Flashcards in Rheobase And Chronaxie Time Deck (10):
Rheobase is the lowest point on a strength duration curve at an infinitely long pulse duration.
In cardiac pacing, when is Rheobase Usually reached?
Between one and 2 ms, at shorter durations, threshold rises
Define chronaxie time
Chronaxie time Is the pulse width at twice the rheobase value
Chronaxie time Approximates the most efficient stimulation pulse duration
Define the strength duration curve
The quantity of charge, current, voltage, or energy required to stimulate the heart at a series of pulse durations
List points to remember when determining energy
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
List the steps to determine Rheobase and chronaxie
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
What dothe root words Rheo and base mean?
Current and foundation
Therefore Rio base is the foundation or minimum current that will produce a response
What do the root words chron and axie is mean?
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
Formula for charge in microulombs
C (charge)= I (current) x T ( pulse width in msec)