Fingertip pulse oximeters, like the highly popular CMS50DL, have an upper heart rate limit beyond which they cannot accurately measure. Very fast atrial fibrillation (AF) can be beyond this upper limit, and this is often cited as a limitation for the use of fingertip pulse oximeters in patients with fast AF. However, heart rate is not a pulse oximeter's only method for screening for AF. A study published in Heart (Tanigawa et al., 2006) showed a significant association between the frequency of oxygen desaturation events estimated through pulse oximetry during sleep, and the presence of atrial fibrillation.

Lin et al. (2015) also showed a significant link between sleep apnea ("apnoea" in British English) and atrial fibrillation. Pulse oximeters are very popular for monitoring events in people with suspected or known sleep apnoea, either for collecting evidence of its occurance or in order to grade its severity. Accurate severity grading is particularly important for people in careers such as professional driving, whose ability to work may depend upon their doctor's diagnosis, based upon the frequency with which they believe the patient to be suffering from significant desaturation events.

If, as these studies show, sleep apnoea does indeed often proceed the onset of AF, pulse oximetry could be an excellent method of early detection for those at risk of AF (so that they can be closely monitored for future anticoagulation and prevention of stroke), as well as a well-validated method for monitoring sleep apnea in itself. In addition, modern fingertip oximeters like the CMS50DL can record heart rates up to 240bpm, meaning all but the most extreme cases will be measurable by this Contec device.

Given the huge societal and economic burden of AF (Rosner et al., 2012), projected to triple by 2050, the importance of putting tools into the hands of individuals to monitor their own health is enormous.



Lin., G., Colangelo, L., Lloyd-Jones, D. (2015). Association of Sleep Apnea and Snoring With Incident Atrial Fibrillation in the Multi-Ethnic Study of Atherosclerosis, Am J Epidemiology 182(1):49-57.

Rosner, G., Reiggel, J., Hickey, K. (2012). The Concept of “Burden” in Atrial Fibrillation. Journal of Atrial Fibrillation 4(5): 400.

Tanigawa, T., Yamagishi, K., Sakurai, S. et al. (2006). Arterial oxygen desaturation during sleep and atrial fibrillation, Heart 92(12):1854-1855.