or out-of-plane approach. This study compares the in-plane technique with a novel anterior out-of-plane technique. The primary objective of the study was to compare the first-pass success rate between the anterior out-of-plane technique approach and the in-plane approach for ultrasound-guided subclavian vein cannulation.

Methods:

This single-centre, open-label, randomised controlled trial included 128 patients undergoing elective surgeries that required central vein cannulation. Patients were randomised to either the anterior out-of-plane or in-plane technique for ultrasound-guided subclavian central venous access. First-pass success rates, puncture and cannulation times, needle redirections, additional punctures, and complications were recorded and compared between groups. Continuous variables were analysed using independent-sample t-tests, and categorical variables with Chi-square tests. Normality was confirmed by the Shapiro–Wilk test; P values < 0.05 were considered statistically significant.

Results:

Successful cannulation was achieved in 119 patients. The first-pass success rate was significantly higher with the anterior out-of-plane approach (95%) compared to the in-plane approach (77%) (P < 0.05). The out-of-plane approach demonstrated shorter puncture [9 (SD: 3) seconds] and cannulation times [148 (SD: 31) seconds) compared to the in-plane approach [17 (SD: 9) seconds and 185 (SD: 32) seconds, respectively]. Additionally, fewer needle redirections, punctures, and complications, including arterial punctures (1 vs 5), were observed with the out-of-plane approach.

Conclusion:

Ultrasound-guided supraclavicular subclavian vein cannulation is more successful and efficient using this novel anterior out-of-plane approach compared to the standard in-plane approach.

INTRODUCTION

Central venous catheterisation is crucial for the anaesthetic management of major surgical procedures and for managing critically ill patients. Ultrasonography has become an indispensable tool in central venous catheter placement, with widespread adoption significantly improving success rates and reducing complications, leading to its preference over traditional landmark-guided techniques.[1] The in-plane approach is generally preferred for ultrasound-guided procedures, as the entire length of the needle is visualised during the procedure.[2]

The proximity of vital structures to the subclavian vein increases the risk of complications, including arterial puncture, haematoma formation, and pleural puncture.[3] Additionally, in the event of accidental arterial puncture, compression of the artery is not possible due to its deeper location. It is essential to develop a thorough understanding of anatomy and sonoanatomy, as well as the skill to prevent complications associated with the procedure.

With the increasing adoption of ultrasound in clinical practice, the risks associated with subclavian vein catheterisation have significantly decreased, particularly when performed by skilled operators.[4,5,6] Among central venous access sites, ultrasound-guided subclavian vein cannulation has shown a higher first-attempt success rate compared to the internal jugular vein (IJV), likely due to the IJV’s tendency to collapse under probe or needle pressure, whereas the subclavian vein is supported by surrounding fascia and resists compression.[7,8]

The standard technique for the supraclavicular approach to subclavian catheterisation is the in-plane approach, where the needle is inserted at the lateral border of the transducer. In-plane approach to any procedure requires a higher level of expertise.[4] For subclavian vein cannulation, the out-of-plane approach is more challenging as the angle of the probe needed to visualise the structures is high. Thus, it is difficult to insert the needle posterior to the probe. A novel ‘anterior out-of-plane approach’ was developed by the author (PUB) to overcome this problem. In this technique, the needle is inserted between the ultrasound probe and the clavicle. The primary objective was to compare the first-attempt success rate between the novel anterior out-of-plane and conventional in-plane approaches for ultrasound-guided supraclavicular subclavian vein cannulation. Secondary objectives included comparing cannulation time, time to venous puncture, operator satisfaction, the number of needle redirections, and complications. We hypothesise that the anterior out-of-plane technique will have a superior first-pass success rate and fewer complications.

METHODS

After obtaining approval from the Institute Ethics Committee (vide approval letter number: JIP/IEC/2022/068 dated 17.08.2022), the study was prospectively registered in the Clinical Trials Registry-India (vide registration number: CTRI/2022/09/045231, dated 05/09/2022, accessible at www.ctri.nic.in). This open-label randomised controlled trial was conducted in patients older than 18 years posted for elective surgeries requiring central venous access in a tertiary care centre between January 2023 and July 2024. The study was conducted in accordance with the principles of the Declaration of Helsinki (2013) and the Good Clinical Practice guidelines. Patients with coagulation disorders, scars, or infections over the needle puncture site on the neck, and patients with chest wall or neck deformities were excluded. Written consent was obtained from all subjects preoperatively for participation in the study and the use of patient data for research and educational purposes. The procedure was done following the induction of general anaesthesia and under mechanical ventilation.

