Flashcards in Rheobase And Chronaxie Time Deck (10):

1

## Define Rheobase

### Rheobase is the lowest point on a strength duration curve at an infinitely long pulse duration.

2

## In cardiac pacing, when is Rheobase Usually reached?

### Between one and 2 ms, at shorter durations, threshold rises

3

## Define chronaxie time

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Chronaxie time Is the pulse width at twice the rheobase value

Chronaxie time Approximates the most efficient stimulation pulse duration

4

## Define the strength duration curve

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The quantity of charge, current, voltage, or energy required to stimulate the heart at a series of pulse durations

5

## List points to remember when determining energy

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The strength duration curve (SDC) is the quantity of charge, current, voltage or energy required to stimulate the heart at a series of pulse durations

These values very significantly as a function of pulse duration

Only charge is approximately linear

In order to set a voltage or pasta ration for parameter output programming, the position that a specific voltage or post a ration occupies on the curve must be known i.e. constants

6

## List the steps to determine Rheobase and chronaxie

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1.Determine the Rheobase, which is the minimum stimulation strength that will produce a response. This is the voltage to which the strength duration curve approximates.

2. Calculate two times Rheobase

3. Determine chronaxie, which is the stimulus generation that yields a response when the stimulus strength is set to exactly 2 times Rheobase

7

## What dothe root words Rheo and base mean?

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Current and foundation

Therefore Rio base is the foundation or minimum current that will produce a response

8

## What do the root words chron and axie is mean?

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Cron means time and axie means axis

Therefore, chronaxie is measured along the time axis and is a duration that gives a response when the nerve is stimulated at twice the Rheobase strength

9

## Formula for charge in microulombs

### C (charge)= I (current) x T ( pulse width in msec)

10