GO2 PEEP Study: The Use of a Bidirectional Oxygenation Valve in the Prevention and Management of Postoperative Atelectasis
Phase: NA
Conditions: Postoperative Atelectasis
Sponsor: Emory University

 
 
 
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Protocol v. 5.0, 11/20/2020 
Protocol Title: GO2 PEEP Study: The Use of a Bidirectional Oxygenation Valve in 
the Prevention and Management of Postoperative Atelectasis 
 
Protocol Short Title: GO2 PEEP Study 
 
Protocol version 5.0, dated November 20, 2020 
 
NCT Number: NCT04253834 
 
Principal Investigator:     
Jeffrey S. Miller, MD 
Division of Cardiothoracic Surgery 
Emory University School of Medicine 
Emory Saint Joseph’s Hospital 
 
Sponsor: 
 
 
PEEP Medical, LLC 
 
 
Protocol Author: 
 
Sean G. Boutros, M.D. 
Houston Plastic Craniofacial and Sinus Surgery 
 
 
 
 
 
 
 
 
 
 
 

 
 
 
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Study Objective 
The objective of this pilot study is to determine the feasibility and safety of a bidirectional oxygenation 
mouthpiece compared to incentive spirometry in the prevention and management of postoperative 
atelectasis. 
 
Hypothesis: 
We hypothesize that the bidirectional oxygenation mouthpiece is a safe and effective respiratory therapy, 
will reduce or prevent postoperative atelectasis, improve oxygenation (PaO2), improve pulmonary 
function tests, and reduce postoperative pulmonary complications in cardiac surgical patients compared 
to conventional incentive spirometry therapy. 
 
Background and Significance 
Postoperative pulmonary complications (PPCs) are the principal cause of morbidity, mortality and 
prolonged hospitalizations in surgical patients, 1-3 which results in a 50% increase in healthcare costs 
compared to postoperative cardiac complications. 4-5 This is especially evident following cardiovascular 
surgery.  Pneumonia, unplanned re-intubation and prolonged postoperative mechanical ventilation (>48 
hours) remain the most concerning adverse events, with a reported incidence between 2-5%. 4-5 One of 
the most common PPCs is atelectasis, resulting in dyspnea, tachypnea and hypoxemia.  A number of 
identified risk factors associated with the development of PPCs are listed in Table 1. 6-14 
 
Postoperative atelectasis is a predictable consequence of anesthesia, surgical trauma, and pain associated 
with breathing.15 This often results in hypoxemia and pulmonary complications. Methods aimed at 
increasing lung volume and treating atelectasis, commonly known as postoperative physiotherapy, play 
an important role in preventing PPCs. These methods include cough and deep breathing, continuous 
positive airway pressure (CPAP), postural drainage, incentive spirometry and positive end expiratory 
pressure (PEEP).  
 
Introduced by Bartlett et al 2,16 over 40 years ago, incentive spirometry has served as a convenient 
approach for the postoperative patient to sustain maximal inflations and encourage deep breathing. 
Minschaert and colleagues found faster recoveries of tidal volumes following conventional protocols of 
incentive spirometry when compared to conventional physical therapy. 17 
 
Although incentive spirometry is used commonly by post-operative patients, evidence fails to support its 
benefit. 18-23   One systematic review stated, “Presently, the evidence does not support the use of incentive 
spirometry for decreasing the incidence of PPCs.” 19 Another meta-analysis found no evidence of benefit 
from incentive spirometry after coronary artery bypass surgery. 22 In addition, a recent study on the 
financial impact of incentive spirometry demonstrated that for the 9.7 million inpatient surgeries 
performed annually in the United States, the total annual cost of implementing postoperative incentive 
spirometry is estimated to be $1.04 billion.24 Most importantly, incentive spirometry is not the ideal 
treatment for atelectasis or hypoxemia.  Incentive spirometry does not provide PEEP.  
 