The study participants were randomly allocated to one of two groups: the In-plane group, which received a USG-guided in-plane approach, and the Out-of-plane group, which received a USG-guided anterior out-of-plane approach. Randomisation was performed using a computer-generated random sequence with block sizes of 4 and 6 by a person who was not involved in the study (OpenEpi version 3.01, OpenEpi Development Team, Atlanta, GA, USA). For allocation concealment, the serially numbered opaque sealed envelope method was used.

GE Healthcare Venue Go™ (GE Healthcare, Chicago, IL, USA) ultrasound machine with a linear probe (8–15 MHz) and a triple-lumen 7-Fr, 13-cm catheter was used for catheterisation. Procedures were performed by anaesthesiologists who were adequately trained under supervision and had successfully done more than 20 ultrasound-guided IJV or subclavian vein cannulations. Patients were positioned supine with their arms adducted, neck extended, and rotated ~30° to the left. The operator stood at the head end; the ultrasound machine was positioned for optimal ergonomics. The probe was held in the non-dominant hand, cephalad to the clavicle and tilted to obtain the confluence view, where the IJV descends inferiorly and joins the subclavian vein horizontally to form the brachiocephalic (innominate) vein.

To obtain the ultrasound image of interest for either technique, the IJV was traced starting from the cricoid level on the lateral side of the neck and slid down until the clavicle was reached. The vein appeared in a short axial (cross-sectional) view. On reaching the supraclavicular fossa, the probe was gradually tilted inferiorly as if to scan the thorax of the patient. A long-axis image of the subclavian artery initially appeared, which could be traced as it joined the carotid artery. Upon further tilting the probe, the artery disappeared from the window, and the rounded IJV gradually changed into an elliptical shape, joining with the subclavian vein that arose from the lateral end of the ultrasound window, forming a confluence at their junction. With the ultrasound probe held abutting the superior border of the clavicle and keeping the confluence and proximal length of the subclavian vein in the ultrasound window, the needle was inserted according to the group it was randomised.

For the in-plane approach, the probe was angulated until a best possible long-axis image of the subclavian vein was obtained, with an adequate length of the vein in view. The needle was inserted from the distal end of the probe, about 0.5 cm away from the probe end, at an angle of 45° to the axis of the probe and skin surface [Figure 1a]. This way, the needle tip from the point of insertion on the skin and its complete shaft along its path were traced using ultrasound imaging, as they advanced towards the subclavian vein. Entry into the vein was confirmed by both visualisation of the needle tip position using ultrasound and the observation of flashback or aspiration of free-flowing venous blood in the syringe. The needle was visualised in an oblique path as it traversed the tissues, and the shaft and tip were seen as the needle was advanced into the vein in the long-axis view. After a successful vein puncture, catheterisation was done using the Seldinger technique.

Figure 1.

a) Image depicting needle insertion angle for the in-plane technique. b) Image depicting needle insertion using the anterior out-of-plane approach

For our novel anterior out-of-plane approach, an ultrasound image of the proximal end of the subclavian vein, seen joining the confluence with the presence of a valve visualised here, was obtained as described above. The difference here is that the required ultrasound window for the anterior out-of-plane approach was obtained with minimal angulation of the probe, about 10°–30°. Here, the pleura was visualised inferior to the posterior wall of the subclavian vein [Figure 2]. The depth of the vein from the skin surface was measured to avoid puncturing the pleura situated inferiorly. With the ultrasound probe placed parallel to the clavicle and angulated optimally to keep the vein in view, the needle was inserted 0.5 cm lateral to the centre of the footprint of the ultrasound probe, in between the clavicle and probe, at an angle of 5° anterior to the probe directed medially towards the confluence and parallel to the pleura under vision [Figure 1b]. The puncture was made with care and dexterity to ensure that the needle was not inserted more than the measured depth in the ultrasound. Its entry into the vein was visualised in an ultrasound view, and a flashback or free aspiration of blood was seen in the syringe attached to the needle. Once free flow of venous blood was confirmed, the ultrasound probe was kept aside, and with the left hand, the needle was held at the skin entry point to stabilise it to prevent inadvertent insertion into deeper structures, with the hypothenar eminence of the same hand resting over the sternum of the patient for stability. After a successful venepuncture, catheterisation was done using the Seldinger technique.

