![]() ![]() The machine also should have markers vertically on the screen to indicate the depth of structures seen, which can be adjusted based on the depth of the target vessel. This usually is achieved by keeping the probe marker facing towards the patient's right side. The probe indicator should be oriented to correlate with the side of the screen that the marker is on so that the movements of the probe correlate with the movements seen on the screen. The US probe indicator is a bump or marking on the side of the probe, which correlates with a marker on one side of the screen (generally the left) for location identification. If the procedure is for central access, full sterile precautions are also required.Ĭlinicians should be familiar with the specific US machine of the home institution, as there are some differences in design. Īside from the supplies necessary for vascular access, an ultrasound machine with a high-frequency capable probe is all that is necessary. This can be done in longitudinal or transverse planes. Once the proper vessel is identified, follow the path of the vessel to identify any branching or tortuosity that may complicate the cannulation. When using Doppler flow, the artery should show a much greater variation in the velocity waveform as compared to the vein. When using color flow mode, it is important to remember that the different colors do not inherently represent artery or vein but instead the direction of blood flow towards or away from the probe, so the operator should be careful to slightly angle probe and interpret the color based on the probe’s angulation. In these cases, the color flow mode or Doppler mode may assist in differentiating between the artery and vein. With hypotension or vessel calcifications, these differences may not be as noticeable. Arteries also have slightly thicker and hyperechoic walls when compared to the veins. In addition to this, when pressure is applied there often will be a pulsatile movement of the arteries. Veins should be easily compressible when pressure is applied using the US probe, whereas arteries will generally not collapse. This can be done using knowledge of anatomy as well as the different characteristics seen on US. One must differentiate between artery and vein before cannulation. The primary alternatives to US-guided IV access are anatomic landmark-guided placement (traditional), intraosseous access, or not obtaining IV or IO access (using intramuscular and oral routes). Other alternative adjuncts to aid in IV access include devices made for trans-illumination. Limitations to the use of US for IV access include the availability of US machines and training required.Īnytime a procedure is considered, the alternatives should be considered as well. Once mastered, the procedure is simple, effective, safe, and presents little to no increased risk or contraindications. While not as common, ultrasound can also be utilized for arterial access and cannulation. The safety and high success rate of US-guided IV access have been proven in the literature, and this effectiveness is the reason for such widespread integration in emergency departments. Ultrasound (US) guidance for intravenous (IV) access has been well documented for more than 20 years and is now routine in many settings for non-emergent central line placement and difficult peripheral IV access. ![]()
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