CNIM Practice Test 2024 New Full Questions and Answers ( Included ) 100% Correct
1. A differential amplifier records:
Only the first two inputs The second half of the inputs The power of the sum of the two inputs The difference between the two inputs
Answer: The difference between the two inputs
2. Accurate representation of an EP waveform requires a match between the:
Signal size and vertical capacity of the digitizer High frequency noise and smoothing operation of the digitizer Dwell time and sampling rate Horizontal resolution and signal size
Answer: Signal size and vertical capacity of the digitizer
Digitization refers to the process of converting the amplitude of an analog signal into a series of numbers. The most accurate representation of the amplitude (vertical resolution) of a waveform will result when the actual amplitude represents the full capacity of the digital conversion. This would be analagous to taking a photograph and using enough tiny pixels to represent the photograph in an appropriate size.Without enough pixels, the photograph will have a low resolution and appear blurry. Using the full capacity of pixels will yield the most accurate representation of the image.
- Due to smaller surface area, subermal needle electrodes will register an impedance that is:
Lower than surface electrodes Increased upon insertion Improved by cleansing the skin Higher than surface electrodes
Answer: Higher than surface electrodes
This question refers specifically to electrode's surface area. Although we know subdermal electrodes are less likely to become dislodged and experience less skin-resistance than surface electrodes, the question is asking specifically about the relationship between surface area and impedance of a fully intact electrode. Impedance is essentially resistance in a more complex relationship (the resistance of an alternating current). And resistance increases when surface area decreases. 1 / 2
Therefore, given two perfectly placed electrodes with optimal contact, the impedance of a tiny needle will be higher than that of a large surface electrode.
4. To stimulate left and right nerves asynchronously:
Answer: delay the second stimulator
this question refers to bilateral asynchronous stimulation - this is also known as interleaving stimulation
5. Stimulus intensity at the tympanic membrane depends on:
acoustic coupling between sound stimulus generator and the ear patient's hearing level relationship between rate of stimulus and the hair cells relationship between SPL and peak equivalent HL
Answer: acoustic coupling between sound stimulus generator and the ear
*After entering the auricle and traveling through the external canal, sound pressure waves create movement in the tympanic membrane, according to their intensity and frequency.Therefore, two primary factors that influence the intensity of sound presented to tympanic
membrane include: sound stimulus generator (transducer) and the ear canal
- An amplifier is set to give an output signal of 1V for an input signal of 10 uV, The gain us:
Answer: 100,000
Gain does not have a unit Gain = voltage out/voltage in
- The most appropriate ECog sensitivity in the oR would probably be
Answer:
10-50 uV/mm 50-100uV/mm 100-150 uV/mm
200-300 uV/mm: 50-100 uV/mm
ECog is EEG recorded directly from the cortex. The units of uV/mm are referring to paper speed, which is why these are not typically the sensitivities we use in the OR. While scalp EEG using subdermal needles in the anesthetized patient usually requires a digital sensitivity of 5-7 uV/mm, the direct cortical EEG will be a larger response and will therefore require a lower sensitivity. The lower the digital sensitivity,the larger the number. This is a y-axis scale, think of it like a zoom. A sensitivity of 50-100 uV/mm is lower than that of scalp EEG, allowing for visualization of large amplitude signals without overlap from neighboring
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