Endocavitary versus Linear Array High-Frequency Probe in Ultrasound-Guided Supraclavicular Subclavian Vein Central Access.

BACKGROUND: Vascular access is a top priority in the critically ill patients. Cannulation - venous and/or arterial - is the first step in any emergency situation. Ultrasound (US)-guided vascular cannulation was found to have a higher success rate and a decreased incidence of mechanical complications as compared with the landmark one. AIM: This study aims to compare subclavian vein (SCV) access through supraclavicular (SC) approach by endocavitary (EC) probe technique versus linear array high-frequency probe technique. SETTINGS AND
DESIGN: A prospective, randomized controlled study conducted on 60 patients. PATIENTS AND METHODS: Study was carried out on 60 adult patients presenting for the surgical intensive care unit in Fayoum University Hospital. Patients were classified into two groups: Group (A) (n = 30): Catheter was inserted using the EC probe and Group (B) (n = 30): Catheter was inserted using the linear array high-frequency probe. STATISTICAL ANALYSIS USED: Student's t-test was applied for calculation of normally distributed variables and Mann-Whitney U-test for nonnormally distributed variables. Categorical data between the groups were compared using Chi-squared test. P < 0.05 indicated a statistically significant difference.
RESULTS: The frequency of successful cannulation of the SCV at first attempt was significantly higher in Group A compared to Group B (P = 0.044). The number of attempts and the time needed for venous access were significantly lower in Group A compared to Group B (P = 0.038, <0.001 respectively). No significant difference was found regarding the incidence of posterior wall puncture, arterial puncture, or hematoma, (P = 0.671, 0.055, 1 respectively).
CONCLUSION: The use of EC probe technique for Subclavian venous access through the SC approach significantly increased the success rate compared to the linear array high-frequency probe.

INTRODUCTION

Subclavian venous catheterization is a preferred route of central venous access in anesthesia. The procedure has a high success rate when compared to other techniques of central venous catheterization (CVC), especially to jugular access, which is considered by most physicians as the safest one.[1]

The supraclavicular (SC) approach is particularly advantageous because of the short distance from skin to vein and the straighter path to the superior vena cava.[23]

To guarantee patient safety, ultrasound (US) imaging provides an excellent vision of the anatomical parts and is increasingly used for central-line placement. Real-time US needle guidance is a precious tool for the needle insertion into the vessel on the first pass with minimal complications.[4]

The aim of this study is to compare the safety and efficacy of subclavian venous catheter insertion through an SC approach. It compares the endocavitary (EC) probe technique versus linear array high-frequency probe technique in critically ill patients.

PATIENTS AND METHODS

This study included 60 adult patients of both sexes undergoing CVC for various indications in the surgical intensive care unit (ICU). Approval of the Scientific and Ethical Committee and written informed consent from patients or their relatives were obtained. The study was carried out from March to September 2017.

The design of the study was a prospective cohort of patients divided into two groups; each group had 30 subjects. The sample size was determined using the outcomes of our pilot study which demonstrated that the cannulation success rate was 80%. To detect 16.7% increase in success rate and an effect size of 0.62, assuming a two-sided Type I error of 0.05, and a power of 0.80, a sample size of 60 patients (30 patients in each group) was be required.

Inclusion criteria included adult patients aged 18-year-old and above either admitted to ICU, combined trauma, surgical, and medical ICU patients.

Exclusion criteria included patients younger than 18-year-old, extensive lung disease (e.g., emphysema), vascular malformations, chest wall deformities, (healed) fracture clavicle, infected injection site, coagulopathy (normalized ratio >1.5), tumor extending into the right atrium, and fungating vegetations of the tricuspid valve.

Full medical history was taken followed by local examination of the SC and infraclavicular areas before catheterization. Subclavian catheterization was performed under local or general anesthesia.

The patients were randomly divided into two groups using a computer-generated random number table [Figure 1]:

Figure 1

Consort flow diagram

Group (A) (n = 30): catheter was inserted using the EC probe (4–8 MHz)

Group (B) (n = 30): catheter was inserted using the linear array high-frequency probe (3–12 MHz).

Steps

Preparation

Complete aseptic precautions (head cap, face mask, scrubbing, sterile gowns, and gloves) before catheterization

The cannulation kit was handled aseptically and laid on a sterile special table

The US probe was handled under complete aseptic technique. The probe was covered with a custom designed sterile cover. The sterile cover was prepared by the operator, and an assistant introduced the probe after coating with gel

Patients were supine in the Trendelenburg position, arms along the body

The anterior chest wall on the right side was sterilized with betadine, in compliance with the recommendations of the hospital infection control unit

Sterile drapes were placed around the aseptic field.

