The Technique for the Usage of Power Injectors - Case Study Example

I.V Power Injectors INTRAVENOUS POWER INJECTORS FOR COMPUTED TOMOGRAPHY-SAFE OR UNSAFE? # 6449 www.academia-reseach.com I.V Power Injectors 2 SAFETY OF I.V POWER INJECTORS FOR COMPUTED TOMOGRAPHY Bolus or power injection of intravenous contrast material is superior to the drip infusion for enhancing normal and abnormal structures during body computed tomography. This system has been used quite safely in adults since 1986. Despite the benefits of this technique, a reluctance in the usage of power injectors still exists because of the concerns of complications related to its use. The most common among these complications is the extravasation of contrast material. Another major but very rare complication is air embolism. These complications can be reduced by ensuring the reliable techniques and experienced staff. The most favored site for injection is ante-cubital vein. The power-assisted injection through a central line bares the risk of rupturing the line, because of lack of the manual control over the pressure line, by power injector. Now simple safety devices have been introduced, which allow the manual control of pressure by means of an interposed three-way stop cork combined with a small syringe for the pressure equalization. The power injectors can be defined as the devices used to inject the radio opaque contrast media during the diagnostic studies, at a controlled rate to enhance the diagnostic image. The advantages of this technique include: 1. Improved image quality, 2. Improved patient through-put, 3. Reduced exposure of personnel to radiation, and 4. Optimized reducibility of scans. [6] I.V Power Injectors 3 But there are certain risk factors, leading to some complications while using the power injectors. The normal peak pressures produced by a power injector during a diagnostic scan can increase the pressure tolerance or pounds per square inch of conventional I.V administration sets, or the small caliber I.V catheters, which are not actually designed to handle the higher pressure. This can result in rupture of the tubing or catheter, ultimately leading to: 1. Sprays of blood and contrast media, 2. Loss of venous access, 3. Fragmentation of catheters with or without embolization possible requiring surgery to remove fragments, 4. Patient’s discomfort or anxiety, 5. Delay of testing and treatment and 6. Waste of contrast media. Certain patient groups are at an increased risk of extravasation. These include patients who cannot communicate properly, like elderly, infants, children and patients with altered consciousness, severely ill patients, and patients with abnormal circulation in the limb to be injected. Abnormal circulation of limbs occurs in patients atherosclerotic peripheral vascular disease, Raynaud’s disease, venous thrombosis, or with history of radiation therapy or extensive surgery. I.V Power Injectors 4 Moreover, certain intravenous access sites have an increased susceptibility to extravasation. These include hand, wrist, foot and ankle venous access sites. So we must avoid using such sites for intravenous access, while considering the use of power injectors. In addition, indwelling intravenous catheters, being in place for more than 24 hours, and those with multiple punctures into the same vein also carry an increased risk for extravasation. Whenever a patient with an increased risk for extravasation requires intravenous contrast material, a low osmolality contrast media (LOCM) should be used, because extravasation of these agents is better tolerated, than that of high osmolality contrast media (HOCM). [2] Besides rupture of tubing leading to any of the above mentioned results, another complication which can rarely occur, if proper measures are not taken is that of air embolism. Clinically significant air embolism is although a potentially fatal, but very rare complication of power injectors. On CT scan, venous air embolism is most commonly identified as air bubbles or air fluid levels in the intrathoracic veins, main pulmonary artery, or right ventricle. Air embolism has also been identified in the intracranial venous structures. Patients with right-to-left intracardiac shunts, or those having pulmonary arteriovenous malformations are at a higher risk of having a neurological deficit from small volumes of air embolism. Treatment options include 100% oxygen administration, hyperbaric oxygen to reduce the size of air bubbles thus restoring the circulation and oxygenation. [2] I.V Power Injectors 5 The intravenous power injector methods for the computed tomography vary, depending upon the vascular access, clinical problems and type of examination. In addition, the mode and method of delivery, either by hand or the power injector, also varies for the procedures listed. [2] The first power injector for CT scan, called as ‘MEDRAD’ was founded in 1964, when M. Stephen Heilman, M.D created the first flow-controlled angiographic power injector in the kitchen of his home near Pittsburgh, Pennsylvania. An emergency room physician by day ‘Doc’ saw tremendous potential in angiography. Power injecting the contrast agent into the vessels, he reasoned, would enhance the image, making it possible to diagnose the heart disease and stroke