RPSGT Exam Instrumentation/ Waveforms Questions with correct Answers

According to the principles of differential amplification, electrical interference can best be prevented if - Answer- The impedances of input elecrodes are similar During a recording, the technologist notices that the HFF on an EOG channel is set at 15Hz. Which of the following is correct? - Answer- Rapid eye movement signals will be attenuated G1 receives an input voltage of -100uv while G2 simultaneously receives -50uv. The polysomnograph sensitivity is set at 10uv/mm. What will be the pen deflection? - Answer- 5 mm upward Sensitivity can be explained in which of the following equations? - Answer- Sensitivity = voltage/pen deflection Which of the following is a function of a differential amplifier? - Answer- To record the differences in the voltages of two inputs Which of the following low/high filter settings are most appropriate for these channels? - Answer- 0.3/35 0.1/35 1.0/35 10/70 Changing the sensitivity of an amplifier from 5uv/mm to 10uv/mm will - Answer- Reduce the pen deflection by one half What is an example of a transducer signal? - Answer- flow channels and respiratory effort channels G1 = -25uv. G2 = -25uv. What is the output voltage? - Answer- 0uv The technician notices equal time constant settings for the chin EMG and the EEG channels during the initial calibrations. What sort of effects might one see in the EMG channel? - Answer- Respiratory artifacts in the EMG G1 = -80uv. The output voltage is 20uv. What is the voltage at G2? - Answer- -100uv The tech is setting up the Grass Polysomnograph. They perform machine calibrations by applying a 50uv voltage to each input. The machine sensitivity is set at 5uv/mm. What should be the height of each pen deflection? - Answer- 10 mm A low filter is set at 1hz. Which of the following statements are true? - Answer- signals at 1hz will be attenuated and may lead to an under scoring of SWS Which of the following filter combinations would be most appropriate for recording the EEG in polysomnography? - Answer- LFF = 0.3hz HFF = 30hz Which of the following is not a bioelectric potential recording? - Answer- Respiratory airflow If a high frequency filter setting of 15hz is used to record EEG, how might this potentially limit the information recorded by the polysomnograph? - Answer- The 15hz HFF setting may attenuate certain types of abnormal fast frequency activity, such as seizure spikes in the EEG and The 15hz HFF setting may attenuate alpha activity while the patient is awake What are two key factors in reducing noise and improving signal quality in a differential amplifier? - Answer- Low and equal impedences at the amplifier inputs Which EEG signal will be attenuated the most with a high filter setting of 15hz? - Answer- Beta Which signal input employs the use of a DC amplifier? - Answer- Capnography In DC circuits __________ opposes the flow of current where in AC circuits ___________ opposes current flow. - Answer- Resistance, Impedance Based on the principles of common mode rejection, which amplifier is the best for rejecting noise? - Answer- CMRR2000 Which amplifier back at the jack box provides impedance matching characteristics between the patient and subsequent cabling back to the polysomnograph? - Answer- Buffer amplifier The frequency response curve shown above would be representative of which sort of polysomnographic channel? - Answer- EEG The polysomnograph sensitivity is set at 7uv/mm. You measure the height of a wave at 8mm. According to the minimal voltage criteria for scoring delta waves, is the voltage of this measured wave sufficient? - Answer- No If the signal on the exploring electrode G1 is more positive than the reference electrode G2, the output voltage is ________ and the pen will deflect__________ - Answer- Positive, downward A device for storing an electrical charge is a? - Answer- capacitor If the patient is breathing 12 BPM what is the frequency of their breathing? - Answer- .2 hz The paper speed of your polysomnograph is running at 10mm/sec. The technician measures a sleep spindle that upon further observation shows 6 cycles across 5 mm of EEG paper. What is the frequency of this spindle? - Answer- 12 hz EEG - Answer- AC amplifier Respiratory effort - Answer- AC or DC amplifier Capnography - Answer- DC amplifier What is frequency Roll Off? - Answer- rate of attenuation outside of filter setting range Asking the patient to open their eyes results in - Answer- slow eye movement such as those seen at sleep onset Alpha rhythm activity is generally most prominent in the - Answer- occipital montage When the left EOG channel becomes positive and the right EOG channel becomes negative it is most likely du