To the Editor:We read with interest the article by Luks and Swenson (1). The authors highlight the fundamentals of pulse oximetry and some of the limitations associated with the use of it at home. In many ways, the coronavirus disease (COVID-19) pandemic has changed how medicine is practiced. Some institutions, including our own, have been overwhelmed with patients with COVID-19 and have instituted novel practices like using a combination of telehealth visits and home pulse oximetry to monitor patients with COVID-19 who might otherwise have been admitted (2).For oxygen saturation monitoring to be successful at home, the device used must be accurate. We previously published a paper describing the inaccuracy of three smartphone apps, which Luks and Swenson review in their article (3). We agree in advising caution against the use of these devices.These authors also cite several articles evaluating the use of consumer-grade standalone pulse oximeters in the clinical setting. They assert that an evaluation of six commercially available pulse oximeters using 22 healthy volunteers is the best study available on the topic (1, 4). We wanted to take a moment to highlight some additional information from a paper we recently published. Our study was an order of magnitude larger than the article by Lipnick and colleagues (4) and evaluated emergency department patients, not volunteers, many of whom were hypoxic (5). We studied 200 patients presenting with hypoxia, chest pain, or dyspnea. Three different consumer-grade pulse oximeters were compared with a medical-grade pulse oximeter. We performed Bland-Altman plots as described by Luks and Swenson as necessary to compare the performance of the devices. All three studied devices had sensitivities of at least 96% when evaluating for hypoxia when using a cutoff value of 92% oxygen saturation. They all had exceptionally good correlation with the control device. Our findings suggest that these devices can reliably measure hypoxia and should be safe for home use. This should provide additional reassurance to providers who wish to monitor patients at home with pulse oximetry.We commend the authors for a well-written and timely review and hope that our additional information will be of interest to your readers. We agree that there are knowledge gaps regarding the use of out-of-hospital pulse oximetry, particularly use among patients with COVID-19, and that further study among this patient population would be useful. Nonetheless, we hope that our findings may still be useful to those making decisions regarding the use of home pulse oximetry.