Related Experiment Video
Updated: Oct 5, 2025
Effects of Surgical Masks on Cardiopulmonary Function in Healthy Subjects
Published on: February 12, 2021
Reduced Effective Oxygen Delivery and Ventilation with a Surgical Facemask Placed under Compared to over an Oxygen
Marvin G Chang1, Takashi Sakano1, Benjamin S Levin1
1Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA.
Objectives:
Consensus guidelines for perioperative anesthesia management during the COVID-19 pandemic recommend that patients wear a facemask in addition to their oxygen mask or nasal cannulae following tracheal extubation, where this is practical. The effects on effective oxygen delivery and ventilation of a surgical facemask under compared to over an oxygen (O2) mask are unclear.
Design:
Single-center, comparative pilot study. Setting. Endoscopy procedure room at a major academic hospital.
Subjects:
Five healthy anesthesiologists. Interventions. Using a carbon dioxide (CO2) sampling line positioned at the lips, the fraction of inspired O2 (FiO2), fraction of expiratory O2 (FeO2), expiratory end-tidal CO2 (EtCO2), and respiratory rate (RR) were measured under the following conditions: (1) a surgical facemask only, (2) a surgical facemask under an O2 mask, (3) an O2 mask only, and (4) a surgical facemask over an O2 mask. Measurements and Main Results. The sampled fractional expired oxygen (FeO2) at the lips was significantly lower when the surgical facemask was under compared to when over the O2 mask (27.9± 1.68 vs. 49.9 ± 6.27, p = 0.001), while there was no significant difference in inspired oxygen (FiO2). The sampled expiratory EtCO2 was significantly higher when the surgical facemask was under the O2 mask compared to when over the O2 mask (28.3 ± 8.5 vs. 23.5 ± 7.6, p = 0.026). The RR was not significantly different when the surgical facemask was under compared to over the O2 mask.
Conclusions:
Effective oxygen delivery and ventilation was reduced (lower FeO2 and increased EtCO2) when a surgical facemask was placed under compared to over an O2 mask.
Related Concept Videos
01:16Oxygen Delivering System II: Venturi Mask and Transtracheal Oxygen
Venturi Mask
The Venturi mask, named after the Venturi effect, is designed to deliver precise oxygen concentrations. It consists of a large tube with an oxygen inlet that narrows down, causing a pressure drop that pulls air in through adjustable side ports. The mask is a lightweight,...
01:26Oxygen Delivering System I: Nasal Cannula and Face Mask
Nasal Cannula
A nasal cannula is a lightweight tube split at one end into two prongs and placed in the nostrils. It is typically used to deliver low to medium levels of oxygen.
Suggested flow rate: The suggested flow rate for a nasal cannula typically ranges between 1 and 6 L/min.
Oxygen percentage setting:...
01:30Administering Oxygen by Mask
Administering oxygen by mask is a common nursing intervention that provides supplemental oxygen to patients with respiratory distress or chronic lung conditions. This procedure involves delivering oxygen at a specified rate through a face mask connected to an oxygen source.
Equipment
The equipment necessary for this procedure includes:
01:21Acute Respiratory Failure-II
The underlying physiological abnormalities that contribute to hypoxemic respiratory failure include:
01:29Administering Oxygen by Nasal Cannula
Nasal Cannulas
A nasal cannula is a lightweight tube split into two prongs placed in the nostrils,...
01:22Cardiopulmonary Resuscitation II: ACLS Airway Management