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SpO₂

Oxygen saturation from the pulse oximeter.

Stub

Imported from the time-source table; the full page is still to be written.
Name in the dataset Solar8000/PLETH_SPO2
Type numeric
Device Solar8000 monitor
Stamped by Recorder PC clock
Unit %

Measurement space

Time side (as stamped): the true time lies between -24.8 s and -4 s from the stamp: the delay range plus the interval one value describes.

Time

From UTC to the stored time stamp

Derived from this signal's timing table; a written chain is still to come.

The clock path first (UTC to the clock that stamps or spaces the samples), then the signal's own path to its stored time. Each bar: the time shift or error the step introduces (pale) and what is left after the atlas's correction (solid), on a log scale; dashed when estimated or assumed.
UTC
The reference every chain starts from.
Recorder PC clock
sync assumed 3 ms – 900 ms · clock link, parameter
Windows time synchronisation to the hospital's time server every 8–24 h (assumed), drifting a few ppm in between. Not observable in the release: dates are shifted to 2100. No step of 0.5 s or more was found.
Recorder PC clock
transport measured 4 s – 4.8 s
Delay from the end of the interval a value describes to its stamp.
Stored time stamp
window measured 10 s – 20 s
The width of the interval one value or sample stands for.

Timing

Against the working reference. Delay: from the end of the interval a value describes to its stamp. Interval: how wide that interval is.

Form Delay Interval Clock domain Status Evidence
as stamped (default) 4 s – 4.8 s 10 s – 20 s Solar8000 numerics measured onset +4 s (+0.4 s PLETH); window 10-20 s estimated, not measured

Combine it with other signals in the synchronisation planner.

Delays

Value

Its value side is still to be described.

Parameters

Parameter Value Status From
SpO₂ onset latency about 4 s to the start of the dip, 8 s to its deepest; window 10–20 s (estimated) measured SpO₂ and pulse rate latency from step events

Observations

Observation Status Summary
Monitor numerics describe the past, never the future established Every monitor numeric describes a window of 3–30 s or more that ended 1–9 s before its stamp. None is stamped before its data exist, so the stamps already respect the availability rule.
SpO₂ freezes in low perfusion established During low perfusion SpO₂ mostly holds its last value rather than blanking (55–70% of 5–20 s episodes); when the probe comes off it blanks within about a second.

Studies

Study Date Status Summary
Value resolution of every signal 2026-10-19 draft How finely every waveform and numeric track in the release records its values. The SNUADC waveforms are 10-bit codes, though VitalRecorder's documentation describes the SNUADC as 12-bit; Primus waveforms use about 10 bits of 12; BIS EEG is a 16-bit grid of 0.05 µV. Numerics are 32-bit floats on decimal grids of 1, 0.1, 0.01 or 0.001, one per track; settings sit on coarser grids of 10 or 100.
SpO₂ and pulse rate latency from step events 2026-10-12 current SpO₂ cannot be recomputed from one plethysmogram, so its timing comes from events that change the PLETH abruptly. SpO₂ lags the recorded PLETH by about 4 s and then smooths over roughly 10–20 s.

Worked examples

Example Side Status Summary
End-tidal to arterial CO₂, and pulse oximetry against blood gas, at the right moment time draft For 4,281 blood gases, reading the monitor when the blood was drawn rather than at the lab stamp makes changes in end-tidal CO₂ track changes in arterial CO₂ far better (within-patient correlation 0.74 against 0.54), and agreement peaks exactly at the estimated draw. Oximetry shows the same timing (agreement peaks at the draw), but the 100% ceiling hides the size of the oximetry gradient for three gases in four.

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