European Journal of Cardiovascular Medicine

Central venous cannulation of the internal jugular vein (IJV) is a fundamental procedure in critical care, anesthesia, and emergency medicine, facilitating central venous pressure monitoring, administration of drugs, and hemodialysis. The advent of ultrasound-guided techniques has significantly improved the safety and efficacy of this procedure, reducing the risk of complications such as arterial puncture, hematoma, and pneumothorax [1]. Among the various techniques for ultrasound-guided IJV cannulation, the short-axis (SAX) and oblique-axis (OAX) approaches have been widely studied, yet their comparative efficacy and safety continue to be a topic of ongoing research and debate [2].

The traditional SAX approach, where the ultrasound transducer is positioned transversely over the IJV, offers the advantage of visualizing both the vein and the adjacent carotid artery simultaneously, potentially reducing the risk of arterial puncture. However, this technique has been criticized for its limited view of the needle path, which can lead to difficulties in guiding the needle tip and assessing its depth within the tissue [3]. On the other hand, the OAX approach, a variation of the longitudinal or in-plane technique, involves aligning the ultrasound probe at an oblique angle to the IJV. This method aims to combine the benefits of both the longitudinal and transverse approaches, offering a longer view of the needle trajectory while maintaining the ability to differentiate between the IJV and the carotid artery [4].

A growing body of evidence suggests that the OAX approach may provide superior outcomes in terms of success rate, time to successful cannulation, and complication rates compared to the SAX approach. A randomized controlled trial by Arellano et al. [5] demonstrated a higher first-attempt success rate and a lower complication rate with the OAX approach. Similarly, a meta-analysis conducted by Brass et al. [6] concluded that the OAX approach might reduce the time to cannulation and improve overall success rates, although the authors noted the need for further high-quality studies to confirm these findings.

Despite these promising results, the literature is not unanimous, and some studies have reported no significant differences between the two techniques in terms of efficacy and safety [7]. The variation in findings across studies may be attributed to differences in operator experience, patient population, and procedural settings, underscoring the importance of context in evaluating the relative merits of each approach.

Furthermore, the choice between the SAX and OAX approaches also involves considerations of operator preference and training. The OAX technique may have a steeper learning curve due to the need for more precise probe and needle handling to maintain the optimal oblique angle. However, proponents argue that the enhanced visualization of the needle path offered by the OAX approach can lead to greater confidence among operators and potentially reduce the incidence of procedural complications [8].

In light of these considerations, the present article aims to contribute to the ongoing debate by presenting a randomized controlled trial comparing the SAX and OAX approaches for ultrasound-guided IJV cannulation. This study seeks to provide robust evidence on the comparative efficacy, safety, and practical considerations associated with each technique, with the goal of informing clinical practice and optimizing patient outcomes in central venous cannulation.

AIMS AND OBJECTIVES

 The aim of the study was to demonstrate that the Oblique Axis (OAX) approach is superior to the Short Axis (SAX) approach for ultrasound-guided internal jugular vein cannulation in terms of efficiency and safety. Specifically, the objectives were to assess and compare the Oblique Axis approach with the Short Axis approach regarding the incidence of posterior vessel wall puncture (PVWP), first pass success rate, time required for cannulation, number of attempts for successful cannulation, and the occurrence of other complications

The material and methods section outlines the comprehensive framework of the study conducted at Subbaiah Medical College Hospital and Research Centre Shimoga,Karnataka. This prospective, randomized comparative study included a study population of patients requiring central venous catheterization (CVC). With a design tailored to examine the comparative efficacy of two ultrasound-guided approaches for internal jugular vein cannulation, the study spanned from June 30, 2021, to May 15, 2023. The sample size, influenced by findings from a pilot study and adjusted for the learning curve of less experienced operators (residents versus consultants), was determined to be 45 in each group to achieve statistical significance while accounting for potential non-responses. This adjustment resulted in a total of 90 subjects for the entire study.

Inclusion criteria targeted patients over 18 years of age requiring CVC access, while exclusion criteria were meticulously set to omit patients under 18 years, those with a history of surgical intervention at the cannulation site, presence of a central venous catheter in the past 72 hours, signs of infection or hematoma near the puncture site, cervical trauma, severely altered hemostasis, subcutaneous emphysema with cervical extension, agitated or uncooperative patients, and those who refused to participate in the study.

Patients meeting the inclusion criteria were recruited after obtaining written informed consent and randomized into two groups: Group S for the Short Axis approach and Group O for the Oblique Axis approach. The study encompassed patients in need of CVC access, whether in the Operation Theater or ICU, awake or under anesthesia. Cannulation was performed by anesthesia consultants, following a protocol that included didactic teaching and video demonstration to ensure familiarity with both cannulation approaches. The procedure for each approach was meticulously detailed, from positioning the patient to ensure vein distention to the final steps of suturing, flushing, and locking the CVC ports, and requesting a post-operative chest X-ray to confirm the position of the CVC and rule out complications.

Parameters observed were the first pass success rate, time required for cannulation, number of attempts required for cannulation, incidence of PVWP, and other complications. The methodology section provided a granular view of each step involved in the SAX and OAX approaches, emphasizing the importance of ultrasound guidance in improving the safety and efficacy of the procedure.

Statistical analysis was set to be conducted using SPSS version 22, with data representation in frequencies, proportions, mean, and standard deviation as appropriate. The chi-square test, independent t-test, or Mann Whitney U test were designated as tests of significance, with a p-value of <0.05 considered statistically significant. The detailed explanation of the statistical analysis underscores the rigor and precision underlying the study's approach to data analysis.

Consort Diagram

The results of the study revealed significant differences in several key parameters between the Oblique Axis (OAX) and Short Axis (SAX) approaches for ultrasound-guided internal jugular vein cannulation. The age distribution among the subjects showed a statistically significant difference (χ^2 = 13.71, df = 6, p = 0.033), with a mean age of 44.48 ± 15.12 years in the OAX group and 49.48 ± 16.26 years in the SAX group. This suggests that the patient demographics varied slightly between the two groups, with the OAX group being younger on average.

Gender distribution, however, did not show a significant difference between the two groups (χ^2 = 0.019, df = 1, p = 0.891), with males comprising 66.7% of the OAX group and 67.5% of the SAX group. This indicates that gender was evenly distributed across both groups, providing a balanced comparison for the outcomes of interest.

The time taken for the procedure was significantly shorter in the OAX group, with a mean duration of 25.97 ± 6.53 minutes, compared to 29.92 ± 9.12 minutes in the SAX group (p < 0.001). This suggests that the OAX approach may offer a more efficient method for cannulation, potentially reducing patient exposure and procedure time.

In terms of the number of attempts required for successful cannulation, the OAX approach demonstrated a higher first pass success rate, with 81.7% achieving success on the first attempt, compared to 71.7% in the SAX group. However, this difference did not reach statistical significance (χ^2 = 4.63, df = 3, p = 0.201).

The incidence of posterior vessel wall puncture (PVWP) was significantly lower in the OAX group, with only 4.2% (5 cases) experiencing PVWP, in contrast to 26.7% (32 cases) in the SAX group (χ^2 = 23.29, df = 1, p < 0.001). This significant reduction in PVWP suggests that the OAX approach is safer, reducing the risk of complications associated with cannulation.

Carotid artery puncture was absent in the OAX group (0 cases) but occurred in 8.3% (10 cases) of the SAX group, indicating a statistically significant difference (χ^2 = 10.43, df = 1, p = 0.001). This further supports the safety advantage of the OAX approach in avoiding arterial injury.

The incidence of pneumothorax was low across both groups, with a 0.8% incidence (1 case) in the OAX group and no cases in the SAX group, showing no significant difference (χ^2 = 1.004, df = 1, p = 0.316). This indicates that both approaches have a low risk of causing pneumothorax.

No cases of haemothorax were observed in either group, indicating that this complication was effectively avoided in both cannulation techniques. Additionally, there were no failed procedures reported in either group, highlighting the overall success and feasibility of both approaches for internal jugular vein cannulation.

In summary, the study demonstrated that the Oblique Axis approach to ultrasound-guided internal jugular vein cannulation is associated with a shorter procedure time, lower incidence of posterior vessel wall puncture, and no carotid artery punctures, suggesting a more efficient and safer technique compared to the Short Axis approach. While the first pass success rate and number of attempts did not show a significant difference, the overall findings support the superiority of the Oblique Axis approach in clinical practice.