Wiring of the vein

For better visualization and good ergonomics, the ultrasonography machine was placed to the left side of the patient while the anesthesiologist was standing on the right side of the patient performing a right subclavian vein (SCV) catheterization.

The sterile plastic sheath was used to cover the US probe including the wire. All cannulation were performed under strict aseptic precaution.

In all patients, an 18G, 6 cm needle attached to a 5 ml syringe was used for venipuncture and a single lumen 20 cm long 14G central venous catheter was inserted.

The probe used for US-guided SC catheterization was placed in the SC fossa, just lateral to the clavicular head of the sternocleidomastoid muscle [Figure 2].

Figure 2

Location of the endocavitary probe and placement of the needle during the supraclavicular ultrasound-guided approach for cannulation of the right subclavian vein

The SCV is best found in the long axis (LA). The needle was advanced under US guidance using an in-plane approach. Proper position of the needle tip in the SCV was achieved by US visualization of the needle tip and aspiration of blood through the needle. After confirming the position of the needle tip in the SCV, a guidewire was threaded through the needle. Proper position of guide wire in the SCV was verified by US imaging.

The probe was placed in the midclavicular region; the needle is advanced in-plane under direct visualization until vessel puncture, then, the wire was introduced using Seldinger technique and verified by US.

Fixation of the catheter in the vein

Using a scalpel, a small snip was made over the wire

The dilator was introduced over the wire to dilate the pathway to the catheter

The dilator was removed; then the catheter introduced

The catheter holder was sutured to skin, and an adhesive plaster was applied.

Measurements

The primary outcome of the current trial was rate of success in SCV cannulation at first attempt.

Secondary outcome includes:

Number of attempts for venous access

Time needed for venous cannulation defined as the time taken from placing the probe over the skin to the point of successful aspiration of blood from the catheter

Posterior wall puncture (PWP)

Arterial puncture

Complications as pneumothorax, hematoma, or catheter-related blood infection.

Post insertion care

The patients had chest X-ray after an operation to detect any complication. The patient had been under full medical supervision for 2 days after the procedure.

Statistical analysis

Data were statistically described in terms of mean ± standard deviation, median, and range, or frequencies (number of cases and percentages) when appropriate.

The comparison of numerical variables between the study groups was done using Student's t-test for independent samples in comparing two groups when normally distributed and Mann–Whitney U-test for independent samples when not normally distributed. For comparing categorical data, Chi-square test was performed. The exact test was used instead when the expected frequency is <5. P < 0.05 was considered statistically significant. All statistical calculations were done using computer program SPSS (Statistical Package for the Social Science; SPSS Inc., Chicago, Illinois, USA) release 15 for Microsoft Windows (2006).

RESULTS

The demographic and laboratory data of both groups were comparable [Tables 1 and 2].

Table 1

Sociodemographic characteristics of patients in both groups

Table 2

Laboratory characteristics of the studied groups

Catheterization

Primary outcome

The frequency of successful cannulation of the SCV at first attempt was 96% in Group A (EC probe group) and 80% in Group B (linear probe group) this was statistically significant (P = 0.044).

Secondary outcome

The number of attempts was significantly lower in Group A (median 1, range 1–3) compared to Group B (median 2, range 1–4) (P = 0.038) [Figure 3].

Figure 3

Comparison between study groups regarding the number of attempts for venous access

The time needed for venous access was 5.1 ± 2.2 min in Group A and 7.1 ± 1.0 min in Group B (P ≤ 0.001) [Figure 4].

Figure 4

Comparison between study groups regarding the time needed for venous access

No significant difference was found regarding the incidence of PWP, arterial puncture or hematoma, (P = 0.671, 0.055, 1 respectively) [Table 3].

Table 3

The primary and secondary outcomes among the studied groups

None of the patients in both groups developed pneumothorax or catheter-related bloodstream infection.

DISCUSSION

This study provides an evidence that the use of EC probe technique for subclavian venous access through the SC approach significantly increased the success rate at first attempt compared to the linear array high-frequency probe with no significant difference in complication rate including PWP, arterial puncture, or hematoma.

SCV catheterization is an important tool and a useful skill in clinical situations where internal jugular vein catheterization may not be possible. This is commonly encountered in patients with cervical immobilization with a neck collar, complex head, and neck surgeries and infections in the neck.[5]

Both SC and infraclavicular procedures can be used for cannulation of the SCV, with the latter being more routinely performed by most operators.[6]

US allows identification of a suitable target vessel and ensures good visualization of the surrounding anatomy, allowing a planned approach. The pathway to, and the site of, vessel puncture can be determined and viewed in real time to avoid specific surrounding structures.[7]

However, the latest National Institute for Clinical Excellence Guidelines require that operators maintain their ability to use the landmark method. In a clinical context, the SC method is still taught alongside the two-dimension US-guided technique, as this may be required in emergencies.[7]

To compare SCV access through SC approach by EC probe technique versus linear array high-frequency probe technique. A prospective, randomized controlled was conducted on 60 patients presenting for the surgical ICU unit. Patients were classified into two groups: Group (A) (n = 30) where the catheter was inserted using the EC probe and Group (B) (n = 30) where the catheter was inserted using the linear array high-frequency probe.

