CBET Medical Equipment Function 4

Question 1

In a pulse oximeter, which physiological principle is used to differentiate oxygenated from deoxygenated hemoglobin?

Accepted Answer

Differential light absorption at two wavelengths (660 nm and 940 nm)

Answer

Pulse oximeters exploit the fact that oxyhemoglobin and deoxyhemoglobin absorb red (660 nm) and infrared (940 nm) light at different ratios.

Question 2

A patient-controlled analgesia (PCA) pump must include which safety feature to prevent accidental overdose?

Accepted Answer

A lockout interval that disables bolus delivery for a set time after each dose

Answer

The lockout interval enforces a mandatory waiting period between boluses, preventing the patient from receiving dangerous cumulative doses.

Question 3

What is the primary function of the inspiratory-to-expiratory (I:E) ratio setting on a mechanical ventilator?

Accepted Answer

It controls the proportion of time spent in inhalation versus exhalation during each breath cycle

Answer

The I:E ratio defines how the breath cycle is divided, affecting gas distribution and hemodynamic impact; normal is approximately 1:2.

Question 4

In electrosurgical units (ESU), the return electrode (dispersive pad) functions by:

Accepted Answer

Distributing current over a large surface area to minimize current density at the patient return site

Answer

The large area of the dispersive pad spreads current so densely is too low to heat tissue, preventing burns at the return site.

Question 5

A phototherapy unit used for neonatal jaundice delivers light primarily in which spectral range?

Accepted Answer

Blue-green light (420–500 nm)

Answer

Blue-green light in the 420–500 nm range is absorbed by bilirubin, converting it to water-soluble isomers that can be excreted.

CBET - Certified Biomedical Equipment Technician Practice Test