Several recent central line snafus at our institution has me thinking about how ultrasound is used in this procedure. Ultrasound no doubt has revolutionized how we perform many procedures, particularly the placement of central lines, and much has been documented in the literature extolling the virtues of using ultrasound.
Direct ultrasound guidance is associated with reduced time to insertion, reduced rate of arterial puncture and hematoma formation, and successful venous cannulation with fewer attempts. But using ultrasound in central lines has another side. It can create a false sense of confidence, a sense that you can never cause a complication if the line is placed under direct guidance.
A case review from Michael Blaivas, MD, explored this concept, laying bare a number of complications, some of them severe, that occurred at his institution. (J Ultrasound Med 2010;29:1285.) The article reviews six cases in which providers who were experienced in the procedure used direct ultrasound guidance. The cases represent only a fraction of the 500 total lines placed during the study period, but the complications were significant. Several patients required surgery to address arterial injury, and one patient developed a large hematoma and died from a loss of airway.
What was the one common thread in all of these cases? Use of the transverse, or short axis, approach to the vein. (Image 1.) In this view, only a portion of the needle is visible at any one time, and the view of the needle tip can be easily lost. This can lead to a misperception of the location of the needle tip and puncture of the posterior wall of the vein. The physician may think that he is visualizing the needle tip on ultrasound, when in fact it's only a portion of the shaft of the needle. (Images 2 & 3.) This is particularly dangerous in patients in whom the vein directly overlies the artery or when the internal jugular is small and easily collapsing.
An inadvertent arterial puncture may occur with even the most careful technique, but it is crucial that the vessel is not dilated until arterial placement can be ruled out. One of the study's most startling findings was that the physician was falsely reassured of venous placement by the initial aspiration of dark, non-pulsatile blood in each case of serious complications. The patient was hypoxic and hypotensive in each case, however, making these findings unreliable.
In light of all this, how can we make ultrasound guided lines safer? Next month: Alternative techniques to minimize complications.
Tip of the Month
Eyelid too swollen to assess extraocular movements? Use ultrasound in the transverse (indicator toward the right) and sagittal planes (indicator toward the head) to document normal eye movements.
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