![]() The adjacent orifices at the tip of the end hole of the double-lumen catheter appeared to permit interaction of the two effusing streams of the incompatible drugs, whereas the staggered orifices of the triple-lumen catheter reduce this interaction. In some cases, millimeter-size fragments of phenytoin precipitate were seen to dislodge from the tip of the double-lumen catheter. Infusion through the double-lumen catheter resulted in an average of 6% loss of phenytoin to precipitate, which, on microscopic examination, appeared as spindle-shaped crystals 25 to 50 microns in length and 5 to 10 microns wide. ![]() White clouds of phenytoin precipitation were observed near the tip of the double-lumen catheter but not the triple-lumen catheter. ![]() Video recordings were made of drug interactions, and assays of phenytoin concentration were performed on samples of the circulating fluid. Flow conditions and drug infusions in the venous model were designed to mimic the in vivo clinical situation to evaluate two central venous catheter types, a double- and a triple-lumen catheter. This study utilized an in vitro model flow system to examine the physicochemical phenomena that occur when two incompatible drugs (phenytoin and total parenteral nutrition) are simultaneously administered through multilumen catheters. Though there are no known documented reports that this practice has been responsible for harmful events in patients, likewise there are no published data to verify the safety and efficacy of this practice. An understanding of the available options in the Emergency Department will assist providers in selecting the optimal catheter for the desired function.Multilumen catheters are commonly used to simultaneously administer incompatible drugs to critically ill patients. Ultimately, selection of the appropriate line varies based upon the clinical presentation of the patient and the indication for the procedure. Finally, flow through a catheter is quickest if the lumen is parallel to the direction of flow (in contrast, for example, to the 90-degree angle seen in the Cordis). Nine French triple-lumen catheters have larger lumens and shorter lengths and are satisfactory for blood administration. Second, shorter catheter lengths correspond to higher flow rates. First, flow is faster through larger diameter catheters. Nonetheless, there are a few basic principles that can help guide providers. This leads to difficulty in predicting reliable flow rates for each line. While sizing is based on the outer diameter of the catheter, the thickness of each catheter can differ, making the inner diameter variable. I believe it was 'Bard' that coined the phrase 'triple lumen'. It is also called a multi-lumen catheter. The exact difference between each catheter gauge was derived from wire manufacturing in the 19th century with no true mathematical formula to predict the difference in each gauge. A triple lumen is a 3 lumen catheter with a proximal port (closest to the skin), medial port (between skin and SVC), and distal port or CVP port in the SVC (superior vena cava) or RA (right atrium) of the heart. ![]() In contrary, the gauge of a catheter is inversely proportional to the catheter size, making a 16 gauge larger than a 24 gauge for instance. Consequently, increasing the French corresponds to an increase in the size of the catheter. For example, a one millimeter catheter would be a 3 French. The French unit is the outer diameter of the catheter in millimeters multiplied by three. By convention, multi-lumen and very large catheters are measured with the French system, whereas single lumen catheters are generally measured by gauge. Traditionally, catheters are sized based on their outer luminal diameter. Each lumen/line will allow for separate infusions through an individual lumen. With multi-lumen catheters each separate lumen is enclosed within a single sheath making the catheter appear to have only one line. One important factor that must be considered when selecting an appropriate line is the size of the lumen(s). PICCs may be single or multiple lumen, having 1, 2 or 3 access lumens. Whether it is administration of medications that cannot be given peripherally or rapid fluid resuscitation, the indication for this procedure can help dictate the type of line that should be placed. Prior to insertion of a central line, providers should carefully consider the indication for the procedure. From a MAC introducer to a single-lumen trauma catheter, there are countless varieties of central venous catheters available to the Emergency Physician.
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