ResMed Data Formats
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S9 Data Format
Data format analysis
Grade: C (extra points awarded for being open)
Negatives
- Only keeps basic summary data when card is left out. NO graphs.
- Unnecessarily deletes high-res flow waveform data after 7 days, all other graphs after 30 days.
- Summary does not contain settings info for each session, only once per day, according to ResMed split, which is not suitable for night-owls.
- Evil SDcard "drift" problem, which cause Events to NOT sync well over flow waveform. Needs a regular card format to work around this.
- Bloaty data format.
Positives
- Manufacturer chose to use an industry standard data format.
- Reasonable assortment of data available, and at a decent resolution.
ResMed S9 Data Format
ResMed chose an intelligent and sensible approach when designing their machines..
They used an industry standard. (Thankyou ResMed for showing common sense!)
EDF+ Format
ResMed uses the European Data Format Plus format.
This format is documented here
It is rather verbose, but sensibly designed..
The Event Annotations are a little tricky.
S9 SDCard Folder Structure
[DATALOG] Folder containing all the session data Identification.crc n/r (not relevant (checksum info)) Identification.tgt n/r Journal.dat n/r STR.crc n/r STR.edf Contains overall summary information
DATALOG Folder
The main data is stored in 4 EDF files per session, with each file name consisting of a date, time, and type, followed by .edf
There is also a .crc checksum file for each of the above, but they are not needed to parse the data.
Example
20110601_021922_EVE.edf (date)_(time)_(type).edf
The 4 File Types
Type Details EVE Event annotation data BRP High resolution graph data SAD Pulse oximetry data PLD Low resolution graph data
File Type Notes
Note: Some foreign language machines use a different set of signal codes in the EDF data.
EVE Event Annotation Data
The S9 series flags the following events:
- Hypopnea
- Apnea
- Obstructive Apnea
- Central Apnea
BRP High resolution graph data
Code Details Units Notes "Flow" Flow Rate ? "Mask Pres" High-res Mask Pressure cmH2O "Resp Event" Respiratory Event ? VPAP
SAD Pulse Oximetry data
Code Details Units Notes "Pulse" Pulse Rate Beats per minute "SpO2" SpO2 (Oxygen Saturation) % Saturation
The oximetry device that records this information is hideously expensive, notoriously unreliable, and ResMed should be ashamed for releasing it.
PLD Low resolution graph data
Signal List
Code Details Units Notes "Snore Index" Snore Index ?? "Therapy Pres" Therapy Pressure cmH2O "Insp Pres" IPAP / Inspiratory Pressure cmH2O "MV" Minute Ventilation ? "RR" Respiratory Rate Breaths per Minute "Vt" Tidal Volume ? "Leak" Leak Rate L/Second (I convert to L/Min) "FFL Index" Flow Limitation Index ? "Mask Pres" Low-res Mask Pressure cmH2O "Exp Pres" EPAP / Expiratory Pressure cmH2O "I:E" Inspiratory : Expiratory Ratio ? VPAP "Ti" Ti?? ? VPAP "Te" Te?? ? VPAP "TgMV" Target Minute Ventialation ? ASV Machines "" Unknown Empty ? "" Unknown Empty ?
most ? fields are known, I just have to look them up again..?? fields really are unknown (to me).
The two empty signals always appear at the end. not entirely sure of their purpose.
STR.edf
This file contains a summary database in EDF format. It contains things like AHI indexes, 95% values, etc...
There is only one copy, in the root directory of the SD-card, and it is updated at the end of a session.
Most records contain one entry per day.
SleepyHead doesn't need much of it, as it provides it's own indexing..
It does contain some data not available elsewhere, most notably EPR data.
ResMed S9 Storage Gotchas
The S9 continuously erases older data to keep the card from overflowing:
- BRP data older than 7 days.
- PLD data older than 30 days.
- Everything older than 365 days.
Regularly backup copies of your SD card to work around this!
SleepyHeads Implementation
SleepyHeads EDF parser and S9 importer has been written from scratch
It consists of two parts
- A generic EDF parser class named EDFParser
- and the custom S9 importer class named ResMedLoader
It is implemented in SleepLib/loader_plugins/resmed_loader.cpp / .h
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