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The Sonic Window: A Novel Vascular Access Device The Sonic Window: A Novel Vascular Access Device Michael Blaivas, MD, FACEP, FAIUM Introduction Ultrasound guidance for vascular access dates back more than 20 years, but the last decade has seen it spread broadly throughout clinical practice as a common point of care ultrasound application. Initial research focused on the utility of ultrasound in providing guidance for central venous access. Multiple studies showed it decreased complications and increased first pass success in internal jugular, femoral and subclavian central line placement.1,2,3 However, despite focus being held firmly on central venous access, it became obvious that ultrasound guidance had considerable utility in peripheral venous cannulation, saving time, money and improving success rates for first cannulation attempts.4,5 Ultrasound guidance allowed a variety of practitioners, including physicians and nurses, to place peripheral lines into extremely challenging patients at the point of care and in many cases, to avoid central venous access. The utility in doing so is several fold. Complications associated with central line placement include hemorrhage, thrombosis, infection, pneumothorax, airway loss and death. Such serious complications are not associated with peripheral venous lines and if the risk of these complications can be avoided completely because the need for central venous access is obviated, then patients, hospitals, providers and society would benefit. Even ultrasound guided central line placement cannot avoid some complications such as infection and thrombosis, yet not having to place a central line at all, can. Because some central lines are placed solely for the purpose of vascular access, even when central venous access is not truly required, there is an opportunity for immediate decrease in morbidity, mortality and cost. Two recent studies have confirmed that introduction of ultrasound guidance for peripheral intravenous line placement significantly decreases the use of central venous access.6,7 In fact, the drop is as large as 81%, with much of the decrease occurring in non-critically ill patients. Therefore, ultrasound is exceedingly helpful in decreasing central line associated complications even without being used for central line placement, by simply improving the capability of vascular access providers of all levels to obtain peripheral venous access. A variety of ultrasound devices are available, ranging in size and price from the small to the very large. The point of care setting typically calls for a more rugged, compact and less expensive ultrasound device, which can be utilized for a wide variety of ultrasound applications. Many departments and units cannot dedicate such a device for vascular access only and providers may compete for availability with other uses such as cardiac, trauma, lung, abdominal, vascular and soft tissue ultrasound applications being performed at the point of care. What is needed is a small, easy-to-use and more affordable ultrasound device specifically designed for vascular access and tailored to peripheral venous line placement. Such a device should be intuitive to use and be easy to handle. 1 Fragou M, Gravvanis A, Dimitriou V, Papalois A, et al. Real-time ultrasound-guided subclavian vein cannulation versus the landmark method in critical care patients: a prospective randomized study. Crit Care Med. 2011 Jul;39(7):1607-12. 2 Hind D, Calvert N, McWilliams R, Davidson A, et al. Ultrasonic locating devices for central venous cannulation: meta-analysis.BMJ. 2003 Aug 16;327(7411):361. 3 Hilty WM, Hudson PA, Levitt MA, Hall JB. Real-time ultrasound-guided femoral vein catheterization during cardiopulmonary resuscitation. Ann Emerg Med. 1997 Mar;29(3):331-6. 4 Brannam L, Blaivas M, Lyon M, Flake M. Emergency nurses’ utilization of ultrasound guidance for placement of peripheral intravenous lines in difficult-access patients. Acad Emerg Med. 2004 Dec;11(12):1361-3. 5 Costantino TG, Parikh AK, Satz WA, Fojtik JP. Ultrasonography-guided peripheral intravenous access versus traditional approaches in patients with difficult intravenous access. Ann Emerg Med. 2005 Nov;46(5):456-61. *Sonic Window is not cleared for sale in the EU. 6 Shokoohi H, Boniface K, McCarthy M, Khedir Al-tiae T, et al. Ultrasound-guided peripheral intravenous access program is associated with a marked reduction in central venous catheter use in noncritically ill emergency department patients. Ann Emerg Med. 2013 Feb;61(2):198-203. 