End Tidal CO2 and Masks: Is There a Correlation?
Phase: NA
Conditions: Hypercapnia
Sponsor: CHRISTUS Health

 
Version 1.1, 6-7-2021 
 
Project Title 
End Tidal CO2 and Masks: Is There a Correlation? 
  
Co-Investigator Information 
 
Michael A. Miller MD 
Department of Emergency Medicine 
CHRISTUS Spohn Hospital Corpus Christi-Shoreline 
(361) 902.6763/512.508.3189 
mellamiller@aol.com 
 
Peter Richman MD 
Department of Emergency Medicine 
CHRISTUS Spohn Hospital Corpus Christi-Shoreline 
(361) 902.6763 
prichmanmdmba@gmail.com 
 
Kimberly Leeson, MD 
 
 
Department of Emergency Medicine 
CHRISTUS Spohn Hospital Corpus Christi-Shoreline 
(361) 902.6763 
kleeson@gmail.com 
 
Lynn Carrasco  
Shoreline Research Coordinator 
CHRISTUS Spohn Hospital Corpus Christi-Shoreline 
(361) 861-1865   
lynn.carrasco@christushealth.org 
 
 
 
Principal Investigator 
 
Mary Cook, DO 
Emergency Medicine Resident 
CHRISTUS Spohn Hospital Corpus Christi-Shoreline/Memorial 
(361) 902.6763 
Cook.maggie428@gmail.com 
 
 
 
 
 
 
 
 

 
Version 1.1, 6-7-2021 
 
Objectives 
 
The primary objective of this study is to evaluate if there are changes present with end tidal 
carbon dioxide while wearing a mask.  A secondary objective is to assess possible changes in 
end tidal carbon dioxide while walking moderate distances while wearing a mask.  
 
Research Question/Hypothesis 
 
This aim of this study is to test the null hypothesis that end tidal carbon dioxide (ETCO2) will 
not change with mask wearing while at rest and while walking a moderate distance of 100 meters 
in a small sample of healthy adult volunteers.  
 
Background to Research Questions 
 
In light of the ongoing COVID-19 pandemic, wearing a mask has become a universal standard as 
an attempt to reduce the spread of COVID-19. As of 2020, more than half of all U.S. states have 
implemented a state wide mandated mask policy1. There are many schools of thought regarding 
the benefits and risks of donning a mask to prevent the spread of COVID-19. There is an 
unproven theory among some that wearing a mask interferes with our natural respiratory 
function, causing hypoxia, altered mental status and other various health issues4. This dangerous 
perception has led some to believe wearing a mask is harmful, and encourages against wearing a 
mask in public. This theory, recently refuted by a study investigating oxygen levels while 
participants wore masks, performed in 2020 by Chan et al. encouraged increased compliance 
with wearing masks2. Another study, preformed by Samannan et al, evaluated whether gas 
exchange abnormalities occurred with the use of surgical masks in subjects with and without 
lung function impairment6. The conclusions of the Samannan studied showed that regardless of 
lung function impairment, the presence of surgical masks did not impact gas exchange6.  
Additionally, a more recent study conducted by Barbeito-Caamano et al concluded that the 
presence of a facemask did not have a significant change in physiologic parameters while during 
exercise5. Although there is evidentiary support that facemasks do not negatively affect oxygen 
status2 and physiologic capacity, there is not strong evidence examining the relationship between 
ETCO2 and facemasks. The relationship between ETCO2 and facemasks is one of importance 
because mild decreases in oxygen have much less dangerous effects compared to the effects of 
rapid accumulations of carbon dioxide. Increases in end tidal carbon dioxide lead to confusion, 
acidosis and in severe cases, respiratory distress and failure.  A study performed by Somers et al., 
in 1989 showed that hypercapnia has greater increases in blood pressure, minute ventilation and 
sympathetic nerve activity than hypoxia3.  
In this newly proposed study, healthy volunteers will all wear the same type of three layer 
surgical mask. Their end tidal carbon dioxide will be measured while at rest without a mask, 
while resting with a mask and then after walking 100 meters in the mask. While previous studies 
have focused on changes in oxygen, there is a lack of research dedicated to analyzing end tidal 
carbon dioxide. This study will hope to show evidence supporting that there is no increase in end 
tidal carbon dioxide while wearing a mask.  
 

 
Version 1.1, 6-7-2021 
 
METHODOLOGY 
 
Study design 
 
This study is a prospective, controlled study involving healthy adult volunteers all of whom are 
resident and faculty physicians, or other medical staff.  There will be no financial compensation.  
 
Intervention 
 
After obtaining appropriate consent, subjects will have their end tidal carbon dioxide levels 
measured in three separate scenarios. Subjects will have their baseline end tidal carbon dioxide 
measured while at rest and without a mask. The second measurement will also occur at rest, but 
while subjects are wearing a mask. Lastly, end tidal carbon dioxide will be measured after each 
participant walks 100 meters, both with and without a surgical mask. These values will be 
compared during the data collection. In each of these scenarios, volunteers will also have their 
oxygen saturation measured.  
 
Setting 
 
A maximum of 200 healthy adults will be enrolled at a Level 2 trauma center.  Activities will be 
conducted inside of the hospital, where there is a large enough space to accommodate subjects 
walking the length of 100 meters. They will walk 100 meters twice, for a total of 200 meters.   
 
Expected Start Date 
 
Upon IRB approval. 
 
Duration of Study 
 
The study should take approximately six months to gather the data.  An additional six months 
will be required to analyze the data and to prepare the study findings. 
 
Study Subjects 
The sample population will include Residents and staff members at Christus Spohn Shoreline. 
The maximum number of participants for this study will be 200.    
 
