Читать книгу Emergency Management of the Hi-Tech Patient in Acute and Critical Care - Группа авторов - Страница 85

CVC occlusion is brought to the attention of ED providers either when patients complain of their catheter not working in the outpatient setting, or when ED’s attempts to instill fluid or draw back blood from a CVC are unsuccessful. CVCs are considered to be partially occluded if fluid can be instilled in them, but blood cannot be drawn back. A CVC is fully occluded if neither fluid instillation nor blood aspiration can be completed successfully. If occlusion is suspected, the first step should be to obtain a chest radiograph to determine the position and integrity of the catheter tubing. Catheter occlusion occurs for a variety of reasons, from formation of medication precipitates within the lumen of the line to development of fibrin sheaths and/or thrombus either within or surrounding the catheter tubing. If a small clot is suspected within the lumen of the CVC, the ED practitioner can attempt to aspirate it from the line with a 10 cc syringe that is half‐filled with saline. This technique is rarely successful in removing clots from implanted CVCs, as the small caliber of the noncoring needle used to access the catheter reservoir makes clot aspiration extremely difficult. If clot aspiration is unsuccessful, lysis of the occlusion can be attempted with a variety of lytic agents, depending on the nature of the blockage (e.g. clot vs. waxy precipitate vs. particulate matter). Practitioners should refer to their institution's guidelines for management of CVC occlusion for details on the use of each lytic agent. In centers where catheter fibrinolysis is not within the usual scope of practice of the ED nurses or providers, lytic maneuvers can also be attempted in consultation with an institutional IV team or with interventional radiology. Because it is possible for fibrin sheaths and large thrombi to embolize into the central venous circulation, it is critical that ED providers be able to recognize the signs and symptoms of pulmonary embolus – tachycardia, tachypnea, chest pain, and hypoxemia – and have a high index of suspicion for catheter‐related thromboembolus if a patient exhibits these symptoms. Indwelling CVCs also bring with them an increased risk of catheter‐associated deep‐ or central‐vein thrombosis. Patients with PICC‐associated thrombosis may demonstrate unilateral limb pain and swelling on the side of catheter insertion. Patients with central venous thrombosis associated with either an externalized CVC (Broviac, Hickman) or an implanted port may demonstrate signs and symptoms of SVC syndrome, including edema of the face, neck, or chest and neurologic changes. Both deep and central venous thrombosis are usually indications for removal of the catheter and initiation of anticoagulation.