HINT: The ultrasound Gel is on the rightIn response to recent confusion:

How can you tell the difference between Ultrasound Gel (used for ultrasound machines) and Electrode Gel (used for defibrillation)?

Answers after the break!

Why is this a problem? When you run out of ultrasound gel, you may delay an ultrasound scan for a few minutes.

In contrast, when electrode gel is removed from its proper location, the defibrillator can’t be used. Although we all feel ultrasound is important, it still hasn’t trumped early defibrillation in ACLS.

So why do you need gel to begin with? There are several reasons.

The gel serves to eliminate any air between the transducer and skin. The acoustic impedance (Z) of air is so different than that of the transducer that all of the sound energy would be lost before transmitting into the tissue. Gel (officially termed coupling gel) serves as a better medium to transmit the acoustic energy from the transducer into the body. It is designed to have an acoustic impedance which will be similar to body tissue and the transducer itself, limiting scatter and maximizing the amount of acoustic energy transmitted.