7 Au AK, Rotte MJ, Grzybowski RJ, Ku BS, Fields JM.Decrease in central venous catheter placement due to use of ultrasound guidance for peripheral intravenous catheters. Am J Emerg Med. 2012 Nov;30(9):1950-4. The Sonic Window: A Novel Vascular Access Device The Sonic Window The Sonic Window is like no other vascular access device available. While it is an ultrasound device, at first glance the images it displays may not be familiar to most users. This is simply because of the scanning format utilized. Instead of a two-dimensional image that is vertical from the skin surface projecting deeper into the tissue, the Sonic Window displays a coronal tissue slice. This is similar to how CT and MRI scans are traditionally displayed, except the slices are oriented horizontally and stacked from skin surface down. The sense novice users attain from first operating the device is that they are able to look at individual tissue slices from just underneath the skin down to 3 cm in depth. Depth is controlled by an easy-to-use thumb operated slider mechanism, giving the operator precise and easy control over ultrasound slice depth selection. Additionally, the slider is specifically designed to allow easy and rapid scrolling through multiple tissue slices in order to identify vessels at different depths. Another notable difference from conventional point of care ultrasound machines is the form factor of the device. It is small, resembling a smart phone or remote control. The Sonic Window is easily held in one hand, leaving the other hand to manipulate a needle or an IV. Site Selection As with any ultrasound guided vascular access procedure, appropriate site selection is important. Basic venous anatomy knowledge is important in order to select sites that are likely to contain accessible, but not previously used veins. These include the upper medial arm where the paired brachial veins and basilic vein are often accessible for cannulation. The cephalic vein on the opposite side of the upper arm is an option in some patients and is rarely cannulated blindly. The forearm and dorsum of the hand and wrist may contain slightly deeper veins that cannot be palpated or seen. However, one of the richest untapped areas in patients is the proximal antecubital fossa. This is an area familiar to many nurses, but in the case of no palpable veins, one can move slightly more proximal where these same veins may be accessible, but are often too deep to palpate. It is an area worthy of a quick look. Simply place the Sonic Window on top of the area of interest after applying ultrasound gel and scan from the surface down a couple of centimeters. This is accomplished with a quick move of the thumb down the depth slide. A vessel, when located, will appear to be a dark or black channel cutting through the background of classic gray scale tissue or an orange mat, if selected, Figure 1. Aligning the vessel so that it runs across the screen of the Sonic Window from one side to the other ensures that the needle can be inserted using the guide markers on either side of the device and help the provider line up directly over the vessel. Driving down at the appropriate angle, usually shallow, the needle appears on one side of the screen and the flash is seen in the hub almost at the same time, Figure 2. Figure 1: Image of an actual patient’s vein prior to cannulation. Notice the accurate depiction of the rough contour and some tortuosity of the vein. This was a dialysis patient with a history of cancer and diabetes who was a severe vasculopath and was about to receive a central catheter just for hydration and intravenous medications. Blind attempts were repeatedly unsuccessful. Figure 2: The image shows a vein as it is being cannulated. The arrows on the right side of the screen point to the needle entering the vein. A flash was obtained as the needle was seen. The Sonic Window: A Novel Vascular Access Device Clinical Experience Fortunately, it was easy to test the Sonic Window in a busy emergency department with high acuity patients. Eight patients were scanned and cannulated. Only one attempt resulted in no veins being located and the absence of any target was confirmed with a conventional ultrasound unit. All others resulted in candidate vein localization and successful cannulation. Vein location included antecubital, cephalic, basilic, forearm veins as well as an external jugular. Several clinical examples are noteworthy. staff reported that no blood could be pulled back for additional blood work shortly afterward. Scanning the cannulation site again with the Sonic Window revealed that the catheter was seated well in the vein and flushed in the lumen only. Fluid resuscitation continued uneventfully through the IV and blood was pulled back successfully at a later time for follow up laboratory analysis. The first was a chronically ill 67-year-old woman on dialysis. After multiple failed blind attempts, the patient was scanned with the Sonic Window. She had few vascular access options peripherally. A new dialysis graft was located in the right arm and an old one in the left. No other sites were found. However, located adjacent to an old, non-functional graft there lay a hidden, unused vein, Figure 3. The Sonic Window allowed easy differentiation of the vein from the old graft and the brachial artery. Patency was confirmed