Three ART tracks carry the PLETH conversion factors¶

In case 818, case 5175 and case 5693 the SNUADC/ART track holds arterial pressure, but its header gives the PLETH conversion (0.394983 per code, offset −198.2504) instead of the ART one (0.987457 mmHg per code, offset −495.626). Converted as stored, the pressure reads about 2.5 times too low.

What it means¶

Read with the stored factors, the median arterial pressure in these cases is 28, 25 and 36 mmHg; read with the ART factors it is 69, 62 and 89 mmHg, matching the monitor's own mean arterial pressure (Solar8000/ART_MBP: 70, 63 and 87 mmHg). The raw codes are an ordinary arterial waveform (medians 572, 565 and 592, against 578 for ART over the release). None of the three cases has a SNUADC/PLETH track.

What is done about it¶

The TimeNet import converts these three tracks with the ART factors (code × 0.987457 − 495.626 mmHg) by default (VITALDB_SCALE_FIX=on) and keeps the stored factors in the metadata. With other readers, convert them by hand. Across the release, the Solar8000 ART numerics are 2.35–2.38 × the waveform read with the stored factors, as expected for arterial pressure stored with the PLETH factors. Found by the signal survey (every conversion factor of every track).