What do Cochrane systematic reviews say about ultrasound-guided vascular access?

ABSTRACT BACKGROUND: Ultrasonography is currently used in investigating many vascular diseases, especially for guiding vascular access. OBJECTIVE: The objective here was to summarize the evidence from Cochrane systematic reviews (SRs) on the effects of ultrasound-guided vascular access as an intervention approach. DESIGN AND SETTING: Review of SRs, conducted in the Division of Vascular and Endovascular Surgery of Universidade Federal de São Paulo. METHODS: A broad search was conducted in the Cochrane Database of Systematic Reviews to retrieve any Cochrane SRs that assessed the effects of ultrasound guidance as a therapeutic approach towards performing any vascular access. The key characteristics and results of all the reviews included were summarized and discussed. RESULTS: Three SRs on venous access at all ages and one review on arterial access in pediatric participants were included. There was low to moderate certainty of evidence that ultrasound increased the success rate from the first puncture and the overall success rate of the procedure; and reduced the total rate of perioperative and postoperative adverse events, number of punctures, time needed to achieve success and rate of failure to place catheters. CONCLUSION: Evidence of low to moderate quality showed that ultrasound-guided vascular access seems to reduce the total rate of perioperative and postoperative complications/adverse effects, number of punctures, time needed to achieve success and rate of failure to perform venous catheterization in adults and arterial punctures in children. There is a lack of information regarding ultrasound-guided arterial puncture in adults. Further studies are still imperative for reaching solid conclusions, especially regarding arterial ultrasound-guided access.


INTRODUCTION
In almost all medical specialties, from pediatrics to geriatrics, at some point, doctors face the need to use vascular access in their patients. In the United States, over 15 million central vascular catheter-days occur in intensive care units per year. 1 Anatomical landmarks have been used as a guide for performing vascular access for a long time, but their use has been correlated with a number of complications (e.g. infections, hematomas, pneumothorax and death). [1][2][3] Over recent decades, ultrasound has been used as a possible aid for diagnostic purposes, including in bedside examinations and for possibly avoiding complications in various procedures. 4 In addition, technological advances have made portable ultrasound viable. [4][5][6] Although there are some practical guidelines that make recommendations regarding standard use of ultrasound to guide venous catheterization, up to 40% of doctors are resistant to using this evidence in their practice. 7,8 A number of guidelines are available for evaluating ultrasound-guide venous access but there is a lack of such guidelines for arterial sites. 9,10 Despite the large amounts of money that have been invested in research on this topic, the relevance of ultrasound-guided vascular access as a therapeutic approach is still a matter of debate, especially in relation to arterial puncture. Because the use of ultrasound as an additional intervention may be a reasonable alternative for improving the results relating to many types of vascular access, it is imperative to assess the effects of ultrasound-guided access through well-conducted randomized controlled trials.

OBJECTIVE
The aim of this study was to identify and summarize the evidence from Cochrane systematic reviews (SRs) regarding ultrasoundguided vascular access, in an overview.

Design and setting
This was a review of Cochrane systematic reviews conducted in the Division of Vascular and Endovascular Surgery, Universidade Federal de São Paulo, Brazil.

Types of participants
We considered all participants who underwent a vascular access procedure, both males and females, of all ages, without any restriction regarding the site of puncture.

Types of interventions
We considered SRs that assessed any vascular access technique, such as the Seldinger technique, as an intervention, if comparison with ultrasound-guided access was made in at least one of the study arms. 11

Types of outcomes
We considered any patient-relevant clinical or laboratory outcomes, as assessed by the authors of the SRs included.

Search for reviews
We conducted a sensitive systematic search in the Cochrane Database of Systematic Reviews (CDSR, via Wiley) on July 3, 2018. We used the following MeSH terms and all related variants in the titles, abstracts and keywords: "vascular access devices", "endovascular procedures", "ultrasonography", "ultrasonography, Doppler" and "ultrasonography, interventional". The detailed search strategy is presented in Table 1.

Presentation of results
The results from the search and the SRs included were presented as a qualitative synthesis (descriptive approach).

Search results
Our search strategy retrieved 221 references and, after screening the titles and abstracts, 11 SRs were preselected. After assessing the full texts, four reviews fulfilled the inclusion criteria and were included in the qualitative synthesis. 12-15

Reviews included
The latest versions of all the SRs included were published between 2011 and 2016. Details regarding the characteristics of the interventions, comparisons and outcomes and the certainty of evidence are presented in Table 2.

Ultrasound use for placement of hemodialysis catheters
The objective of this systematic review 12    A meaningful reduction in the time required for successful vein puncture, from the time when the skin was anesthetized, was found with real-time ultrasound guidance (MD -1.40 minutes; 95% CI: -2.17 to -0.63).

Complications
Real-time ultrasound guidance was found to significantly decrease the risk of carotid artery puncture (RR 0.22; 95% CI: 0.06 to 0.81) and led to a significant reduction in the risk of hematoma (RR 0.27; 95% CI: 0.08 to 0.88). There were no differences between patient groups regarding the risk of pneumothorax or hemothorax (RR 0.23; 95% CI: 0.04 to 1.38).

Conclusions of this study
There are benefits from the use of real-time 2D Doppler ultrasound guidance with regard to the number of catheters successfully inserted on the first attempt. There was lower risk of arterial puncture and hematomas and less time was taken for successful vein puncture.

