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25 — The Role of Ultrasound in Central Vascular Access Device Placement
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through both walls of the vein into a neighboring artery. When recognized, the device should be re- moved and pressure applied to the site. An arterio- venous fistula may close on its own or may require intervention to close.
Nontarget Puncture
Nontarget puncture occurs when the access needle is directed to a neighboring structure such as an ar- tery or lung. Careful identification and differentia- tion of arteries from veins prior to and during initial puncture will minimize the likelihood of inadvertent arterial puncture. Use of a small access needle will minimize the risk of bleeding should a nontarget puncture occur. In the event of arterial puncture, the needle should be immediately removed and gentle pressure should be applied to achieve hemostasis. A sterile occlusive dressing should be applied once hemostasis is achieved, and the patient’s vital signs should be monitored. The site should be assessed frequently for an expanding hematoma, which could compromise venous blood flow or respiratory status, particularly with a carotid artery puncture. Inadver- tent puncture of the lung may result in pneumotho- rax, or a collapsed lung. Pneumothorax is one of the most serious and potentially life-threatening compli- cations of central venous catheterization. The com- plication rate varies from 0% to 6% but has been reported as high as 12.4% with inexperienced prac- titioners.6 Pneumothorax accounts for 25% to 30% of all reported complications of central vein catheter insertion.7,8 The internal jugular vein approach has been shown to have a lower risk of pneumothorax compared to subclavian vein cannulation.9,10,11 The failure of the first attempt at catheter insertion is also associated with a significant increase in pneu- mothorax risk. A small pneumothorax can be treated conservatively with observation. If the patient is symptomatic, or the pneumothorax enlarges, place- ment of a pleural drainage catheter may be required.
Bleeding
Bleeding with or following VAD placement may oc- cur because of traumatic or difficult VAD insertion, comorbid conditions such as a coagulopathy or oth- er hematologic disorders, and concurrent treatment with certain medications. Medications that increase the likelihood of bleeding include clopidogrel, warfa- rin, aspirin and other nonsteroidal anti-inflammato- ry drugs, and heparin. When possible, these medica- tions may be discontinued prior to device placement. If discontinuation is not clinically feasible, other measures can be taken to reduce the risk of bleeding. These include the use of hemostatic dressing mate- rials, a change in VAD selection to a less invasive device, and administration of blood components or reversal agents.
Air Embolism
Air embolism during central VAD placement occurs when air enters the venous system via the needle, sheath, or device. Although unusual, it is a serious complication that can result in respiratory compro- mise and even death. The risk of air embolism can be minimized by using valved sheaths, performing ex- change maneuvers efficiently, and ensuring that cath- eter lumens are flushed, secured, and locked. If the patient is symptomatic, the patient should be treated symptomatically with oxygen and supportive care. Air emboli are not often seen within the target vessel as these emboli move quickly within the blood stream.
Cardiac Arrhythmias
Cardiac arrhythmias during VAD placement typically occur when guidewires are advanced into the heart, triggering the heart’s conduction system. This is of- ten transient, and patients are often asymptomatic. In the absence of symptoms, arrhythmias are detected through use of intraprocedure cardiac monitoring.
SUMMARY
Ultrasound imaging has allowed clinicians to improve assessments and decision making prior to device placement by helping to identify target vessels and determin- ing their suitability for use. Coupled with optimal device selection and the develop- ment of an infusion plan, ultrasound imaging is an integral component of access planning and placement. Real-time ultrasound imaging helps minimize placement complications by allowing the clinician to visualize venous access, avoid neighbor- ing structures, and guide devices into position. Once thought to be a useful tool for access-limited or challenging patients, ultrasound imaging is now the standard of practice for central vascular access device placement.