You can hear the familiar voice before you even step into the exam room. “This is ridiculous,” says Susan, one of your most frequent fliers. “I have been poked seven times today and your nurses still can’t find a vein. I’m tired of feeling like a pincushion.”
Susan has been a vascular access nightmare since she was a young woman. She has chronic pain, due to both metastatic lung cancer and chronic pancreatitis, but today, the porta-cath on her chest looks as red and angry as her face after the seven unsuccessful peripheral IV attempts.
Thankfully, you’ve just led a workshop on how to perform ultrasound-guided peripheral IV’s and your intern steps up to the plate. She grabs the ultrasound machine and the requisite IV supplies, then gets started in no time. She begins by applying ultrasound gel and scanning the medial aspect of Susan’s arm just proximal to her medial epicondyle with a high-frequency linear probe. Without the need for a stand-off pad, she visualizes the deep brachial vein quite clearly on the screen making certain that it collapses with gentle pressure and is non-pulsatile. The brachial artery would be pulsating and wouldn’t easily collapse from downward pressure of the probe. Unfortunately, the vein is measuring out to be almost 3 cm below the skin’s surface and angiocath needles that long are not available in your department. Your intern then scans a bit more distally and follows the vein until it becomes more superficial at the forearm.
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Your intern chooses to perform the procedure in a static fashion where she uses ultrasound to locate the vein before venipuncture. With dynamic cannulation, she would actually visualize the needle entering the vein during the procedure. Following localization, your intern uses the needle hub to mark the course of the vein by making two skin indententaions along the patient’s skin. After putting down the ultrasound probe, she preps the patient in a sterile fashion and threads the vein using her two skin indentations as a guide. Within seconds, an 18-gauge peripheral IV has been successfully inserted and both you and your patient are wowed by your intern’s newfound ultrasound skills.
Brady Pregerson runs the QE Emergency Medicine Ultrasound Course, has a free Ultrasound Image Library online and is the author of the Emergency Medicine Pocketbook series (www.ERPocketBooks.com).
Teresa Wu is the Director of Simulation Education and Training for Graduate Medical Education and is a member of the Ultrasound Faculty at Orlando Regional Medical Center in Orlando, FL.
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Guided Peripheral IV Insertion
~ If a peripheral vein cannot be readily visualized or palpated, ultrasound can be used to help localize the vein. Cleanse and sterilize the area of interest in a standard manner and apply a tourniquet proximally to enhance venous filling.
~ Use a higher frequency probe: for superficial structures such as veins. In general, peripheral vein visualization should be performed with a 7.5 to 10 MHz linear array transducer.
~ Optimize the acoustic interface: Apply a large amount of ultrasound gel to improve the acoustic interface. If the patient is thin and devoid of much subcutaneous fat, use an acoustic standoff pad to improve your sonographic window. If standoff pads are not available, improvise with a 100-250ml bag of normal saline or a fluid filled glove sandwiched between two layers of ultrasound gel.
~ Don’t mistake veins for arteries: Veins have thinner walls and will collapse easily under pressure, while arteries will remain patent and pulsatile during the scan. Application of color-Doppler over the vessel of interest can also help distinguish an artery from a vein. If the vessel of interest is an artery, pulsations will be visible that correspond to the patient’s peripheral pulse.
~ Don’t collapse your target: Because superficial veins may collapse readily under even slight pressure, care must be taken to prevent inadvertent collapse by minimizing the amount of force applied to the skin with the ultrasound transducer. If you don’t see a vein where you think one should be, try reducing the pressure of the probe on the skin and see if your vein then appears.
~ Map the vein: Visualize the target vein in both longitudinal and transverse orientations to look for bifurcations and to map out the vessel’s anatomical course.
~ Static Cannulation: Once a peripheral vein has been localized, if you choose to use a static technique (AKA localization and mapping) you will need to mark the skin over the vein. It’s best to mark at least two locations, one on each side of your planned entry point. To do this, you can use a sterile surgical pen, or pressure from the round opening of the angiocath cover.
~ Dynamic Cannulation: If the procedure is performed in a dynamic manner (AKA real time guidance), remember to use sterile ultrasound gel and prep the ultrasound probe in a sterile fashion. Remember that direct visualization of the needle will only be noted when the ultrasound beam is angled directly at the needle. Because the field visualized by ultrasound is so narrow, needle position may need to be inferred by visualizing ring down artifact, soft tissue movement, and tenting of the wall of the target structure.
~ Practice: Remember that “Practice Makes Permanent” so take advantage of the benefits of bedside ultrasound.