Malpositioned central venous catheters occurs in about 7% of central line placements. A malpositioned central line is any central venous catheter where the tip is located anywhere other than the superior vena cava (SVC) for internal jugular lines or subclavian lines or a location other than the inferior vena cava (IVC) in femoral lines. Malpositioned femoral lines are very uncommon as long as the central venous catheter (CVC) is intravascular and not in the artery and therefore will not be the focus of this blog. A malpositioned CVC is important because the central line can be directed opposite to normal venous blood flow and can increase the risk of vein erosion, perforation and catheter wedging. If the central line is directed retrograde in the internal jugular vein, the infusate is directed towards the brain which can cause obvious adverse effects.
Central venous catheter malpositioning can be caused by congenital anatomic variants, difficult body habitus, acquired vein stenosis, poor operator technique or bad luck. In general, left-sided central venous catheter insertions have more CVC malpositions than right-sided CVC insertions. In one study of nearly 1,800 central line insertions, the authors found that malpositioned CVCs occurred in 6.7% of all patients and that the left IJ lines were malpositioned 12% of the time, subclavian veins malpositioned about 8.5% of the time and right IJ was malpositioned 4.3% of the time.[1] This was presumed to be from the presence of the long left brachiocephalic vein and the presence of small tributaries (left supreme intercostal vein) which can more easily allow the wire to travel into the left subclavian vein, the left supreme intercostal vein or into a persistent left superior vena cava (congenital anomaly).
Patients who are morbidly obese and who have large pendulous breasts can have more CVC tip migration with body position changes and with respiratory variation compared with thin patients. This tip migration can increase the chance of CVC malpositioning in morbidly obese patients. Additionally, acquired venous anatomical changes can occur from a dominant supreme intercostal vein drainage to the hemiazygous vein or venous compression/stenosis from prior surgery, radiation, prior central lines, compression due to malignancy or benign masses or partial thrombosis of a vein that can alter venous resistance to normal blood flow.
There are some technical tips that the operator can use to optimize her/his chances of a properly positioned central venous catheter. First, if other operators have had malpositioned lines or difficulty placing a line in a certain location, the patient may have altered venous anatomy and I would choose a different insertion site. Knowing that you have the best chance of a properly positioned line in the right IJ location, I would choose that site over others if possible. If the right IJ site is not possible, a subclavian line is preferred over the left IJ location to prevent malpositioning. If a subclavian line is being performed, have the patient turn their neck in the direction of the insertion site to partially compress the ipsilateral IJ vein to decrease the chance the wire flows up the ipsilateral IJ. Additionally, the insertion needle bevel and the J curve of the wire can both be directed caudad for all subclavian line insertions to optimize the chance the wire flows into the SVC. For IJ lines, the insertion needle bevel can be directed medially and the J curve of the wire can be directed to the left to optimize the chance of the wire flow into the SVC.
As a general rule of thumb, a malpositioned central line should be replaced or repositioned (rewired) if identified. Rewiring a central line is best done using fluoroscopy if available and careful attention to sterility since you are removing the old CVC and placing a new one over the new sterile wire. Rewiring a line requires a bit of extra training and should be performed by an experienced operator. If a central line is malpositioned such that the tip is directed against normal venous flow, it should be replaced. If a central line is positioned in a small tributary vein (e.g., the hemiazygous vein), it should not be used for for hypertonic fluid infusions or at a high flow rate since the CVC is in a smaller vessel.
REFERENCES:
- Schummer W et al. Mechanical complicatons and malposition of centra venous cannulations by experienced operators. A prospective study of 1794 catheterizations in critically ill patients. Intensive Care Med. 2007; 33(6): 1055-9.
- Roldan C et al. Central Venous Catheter Intravascular Malpositioning: Causes, Prevention, Diagnosis and Correction. Western J Emer Med. 2015; 16(5): 658-664.