Are you mainly concerned if whether the studies distinguished N3 from N4? Or are there other aspects you are interested in?
Both the AASM Alternative Hypopneas and the AASM Recommended Hypopneas did not require a 3% desaturation and/or arousal to be annotated. These events are marked independent of whether any associated desaturation were linked with the event.
The datasets on the NSRR do not have this info.
The PPG signal is not available for the SHHS studies. For adult studies with this signal, I would suggest MESA, Heartbeat, HomePAP, BestAIR, or ABC.
Yes, you are correct that hypopneas were scored from the airflow, thoracic, or abdomen signals for SHHS. I don't believe there is a way to identify which signals were used for hypopnea scoring for SHHS2. Taken from the manual "Variation in signal amplitude on airflow, thoracic and abdominal channels: In some studies, information appears qualitatively different from different channels. Scoring will be done from the channel that correlates the best with the changes in the oxygen saturation. If there are no changes in O2 saturation, scoring will be done from the channel that shows the clearest amplitude variation. In cases where the thermister varies from the inductance channels, and the inductance channels appear mostly artifact free, the inductance channels will be used for event identification and classification. When in doubt, use data from the inductance and saturation channels to identify/classify events." The RESPSCCH variable was not collected for SHHS2. I am not aware of any other variables which would provide the information you seek.
Sleep Heart Health Studies were collected prior to AASM rules and do not follow the standard AASM guidelines for hypopnea scoring. Please refer to the manual referenced above for respiratory event scoring procedures.
Signals such as the ones you list are available in the datasets. Available signals vary per dataset. Individual studies can be downloaded.
I agree with Mike that you can obtain a count of "obstructive apneas with arousals but WITHOUT a >=4% oxygen desaturation (NREM/Supine)" by taking the difference of 'oanba4' and 'oanbp4'.
Unfortunately, with the variables that are available, there is not a way to determine OAs WITHOUT Arousals, but WITH >=4% desaturations (in NREM, Supine sleep). You will need to use the raw data to assess this.
I compared your values/amounts to the values/amounts in the software. While I agree with Remo Mueller that I am not seeing the same negative HPos values, my duration amounts are equivalent to your calculations. I would agree that you can ignore the -0.5 value. It appears that the studies start with a “?” annotation that occurs for 1 second, so disregard. In regard to the values:
S (Supine) = -0.4
LL (Lateral Left) = -0.3
LR (Lateral Right) = -0.2
PL(Prone Left) = -0.1
PR(Prone Right) = 0
U (Upright) = 0.1
The LOC and ROC signals are the EOG signals.