Wk12-31-Programming Workflow Flashcards
What are the 5 steps in the programming workflow?
1) Impedance measurement
2) Set Basic Parameters
3) Assess Upper and Lower Limits of EDR
4) Stimulation and Ax
5) Further adjustment to Upper and Lower limits of EDR/Basic Parameters as needed
What’s another name for impedance measurements?
Telemetry ax (assesses integrity of electrodes)
4 possible options for every single electrode:
- normal
- open circuit = extremely high impedances
- short circuit = neighbouring electrodes impacted
- short circuit = distant electrodes impacted
*Oticon needs a distance measurement before this step to determine if the coil is appropriate
What is the purpose of telemetry/impedance measures?
To determine if normal electrical transmission is occurring between the electrode and the nerve (normal levels)
Impedances are higher d/t:
- air bubble
- otosclerosis or connective tissues formation
- fault in the lead
- extrusion in the electrode array
- have impact on battery life and sound quality
What should you do if a short circuit in neighbouring electrodes is noted?
1 or both should be shut off
- decision based on age of patient and patient percept (e.g. clear beep vs static sound on one or both?)
What should you do if short circuit is noted in distance electrodes?
Shut off both - will result in frequency allocation adjustment
What are the “Basic Parameters” to be set?
Speech encoding strategy (can select number of maxima and rate of stimulation) (d/t philosophy of cognitive load)
Grounding Method (might adjust if facial nerve stimulation)
Pulse characteristics (e.g. pulse duration/width depending on company) (loudness growth)
Audiometric thresholds for EAS (software requires thresholds to account for audibility/cut-off frequency of HA vs CI)
How are the lower limits of the EDR assessed?
Objectively and subjectively
Measure - modified Hughson-Westlake Procedure
- count the beep
- psychophysical loudness scaling
Assign - input a minimum level (difficult to ax patients)
Estimate - determined as percent of upper limits of the EDR (find MCL and set threshold as 10 percent of that)
What methods can we use to behaviourally assess lower limits of EDR for paediatrics?
- behavioural observational audiometry
- VRA
- CPA
**inaccurately set lower limits
Too high = soft sounds are too loud, continuous noise perceived as humming
Too low = unable to detect soft sounds
How can we assess upper limits of EDR?
Objective and subjective methods to set MCLs
Measured - psychophysical loudness scaling or eSRT (have user determine MCL listening to live speech)
- loudness balancing (compare adjacent pairs or triplets; use comparison chart to ax
- sweeping (ax sound quality, pitch transitions, and equal loudness)
Consequences of inaccurately setting upper limits:
Too high = discomfort, poor speech recognition, non-use
Too low = poor speech recognition and/or poor sound quality
How do we assess upper limits of the EDR for paediatrics?
- eSRT
- global increase in levels while listening to speech and watch for behavioural change (e.g pull device off or cry) (set below - can use this on individual electrodes as well)
- channel specific stimulus increases and watch for behaviour change
- ECAPs used as a guide for upper levels (combine w/ global increase, etc)
- psychophysical loudness scaling (depends on age, compliance, and consistency)
How can we predict the upper limit of electrical stimulation without psychophysics?
eSRT (electrically evoked stapedius reflex threshold)
eCAP (electrically evoked compound action potentials)
Progressive MAPs (paediatrics, dementia, etc)
How is the eSRT used to estimate upper limit?
eSRT (electrically evoked stapedius reflex threshold)
- requires impedance bridge and programming equipment
- increase upper limit of stimulation until reflex is observed and then decrease again until reflex disappears
- often uses contralateral reflex
- do on multiple channels to determine overall “shape”
- correlation: r = 0.87 (when able to be measured)
How can the eCAP be used to predict upper limits?
- CI is stimulated using pre-defined parameters
- Pulse amplitude or duration (depending on company) is increased
- measured response performed via reverse telemetry which correlates with wave I of the ABR
How are progressive MAPs done?
- select a shape and program of stimulation (lower limit and upper limit for each electrode)
- used to encourage CI user to get comfortable slowly with increasing stimulation levels.
- listener starts in one program then, when beginning to struggle, moves on to program with higher levels
How can we stimulate and assess function for the CI user?
Following acclimatization to MAP:
- aided audiometry (sound field)
- Ling-6 sound ax (*if new/recent change, may see some mix-ups)
- speech perception testing (HINT, AzBio, CNC) (usually about 3 months post-activation)