Figure 2.

Sonographic window to be obtained for both approaches with the subclavian vein (SCV) and brachiocephalic vein (BV) visualised. The pleura (indicated with a yellow arrow) is seen inferior to the posterior wall of the SCV. The needle insertion path is depicted as a red line with the predicted direction of the needle (red dotted line), which is parallel to the pleura

An assistant observed the procedure, noting the approach used, first-pass success (a single needle insertion with blood aspiration from all three catheter lumens without additional skin or vein punctures), the number of extra skin and vein puncture attempts, needle redirections (needle withdrawal to the subcutaneous plane and redirection towards the vein), and any complications such as arterial puncture, haematoma, haemothorax, or pneumothorax. Timing started at needle insertion, with the time to blood flashback in the introducer needle recorded as ‘time to vein puncture’. The ‘time for successful cannulation’ was marked when blood was aspirated from all three catheter lumens. At the end of the procedure, the ease of using the technique was measured on a 5-point Likert scale (poor, fair, neutral, good, or excellent) as assessed by the operator. Complications such as haematoma and arterial puncture were diagnosed immediately using ultrasound. Postoperative chest radiographs confirmed correct catheter placement and excluded complications.

The study’s sample size was calculated using OpenEpi software (OpenEpi version 3.01, OpenEpi Development Team, Atlanta, GA, USA) to compare the first-pass success rate between groups, aiming to demonstrate a 24% superiority margin (72% vs 48%) for the out-of-plane approach from a previous study by Vezzani et al.[9] With a 5% significance level and 80% power, 64 participants were needed per group, totalling 128.

Data analysis was conducted using the Statistical Package for the Social Sciences (SPSS) statistics software, version 19.0 (International Business Machines Corporation (IBM Corp.), Armonk, NY, USA). Normality of all continuous variables was assessed using the Shapiro–Wilk test and confirmed to be normally distributed. Therefore, continuous variables (time to vein puncture and cannulation) were expressed as mean [standard deviation (SD)] and compared using independent-sample t-tests. Categorical variables (first-pass success, additional skin/vein punctures, needle redirections, and complications) were presented as frequencies and percentages and compared using the Chi-square test. A P value of <0.05 was considered statistically significant.

RESULTS

A total of 128 patients were enroled and allocated to either the in-plane or out-of-plane group for supraclavicular subclavian vein cannulation. The procedure was attempted in 126 patients [Figure 3], with comparable demographic characteristics between groups [Table 1].

Figure 3.

Consolidated Standards of Reporting Trials (CONSORT) flow diagram

Table 1.

Demographic data of study participants

Characteristics	In-plane (n=64)	Out-of-plane (n=64)
Age (years)	49 (46.27, 51.78)	47.9 (44.6, 51.2)
Gender (male/female) n (%)	34/28 (54.8/45.2)	34/30 (53.2/46.8)
Weight (kg)	65.6 (63.2, 67.9)	63.2 (60.9, 65.5)
Height (cm)	162.8 (161.6, 164)	163.2 (162.0, 164.3)
BMI (kg/m2)	24.82 (3.95) (23.852–25.788)	23.72 (3.17) (22.943–24.497)

Values expressed as mean (standard deviation) (95% confidence interval) and frequency (n); BMI=body mass index

In the in-plane group (n = 62), successful cannulation was achieved in 56 cases, while six procedures were abandoned, five due to inadvertent arterial punctures and one due to guidewire resistance. In the out-of-plane group (n = 64), 63 were successfully cannulated, and one case was abandoned due to arterial puncture. The success rate was significantly higher in the out-of-plane group (98.4%) compared to the in-plane group (90.3%) (P < 0.05; Chi-square test used) [Table 2].

Table 2.

