Requested metric: respiratory pattern variability

[tsalo]

Respiratory pattern variability (RPV) is a run-level metric created by in Power et al. (2018). The metric can also be calculated as a time series using a window, which in Power et al. (2019) is referred to as ENV.

Per Power et al. (2018):

To capture the variability of the respiratory patterns, the respiratory belt waveforms (which are in arbitrary units) were z-scored, the envelope of the resulting waveform was calculated, and the SD of this envelope was then calculated.

From Power et al. (2019):

These include respiration variation (RV), which is the standard deviation of the belt trace within a (6-s) window (Chang et al., 2009), the envelope of the respiratory trace (over a 10-s window, ENV) (Power et al., 2018), and the change in belt magnitude over a breath cycle (respiratory volume per time, RVT) (Birn et al., 2006).

[smoia]

@CesarCaballeroGaudes , do we have this in our plans already?
It would be good to add it!