Ultrasound Technology PDF

# International Normalized Ratio (INR), continued | Component | Normal Range for adults | Comments | |---|---|---| | Prothrombin Time (PT) | 11-13.5 seconds | PT, the time in seconds, is measured in plasma to form a clot in the presence of sufficient concentration of calcium and tissue thromboplas...

# International Normalized Ratio (INR), continued | Component | Normal Range for adults | Comments | |---|---|---| | Prothrombin Time (PT) | 11-13.5 seconds | PT, the time in seconds, is measured in plasma to form a clot in the presence of sufficient concentration of calcium and tissue thromboplastin by activating coagulation via the extrinsic pathway | | Partial thromboplastin time (PTT) | 25-35 seconds | There are many anticoagulant therapies that may increase a patient's risk of bleeding that will not be evident with routine lab values. Performing a comprehensive chart review of patient's current medications and anticoagulants enables the practitioner to take appropriate caution in deciding what VAD to use and take the appropriate care in the insertion of that device | | activated partial thromboplastin time, aPTT, intrinsic pathway coagulation factor profile | | | # Stages of Chronic Kidney Disease (CKD) | Stages | Description | GFR | |---|---|---| | Normal | Normal kidney function without proteinuria | Greater than 90 | | Stage 1 | Kidney damage with normal or elevated GFR | 90 or higher | | Stage 2 | Kidney damage with mildly decreased GFR | 89 to 60 | | Stage 3a | Mild to moderate loss of kidney function | 59 to 45 | | Stage 3b | Moderate to severe loss of kidney function | 44 to 30 | | Stage 4 | Severe loss of kidney function | 29 to 15 | | Stage 5 | Kidney failure and need for transplant or dialysis | Less than 15 | # I. VESSEL IMAGING AND ASSESSMENT - Ultrasound technology - Studies support safety, efficacy, and superiority of ultrasound (US) guidance with CVAD insertion - Ultrasound is used to locate vessels, determine vessel depth, diameter (catheter to vessel ratio) health and compressibility as well as identify clinically significant surrounding structures - Ultrasound-guided CVAD placement is associated with high success rate, decreased mechanical complications, safer and more efficient catheter placement # Table 7. Ultrasound Technology | Term | ULTRASOUND PHYSICS | Description/Definition | |---|---|---| | Frequency | | Cycle per second of sound energy | | Hertz (Hz) | | Number of times a phenomenon occurs in one second | | Megahertz (MHz) | | A frequency of 1 million cycles per second | | Medical ultrasound | | High frequency sound waves between 2 MHz and 15 MHz | | Attenuation | | Loss of US energy as it travels through a material or medium. The higher the frequency, the greater the attenuation or greater the loss; less depth the lower the frequency, there is less attenuation and greater depth penetration | | Penetration | | The higher the frequency of high frequency sound (US) waves, the less penetration through soft tissues or less depth | | Reflection | | High frequency sound waves travel through soft tissue and fluid and are bounced back or "reflected" at interfaces between materials. US cannot travel through air. Fluid such as blood and water are poor reflectors of US waves, appear as black. Soft tissues: varying degrees of moderate reflection of US waves, producing images of varying degrees of gray. Bone/metal: US cannot travel through solid materials; US is nearly completely reflected back and interface appears white | # Term | Description/Definition | |---|---| | Resolution | Quality of image; ability to differentiate anatomic structures with detail. The higher the frequency, the higher the resolution, but decreased penetration (the ability to see shallow images very clearly). The lower the frequency, the lower the resolution but increased penetration (can see deeper images but with less clarity) | | Transducer Probe | ULTRASOUND IMAGING COMPONENTS. A device connected to the US machine that is placed on the patient's skin over the area to be visualized. Views 1mm width and only directly where probe is aimed. Receives US waves reflected back into the probe using piezoelectric crystals that creates an image on the ultrasound screen | | Gain | Amplifies reflected energy waves or signals and affects the brightness of the image. If the gain is too low the image will be too black and if the gain is too high the image will be too white | | Transverse Plane | The cross-sectional dimension of an object being visualized with US (vessels will appear as circles) picture | | Longitudinal Plane | Lengthwise dimension of an object being visualized with US. Vessels will appear as long tubes | | Orientation Marker | A ridge or marker on one end of the transducer to allow the user to consistently allign the probe relative to the patient's body and correlate with the orientation marker on the ultrasound display screen | | Ultrasound Gel | Allows ultrasound energy to be transmitted from the transducer probe into the soft tissues of the body, and eliminates the air interface (air cannot transmit US waves)| | Sterille Probe Covers | Designed to maintain a sterile field | | Real-Time Imaging | The repeated process producing rapidly changing images | | Depth of Image | Depth of visualization through tissue, in centimeters (cm), from the skin surface (top of the display screen) downward. Depth can be controlled by the user to increase the field of view or to look deeper. It is usually set at the beginning of the scan based on patient parameters (depth of object visualized) and user preference | | Needle Guides | A slot in the transducer that allows for attachment of a pre-manufactured guide that aligns the needle at the correct angle to enter vein based on the depth of the vessel. When using ultrasound, a practitioner either uses a needle guide or else a free hand approach in which the practitioner is solely responsible for the angle/depth/trajectory of the needle | # IDENTIFICATION OF VESSELS USING ULTRASOUND - Veins (for purposes of VAD insertion) - In transverse view, veins appear as round objects with a blackish center as blood is a poor reflector of US waves. In the longitudinal view veins appear as tubes with a blackish center. - When transducer probe compresses soft tissue, veins collapse easily, remain collapsed and will not pulsate - Arteries - In transverse view, arteries appear as round objects. In the longitudinal view, arteries appear as tubes. - With light to moderate compression of the US probe, arteries pulsate