Comparison of success rate, procedural times, and additional attempts in cases with successful cannulation

Parameter	In-plane (n=62)	Out-of-plane (n=64)	P
Procedure abandoned (n)
Arterial puncture	5	1	-
Inability to pass the guidewire	1	0
Overall success rate (n)	56/62 (90.32%)	63/64 (98.43%)	0.04
First-pass success rate (n)	43/56 (76.8%)	60/63 (95.2%)	0.003
Time taken for venous puncture (seconds)	17.85 (9.07) (15.42, 20.29)	9.41 (3.08) (8.63, 10.19)	<0.001
Time taken for successful cannulation (seconds)	185.90 (32.75) (177.12, 194.66)	148.36 (31.10) (140.53, 156.20)	<0.001
Cases requiring needle redirections (n)	23 (41%)	4 (6.3%)	<0.001
Cases with additional skin puncture (n)	14 (25%)	3 (4.8%)	0.002
Cases with additional vein puncture (n)	6 (10.7%)	2 (1.6%)	0.146

Values expressed as mean (standard deviation) (95% confidence interval) and frequency (n)

First-pass success was also significantly better in the out-of-plane group (95.2%) versus the in-plane group (76.8%) (P < 0.05). Mean time for vein puncture was shorter in the out-of-plane group (9.41 (SD: 3.08) s) [95% confidence interval (CI): 8.63, 10.19] than in-plane (17.85 (SD: 9.07) s) (95% CI: 15.42, 20.29), as was mean total cannulation time [148.36 (SD: 31.10) s (95% CI: 140.53, 156.20) vs 185.90 (32.75) s (95% CI: 177.12, 194.66) (independent t-test) (P < 0.05) [Table 2]. Fewer redirections (4 vs 23), additional skin punctures (3 vs 14), and re-attempts at vein puncture (1 vs 6) were required in the out-of-plane group [Table 2]. Complications included one haematoma in the in-plane group and one catheter misplacement in the out-of-plane group. Arterial punctures were more common in the in-plane group (5 vs 1) [Table 3]. Operator satisfaction was significantly higher with the out-of-plane approach, with 92.2% rating it as ‘excellent’ compared to 53.2% for the in-plane technique [Table 3].

Table 3.

Comparison of operator satisfaction and incidence of complications

Parameter	In-plane (n=62)	Out-of-plane (n=64)	P
Operator satisfaction
5 - Excellent	33 (53.2%)	59 (92.2%)	<0.001
4 - Good	15 (24.2%)	3 (4.6%)
3 - Neutral	8 (12.9%)	1 (1.6%)
1 - Poor	6 (9.6%)	1 (1.6%)
Complications
Haematoma (n)	1 (1.61%)	0	-
Catheter misplacement (n)	0	1 (1.56%)	-
Arterial puncture (n)	5 (8.06%)	1 (1.56%)	-
Pneumothorax (n)	0	0	-
Haemothorax (n)	0	0	-
Difficulty in passing the guidewire (n)	1 (1.61%)	0

Values expressed as frequency (percentages)

DISCUSSION

In our study, the anterior out-of-plane approach showed a significantly higher first-pass success rate (95% vs 77%), shorter puncture and cannulation times, and fewer complications compared to the in-plane approach. Additionally, fewer needle redirections and complications, including arterial punctures (1 vs 5), were observed with the out-of-plane approach, with a superior operator satisfaction. The landmark technique for subclavian vein cannulation involves needle insertion at the junction of the clavicle’s upper border and the lateral margin of the sternomastoid muscle. The subclavian vein’s large size (up to 2 cm in adults), consistent patency, and protection by surrounding structures provide clear advantages. The supraclavicular approach allows the needle to traverse mainly fascial tissue to reach the vein, simplifying cannulation.

Several studies have compared subclavian vein and IJV cannulation. Trabelsi et al.[7] compared ultrasound-guided in-plane supraclavicular subclavian vein (IP-SSCV) catheterisation with out-of-plane IJV cannulation. They found the IP-SSCV group had fewer guidewire advancement issues, shorter insertion times, and higher first-attempt success rates. These differences were attributed to IJV collapsibility under probe or needle pressure and anatomical variability affected by respiration and volume status, supporting the preference for subclavian vein cannulation. Similarly, Gowda KY et al.[8] compared ultrasound-guided IJV cannulation with brachiocephalic vein (BCV) cannulation via the in-plane technique. Their BCV approach targeted the same sonoanatomy as our in-plane method, reporting an 81.8% first-attempt success rate and an average cannulation time of 150.70 (64.26) seconds, comparable to our in-plane group outcomes.