PEEP is a well-known pulmonary physiologic principle.  There are on average 600 million alveoli in the 
lung. Each alveolus has surfactant to resist the natural propensity for these small air sacs to collapse during 
exhalation. Despite this surfactant, some alveoli will collapse and not be available for gas exchange.  This 
atelectasis results in a ventilation/perfusion mismatch where alveolar units are perfused but not 
adequately ventilated. This is referred to as shunting and results in hypoxemia (decreased PaO2).  

 
 
 
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Atelectasis, shunting, and hypoxemia are very common complications of surgery and result in significant 
morbidity and mortality in surgical patients.   
 
PEEP decreases the propensity for the alveoli to collapse by increasing the air pressure in the lungs.  This 
residual pressure in the lungs at the end of exhalation decreases shunting and allows for more complete 
gas exchange and improved oxygenation.  In patients, PEEP is one of the safest ways to increase PaO2 and 
is used on almost all modern ventilator settings.   
 
We have developed a simple, comfortable, and straightforward silicone-injected, bidirectional 
oxygenation mouthpiece that effectively delivers PEEP with every breath (image 1).  The purpose of this 
pilot study is to demonstrate the safety and feasibility of the bidirectional oxygenation mouthpiece in 
cardiac surgical patients, compare this novel device to conventional incentive spirometry, and identify any 
potential benefits to respiratory dynamics.  
 
Image 1. Bidirectional oxygenation mouthpiece 
 
 
Initial testing using the bidirectional oxygenation mouthpiece on healthy subjects has been encouraging.  
Crouse et al. studied nine subjects during exercise and reported that the “Wearable Positive End-
Expiratory Pressure Valve Increases Aerobic Capacity and Performance.” 25   Subjects were assigned at 
random to the novel bidirectional oxygenation mouthpiece, a standard oxygenation mouthpiece, or 
nothing at all.  Subjects wearing the bidirectional oxygenation mouthpiece showed an improvement in 
VO2 max of 6.1% compared to the standard mouthpiece and 4.0% compared to no mouthpiece.  The 
endurance test showed an improvement of 6.5% compared to the standard mouthpiece and 6.0% 
compared to no mouthpiece.  All results had p-values < 0.05.  No adverse events were reported during 
the testing.  Furthermore, the consumer version of this device, which is being used by athletes during 
vigorous exercise, has sold over 2000 units to date with no reported adverse events.  
 
Research Design and Methods 
Design 
This pilot study will utilize a single center, prospective, randomized controlled study design. 
 
 

 
 
 
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Target Study Population 
Patients undergoing coronary bypass and/or valve replacement will be evaluated for study eligibility, and 
will be preoperatively selected according to the below criteria: 
 
Inclusion Criteria 
1. Undergoing CABG and/or valve replacement surgery 
2. Able to provide written informed consent 
3. Maintenance of an arterial line postoperatively 
 
Exclusion Criteria 
1. Active smoking, within three months of surgery 
2. FEV1 <75% predicted 
3. Relative risk to develop pulmonary barotrauma as evident by history of pneumothorax or 
emphysema 
4. Unable or unwilling to provide informed consent, cognitive impairment  
 
Study Endpoints 
Primary Endpoint  
1. Pa02 level at 1, 6, 12 and 24 hours post-extubation.   
 
Secondary Endpoints  
1. Atelectasis on CXR (Atelectasis Severity Score) immediately post-op and on postoperative days 1-
4 
2. Oxygen requirement 1, 6, 12 and 24 hours post-extubation and daily each morning 
3. CO2 level at 1, 6, 12 and 24 hours post-extubation 
4. FEV1 and FVC measurements pre-op and on postoperative day 3  
5. Respiratory rate 1, 6, 12 and 24 hours post-extubation then daily each morning 
6. Peak body temperature every 24 hours (as a marker of atelectasis)  
 
Study Procedures 
After an eligible patient has provided written informed consent, he/she will be randomly assigned to one 
of two study cohorts: incentive spirometer (Control Arm) or Bidirectional Oxygenation Valve (G02 
Mouthpiece). 
 
