27, 9
Registry data from adult patients with respiratory failure undergoing ECMO between January 2019 and July 2020. 372 paired peripheral pulse-oximetry and arterial oxygen saturation readings in the 92–96% range, among patients identifying as White, Black, Hispanic or Asian; roughly three-quarters had confirmed COVID-19.
Among patients with pre-ECMO pulse-oximeter measurements between 92 and 96 percent, 10.2% of White patients had an arterial oxygen saturation below 88%, compared with 21.5% of Black patients — roughly double the risk of occult hypoxaemia.
PROVENANCE WARNING — THE WEAKEST IN CHAPTER 27. This row was built entirely from a journal-watch summary (Beck S, Honan B, Mallows JL, Ting J. Emergency Medicine Australasia 2022;34(2):303–305, DOI 10.1111/1742-6723.13957). The primary paper was not retrieved; its author list, methods and exact cohort definition were not seen. The summarising authors record the study's own limitations: the mechanism is unknown, it relies on documented race rather than objective skin-tone measurement, and it is not known whether all oximeter devices are affected equally.
Why it is kept despite the provenance. It is the only evidence reaching this book on occult hypoxaemia in an ECMO population specifically, and it converges with the practical-guide textbook's separate statement that pulse oximetry error rises from 2–3% to 3–7.2% on ECMO. Together they shift where the burden of proof sits when an oximeter reads reassuringly on a circuit — which is the only claim Chapter 27 makes from it.
Read SECOND-HAND ONLY. DOI reproduced from the summarising article and not independently resolved.