Ultrasound-guided peripheral venous access: a meta-analysis and systematic review

Introduction

Peripheral venous access is essential for emergency care, for the delivery of life-saving medications, fluids, and laboratory analysis. Obtaining necessary peripheral venous access is difficult in approximately 35% of patients who present to the emergency department (1). With multiple failed attempts at peripheral venous access placement, patients experience pain, suffer delays in their care, and are also at risk for infection (2). In circumstances in which no peripheral venous access is possible, central venous access is often the alternative (3). Central venous lines have enormous risks, including infection, arterial puncture, bleeding, thrombosis, pneumothorax, hemothorax, air embolism, and catheter misplacement. Reducing central line associated bacterial infections has become a priority of several governmental agencies, healthcare providers, insurers, and regulators due to the increased cost and morbidity associated with central lines (4, 5). The insertion of central lines due to poor peripheral venous access without other appropriate indications poses an unnecessary risk for the patient.

One alternative to traditional landmark-driven, palpation, or blind techniques of placing peripheral venous lines is using ultrasound guidance for placement. Several studies have been published evaluating the efficacy of ultrasound-guided peripheral venous access, with some finding a benefit and others no benefit, compared with traditional techniques (6-12). The objective of this study was to determine through a systematic review of the literature and meta-analysis whether success rates, time to cannulation, and number of punctures required for peripheral venous access are improved with ultrasound guidance compared with traditional techniques in patients with difficult peripheral venous access.

Methods

Study design

A systematic review protocol was created to specifically address the study question. The protocol was reviewed and agreed upon by all co-investigators a priori. This study was approved as exempt by the institutional review board.

Search strategy

The following databases were selected for search: MEDLINE, Web of Science, The Cochrane Library, ClinicalTrials.gov, Cumulative Index to Nursing, and Allied Health Literature. A basic web search was also performed. The search strategy was designed by a medical librarian [CH] with experience in systematic reviews and the searches were conducted with the assistance of the librarian. No limits were used in any database search. All languages, ages, providers, and patient settings were included. The search was conducted in ­November 2012 and was not otherwise limited by date. Search terms included ultrasonography, sonography, intravenous, catheter, vein, venous access, intravenous lines, intravenous (IV) insertion, cannulation, and several variations of these words. Cited references from all selected articles were reviewed for any additional studies.

Study selection

Specific inclusion and exclusion criteria were chosen a priori to accurately answer the study question and minimize bias in the selection process. Studies were included in this meta-analysis if they met the following criteria: patients of any age identified as having difficult peripheral venous access; real-time ultrasound guidance was used for peripheral venous cannulation; and inclusion of at least one of these outcomes (success rates of peripheral venous placement, time to successful cannulation, and number of punctures required for successful cannulation). The definition of difficult peripheral venous access is variable throughout the literature. For the purposes of this analysis, minimum criteria were defined as a patient history of difficult peripheral venous access or a ­minimum of two failed traditional palpation or landmark-based attempts. Peripheral venous access was defined as placement in a peripheral vein, a catheter length not exceeding 9 cm, and termination of the catheter in a peripheral vein. Literature was screened by title or abstract review by two independent reviewers [LS, IF]. Discrepancies were reviewed by a third party [US]. Full-text articles were assessed for eligibility by two independent reviewers [LS, IF] with discrepancies reviewed by a third party [US]. Chosen articles were assessed for study quality by LS and IF. Studies with risk of bias that was deemed to be serious were excluded.

Outcome measures

The primary outcome measure was success rate of peripheral venous placement. The secondary outcomes were time to successful cannulation and number of punctures.

Data analysis

Data were abstracted from reports using standardized forms by two extractors [US, LS]. Data were then compared and disagreements were discussed by abstractors and reviewed by a third party [IF].

We used random effects models using the method of DerSimonian and Laird, with estimates of heterogeneity taken from the Mantel-Haenszel model (13) to estimate the pooled odds ratio (OR) for success, weighted mean difference for number of punctures, and time to cannulation. Forest plots were used to present results for each outcome. Funnel plots were used to look for evidence of publication bias. All analyses were done using Stata v.12.1 (StataCorp, College Station, Texas, USA) using the “metan” module.

Results

After database review, removal of duplicates, title and abstract review, and full article review, seven studies were identified for final analysis (Fig. 1 and Tab. I) (6-12). These included six peer-reviewed publications and one peer-reviewed abstract. One governmental publication was excluded due to high risk of bias due to failure to use intention-to-treat analysis, failure to meet a priori power analysis, and lack of peer-review (14).

Table I -

Characteristics of studies included in meta-analysis

	Study design	Location	Operator	Age group	Ultrasound-guided cannulation technique
RCT = randomized controlled trial; ED = emergency department.
Aponte 2007 (6)	RCT	Surgical suite	Nurse anesthetist	Adults	Transverse
Benkandra 2012 (7)	RCT	Surgical suite	Physician	<3 years	Long-axis
Costantino 2005 (9)	Prospective,systematically allocated	ED	Physician	Adults	Transverse
Costantino 2010 (8)	RCT	ED	Physician	<10 years	Transverse
Doniger 2009 (10)	RCT	Pediatric ED	Nurse	Adults	Transverse
Kerforne 2012 (11)	RCT	Intensive care unit	Nurse	Adults	Not reported
Stein 2009 (12)	RCT	ED	Physician	Adults	Long-axis and transverse

Fig. 1 -

The pooled random effects OR for ultrasound-guided peripheral venous access success versus traditional technique peripheral venous success was 3.96 [95% confidence interval (95% CI) 1.75-8.94), indicating that ultrasound-guided peripheral venous access was successful more frequently than traditional methods (Fig. 2). The heterogeneity Chi-squared p-value was 0.12; however, the overall I-squared (proportion of results attributable to heterogeneity] was 41% and the between-study variance Tau-squared equal to 0.465. The funnel plot showed no obvious asymmetry (Fig. 3). One study was identified as a potential outlier (9). Sensitivity analysis ­excluding this study gave a pooled random effects OR for ultrasound-guided success versus traditional success of 3.13 (95% CI 1.71-5.73) with a heterogeneity Chi-squared p-value = 0.80, I-squared = 0%. Another sensitivity analysis for all seven studies using a fixed effects model gave a pooled OR of 4.47 (95% CI 2.59-7.71).

