The lab time is neither the draw nor the result¶
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.
| Status | established: shown on many cases, with a control. |
| Clocks | Hospital records clock |
| Devices | Clinical records |
| Variables | Blood gas result time, Central lab result time |
What it means¶
A model that uses a lab value at its timestamp sees the future. The physiology it describes happened 3–30 minutes earlier.
What is done about it¶
Lab labels carry available_at = lab time plus an assumed turnaround, and a lab_draw label marks the matched draw.
Evidence¶
| 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. |