The observed 20% increase in first-pass success rate with the out-of-plane approach holds important clinical relevance. First-pass success is critical in minimising procedure time and patient discomfort, particularly in emergency or technically challenging vascular access scenarios. Multiple needle passes increase the risk of complications such as haematoma formation, arterial puncture, and infections, which may negatively impact procedural outcomes. Additionally, achieving success on the first attempt contributes to greater operator satisfaction by reducing procedural stress and improving confidence, as reflected in the operator satisfaction scores. Thus, the higher first-pass success rate associated with the out-of-plane technique reflects not only statistical significance but also meaningful clinical and practical benefit.

Subclavian vein cannulation can be performed via infraclavicular or supraclavicular ultrasound-guided approaches. The infraclavicular technique is often challenged by clavicular shadowing, necessitating a lateral needle insertion. In contrast, the supraclavicular approach provides superior visibility of the subclavian vein.[4] Jaiswal et al.[3] confirmed that the supraclavicular technique leads to shorter procedural times, better first-pass success rates, and reduced puncture times compared to the infraclavicular method.

The supraclavicular out-of-plane technique provides a direct, shorter needle path from the skin to the vein, consistent with our finding that needle redirections were more frequent in the in-plane group (41.1%) than in the out-of-plane group (6.4%). Ultrasound mechanics enhances this approach’s ergonomic advantages. The linear probe fits well across the supraclavicular fossa, and the needle appears as a dot in the out-of-plane view, facilitating confirmation of its position inside the vein lumen. This allows for optimal catheter placement centrally within the vessel, reducing wall trauma and enhancing safety. Additionally, with the pleura located beneath the vein, the needle’s tangential path lowers the risk of pleural puncture.

The in-plane long-axis view demands precise alignment to visualise the needle’s oblique path, contributing to longer procedure times. Mistaking the needle shaft for its tip due to imperfect beam alignment can lead to complications such as arterial or pleural puncture. The angulated probe position complicates needle visualisation further, and minor probe angle changes can erroneously display the artery instead of the vein.[10]

The out-of-plane approach benefits from a shorter needle trajectory as the needle is inserted almost perpendicularly to the skin, with the subclavian vein or confluence being the first superficial structure encountered. While visualising the entire needle shaft and tip is generally preferred in ultrasound-guided vascular access, this is less critical here. The reduced skin-to-vein distance (typically 1–1.5 cm) facilitates quicker venipuncture, contributing to higher operator satisfaction scores. Blaivas et al.[10] noted that short-axis, transverse views (out-of-plane) are easier for novices to learn than long-axis, longitudinal views (in-plane), which require tracking the entire needle length through tissues. This may explain the greater ease and acceptance of the out-of-plane approach among operators.

This study did not assess the time taken to acquire the ultrasound image in either approach, which differs between methods and could influence procedural duration. Additionally, catheter length was not compared between groups; the longer skin-to-vein distance in the in-plane approach could necessitate longer catheter lengths compared to the more direct venous access in the out-of-plane technique. In addition, blinding of the operator was not feasible due to the nature of the intervention, as the technique used for cannulation was inherently identifiable to the performer, which may be a potential source of performance bias.

CONCLUSIONS

For ultrasound guided supraclavicular approach to subclavian central venous cannulation, the first-pass success rate is significantly higher using the novel anterior out-of-plane approach. Practice, caution, and a certain amount of dexterity are needed for this novel technique.

Conflicts of interest

There are no conflicts of interest.

Presentation at conferences/CMEs and abstract publication

Paper presented at the ISACON SOUTH ZONE 2024, Tamil Nadu, on 21^st July 2024 and received best Paper Award.

Study data availability

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

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

The authors confirm that no AI tools or language models (LLMs) were used in the writing or editing of the manuscript, and no images were manipulated using AI.

Declaration of Use of Permitted Tools

All scales, scores, figures, and tables are not copyrighted.

Authors contributions

NMN, MVK, and PUB contributed to the study’s conception and design. NMN, AG, and RR collected and analysed the data. NMN and RR drafted the manuscript, and PUB revised the manuscript. MVK and AG performed statistical analyses and revised the manuscript.

Supplementary material

Nil.

Funding Statement

Nil.