Inclusion Criteria: 
Healthy individuals between the ages of 18 and 75  
Consent to participate in this study   
Resident and ancillary staff  
 
Exclusion Criteria: 
Patients 
Inability or refusal consent 
Inability to walk the predetermined distance  
History of lung disease 

 
Version 1.1, 6-7-2021 
 
History of significant cardiac disease 
People under the age of 18 and over the age of 75  
 
Equipment/Supplies/Services 
 
Supplies and services used for the study will consist of standard issued surgical masks, portable 
vital sign monitors of an undetermined brand, end tidal carbon dioxide measuring device better 
known as mask capnography, oxygen saturation measurement device, respiratory therapists.  
 
Data Collection 
 
Trained respiratory therapists will use the portable monitors to measure End tidal carbon dioxide 
values as well as oxygen saturation values. All values will be recorded into Excel.  
 
Data Analysis 
 
Statistical support will be provided by a member of the research team specializing in statistical 
analysis. De-identified ordinal data will be entered into an Excel spreadsheet and imported into a 
statistical analysis software program. Data will be analyzed by chi-square testing.  
 
 
Data Management 
 
There will be minimal collection of protected health information including a name and signature. 
All data will be de-identified. Numerical data will be stored on a private, secure computer, 
owned by the principal investigator under fingerprint and password encryption. The signed 
consent forms will be kept in a locked file, stored in the locked office of Lynn Carrasco, 
Research Coordinator. Her office is located on the 9th floor administrative office of CHRISTUS 
Spohn Hospital Corpus Christi-Shoreline. Only the Principal Investigator, Co-Investigators, and 
Statistician will have access to the data. All identifying information will be destroyed upon 
completion of the study. 
 
 
 
Identified Risks/Ethical Considerations 
 
Foreseeable risks include participant discomfort, shortness of breath and incidental exposure to 
COVID-19 as there will be measurements taken while a mask is not worn.  There will be a 
session of counseling to discuss risks and complications of the participating in the study.   There 
is a possible risk of breach of confidentiality. However, all effort will be made to protect the 
subjects’ personal information. Identifying features of the patients will not be used, recorded, or 
presented in any abstract, manuscript, or oral presentation.  
 
Benefits of Proposed Research to the Subjects and Others 
 
 

 
Version 1.1, 6-7-2021 
 
Results of this study should disprove the theory that wearing a face mask interferes with natural 
respiratory function, causing hypoxia, altered mental status and other various health issues and 
instead provide evidence of the safety in compliance of wearing face masks in public to reduce 
exposure to the COVID-19 virus.  This will benefit the general public by encouraging ongoing 
compliance with mask wearing policies.  
 
 
Study Registration 
 
This study will be registered with Clinicaltrials.gov after approval by the IRB and prior to 
participant enrollment.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
References 
1. https://masks4all.co/what-states-require-masks/ 
2. Chan NC, Li K, Hirsh J. Peripheral Oxygen Saturation in Older Persons Wearing 
Nonmedical Face Masks in Community Settings. JAMA. Published online October 
30, 2020. doi:10.1001/jama.2020.21905 

 
Version 1.1, 6-7-2021 
 
3. Somers, V. K., et al. “Contrasting Effects of Hypoxia and Hypercapnia on Ventilation 
and Sympathetic Activity in Humans.” Journal of Applied Physiology, vol. 67, no. 5, 
1989, pp. 2101–2106., doi:10.1152/jappl.1989.67.5.2101.  
4. Rosner E (2020) Adverse Effects of Prolonged Mask Use among Healthcare 
Professionals during COVID-19. J Infect Dis Epidemiol 6:130. 
doi.org/10.23937/2474-3658/1510130 
5. Barbeito‐Caamaño, C, Bouzas‐Mosquera, A, Peteiro, J, et al. Exercise testing in COVID‐
19 era: Clinical profile, results and feasibility wearing a facemask. Eur J Clin Invest. 
2021; 51:e13509. https://doi.org/10.1111/eci.13509 
6. Samannan, Rajesh, et al. “Effect of Face Masks on Gas Exchange in Healthy Persons 
and Patients with Chronic Obstructive Pulmonary Disease.” Annals of the American 
Thoracic Society, vol. 18, no. 3, 2021, pp. 541–544., doi:10.1513/annalsats.202007-
812rl.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
Version 1.1, 6-7-2021 
 
 
 
CONSENT 
We are conducting a study to assess the impacts of mask wearing on end tidal carbon dioxide in 
at most two hundred healthy volunteers.  
This experiment will involve wearing a standard issued hospital surgical mask. You will wear 
this mask while at rest and while walking one hundred yards. You will be attached to a portable 
vital sign monitoring machine and your end tidal carbon dioxide will be measured while at rest 
and while walking the predetermined distance. Should you have systemic health issues or 
barriers to this experiment, you will not be able to participate in this study. Additionally, if you 
are not able to comfortably walk one hundred yards, you will not be able to participate in this 
study. The entire study should take between five and ten minutes.  
Wearing a mask and exerting one’s self has very mild, but present risks. Risks include 
discomfort, shortness of breath and possibly light-headedness or syncope. In order to prevent 
these risks, if you become too uncomfortable throughout walking one hundred years you will be 
asked to discontinue the study.  
Your participation in this experiment is completely voluntary and will have no effect on your 
relationship with CHRISTUS Spohn Health Hospital Corpus Christi. There will be no financial 
benefit should you choose to help, which will be provided at time of participation. Please know 
that I will work to ensure that your privacy is protected.  I will not identify you and all 
information that is recorded will be stored in a secure location. 
Do you agree to voluntarily be subject to this research study? 
Please circle one: 
Yes                               
 
 
 
 
No 
PRINT name: 
___________________________________________________________________ 
 
SIGNATURE: 
___________________________________________________________________ 
 
 

 
Version 1.1, 6-7-2021