Programming and Coding Flashcards
Telemetry
Confirms proper communication between the processor and the electrodes
AB and Cochlear:”impedance”
Medel: “telemetry”
Neural response assessment
Electrophysiology response from nerve in response to electrode stim
Useful for pediatrics who can’t give subjective measurements
T levels
Measures threshold for sound on each electrode (only cochlear devices)
Measures the lowest amount of electricity needed to be perceived as sound
C or M levels
Comfort levels measured using a scale
-Upper loudness levels.
Speech strategies
Different methods of stimulation that can produce diff perceptions from the patient
- sequential
- simultaneous
- both
Connecting equipment
You’ll need:
- computerized processing unit/ interface (cpu/cui); the “pod” that allows the computer to communicate with the processor
- implant
- processor
- the patient
Prepare equipment: AB
- Verify connection of components: coil to cable to processor
- Initialize processor
- which ear, modality of use (bilateral, unilateral, bimodal)
- do this when loading/reassigning a processor - Condition electrode array
Stimulate all channels at the same time
Gets rid of buildup around array
Perform this at activation, 1wk follow-up, returning on channel
Prepare equipment: Cochlear and medel
- Verify connection of components: coil to cable to processor
- Reset processor as needed
Impedance
Stimulus parameters: current, voltage, stim. Width
Material of electrode surface: (an inverse relationship) narrower contact, more impedance
Nature of the medium of transmission is specific to each electrode: air vs tissue
Measures the opposition to electrical, current flow
Impedance (kiloOhms)=voltage/current
Voltage= impedance x current
When current is cons at increase in impedance will increase voltage
More resistance to flow = higher impedance
Deactivated electrodes
Short electrodes (-<1kOhmn)
- wires touching and likely to send stim across channels
- always in pairs
- turn off and leave off forever
Abnormally high impedance (>30kOhmn)
- broken wire
- air bubble; current can’t travel through air—> remeasure post stimulation
- may decrease with use or by increasing the pulse width
NRT
Neural Response Telemetry
-Cochlear specific
-use of the electrically evoked compound action potential
—gross potential that reflects synchronous firing of a large # of electrically stimulate n8 fibers
—-reflective of wave I of acoustic ABR and comfort levels or upper dynamic range
AB: Neural response imaging (NRI)
Auto NRT
Cochlear Specific
Steps:
1. Select # of channels to run (3, 5,9) a low, mid and high. Running all will take a long time
- Click measure
- Watch measurements and pt reaction
- Prepare to skip channels if pt. Reports discomfort
- Software will move on to next channel if stimulation reaches compliance w/o achieving a response
Auditory neuropathy won’t have NRT
No need to measure later because they should be stable
Terminology
Programming/mapping: Measuring thresholds, tolerance levels, assessing implant status
MAPs: configurations of current units (CU); processing strategies; stimulation rate
Programs: configurations of MAPs; similar of hearing aid programs;use of different programs
Flex NRI
AB specific
NRI= Neural Response Imaging
1. Select channels to stimulate on (avoid most basal @ activation- build up)
2. Recording channel is 2 apical from stim
3. Select level of ordering
–low to high (awake pt.)
–high to low (sedated/surgery in OR)
4. Set min and max stim levels (100-250 uV)
-look for 3 repations of response per channel
5. Crates EP Growth FUnction (best regression line)
6. tNRI corresponds to M levels (not as nicelys to C levels for Cochlear)
NRI/NRT not in MedEl
Clinical Utility of NRT/NRI
- Stable over time
- Used w/ impedances to see if change in performance is due to device function or neural responsiveness; Pt not doing well and impedances are weird, recheck this and if abnormal, may indicate a soft failure.
