PRACTICE TEST: BASIC TEE
Which of the following is a characteristic of ultrasound?
a) Travels at a constant speed, regardless of the medium
b) Can travel in a vacuum
c) Composed of longitudinal waves
d) Produces net particle displacement on the medium
(c). Ultrasound travels as a series of longitudinal pressure waves without net particle displacement of the medium. It cannot travel in a vacuum, and its speed is different in different media.
Which of the following statements is true regarding ultrasound?
a) Ultrasound waves have a frequency greater than 0.02 MHz
b) Imaging transducers have frequencies of 20 to 30 MHz
c) Frequency is directly proportional to wavelength
d) Frequency is determined by the medium through which sound is traveling
(a). Ultrasound waves have frequencies greater than 0.02 MHz, or 20,000 Hz. Remember that MHz is a 106 multiple. Imaging transducers usually range from 3.5 to 12 MHz, and frequency is inversely proportional to wavelength.
Which of the following tissues has the lowest speed of propagation for ultrasound waves?
(e). The lung has the lowest speed for conduction of sound (500 m/s approximately). This is because lung fields primarily represent air. Recall that the speed of sound is slowest in air and progressively faster in stiffer materials.
Which of the following is an absolute contraindication for TEE?
b) Bleeding esophageal varices
Of all the options the only absolute contraindication is active upper gastrointestinal bleeding (b); the rest of them are relative contraindications.
The small wheel on the TEE probe controls which of the following probe motions?
c) Turn to the right/left