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49 Cards in this Set
- Front
- Back
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VNS Therapeutic Range |
Output current of 1.5-2.25 mA Dosing range: 0-3.5mA |
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Initial Dose |
0.25 mA |
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Common Pulse Width |
250 to 500 microseconds |
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Dosing Parameters |
Output current Signal frequency Pulse width Signal on time Signal off time |
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What is the goal of dosing? |
Maximize therapeutic effect Minimize side effects |
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Dosing: Phase 1 |
Ramp up Output current to 1.5-2.25 mA |
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Dosing Phase 2 |
Increase duty cycle Every 3-6 months |
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Side effect managment |
Adjust: pulse width, output current, and threshold for Autostim |
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Shortest off time for AutoStim |
1.1minutes |
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Strategies to Manage Side Effects |
1. Reduce pulse width 500-250 2. Reduce signal frequency 30 to 25 or 20 3. Reduce output current: Aspire 0.125 0.25 in others |
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AutoStim: Strategies to manage side effects |
1Verify heartbeat detection auto stem: Adjust heartbeat sensitivity if necessary reduce pulse width, reduce on time, reduce output current Increase threshold for autostim current 10% |
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Impedance Range |
Low less than 600 ohms More than 5300 ohms |
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Exclusion zone for MRI |
C7 to T8 |
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MR conditional |
VNS therapy MRI approval |
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Output current |
Amount of elected current (mA) delivered during a single pulse of stimulation |
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Pulse Width |
Duration of a single pulse (microseconds) |
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Signal Frequency |
Number of pulses per second (Hz) |
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Dose Wave |
VNS delivers a series of pulses (pulse train) |
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Ramp up/ramp down period |
2 seconds for each |
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On time |
Duration of time pulses are delivered |
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Off time |
Interval between on-time INCLUDES RAMP UP/ramp down |
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Lowest off time for AutoStim? |
1.1 minutes Can cause overstimulation with AutoStim enabled |
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Magnet mode: AutoStim |
0.125 mA higher than AutoStim mode |
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Primary operating mode for VNS |
Normal Mode |
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Typical duty cycle |
30 seconds on 5 minutes off |
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Magnet Mode parameters |
Output current mA Pulse width usec Magnet on time seconds |
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AutoStim side effect strategy |
1. Verify heartbeat detection: adjust sensitivity 2. AutoStim: LOWER-1-pulse width, 2-ON time, 3-Output current 3. Raise AutoStim threshold 10% |
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Define normal mode stimulation |
Most common used mode manages 25 hour on and off time. |
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Aspire SR: how long does magnet need to be applied? |
6 seconds |
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How do we measure lead impedance? |
Ohms |
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Signs of a short circuit? |
Less than 600 ohms |
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What’s needed for generator diagnostics? |
Test resistor kit. |
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Magnet above normal? |
0.25 |
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AutoStim above magnet |
0.125 |
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Tunneler: how much does it bend? |
25 degrees |
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Before running diagnostics: tell the anesthesiologist: |
Systole and bradycardia May happen |
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Implantable VNS components: |
Lead Generator |
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Why perform device diagnostics? |
Test the integrity of the system The lead and generator |
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Why perform device diagnostics? |
Test the integrity of the system The lead and generator |
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OR: high impedance |
Lead fracture Incomplete insertion Electrode detachment from Bahia neeve |
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AutoStim enforced off time |
Same as AutoStim on time |
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AutoStim enforced off time |
Same as AutoStim on time |
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Length of blackout time? |
30 seconds |
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How does AutoStim work? |
Algorithm that measures heart rate increases relative to background heart based on a pre programmed threshold |
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Size of strain relief bend? |
3 cm |
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What model is Demi pulse duo? |
104 |
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Minimum R-wave for heartbeat detection? |
0.4mV |
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Patient kit |
Two magnets Two patient ID cards |
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Dual pen generators |
102R 104 |