Ultrasound guidance versus anatomical landmarks for internal jugular vein catheterization
This systematic review 13

Main findings
Use of 2D ultrasound improved the overall success rate by 12% (23 trials with 4,340 participants; RR 1.12; 95% CI: 1.08 to 1.17; P-value < 0.00001; I² = 85%), with no difference between use of Doppler and use of 2D ultrasound. However, the quality of this evidence was very low, due to uncertainty regarding the analysis on data from Doppler ultrasound.
The 2D ultrasound reduced the number of attempts needed to succeed (16 studies; 3,302 participants), with very low quality of evidence. Only at the first attempt was it found that Doppler

Conclusions of this study
This systematic review 13 suggested that use of 2D ultrasound in relation to venous catheter insertion into the internal jugular vein improves the results and diminishes adverse events, with very low to moderate quality of evidence. Use of Doppler ultrasound was better at the first attempt, with no difference in other outcomes. These results should be used with caution because of the quality of the present evidence and heterogeneity.

Ultrasound guidance versus anatomical landmarks for subclavian or femoral vein catheterization
Similarly to the review by Brass et al., 13

Main findings
For subclavian/axillary vein cannulation, the quality of the evidence was low regarding the overall success rate. There was no evidence that use of 2D ultrasound or Doppler ultrasoundguided puncture techniques made any difference in this outcome (RR 1.05; 95% CI: 0.97 to 1.13; P-value 0.22; I² = 78%).
However, for femoral vein catheterization, a small increase in the overall success rate was reported (RR 1.11; 95% CI: 1.00 to 1.23; P-value 0.06; I² = 50%) with moderate quality of evidence.
For subclavian/axillary vein cannulation, there was no evidence of any difference between landmark and 2D real-time puncture ultrasound regarding the number of attempts needed to succeed (MD -0.38; 95% CI: -1.26 to 0.50; P-value 0.39; I² = 92%).
However, the quality of the evidence was very low. For femoral vein catheterization, this outcome was reported in only one trial.
There was no evidence of any difference in the time taken to achieve successful cannulation for the subclavian/axillary vein

Conclusions of this study
2D ultrasound improves the safety and quality, compared with an anatomical landmark technique for the subclavian or femoral vein, but the results are uncertain.

Ultrasound-guided arterial cannulation for pediatrics
Ultrasound guidance may be useful not only for central venous access, but also in arterial and peripheral cannulation. 15  The review authors were unable to perform a meta-analysis on the time taken for successful cannulation and the number of cannulas used. The number of attempts required for successful cannulation was presented in two studies, but no meta-analysis was possible.
The review authors did not conduct a sensitivity analysis.
However, results regarding the need for assistance from another operator (i.e. the primary operator failed when attempting to insert the cannula and asked for help) were presented in one of the studies. A rate of 30.6% was reported in the ultrasound group, versus 33.7% in the palpation group (P = 0.73; 152 catheters).

Complications
The rate of complications such as hematoma was significantly reduced when using 2D ultrasound guidance during radial artery cannulation (RR 0.20; 95% CI: 0.07 to 0.60). The quality of the evidence was moderate. No studies reported any data on ischemic damage.

Conclusions of this study
There is evidence of moderate quality to support the use of ultrasound guidance for radial artery cannulation. Improved success rates at the first and second attempts were identified, along with lower complication rates, compared with the other techniques.
Improved success rates at the first try may be more pronounced among infants and young children.

DISCUSSION
The overall analysis on the reviews included suggested that use of 2D ultrasound-guided vascular access provided benefits, compared with use of anatomical landmarks and the palpation technique alone.
Reduction in the total rate of perioperative and postoperative complications/adverse effects was found in one of the reviews in relation to internal jugular vein catheterization using 2D ultrasound. Hematoma formation was reduced through application of ultrasound in all of the four SRs included. However, none of these reviews addressed the impact of use of ultrasound on patient discomfort and mortality. Nor did they evaluate the impact of different types of devices (e.g. point-of-care versus standard devices) and the skill with which these instruments are applied.
The major limitation of this overview was the small number of reviews included. Another limitation was that one of the reviews was out of date in the sense that it did not evaluate the evidence using the GRADE approach. 12 This imposed limits on comparison of the evidence with that of the other reviews. Another issue was the low certainty of the evidence regarding most of the outcomes and the lack of evidence regarding arterial puncture in adults. Over recent decades, use of endovascular procedures has increased, and use of arterial accesses in adults, frequently via the radial or femoral artery, has become a routine procedure. Use of other arterial access points, such as the radial artery, especially in intensive care units for hemodynamic evaluation or blood sample collection, has given rise to concerns regarding avoidance of adverse events, considering that puncture may be performed frequently.
Nevertheless, all of the reviews included suggested that use of ultrasound for guided vascular access provided various benefits, compared with use of anatomical landmarks (vein puncture) and palpation (artery puncture) alone.
Some of the most recent clinical practice guidelines [16][17][18] assessed the outcomes from ultrasound-guided vascular access only superficially or did not assess these outcomes, and they did not include any of the Cochrane SRs evaluated here. [12][13][14][15][16][17][18] Therefore, the results from the present review may also serve to improve the next versions of the guidelines relating to vascular access. [16][17][18] CONCLUSION Even with limitations regarding the quality of evidence, all of the four Cochrane reviews included in this overview showed that ultrasound guidance for vascular access provided some benefits.
There is a lack of information regarding ultrasound-guided arterial puncture in adults. Therefore, further well-designed and wellconducted studies from which solid conclusions can be reached are still imperative, especially regarding arterial ultrasoundguided access. Additional evidence with high certainty regarding ultrasound guidance for venous and arterial puncture is needed in order to build up a robust body of evidence in this setting.

Ethics
This was not a primary study, i.e. we did not deal directly with patients. Therefore, no ethics committee approval was necessary.