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  1. Farjo, Linda RN


A discussion of complications related to the use of central venous catheters (CVCs), literature review, and a retrospective study were performed to see if blood collection from peripherally inserted central catheters (PICCs) in the treatment of oncology patients was a feasible option. The results were used to evaluate and update the institution's policy.


Nursing is a dynamic profession. Ideally, policies and procedures should be evaluated, revised, and updated to reflect current research. Blood sampling from central venous access devices (CVAD) is an accepted practice in many institutions. Periodic review of this practice is encouraged to ensure optimal patient outcomes.


Four main groups of central vascular access devices (CVAD) have been used since the 1980s. They are implanted ports, tunneled catheters, non-tunneled catheters and peripherally inserted central catheters (PICC). 1,2 Implanted ports are usually reservoirs attached to a single lumen catheter, most commonly implanted under the skin of the chest wall region. Accessing the port necessitates placing a non-coring needle into the hub of the port. 1 Tunneled catheters are often made of silicone and have 1 lumen to 3 lumens. 1 A portion of the catheter is tunneled through the subcutaneous tissue and then is terminated within the superior vena cava. Both of these catheters are usually inserted in the operating room. 1,2


Non-tunneled catheters are usually inserted at the bedside into the internal jugular or subclavian vein. These catheters are usually used for short-term treatment while the patient is hospitalized. 2 Most CVADs require insertion by a physician. A qualified nurse can insert PICCs at the bedside. 1,3 PICCs are made of silicone or polyurethane and can have 1 lumen or 2 lumens. All PICCs are inserted into a peripheral vein, preferably the cephalic vein or basilic vein. The catheter is guided proximally until the tip is located in the superior vena cava. 3 The tip of most PICCs is open end, with the exception of the Groshong PICC (Bard, Salt Lake City, Utah). The Groshong PICC has a valve that opens inward for aspiration and outward for infusion. 3


These CVADs may be used to deliver medication, long-term intravenous antibiotics, chemotherapy, blood product replacement, parenteral nutrition, and to obtain blood specimens for analysis. 4 When operating properly, they allow the patient to receive treatment without delay. However, when complications arise, indwelling CVADs can present problems that are frustrating to the patient and the nurse caring for the patient. Although infection and occlusion are the most common complications, 5 other factors such as thrombus formation may also contribute to these complications. 2


Catheter occlusions can be divided into three categories: mechanical, nonthrombotic, and thrombotic. 6 Mechanical obstruction can be internal or external. External mechanical obstruction, caused by kinked or clamped tubing, compresses the catheter lumen. 4,6 Internal mechanical obstruction can be the result of catheter tip migration into a smaller vein or the tip resting against a vein wall. 6-8 Even if the catheter tip is in the superior vena cava, it can become obstructed when it is compressed between the clavicle and the first rib, a condition known as "Pinch-off" syndrome. 4,6


Nonthrombotic occlusions can be the result of intraluminal crystallization of total parenteral nutrition mixtures and drug incompatibilities. 6 Precipitates can occur gradually, causing a sluggish flow, or they may be immediate, resulting in total occlusion of the catheter. 6 Extraluminal events such as a fibrin tail or fibrin sheath can affect catheter patency, causing a partial or complete occlusion. 4 A fibrin tail, which is the accumulation of fibrin, blood cells, and platelets that adhere to the tip of the catheter, can occlude the back flow of blood, thus creating a one-way valve. 4,6 The infusion of fluid is not affected, but successful blood sampling becomes difficult. Almost all catheters develop these fibrin tails or sheaths within the first 24 hours. 7 When the progression of the fibrin tail totally encases the tip of the catheter, aspiration of blood and the ability to infuse fluid becomes impossible. 4-6


Thrombotic occlusions can originate either outside the catheter lumen or inside the catheter lumen. 7,8 Several factors can lead to thrombus development: venous stasis, vessel wall trauma, or stenosis and hypercoagulable states caused by diseases such as cancer and diabetes. 7 In fact, thrombus development around the outside of catheters has been seen in a high number of cancer patients because they possess a majority of the risk factors. 9 A thrombus can occur inside the catheter from either blood reflux or when a clot grows into the lumen from outside. 7


The importance of a functioning catheter can best be seen in oncology patients. These patients have poor vascular access and hence rely on their catheters to work properly. Many of them have their lab work drawn from CVADs. At the York Hospital oncology unit, blood has traditionally been drawn from all the CVADs except the PICCs. Some nurses in the oncology unit have questioned the rationale of prohibiting blood draws from these patients with PICCs, as patients on other units in the hospital can have blood samples obtained by qualified nurses from identical catheters. A theory was proposed that the hypercoagulopathy of oncology patients precluded the use of PICCs for this purpose. This question served as the impetus for the reevaluation of our policy regarding blood collection from PICCs.


Two specific issues were evaluated: Does a relationship exist between catheter type and catheter occlusions? Also, is a medical condition more frequently seen in patients who suffer catheter occlusions?