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Start by clicking Analysis → Find cycle

IN the first tab, select “Peaks”. For exhale onset, select “Positive/Upward” (peaks), for inhale onset, select “Negative/Downward” (dips).

For later troubleshooting: if the software is doing a poor job at placing correct markers on the signal, change the threshold and look at the new result. If improved, see you can further improve it by deleting the existing markers and rerunning this step with a different threshold.

Selection tab:

Usually can stay in default mode.

Output tab:

This part is critical because we want the software to find peaks (and later troughs) and to place a marker at the exact peak to show the timing of each breath. In order to do that, click on the Events subtab, then check the box Output events. If you want markers for the peaks, select Maximum. The top dropdown menu is where you want to find the maximum of the signal. Select your respiration channel (CH2). Output type means what your marker should represent. Select Respiration → Expire start. The bottom dropdown option is where you want the marker to go. Select Respiration (CH2).

Event 2 sometimes works and sometimes doesn’t. You can try and make it Minimum and Inspire start.

If it causes a mess, you can delete all Inspire start markers (instructions see below).

Missing markers

Other marker issues

  1. If you find multiple exhale markers stacked on top of each other, these need to be removed. Right-click → clear event

  2. It’s up to your own logic to decide what constitutes a breath. the software is not that smart. It will take any up and down signal, for example the second “Incorrect placement” example below. The tallest peak in that example is the exhale onset. The small jagged peaks along the down slope are not individual breaths, so all markers until the dip should be removed.

Marker removal

  1. To remove single markers, hover over any marker → right-click → clear event.

  2. To remove several markers at once, you can select the removal tool below. It removes the marker closest to where you click if you click once. Alternatively, you can use it like the selection tool and it will remove all markers within the selection.

  3. To remove all events, hover over any marker → right-click → edit event → clear → select what you want remove (e.g. expire start, inspire start or flag). E.g. check the box for “type” and select “respiration → expiration” → ok. This will remove all expiration markers in the entire file. CAUTION: this action cannot be undone! You can check the box for channel and select CH2 Respiration to ensure you are only removing expiration markers in your respiration channel. For example, you may also use the same types of markers for CO2 analysis in channel 16.

Adding markers

Place flag markers on the peaks of the signal where the expiration markers are missing:

Placing the correct markers

Expiration markers

Then go to Analysis → Find cycle

Under the Cycles/Peaks tab, select “Events”, then “Start event” → “Notes” → “Flag”

Under “End event”, also select the flag and under both “located on”, select the respiration channel 2.

REPLACE IMAGE

Go to the selection tab. Since we used eye balling to place the flag markers, we now want to select an area around the flag in which we can tell the software to place the correct markers exactly on the maximum signal of each breath cycle.

We have to provide a range to the left of the flag (“Left edge”) and to the right of the flag (“Right edge”).

The left requires you to add a “-” in the “seconds” box, followed by a number. Try something like -1 and under right edge, try 1. On the bottom of the window, you will see the selection range appear in blue. Make sure all peaks are included by the selection.

REPLACE IMAGE

Go to the Output tab → Events. Check the “Output events” box. Here we tell the software to output new markers (Events) onto our respiration signal. Select “Maximum”, i.e. top of the peak (for inspire start, we would select “Minimum”). The top dropdown channel is where the software will look for signal peaks. The Output type is “Respiration → Expire start”, i.e. we want to output exhalation markers. The “Output channel” is where the systole markers will be placed. If this seems confusing, you can technically find peaks on the respiration channel and output markers onto a different channel, such as CO2. Under “Event 2” on the bottom, select “None”.

Click “Find all cycles” on the bottom.

REPLACE IMAGE

The software will ask where you want to start looking for markers. Click “Set to origin”.

Clear flag events

Now you want to remove the flags that are no longer needed.

Right-click on any event → edit event → clear → are of type flag → on CH2 Respiration → ok → cannot be undone ok

Inspiration markers

Automated signal detection

  1. Place flags into the dip of each breath cycle, wherever missing.

  2. Analysis → find cycle

    1. Peaks/Events:

      1. Select Event

      2. Start event: Flag; CH2, Respiration

      3. End event: Flag; CH2, Respiration

    2. Selection:

      1. Select are around flags where the dips are included

    3. Output:

      1. Output events check

      2. Event 1: Minimum

      3. Input and output channel: CH2, Respiration

      4. Output type: Respiration → Inspire start


Clear flag events

Right-click on any event → edit event → clear → are of type flag → on CH2 Respiration → ok → cannot be undone ok

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