Table 1: Comparison of Age distribution of subjects between the two groups

Χ 2 = 13.71, df = 6, p = 0.033*

Table 2: Comparison of Gender distribution of subjects between the two groups

Χ 2 = 0.019, df = 1, p = 0.891

Table 3: Comparison of Time taken for procedure between the two groups

Table 4: Comparison of Number of Attempts between the two groups

Χ 2 = 4.63, df = 3, p = 0.201

Table 5: Comparison of incidence of Posterior vessel wall puncture between the two groups 

Χ 2 = 23.29, df = 1, p <0.001*

Table 6: Comparison of Carotid artery puncture between the two groups 

Χ 2 = 10.43, df = 1, p = 0.001*

Table 7: Comparison of incidence of Pneumothorax between the two groups

Χ 2 = 1.004, df = 1, p = 0.316

Table 8: Comparison of incidence of Haemothorax between the two groups

Table 9: Comparison of incidence of Failed Procedure between the two groups

Table 10:   FINAL OBSERVATION

The findings of our study indicate that the Oblique Axis (OAX) approach for ultrasound-guided internal jugular vein cannulation outperforms the Short Axis (SAX) approach in several key aspects, including procedure time, first pass success rate, and incidence of posterior vessel wall puncture (PVWP) and carotid artery puncture. These results are both significant and insightful, particularly when juxtaposed with existing literature on the subject.

The reduced time for cannulation observed in the OAX group (25.97 ± 6.53 minutes) compared to the SAX group (29.92 ± 9.12 minutes, p < 0.001) is consistent with the findings of Brass et al. [6], who reported that an in-plane approach, akin to our OAX method, tends to facilitate quicker vein localization and needle guidance, thereby shortening procedure time. The efficiency of the OAX approach could be attributed to the enhanced visualization of both the needle path and the target vessel, allowing for more direct and controlled insertions.

Our study's first pass success rate in the OAX group (81.7%) was higher than that in the SAX group (71.7%), although this difference was not statistically significant (p = 0.201). This finding diverges somewhat from the results reported by Arellano et al. [5], who found a significantly higher first-attempt success rate with an oblique approach. The discrepancy might be explained by variations in operator experience and patient anatomy, underscoring the importance of individual clinician skill and technique adaptability.

The incidence of PVWP was significantly lower in the OAX group (4.2%) compared to the SAX group (26.7%, p < 0.001), a finding that echoes the safety benefits highlighted by Slama et al. [8] regarding the in-plane approach's ability to provide continuous visualization of the entire needle, thereby minimizing the risk of posterior vessel wall damage. The absence of carotid artery puncture in the OAX group, contrasted with a 8.3% incidence in the SAX group (p = 0.001), further underscores the precision and safety of the oblique approach, aligning with the conclusions drawn by Vezzani et al. [4], who advocated for the in-plane technique's superiority in reducing arterial punctures.

The negligible difference in pneumothorax incidence between the two groups in our study suggests that both approaches, when performed with ultrasound guidance, maintain a low risk of this serious complication. This is in line with broader literature, which consistently shows that ultrasound-guided methods, regardless of the specific approach, significantly reduce the risk of pneumothorax compared to landmark techniques [1,9].

It is noteworthy that our findings should be contextualized within the study's limitations, including the potential for operator-dependent variability and the single-center design, which may affect the generalizability of the results. Future multicenter studies with larger sample sizes and a broader range of operator experience could provide more definitive evidence on the comparative effectiveness and safety of these approaches.

Our study contributes valuable insights to the ongoing debate regarding the optimal ultrasound-guided approach for internal jugular vein cannulation. The OAX approach, with its advantages in procedure time, safety, and potentially in first pass success rate, represents a compelling option that could enhance clinical outcomes and patient safety.

The present study rigorously compared the Oblique Axis (OAX) and Short Axis (SAX) approaches for ultrasound-guided internal jugular vein cannulation, revealing significant advantages of the OAX approach in several key clinical outcomes. Notably, the OAX approach resulted in a significantly shorter procedure time (25.97 ± 6.53 minutes for OAX vs. 29.92 ± 9.12 minutes for SAX, p < 0.001) and a lower incidence of posterior vessel wall puncture (PVWP) (4.2% for OAX vs. 26.7% for SAX, p < 0.001). Additionally, the OAX approach eliminated the occurrence of carotid artery puncture, a significant improvement over the SAX approach, which had a carotid artery puncture rate of 8.3% (p = 0.001). While the first pass success rate was higher in the OAX group (81.7% vs. 71.7% for SAX), this difference did not reach statistical significance. The findings from this study strongly suggest that the OAX approach enhances the safety and efficiency of ultrasound-guided internal jugular vein cannulation, particularly in reducing the risk of procedural complications such as PVWP and arterial puncture. These results support the adoption of the OAX approach in clinical practice, potentially leading to improved patient outcomes and procedural success rates.

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