Fig. 2 -Fig. 3 -

For time to cannulation, there were a total of five studies included (6, 8, 10-12). The pooled weighted mean difference was -1.07 min (95% CI -4.66 to 2.52) for ultrasound-guided peripheral venous access compared with traditional methods (Fig. 4) suggesting no difference in time to cannulation between the two techniques. Heterogeneity Chi-squared p-value = 0.003 and I-squared = 74.6%.

Fig. 4 -

To evaluate number of punctures required for each technique, four studies were included (6, 8, 9, 12). The pooled weighted mean difference was -0.50 punctures (95% CI -1.36 to 0.35) for ultrasound-guided peripheral venous versus traditional cannulation techniques (Fig. 5), indicating no difference in number of punctures for ultrasound-guided peripheral venous access compared with traditional techniques. The heterogeneity Chi-squared p-value was less than 0.001 and I-squared equal to 83.1%.

Fig. 5 -

Discussion

The results of this meta-analysis demonstrate improved success of peripheral venous placement with the use of ultrasound guidance. This study was limited, however, as very few studies of sufficient quality met inclusion criteria. Other meta-analyses that have been published on this subject included studies judged to be of poor quality, were not peer-reviewed, did not use intention-to-treat analysis, or that did not meet a priori power analysis (15, 16). We included one study that was not a randomized controlled trial but rather a prospective systematically allocated study. In this trial, patients were ­allocated to each arm based on odd or even days. We found that this methodology, though not entirely randomized, was very unlikely to introduce any significant bias.

Our systematic review and meta-analysis used random effects models to calculate pooled summary statistics despite having a nonsignificant heterogeneity Chi-squared p-value. Given the relatively small number of studies (<10) in our meta-analysis, the power of the Chi-squared test for heterogeneity may be insufficient to detect significant heterogeneity if it is present. Thus, using a random effects model is more conservative, as it can account for study to study variability. Previous meta-analyses on this topic used fixed-effects models (presumably due to nonsignificant tests for heterogeneity) despite the small sample size and may have overestimated the effect size for ultrasound-guided peripheral venous techniques (15, 16). A fixed effects model would have increased our estimated effect size (OR 4.47).

In our meta-analysis, we detected no significant difference between ultrasound-guided techniques and traditional techniques in time to cannulation and number of punctures required for successful cannulation. We found significant heterogeneity between studies for these outcomes. The variation of technical skills required for ultrasound-guided cannulation between operators could have contributed to the heterogeneity and distorted our pooled estimates. With no significant differences in time to cannulation and number of punctures, ultrasound-guided peripheral venous access may not have a direct impact on patient satisfaction. However, the increased success rates of ultrasound-guided peripheral venous access compared with traditional techniques may obviate the need for central venous access with its associated mechanical and infectious complications.

Although the use of ultrasound guidance for the placement of peripheral venous puncture has advantages, there are known limitations to its use. Many ultrasound-guided peripheral intravenous lines are placed in the deep brachial vein and there is a documented increased risk of intravenous contrast extravasation from catheters in brachial veins compared with antecubital veins (17). The risk factors associated with difficult landmark-guided intravenous access (diabetes, intravenous drug use, sickle cell disease, prior chemotherapy, and obesity) can present challenges even with ultrasound-guided approach due to sclerosed veins, smaller vein diameter, and abnormal distribution of veins (18, 19). In addition, success of ultrasound-guided peripheral venous access is limited by the vessel depth. Low success rates were reported with vessel depth greater than 1.6 cm (20).

Limitations

Our study may contain publication bias despite performing a comprehensive literature search. In addition, it is possible that our meta-analysis incorporated the biases of the individual studies we included in our analyses and potentially created new sources of bias through study heterogeneity. The variation among study subjects in age and practice setting may limit the conclusions that can be reached because of heterogeneity of the patient population. The types of practitioners performing ultrasound-guided peripheral venous placement differed among the studies as did their level of training, which also added heterogeneity among the studies. In addition, we were unable to evaluate any effect on clinical outcomes (e.g., infection rates, delayed treatment, and so on) based on the studies included in our meta-analysis.

Conclusion

In patients with difficult peripheral venous access, ultrasound guidance increased success rates of peripheral venous placement when compared with traditional techniques. However, ultrasound guidance had no effect on time to successful cannulation or number of punctures required for successful cannulation.

A meta-analysis flow chart for study selection.

Forest plot comparing success rates of ultrasound-guided peripheral venous cannulation versus traditional venous cannulation techniques.

Funnel plot of studies evaluating success rates of ultrasound-guided peripheral venous cannulation versus traditional venous cannulation techniques.

Forest plot comparing time to cannulation of ultrasound-guided peripheral venous cannulation versus traditional venous cannulation techniques.

Forest plot comparing number of punctures using ultrasound-guided peripheral venous cannulation versus traditional venous cannulation techniques.

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