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Endoluminal Brushing: A Sweeping Change in Catheter Management?
Anthony C. Nicholls, PhD, Alpha-VT Consulting, Liss, Hampshire, England
The Endoluminal Brush is a device that allows clinicians to procure a sample of biofilm from a catheter in situ to test for catheter-related blood stream infection (CRBSI). It can also be used to remove occluding debris from catheter lumens and thus restore patency to blocked lines.
How It Works
The Endoluminal Brush consists of a looped strand of stainless steel wire twisted to hold nylon bristles, in a brush head, at its distal end. The device is fully enclosed inside a sterile plastic sheath having a standard luer lock connector at the brush end and a seal at the handle end. The Brush’s luer lock is connected directly to the catheter hub and introduced, 1 cm at time, into the catheter lumen. When it has been advanced to the end, it is withdrawn in a single, steady movement back into the sheath.
Before use, the length and diameter of the catheter lumen must be known so that the correct Brush can be selected. The Brush must be of greater diameter than the lumen (see figure 1) such that, on introduction, it is compressed into a “Christmas tree” profile, thus orientating all the bristle tips to the hub of the catheter and opposed to the direction of motion (see figure 2). In this mode the bristles should slide over the debris, pushing nothing in front of the Brush. Upon withdrawal, all the bristles face the direction of motion and “scrub” debris from the walls. Because the Brush is spirally wound it “rifles” the lumen on the way back, avoiding any need to twist or push back and forth (see figure 3).
In the same way that paint brushes retain paint that can only be removed by vigorous washing, the Endoluminal Brush holds the debris that it removes. This debris can be examined in the laboratory for the presence of micro-organisms. Use of the Brush has been shown to be safe and without complication.
Once the Endoluminal Brush has been retrieved from the catheter lumen, the brush head is cut off and sent in a specimen tube to the microbiology laboratory. In the lab the debris is removed from the bristles by vortex mixing and cultured on blood agar plates. Counts of greater than 100 colonies indicate a CRBSI is likely. Clinical research has shown that Endoluminal Brush culture results are more accurate than the Maki Roll, Cleri Flush or Quantitative blood culture (QBC) in the diagnosis of CRBSI. In addition, unlike the techniques of Maki and Cleri, it allows the catheter to remain in place while the test is conducted, and unlike QBC it does not require the taking of peripheral blood samples for comparative data.
Some 25% of catheters will become occluded during use: 60% will fail because of blood clots (thrombus) and 40% because of mechanical obstruction (kinking, pinch-off etc.), drug or mineral precipitation or lipid deposition. While thrombolytic drugs such as tissue plasminogen activator (t-PA) clear 60 to 80% of thrombolytic occlusions, they are unable to clear other types of occlusions.
The Endoluminal Brush has been widely used to restore patency and has an efficiency equal to or better than t-PA in thrombosed catheters. It has also been used in combination with thrombolytic drugs. However, the main advantage of the Brush is that it will remove all debris, regardless of its nature, and, that it physically removes, rather than dissolves, the debris and its colonizing micro-organisms. Researchers have shown that a single brushing, followed by the withdrawal of 10 ml of blood through the line, reduces the bacterial count between 70 and 90%.
Since endoluminal build up of proteinaceous debris is widely thought to be the precursor of infection and occlusion, it is important that as soon as a catheter shows signs of blockage - slowing pump rate, resistance to infusion, pain on infusion, inability to withdraw blood or repeated pump alarms - interventional action is taken. Current research in England, Australia, New Zealand and the United States is examining the use of prophylactic or preventive brushing to eliminate catheter dysfunction and lower infection rates. Results are expected to start being reported early in 2004.
Where the Brush Is Used
The Endoluminal Brush is approved for use in the sampling for micro-biological analysis of, and removal of, occluding debris from CVCs in the United States, Canada, Australia, New Zealand, South Africa, Brazil, Colombia, Argentina, Czech Republic, Turkey and all countries in the European Community and Scandinavia. (Editor’s note: because the Brush is newly approved by the FDA, and only recently available, it is not yet widely in the U.S.) In all countries, except the USA (where submission is underway), the Brush is also approved for use in renal catheters.
The Brush may be used alone or in combination with chemical solutions to remove blockage. With thrombi, t-PA is the drug of choice: with calcium phosphate deposits, 0.1 N hydrochloric acid may be used. With phenytoin or tobramycin, sodium bicarbonate 1mEq/ml is recommended, and with aminophyline, ammonium chloride 1mEq/ml. Finally, for lipid or protein deposits, 70% ethanol or 0.1N sodium hydroxide are best.
Dr Nicholls is Managing Director of Alpha-VT Consulting in Liss, Hampshire, England and was the founding CEO and chairman of FAS Medical Limited, the Company that developed the Endoluminal Brush. References are available upon request.
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