Permuted block randomization will be employed to ensure balance between groups when the number of 
recruited patients reaches a multiple of the block size. All patients will undergo additional postoperative 
respiratory therapy, including: deep breathing exercises, directed cough, early mobilization and optimal 
analgesia per routine care. Mouthpieces for each study arm will be provided to a patient throughout the 
hospitalization.  
 
Both cohorts will use the assigned device following similar protocols: 
1. Proper positioning of the patient in bed. 
2. Proper positioning of the incentive spirometer or Go2 mouthpiece. 
3. A breath cycle will consist of 10 breaths every hour while awake. See instructions in Appendix A. 
4. The research assistant will provide adequate training for both devices and will supervise their use.  

 
 
 
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Arterial blood gases (ABGs) will be collected on 2L/NC (x 5 min) at 1, 6, 12 and 24 post-extubation (+/- 1 
hour). Pt. will be asked to use assigned device (incentive spirometer or GO2 mouthpiece) before each ABG 
is collected.  Blood samples will be tested locally at the Emory St. Joseph’s Hospital Laboratory.  
 
A chest radiograph will be obtained immediately post-op and daily on post-op days 1-4 to assess the 
presence of atelectasis using the atelectasis severity score. X-rays will be read by a single radiologist in a 
blinded fashion.  
 
Respiratory rate will be measured 1, 6, 12 and 24 hours post-extubation then daily each morning.  
 
Body temperature will be measured per nursing routine (as a marker of atelectasis). Temperature max 
will be recorded each 24 hours.  
 
Schedule of Assessments  
                                    
Study Procedures 
Baseline 
(up to 30 days 
before surgery) 
Post-Op 
POD 1 
POD2 
POD3 
POD4 
Consent 
X 
 
 
 
 
 
Pulmonary function 
test (PFT) 
X 
 
 
 
X2 
 
Randomization 
X 
 
 
 
 
 
Treatment: breathing 
exercises with 
mouthpieces 
 
X 
X 
X 
X 
X 
Arterial blood gas 
(ABGs) 
 
 
X1 
X1 
 
 
Chest x-ray with 
Atelectasis Severity 
Score 
X 
X 
X 
X 
X 
X 
RR and body temp 
 
X 
X 
X 
X 
X 
Peak Body Temp 
 
 
X 
X 
X 
X 
Adverse Events 
 
X 
X 
X 
X 
X 
Use of Device 
Questionnaire 
 
 
 
 
 
X3 
1ABGs 1, 6, 12 and 24 post extubation. 
2Peformed for research purposes only 
 3Can be done from POD4 up until discharge from hospital 
 
Statistical Analysis Plan 
As a pilot study, our goal is to examine the feasibility and safety of conducting this pilot study on a larger 
scale. We evaluate the feasibility of recruitment, retention, assessment and implementation of the 
proposed interventions. We wish to identify any potential flaws in the study design and potential 
challenges in the subsequent large-scale study. Moreover, the pilot data will give us a first impression of 
the variability and effect sizes of Pa02 in the patient population of interest and thus assist in the sample 

 
 
 
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size and power calculation of the subsequent larger study. Finally, the data that we collect from this pilot 
will help identify modifications needed in the planning and design of the subsequent study.  
 
We will also assess safety of the new mouthpiece with close monitoring of patient symptoms, physical 
exam, PaO2, PCO2, CXR results, vital signs, and temperature.  At the conclusion of the study, we will 
attempt to assess between-group differences, but given that low power is characteristic of pilot studies, 
statistical significance is not the focus of the analysis. However, we plan to provide statistical summaries 
that would be useful in the subsequent study and to other researchers, such as number of patients 
screened per month, number of patients enrolled per month, proportion of screen eligible who enrolled, 
lost-to-follow rate, study costs.  
 