and cannulation successful. Another noteworthy patient was a 20-year-old non-compliant diabetic man who was a frequent ED user. The patient typically received a central line, for hydration, IV insulin and anti-emetics, due to lack of peripheral vascular access options. His external jugular veins were used up previously and could no longer be palpated or seen. Interrogation of the common deep peripheral venous access sites showed multiple scarred and thrombosed veins. However, the Sonic Window revealed a patent right external jugular close to the clavicle. Cannulation was successful; however, nursing Figure 3: An arm with an old dialysis graft that had no obvious veins, yet held a good vein for cannulation, found with the Sonic Window. Sonic Window Handheld Ultrasound Designed to improve first stick success of Peripheral Intravenous Access For more information visit: bkultrasound.com/sonicwindow sonicwindow *Sonic Window is not cleared for sale in the EU. The Sonic Window: A Novel Vascular Access Device Additional Utility There is additional utility to the Sonic Window when placed into the vascular access provider’s hand. When doubt exists about the identity of a vessel, either artery or vein, the Sonic Window offers a unique solution. Compression of the area will cause a normal vein, suitable for cannulation, to slowly disappear and appear to fill in. An artery however, or a thrombosed or scarred vein will not, Figure 4. Figure 4: In this series of three images a vein (vertical arrows) is seen running across the screen arrows. As compression is applied, it collapses, confirming patency. The middle image shows the filing in process occurring as the venous lumen collapses under pressure. Due to the angle of the arm and vein, the vein collapses on the screen from left to right. The middle image has caught the vein collapse half way in its progress. The right image shows the entirety of the vein collapsed, arrowheads. This vein is suitable for cannulation. Not all cases of vascular access are for catheter placement and some patients simply need to have blood drawn. However, in the same difficult vascular access patients, multiple sticks are often required to withdraw blood for laboratory use. The Sonic Window has a role to play in such patients as well. Easily carried in a pocket, rapidly activated and ideal for guiding a needle and visualizing it as it enters a vein during venipuncture, the Sonic Window is a logical phlebotomy tool. Similarly, arterial blood gases (ABGs) are often complicated by body habitus, poor circulation and indistinguishable pulses. The unique ability of the Sonic Window to easily identify and stay over the radial artery makes it a potential tool for anyone cannulating the radial artery for blood sampling. Literature support for ultrasound guidance in radial artery cannulation has emerged making it clear that arterial cannulation benefits from ultrasound use.8,9 Using the Sonic Window for ABGs and arterial line placement means knowing where your target is, despite the thready pulse, and guiding the needle right to it. By aligning the Sonic Window over the catheter in one view, providers are able to check that the catheter is still in a good position, as seen in Figure 5. Additionally, flushing the catheter allows the operator to visualize a disturbance in the vein, just past the tip of the catheter, again confirming an intra-vascular location. Unlike performing the same task with a conventional B mode ultrasound device, the Sonic Window requires considerably less hand eye coordination. Using a conventional ultrasound machine requires an in plane/long axis visualization, precisely holding the transducer over the tip of the catheter and in the middle of the vein. This can be challenging to novice ultrasound users. When using the Sonic Window, the provider positions the device over the vein and does not have to move or adjust any further. A gentle flush with the other hand confirms catheter positioning. 8 Shiver S, Blaivas M, Lyon M. A prospective comparison of ultrasound-guided and blindly placed radial arterial catheters. Acad Emerg Med. 2006 Dec;13(12):1275-9. 9 Schwemmer U, Arzet HA, Trautner H, Rauch S, Roewer N, Greim CA. Ultrasound-guided arterial cannulation in infants improves success rate. Eur J Anaesthesiol. 2006 Jun;23(6):476-80. Summary Dynamic guidance for vascular access was an early point of care ultrasound application and it is now the standard of care for central line placement. Despite 20 years of clinician use and experience, it is only recently that providers have widely recognized, and research has proven, that ultrasound guidance for peripheral line placement decreases the rate of central line placement and therefore any associated complications with the practice. The Sonic Window is specifically developed to simplify ultrasound guidance for vascular access with ease of use, an ideal form factor, as well as utility for multiple vascular access applications.