Blood pH values missing from labevents between MIMIC-IV 1.0 and 2.1 versions

Prerequisites

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Description

Hi,
I've been some analysis involving blood gases measurementes in MIMIC-IV. The work was on standby since last year and now I restarted it using version 2.1.

With this I've noticed that almost all blood pH values (from the table labevents with itemid 50820) below 7.24 are missing. I've also used the itemid's 50831, for pH of "Other Body Fluid " and the best that could get were about more 50 results below 7.24.

With the previous version I had thousands of results below 7.24.

If I search for the specimen_idof one of those low values from the 1.0 version in the 2.1 version the results are from a blood gas analyser but are incomplete (at least without pH but also pCO2, pO2, etc, but with sodium, potassium, hematocrit). You can try searching the specimen_id of lavbevents 55927374, 55411879 or 28628306.

Is there any reason for removing those results or there was mistake somewhere when retrieve the values?

Best regards,
João Colaço

Start by comparing labevents records for itemids 50820 and 50831 between MIMIC-IV versions 1.0 and 2.1, using specimen_ids 55927374, 55411879, and 28628306. Trace how the blood gas analyzer values were retrieved and determine whether the missing pH, pCO2, and pO2 values are an expected version change or a data error; done means documenting the cause and the required correction.