Some researchers may need to calculate Minute Volume (MVb) at the "average" level using the expression MVb=f*TVb rather than using a value based on the average of each individual breath. This article explains the difference between data logging methods and the procedure for creating a custom parameter to calculate MVb at the top level.
Default FinePointe data logging methods
The parameters that are logged in the FinePointe data tables are calculated using two different methods.
Time based or breath based logging with more that one breath
The first method is used with the algorithm settings set to time based logging or breath based logging with more than one breath. In this case, each parameter logged in each line of the data table is an average of each accepted breath in that period.
Here is an example using MVb. In a 2 second log period that contains 3 accepted breaths, the displayed MVb value is obtained by averaging the MVb values of the 3 individual breaths : (121.2 + 130.6 + 118.0)/3 = 123.267. (Note that the individual breaths are calculated using MVb= f*TVb)
The same is true for breath based logging periods that contain more than one breath. The displayed parameter values are an average of the individual breaths contained in the logging period.
Breath based logging with a single breath
The second method used to calculate the lines logged in the data table is only used when logging one breath per line. In this example the algorithm settings are set to Breath Based with 1 breath per line with a 1 breath average. In each logged breath, the parameters are determined by using the default analyzer expressions.
For example, MVb is calculated using this expression, not by averaging breaths:
MVb = f*TVb
How to create a custom parameter that calculates MVb in data tables that use averaging
- Open your study in FinePointe and navigate to the home view of the study
- Click the Analyzer Expressions button on the main toolbar in the Study Settings sectio
- The Analyzer Expressions tool should open. Next, click the "Create New Parameter" button
- The Analyzer Expression builder should open. Enter the following values:
- Parameter: MVb-Ave
- Unit: ml/min
- Enter this expression on the keypad: f*TVb
- Click the "OK" button. The Expression Builder should close
- Click the "OK" button on the Analyzer Expressions tool to close it also
- Open one of your recordings in the study and expand the view so you can see all of the columns in data table. Note that the new parameter named "MVb-Ave" appears on the far right. Left-click on the column heading "MVb-Ave" and drag it to the left and drop it just to the right of the parameter named "MVb"
- The table should look like this after moving the column:
- You can see above that the MVb-Ave parameter is being calculated using the expression f*TVb. For example, if you calculate the line logged at 00:32:24 the result is the same as MVb-Ave (251.5 * 1.598 = 401.9)
- Please note that the new custom parameter automatically becomes available when building reports: