Face mask use does not impact oxygen saturation in asthma patients

The use of face masks to reduce transmission of COVID-19 does not appear to affect oxygen saturation levels in individuals with asthma, according to a study presented at AAAAI 2021.

“Mask use at rest did not decrease SpO₂ levels in patients with or without asthma, regardless of mask type worn, duration of mask use, or demographics,” noted the authors.

Researchers from the University of Michigan, Ann Arbor, Michigan, US, enrolled 230 adults and children who presented at the Michigan Medicine Allergy clinic between September 10 and October 23, 2020. The participants were asked to complete surveys which included information on their demographics, asthma diagnosis, perceived control of asthma, and the type of masks they used. Patients were measured for pulse oximetry while wearing a mask and were asked to detail how long they had been wearing the mask continuously before the measurement was taken.

Of these, 223 patients (27 percent aged ≤19 years, 40 percent male, 78 percent White) were included in the analysis, 102 and 121 with and without asthma, respectively (46 and 54 percent, respectively). Patients with asthma were mainly White (76 percent), aged 0–19 or 20–45 years (34 percent each), female (58 percent), and used fabric masks (63 percent).

Oxygen saturation, as measured with SpO₂ levels, was comparable in patients with and without asthma, ranging from 93–100 percent for both groups with a mean level of 98 percent. [AAAAI 2021, abstract L18]

Mean SpO₂ levels did not significantly differ when the findings were adjusted for sex (mean 98 percent in both male and female patients) or race (mean 98.5 percent in African-Americans, 98 percent in Caucasians, and ranging from 98 to 99.5 percent in other races).

SpO₂ levels also did not significantly differ when adjusted for type of mask used (mean 98, 98, and 99 percent for fabric, surgical, and N95 masks, respectively) or duration of use (mean 98 percent for <1 hour and 99 percent for ≥1 hour).

Among the 100 patients with asthma who documented their level of asthma control, mean SpO₂ levels did not significantly vary regardless of whether asthma was well-controlled (n=80; 98 percent), somewhat controlled (n=18; 98 percent), or uncontrolled (n=2; 97 percent).

The use of face masks is recommended to reduce COVID-19 transmission and will most likely be recommended even after widespread vaccination against COVID-19, said the authors. While patients with asthma are not excluded from wearing masks, there is a lack of information on whether mask wearing affects oxygen saturation in this population, they said.

“This data reinforces that wearing a mask, whether it is a surgical mask, cloth mask, or N95, is completely safe [and] this is true for all individuals, whether they have a diagnosis of asthma or not,” said study co-author Dr Alan Baptist from the University of Michigan.

“Wearing a mask is an essential step we can all take to reduce the spread of COVID-19. I hope this latest data will deliver peace of mind to individuals who are worried that wearing a mask may be dangerous, especially for those individuals who have asthma,” he said.