Rheobase And Chronaxie Time

Question 1

Define Rheobase

Answer 1

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

Question 2

In cardiac pacing, when is Rheobase Usually reached?

Answer 2

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

Question 3

Define chronaxie time

Answer 3

Chronaxie time Is the pulse width at twice the rheobase value

Chronaxie time Approximates the most efficient stimulation pulse duration

Question 4

Define the strength duration curve

Answer 4

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

Question 5

List points to remember when determining energy

Answer 5

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

Question 6

List the steps to determine Rheobase and chronaxie

Answer 6

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

Question 7

What dothe root words Rheo and base mean?

Answer 7

Current and foundation

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

Question 8

What do the root words chron and axie is mean?

Answer 8

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

Question 9

Formula for charge in microulombs

Answer 9

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

Question 10

Formula for energy

Answer 10

E (energy in micro joules) =
I (current) x V x T (pulse width in msec)

Multiply mean current by mean voltage by pulse duration