Hypoxemia out of proportion to respiratory effort — “silent hypoxemia” — has been reported in patients with COVID-19. Given our lack of understanding of reliable predictors of severity in patients with COVID-19 who may appear well enough to be discharged, some authors have recommended the use of outpatient pulse oximetry to identify decompensating patients.
https://www.jwatch.org/na51896/2020/06/26/pulse-oximetry-outpatients-with-covid-19