Blood gas result time¶

Time stamp of a blood gas result in the lab table.

Stub

Imported from the time-source table; the full page is still to be written.


Name in the dataset	`lab_data (blood gas)`
Type	event
Device	Clinical records
Stamped by	Hospital records clock

Measurement space¶

Time side (lab timestamp): the true time lies between -731 s and -190 s from the stamp: the delay range plus the interval one value describes.

Time¶

From UTC to the stored time stamp¶

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.

Hospital records clock

sync assumed

The laboratory and anaesthesia record systems keep hospital time (KST). Their offset from UTC and from the recorder PC is not observable in the release, which shifts every case to 2100.

Blood draw

processing measured 3.17 min – 12.2 min → 28 s – 117 s after correction · parameter, What the lab timestamp marks, Arterial line accesses in the pressure waveform

Blood is drawn from the arterial line (an access, 28–117 s long) and analysed in theatre or sent on. The specimen is stamped 3–12 min after the draw; the lab_draw label marks the matched access.

Result known

processing assumed

The result follows an unrecorded turnaround; a value is known no earlier than its timestamp plus that turnaround.

Stored lab time

stamping measured 1 s

Whole seconds, one time per specimen shared by every analyte of the panel.

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
lab timestamp (default)	3.17 min – 12.2 min	1 s	Clinical and lab records	measured	3-12 min after the access (modes ~4, ~9 min); the value is known later
draw time from arterial access	10 s – 100 s	28 s – 117 s	Clinical and lab records	estimated	access 28-117 s (p10-p90); matched 0-15 min (gas) or 0-30 min (central) before

Combine it with other signals in the synchronisation planner.

Value¶

Its value side is still to be described.

Parameters¶

Parameter	Value	Status	From
Blood gas timestamp after the draw	7.2 min (p10–p90 3.2 to 12.2; two modes, 2–6 and 8–12 min)	measured	What the lab timestamp marks

Observations¶

Observation	Status	Summary
The lab time is neither the draw nor the result	established	VitalDB's lab timestamp marks the specimen (logged at the lab, or entered from a theatre analyser): minutes after the draw and before the result, whose time is not recorded.

Studies¶

Study	Date	Status	Summary
What the lab timestamp marks	2026-10-13	current	VitalDB's lab time is a per-specimen timestamp: not the draw, and not the result. Blood gases are stamped 3–12 minutes after the draw, central-lab panels about 8–24 minutes after it, and the result follows a turnaround the release does not record.
Arterial line accesses in the pressure waveform	2026-10-11	current	Flushes, zeroing and blood draws leave clear signatures in the arterial pressure. A detector finds them in the waveform alone (about one access per hour) and matches 77% of lab draws to an access within 15 minutes, against 26% for random times.

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.

Tags: stub