- Measure w/in first few months of stim (baseline)–> annually/bi-annually afterwords
- loosely correlates with Ms/Cs as a guide to max comfort levels
- Can assess pitch at activations “same vs diffierent” or high vs low
Terminology per company
Cochlear:
Ts and Cs are required
AB/MedEL: Ts are optiona (will be interpolated from Ms) l and Ms are required
SF thresholds per compant
Cochlear: 20-25 (slight)
AB/M: 30-35 (mild)
Challenges of NRT/NRI
Highly influenced by
- neural survival and synchronous activity
- nerve survival re: measuring electrode
To reduce noise
- remove contra CI
- Increase high level and # of averages (AB)
- decrease sample per data point
ESRT
-electrically evoked spatial reflex thresholds
-Electrical stimulation to implant
Measure SRT in nonimplanted ear
—immittance bridge or in OR w/ bridge
-ESRT occurs at or near max levels used by processor
-Not recorded in 25-35% of patients **
-Pt.s participate to a degree
How to perform ESRT
- Place probe in contralateral ear
- continuously record acoustic admittance w/ 226 Hz probe tone within Decay screen
- Present programming stim used for upper limit of DR (C/M level)
- Change in admittance occurs time locked with stimulus when presentation level is the ideal intsenity for the upper limit of the DR
Medel is the only one with ESRT screen
Must consider hx. of middle ear disorder
Stimulation Mode
location of the reference electrode re: active electrode
Monopolar (ground is outside of the cochlea)
Bipolar (stim occurs w/in cochlea)
Cochlear and AB: either
Medel: monopoglar only
DR
For speech (single)- 30 dB multiple speakers >60 dB
NH: 100 dB
CI: 3-20 dB
distance between Ts and C
Input DR (IDR): CI select the range of intensities o output to code
Threshold trouble shooting
T’s are too loud
-person hears motor noise of processor. Turn mics off and no longer hear, turn T’s down
Child w/ 5 dB to NBN: adjust T levels
Bring Ts up for better thresholds and lower Ts for poorer thresholds
Threshold
Cochlear Nucleus: ser at a level at or just above threshold
“just barely detecting
Medel CIS: highest stim where no sound is perceived
T tail: audible over a given range–> set at upper limit of their range.
T levels in Ped
May use with objective offset programming method
At least one behavioral and at least one electrode measurement
–Behaviorally: VRA (booth, puppets)
CPA
Comfort levels/Most comfortable levels
Upper limit of DR
Cochlear (Cs): set below max. comfort (right below UCL) due to summation across electrode
Medel: highest stim level at which sound is loud, but comfortable
AB: most comfortable level-daily listening level. Speech burst are used for setting M-levels (groups of 4 using broadband stim)
C/M level measurements
ascending technique
-switching from older map: decrease globally by 10 cus and then ascend.
-steep loudness growth in some
loundness charts are helpful
Influences on levels
Speech processing strategy
Bipolar vs monopolar
stim rate (increase in rate, level decreases)
Proximity of electrode array to modiolus (further= more current level, modiolus hugging (lower level)
Loudness balancing
Ensure equal loudness on all electrodes
- Two methods
- -balancing (low to high)
- -sweeping (pulse on each channel)
Compliance levels
- amount of voltage allowed for each electrode
- “out of compliance” = max voltage available from implant is not sufficient to generate the desired current level
- going to sound soft.
- -cant increase stim units.
solution: increase the pulse width.
Consequences of being out of compliance
-Insufficent loudness growth, variable loudness, lack and loudness growth
distorted sound
poor battery life
decreased performance
Power optimization
- can better type provide enough voltage to deliver the requested amount of current
- as required voltage increases, battery life decreases
- ->pot. solution: decrease pulse rate
- want to use automatic power as much as possible.
This is measured when the coil is on the pt.’s head
Calculated for each map by determining how much power is needed in the worst case condition to ensure all electrodes
are w/in compliance
Live voice modifications
Tilting Increase/decrease levels on all channels -echoy/boomy= upper limits, bring down C/Ms -low level humming= Ts (bring them down) Gain- too loud, bring down on the processor programming Freq. adjustments -Tinny-HF -Hallow -MF -boomy-LF
Noise reduction
AGC autosensitivity
Adaptive DR Organization (ADRO)- gain adjsutmet at each freq. band
BEAM- multi mic
-cochlear and AB
Patient conrtols
Programs
Volume (Cs/Ms)
Sensitivity (distance of hearing and perception in noise)
Processing strategey
set of rules to convert acoustic input into electrical output
sequential or paired Captures following parameters of sound -Time (well) -Intensity -Spectral (poorly)
Temporal domain
-temporal envelope is important (and is perceived), but so is fine structure.
Intensity domanin
- directional mics
- mic placement (hear level, head piece, t mic)
- automatic gain control (AGC)
- input DR compression –> takes IDR and puts into electrical DR
Spectral domain
NH: 20-20, 000 Hz
CI: ~250-8000 (AB and M =60dB at 250)
-not much resolution needed for speech as with music. Music of diff, but close freq will be passed through the same filter (perceived as the same sound)
Processing strategies
- Continuous interleaved sampling (CIS) -simplest
- HiResolution AB
- Advanced combination encoder (ACE) Cochlear
- Spectral peak (SPEAK)
- Fine structure processing (FSP) Medel
Continuous interleaved sampling
sequential
slowest (1000 stim rate)
simpliest - 8 channels
bandpass filters
AB’s version= Multiple pulsatile sampler (MPS) double the stim rate, increases the “temporal” resolution
Medel uses CIS+ and HDCIS- wider freq range and use of virtual channels for improved “spectral” resolution.
