الفهرس 
The subclavian veinOnly 14 pages are availabe for public view
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Abstract
Today, central venous catheters are an essential component of a multitude of therapies that span diverse patient populations. Achieving traditional central venous access via the jugular, subclavian, or femoral veins by using surface landmarks may be sufficient in many patients. However, the wide variability in vascular anatomy, in addition to so many other factors, demonstrates flaws in the concept of blind landmark-based techniques even in routinely used vessels. The internal jugular veins are probably the most commonly used sites for tunneled catheters.
Reported complications of central venous catheterization represent only the tip of the iceberg and are likely to be considerably higher for the more difficult case or novice operator. Ultrasonography has proved to remarkably decrease the complication rate, specifically the immediate complications rather than the delayed ones. US role has extended to managing and treating some of these complications and even maintaining the vascular access service in order to promote optimal catheter management.
Orientation of the ultrasound basic physical principles and probe designs and selection is a skill that takes some practice. However, the time spent understanding and practicing the technique will be repaid many times over when performing these invasive procedures.
Many interventional radiology suites are equipped with dedicated ultrasound machines, or ultrasound equipment is readily available and can be used to evaluate the site of planned vascular access before catheter placement even at the bed side with so many other advantages that US imaging hold exquisitely.
The vessel to be cannulated may be located with ultrasonography via several accepted variations including the static (indirect) method and the dynamic (real-time) method, each with its own advantages and disadvantages. Also, ultrasonography allows visualization of the guide-wire, the catheter and its relative location to the vein.
The National Institute for Clinical Excellence (NICE) has provided clinical guidelines for the use of real-time B-mode ultrasound for CVC insertion in which 2-D imaging ultrasound guidance is the preferred method for CVC insertion in the IJV in elective situations, moreover it should be considered in most clinical circumstances whether elective or emergency. However, physicians using 2-D imaging ultrasound guidance should be appropriately trained to achieve competence. On the other hand, audio-guided Doppler ultrasound guidance is not recommended.
The challenge is how to fund widespread distribution of ultrasound machines and train large numbers of personnel in their use. However, there has been significant cost savings associated with the use of ultrasound by avoiding the economic impact of treating the complications avoided by such technique.
In conclusion, although imaging guidance is not necessary for obtaining routine venous access, interventional radiology can provide an invaluable service in both routine and difficult cases. Its use is gradually increasing as a new generation of clinicians acquires ultrasound skills and appropriate bedside machines become available.