With a few tweaks, pulse oximeters can double up as BP monitoring tools in the near future, suggests a joint research undertaken at Canadian and Chinese health facilities.

Past studies have explored using oximeters for blood pressure assessment but the study led by The University of British Columbia (UBC) is the first to provide supportive evidence based on actual patient records and the first to examine large sample sizes obtained in two different countries.

"We found that the oximeter, which clips on to a finger or toe to measure heart rate and the amount of oxygen in the blood, can detect normal, elevated or high blood pressure with up to 95 percent accuracy," said lead researcher Mohamed Elgendi, an adjunct professor of electrical and computer engineering at UBC.

"This suggests that it can, with a few tweaks, do double duty as a BP monitor in the future," he added in a paper described in the Journal of Clinical Medicine, Biosensors, Diagnostics, and Scientific Data. For their analysis, the UBC team examined oximeter records from 121 patients registered at a hospital in Boston and 219 admitted to a hospital in the Chinese province of Guilin. 

They ran the oximeter information through a unique mathematical programme they had developed and found nine electrical signatures, or patterns, that correlated significantly with hypertension. "The consistent presence of these patterns in data collected from two different countries proves that the pulse oximeter is a reliable tool for hypertension assessment," said Elgendi. "When we added electrocardiogram data to oximeter data, we were able to improve the detection of pre-hypertension".

Elgendi and his team are working on replicating their studies on other groups of patients over the next several months. They're also refining their algorithm so that it can be used on a larger scale by oximeter manufacturers. "While the inflatable cuff is easy to use, its accuracy depends on its placement on the arm and the observer's skill," said Elgendi. Another technique, intra-arterial blood pressure measurement, is highly accurate but invasive, requiring the doctor to insert a needle into an artery, he added.