In the current study, the EC probe technique was demonstrated to be more effective in SCV cannulation at first attempt with less number of attempts for venous access and considerably shorter time needed for venous access than with the linear array high-frequency probe technique.

In accordance with our results, in the study of Byon et al.,[8] the authors performed SCV catheterization guided by US through both the SC and infraclavicular (IC) routes. The authors' success rate was 100%, with no incidence of complications in the SC group. The success rate of Breschan et al.[9] was 98.9%.

In the present study, there is no significant difference between both techniques in inducing PWP, arterial puncture or hematoma. None of the patients in both groups developed pneumothorax or catheter-related bloodstream infection.

In agreement with the above, LeFrant et al.[10] found that the rate of complication was reduced with the use of US: This is explained by the fact that the SCV is anterior and inferior to the SC artery. It is separated by the thickness of the anterior scalene muscle (10–15 mm).[6] The SC artery should not be punctured unless the posterior angle is exceptionally increased (approximately 70°) or unless the skin entry point is moved posteriorly over 1 cm.[11]

Contrastingly, Lu et al.[6] noted that the complication rate of arterial puncture seemed to be higher in the SC groups than in the infraclavicular groups. The authors attributed this to the fact that the subclavian artery and vein are more tightly bundled and parallel in infants than in adults, making it easy to accidentally puncture the subclavian artery by the SC route. This different opinion could be attributed to the different study population since the study was performed on patients in the pediatric age group.

In the current study, pneumothorax was not reported in any of the patients. This finding was against our expectations since it was assumed that the SC approach is more likely to produce pneumothorax. This could be attributed to the presence of the underlying first rib that serves as a barrier between the SCV and parietal pleura reducing the risk of pneumothorax.[11]

On the other side, different complication rates were reported by Fragou et al.[12] regarding arterial puncture (5.4%), pneumothorax (4.9%), and malposition (11.0%), while the complication rate of Hussain et al.[13] was 2.8%.

This difference might be due to the relatively small number of patients in the current study group and that this approach depends on manual skills and practice.

In previous studies, it was reported that the use of real-time US for SC SCV cannulation is limited because of a lack of space in the SC area for both the US probe and the needle used for cannulation.[14]

To overcome this limitation, Mallin et al. described an SC approach using an EC probe with a smaller footprint, allowing adequate space for real-time US-guided cannulation.[7] Using the EC probe technique, the vein is encountered quite superficially, (typically at 0.5–1.5 cm) with a characteristic give as the needle enters the lumen.[7] As most US systems are not routinely provided with EC probes, currently available literature favors the infraclavicular route as the preferred approach for SCV cannulation. Future studies focusing on smaller US vascular probes may lead to better evaluation of the SC approach.

Limitations of the current study were the exclusion of neonates, pediatric patients, and obese patients.

Since the number of randomized controlled trials of variable methodological quality that have addressed US use for SCV catheterization is limited, the current study findings should be interpreted with caution.

No studies reported infection, thrombus, or arrhythmias. This is somewhat surprising given that many of these adverse events are expected with subclavian catheterization; this could represent selective reporting or a failure to screen for such outcomes. Moreover, this could be attributed to the operator experience.

Future studies will need to determine which patients and physicians benefit the greatest from US use for subclavian catheterization. Because US-guided vascular access is an effective but operator-dependent technique, its increased costs may be useful for untrained physicians accessing the SCV in obese and conscious patients.

Cost efficiency must also be taken into consideration as US-guided placement includes staff training, purchase, and maintenance of the machine all being affordable.

The current study investigated successful cannulation of the vessel. We did not evaluate insertion of the needle into the venous access site by LA or short axis. Therefore, we cannot conclude whether using the LA approach may be more difficult due to the insertion of the needle tip close to the lateral wall during catheter placement. Further investigations are required to determine whether LA approach is associated with any difficulties with central venous catheter placement.

Future studies of US-guided subclavian catheterization should consider larger number of sample size and considering guidelines for better reporting of complications.

CONCLUSION

The EC probe technique proved better than the linear array high-frequency probe technique for the SC approach of SCV catheterization regarding successful cannulation at first attempt, number of attempts to achieve a successful cannulation and procedure time. Therefore, its use in US guided vascular cannulation is recommended to ensure secure patent and rapid vascular access in critically ill patients.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.