British journal of anaesthesia
October 16, 2026 · via Europe PMC
Electrolyte redistribution during acute respiratory acid-base changes: an in vivo study using apnoea testing.
Heldeweg MLA, Krbec M, Vancura M, +5 more, Giosa L.
AI summary — for doctors, generated from the abstract only
In brain-dead patients undergoing apnoea testing, acute respiratory acid-base changes caused predictable strong ion difference shifts that a simple pH correction approximates well.
What was studied
A multicentre retrospective study of 263 patients undergoing apnoea testing before organ donation, examining pH-dependent change in strong ion difference (SID), individual electrolytes, effect modification, and agreement versus a bedside correction (change in SID = -15 x change in pH).
Key findings
- In 263 participants, pH fell from 7.40 (0.07) to 7.23 (0.07) and returned to 7.40 (0.08).
- Per pH unit increase, SID changed by -11.7 meq/L (95% CI -13.1 to -10.3).
- Na and Cl redistribution was modulated by haemoglobin concentration; the remainder of the results is cut off in the abstract.
Clinical relevance
Helps interpret electrolyte and acid-base changes during acute ventilatory disturbances.
Who should care
Limitations
Retrospective, in a specific population (brain death), so generalisation to other patients is uncertain; some results are truncated in the abstract.
Electrolyte shifts with acute respiratory pH change are measurable and roughly predictable.
This is an AI-generated summary of the published abstract, not a clinical recommendation. It may not reflect the full text or subsequent updates — verify against the original source before acting on it.
Abstract
Background
Acute respiratory acid-base changes induce pH-dependent electrolyte redistribution. Although this response has been characterised in vitro, the in vivo changes depend on multicompartment buffering and remain poorly defined.
Methods
We conducted a multicentre retrospective study of patients undergoing apnoea testing for organ donation after determination of brain death, a clinical model allowing in vivo study of acute ventilatory changes. The primary outcome was the pH-dependent change in strong ion difference (SID). Secondary analyses examined individual electrolytes, pH-SID effect modification by physiological variables, and how well the derived model agreed with observed SID changes compared with a simple bedside pH-correction method (ΔSID=-15×ΔpH).
Results
In 263 participants, pH decreased from 7.40 (0.07) to 7.23 (0.07) and returned to 7.40 (0.08). Per pH unit increase, SID changed by -11.7 meq L-1 (95% CI -13.1 to -10.3; P-1).
Conclusions
Acute respiratory acid-base disturbances produce in vivo Na and Cl redistribution associated with pH change that are modulated by haemoglobin concentration. The observed pH-dependent electrolyte redistribution is consistent with physiological buffering and can be reasonably approximated using a simple bedside pH-correction model.
DOI
10.1016/j.bja.2026.09.015
PMID
42888143
Research metadata (titles, abstracts, authors, publication dates) is sourced from Europe PMC, which aggregates content from PubMed/MEDLINE, PubMed Central, and other providers under the U.S. National Library of Medicine (NLM/NCBI). NLM does not claim copyright on abstracts; the original journal publishers or authors may hold rights to the full articles. AI-generated summaries are derived only from the abstract, never the full text, and are always labeled as AI-generated.
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