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Start by clicking Analysis → Find cycle
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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.
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Selection tab:
Usually can stay in default mode.
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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).
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Missing markers
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Other marker issues
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To remove single markers, hover over any marker → right-click → clear event.
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.
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.
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Under “End event”, also select the flag and under both “located on”, select the respiration channel 2.
REPLACE IMAGE
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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.
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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
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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
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The software will ask where you want to start looking for markers. Click “Set to origin”.
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