Ever finally step away from a busy resuscitation and someone stops you for peripheral IV access? You set up everything, have the patient positioned, and then notice there is no sterile ultrasound gel. No gel? No problem. The trick is to eliminate anything of poor acoustic impedance between the ultrasound probe and the patient’s skin.
Trick of the Trade
1. Apply a transparent adhesive dressing with a thin alcohol layer on the probe
Instead of using gel, we squeeze alcohol pads to create a thin alcohol layer and place a transparent adhesive cover, such as Tegaderm ©. The thin alcohol layer serves to eliminate any air bubbles under the adhesive cover as well as minimizes residual adhesive material sticking to the probe when removing the cover. The adhesive cover itself serves as a sterile barrier and a slick surface to improve probe maneuverability. Note that some ultrasound manufacturers do not recommend the use of isopropyl alcohol on their transducers. Therefore check your specific ultrasound’s recommendations before trying [1, 2].
2. Use sterile saline instead of gel on the patient’s skin
Squirt normal saline flush on the patient’s skin to create a coupling medium between the probe and the patient.
Why it works:
Ultrasound procedures use a range of frequencies (1.5-20 MHz) to visualize internal structures and require a medium to replace air, which has a poor acoustic impedance for the ultrasound waves . Acoustic impedance is defined as the resistance of the propagation of ultrasound waves through tissues and is the product of the density and speed of sound in the tissue . Ultrasound gel has an acoustic impedance that is similar to soft tissue and is therefore considered the ideal medium . Because most soft tissue is comprised of water, the acoustic impedance of water, and therefore 0.9% saline, is actually pretty similar , as demonstrated by water bath techniques for ultrasounding distal extremity injuries .
We find great visual clarity for performing ultrasound-guided peripheral IVs using this trick, as shown in Figure 1.
Read other Tricks of the Trade articles.
- Cleaning and Disinfecting FUJIFILM SonoSite Products User Guide [PDF]. Sonosite. 2015. Accessed April 5, 2023.
- Disinfectants and Cleaning Solutions for Ultrasound Systems and Transducers [PDF]. Philips. 2021. Accessed April 5, 2023
- Afzal S, Zahid M, Rehan ZA, et al. Preparation and Evaluation of Polymer-Based Ultrasound Gel and Its Application in Ultrasonography. Gels. 2022 Jan 6;8(1):42. doi: 10.3390/gels8010042. PMID: 35049577; PMCID: PMC8774352
- Suzuko S, Peter G, Philipp L. 20 – Local Anesthetics, Ed(s): Hugh C. Hemmings, Talmage D. Egan, Pharmacology and Physiology for Anesthesia (Second Edition), Elsevier, 2019, Pages 390-411, ISBN 9780323481106. DOI: 10.1016/B978-0-323-48110-6.00020-X
- R. Alkins, K. Hynynen, 10.08 – Ultrasound Therapy, Editor(s): Anders Brahme, Comprehensive Biomedical Physics, Elsevier, 2014, Pages 153-168, ISBN 9780444536334. DOI 10.1016/B978-0-444-53632-7.01010-8
- LeDonne S, Sengupta D. US Probe: Ultrasound Water Bath for Distal Extremity Evaluation. Alerhand S, Singh M, editors. emDOCs.net – Emergency Medicine Education. 2017.