patients who regularly came through the emergency room. Doc’s invention was the first in the long list of MEDRAD innovations. Later on, the first injector technology for computed tomography and magnetic resonance imaging was introduced. [7] The power injected injection of contrast material into an ante-cubital vein is a commonly used method for CT scans. It has been proven to be superior to manual injection. But the risk is that, power injection through a central line can cause rupture of the line, because a manual control over the pressure applied by the power injector is lacking. [5] Power injection should be applied in a larger peripheral vein, such as antecubital or a large forearm vein which can take the higher flow rate and pressure. For a peripheral venipuncture site, a flow rate of 1.5ml/sec is preferable. [2] I.V Power Injectors 6 Despite above discussion, we must mention that power injection of some central venous catheters can be performed safely, only to keep a few precautionary measures in mind: First of all, the proper location of catheter tip must be confirmed either by CT scout scan, or a recent chest radiograph. Before the catheter is connected to the injector tubing system, the catheter tip position should be tested for the venous back flow. At some occasions, the back flow will not be obtained, because of positioning of the catheter tip against the wall of the vein in which it is located. If there is no abnormal resistance to the injected saline, it is safe to administer the contrast material through the catheter safely. Otherwise, an alternative venous site should be sought. [2] It is important to avoid a prolonged admixture of blood and the contrast media, especially the non-ionic agents, whenever possible; the same being true for the admixture of contrast media and any medications, except for heparin. Regarding the technique for the usage of power injectors, the use of metal needles for administration should be strictly avoided. Instead, a flexible plastic cannula should be used. Also consider the flow rate for the gauge of the catheter used. 22-gauge catheters are able to tolerate a flow rate of up to 5ml/sec, but a 20-gauge or larger catheter is preferable for a flow rate of 3ml/sec or higher. .Before injecting the contrast media, the patency of the catheter must be assured. [2] The power injectors must be used with extreme care in children coming for CT scan, because they have an increased risk for the extravasation. According to a study, the use of power I.V Power Injectors 7 injectors through 18-24 gauge angiocatheters in children is safe when meticulous technique is used and personnel are appropriately trained. [3] According to another study, the pressure limited power injection through all types of central lines is safe in children. Also, 30 kg can be used as a cut off weight for power injection. [4] In recent years tremendous advancements have been made in the injector technology to specifically address the draw backs of the earlier concepts. The most recent of them is the introduction of a next generation fluid management injection system having a potential to alleviate earlier concerns. This and other advancements in the technology of power injectors will further enhance the use of this beneficial invention in the field of radiology. I.V Power Injectors 8 REFERENCES 1. Melissa Eakle & Susan Lange (2004). Power Injectors put I.V lines under pressure. Retrieved April 13th, 2008, from the World Wide Web: http://www.fda.gov/cdrh/medicaldevicesafety/tipsarticles/nj/1104.pdf 2. Injection of Contrast Media. Manual on Contrast Media. Retrieved April 13th, 2008, from theWorld Wide Web: http://www.acr.org/SecondaryMainMenuCategories/quality_safety/contrast_manual/InjectionofContrastMediaDoc14.aspx 3. Amaral JG, Traubici J, BenDavid G, Reintamm G, Daneman A (2006). Safety of power injector use in children as measured by incidence of extravasation. Medscape Internal Medicine. Retrieved April 13th, 2008, from the World Wide Web: http://www.medscape.com/medline/abstract/16861567 4. Cynthia K. Rigsby, Eric Gasber, Roopa Seshadri, Christine Sullivan, Mary Wyers & Tamar Ben-Ami (2007). Safety and efficacy of pressure-limited power injection of iodinated contrast medium through central lines in children. American Journal of Roentgenology AJR 2007; 188:726-732. Retrieved April 13th, 2008, from the World Wide Web: http://www.ajronline.org/cgi/content/full/188/3/726 I.V Power Injectors 9 5. P. Rogalla, N. Meiri, R.F. Thoeni, H.I. Goldberg, M.B. Hamm (2004). Technical Note, Contrast Media. Springer Link Journal Article. Retrieved April 13th, 2008, from the World Wide Web: http://www.springerlink.com/content/f7uwynn07rculrbg/ 6. Joao Guilherme Amaral, Jeffrey Traubici, Guila BenDavid, Gail Reintamm, Alan Daneman (2005). Safety of power injector use in children as measured by incidence of extravasation. Pediatric Imaging, original research. Retrieved April 13th, 2008, from the World Wide Web: http://www.ajronline.org/cgi/reprint/187/2/580.pdf 7. History of power injectors for CT scan. Yahoo answers. Retrieved April 13th, 2008, from the World Wide Web: http://answers.yahoo.com/question/;_ylc=X3oDMTE1MmI4N2IyBF9TAzIxMTU1MDAxMTgEc2VjA2Fuc19ub3QEc2xrA3N1YmplY3Q-;_ylv=3?qid=20080413154238AA9JbU7 Read More