Ultrasound-guided vascular access: Trends and perspectives

Published on 22/03/2015 by admin

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Ultrasound-guided vascular access: Trends and perspectives

Ultrasound-guided vascular access (UGVA) was introduced in the preceding chapter. This chapter highlights a few tips for novices as well as additional techniques and innovations that would assist skilled operators in definitively identifying the target vessel and improving catheterization in the intensive care unit (ICU).

Many randomized controlled trials and meta-analyses have associated UGVA with a considerable reduction in complications and increased first-attempt success when compared with standard landmark techniques.1-3 As 1 of their 11 practices to improve patient care, the Agency for Healthcare Research and Quality (AHRQ) recommends the use of ultrasound for placement of a central venous catheter (CVC).4 The National Institute for Clinical Excellence (NICE), as part of their NICE technology guidelines, advocated the routine use of UGVA.5 Most recently, an international, evidence-based consensus statement was developed to assist clinicians in performing UGVA and as a reference for future clinical research. The group advised that ultrasound guidance can be used not only for central venous cannulation but also for peripheral and arterial cannulation. In addition to guidance, the group recommended the use of ultrasound to check for immediate and life-threatening complications, as well as catheter positioning.6

Patient and technical considerations

The implementation of a simple three-step UGVA technique (pre-procedural scanning, real-time ultrasound-guided cannulation, post-procedural scanning) maximizes success rates and decreases complications in the intensive care unit (ICU).6 A pre-procedural scan is recommended to guide the selection of an optimal target vessel.46 Usual criteria for the selection of an optimal vein are:

Normal venous patency (venous collapse during breathing or compression without signs of thrombosis)

Easy accessibility (relatively short distance from the skin surface to the vessel wall)

Adequate size (vessel size less than three times the caliber of catheter may carry a greater risk for thrombosis)7

Absence of anatomical variation

Intended purpose of cannulation (i.e., neck surgery often requires infraclavicular vascular access)

Intended duration for catheter placement (i.e., a cancer patient receiving chemotherapy often requires long-term vascular access)

Complication rates after the implementation of landmark techniques differ between sites (Chapter 10). The internal jugular vein carries the highest risk of accidental arterial puncture and hematoma, the subclavian carries the highest risk for pneumothorax, hemothorax, and catheter malposition, while the femoral vein carries the highest risk for thrombosis and infection (Table 11-1). The subclavian vein is considered advantageous in the ICU (compared to the internal jugular or the femoral vein) as it carries the lowest infection risk. However, recent studies show that Chlorhexidine gluconate -impregnated sponge dressing when used with the standard care decreases the incidence of major catheter-related infections from 1.4 to 0.6 per 1000 catheter-days.8 The American Society of Anesthesiologists Task Force on Central Venous Access recommends the use of a central line insertion work and safety checklist and bundling of required equipment to minimize errors, risk of infection, and complications.9 These measures have shown reduction (up to 66%) in central line-associated bloodstream infections.10

Preprocedural tips

A few practical tips when performing an ultrasound-guided central venous cannulation for the first time include:

Notably, a thorough preprocedural scan at a prospective region of interest (ROI) should be performed because of the frequent finding of venous and arterial asymmetry between symmetric sites. In that sense, anatomic diversities may exist as well in occasional patients (e.g., duplicated femoral vein). Venous compressibility and patency should be examined because exclusion of thrombosis is mandatory (Chapter 9). The latter is more commonly observed at the common femoral vein site than at other cannulation sites, and ultrasound monitoring of a central line may reveal cases of catheter-related thrombosis (Figure 11-2). Occasionally, trauma to the venous wall, trapped air, hematomas, arteriovenous fistulas, or injuries to nonvascular adjacent structures may be identified after a “clumsy” blind attempt or multiple blind penetrations, which could produce local trauma (Figure 11-3). Estimating vessel size is equally important, as previously mentioned. The size of the internal jugular vein can be evaluated before and after a Valsalva maneuver, which may make a relatively small-caliber vessel that is seemingly difficult to catheterize become robust and easy to puncture.11 Moreover, the diameter of the internal jugular vein is usually found to be larger when the vessel is depicted in the lower neck area (scanning caudally toward the clavicle) than in the upper neck area (scanning cranially toward the mandible). When planning on catheterizing the internal jugular or subclavian vein, the pleura should be assessed for a sliding lung while identifying the vasculature.