We will also summarize patient characteristics at baseline and during follow-up using mean ± standard 
deviation (or median and interquartile range, as appropriate) for quantitative variables and frequency 
(percentage) for categorical variables. Summary statistics on Pa02 will be reported at each measurement 
occasion for each group. We will also attempt to fit a mixed effects model to examine between-group 
differences in Pa02 at each study visit. An error covariance structure most appropriate to the data will be 
chosen. Every effort will be made to ensure complete follow-up, and to handle missed visits, missingness 
at random will be assumed. Finally, a qualitative review will also be provided, and this will include, among 
others, an evaluation of the representativeness of the patient volunteers, a discussion on how to refine 
the data collection tools, how to improve the database, how to track patients better as well how to 
improve implementation of the proposed intervention.  
 
Sample Size and Accrual 
The sample size for this pilot study will include 20 patients undergoing coronary bypass and/or valve 
replacement surgery, however, we anticipate that approximately 40 patients may be consented to 
account for patients that may be ineligible, screen fail, or withdraw from study. This is the number of 
anticipated eligible patients that may be recruited over a period of 2 months. This number is deemed 
sufficient to demonstrate the feasibility and safety of the bidirectional oxygenation mouthpiece. 
 
General Design Limitations 
Possible pitfalls may include unsupervised use of the assigned mouthpiece or unexpected non-pulmonary 
complications secondary to the surgery which may affect the results of the analysis. Also, subjects opting 
out of the study may represent a potential drawback, secondary to pain or fatigue, or evidence of 
hyperventilation and/or respiratory alkalosis.  
 
Protection of Human Subjects 
Institutional Review Board (IRB) Review and Informed Consent 
Screening and enrollment will not begin until the Emory University IRB has approved the study protocol 
and informed consent form.  
 
A physician investigator or study team designee(s) will obtain the informed consent document and verify 
the date of consent document is within the IRB approval period. 
 
A physician-investigator or study team member designee(s) will begin the informed consent process 
with the subject ≥24 hours in advance of surgery and/or study procedures when possible. This will allow 
the subject sufficient opportunity to consider whether or not to participate in a study. The informed 
consent process may begin either in-person with the patient or by telephone. 

 
 
 
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The person obtaining informed consent will meet the subject in a private area to present the consent 
document to the subject, provide a description of the study purpose, procedures, risks/benefits, 
alternative treatment options, and follow-up schedule. The subject will be given adequate time to fully 
understand the study, including risks and benefits and study-required follow up visits, and time to ask 
questions.  
 
If the subject volunteers to participate in a study, he/she must verbalize understanding of the consent 
before he/she signs. The person obtaining informed consent will obtain all required signatures on the 
informed consent and HIPAA documents. The subject’s consent will be obtained before any research 
related procedures are performed. 
 
e-Consent 
The consent process begins when a patient is screened, identified and verified as eligible for study 
participation. During the Zoom teleconference call, a member from the study team will discuss the 
consent form in its entirety with the potential participant. The patient will be offered ample time to 
discuss the consent form with family and or friends, and have questions answered. In DocuSign, 
potential subjects have the ability to review the consent document as freely as they would if they 
were consenting in person. They also have the opportunity to exit the document without signing. 
 
The process for obtaining e-consent is outlined below: 
1. First, the IRB approved, stamped consent forms are added to an envelope in DocuSign. 
2. Recipients (subject/coordinators) are then added to the envelope and signature and initial 
fields are assigned to them on the IRB approved consent form. 
3. The consent is then sent to the patient via email. 
4. Once the consent document is completed by all parties, a signed copy is forwarded to the 
subject via email. The completed document is also saved on the research team’s secure, 
internal shared drive. 
 
Subject Confidentiality  
Subject confidentiality will be guaranteed by storing all data collected in a password-protected database 
with no associated PHI or patient identifier information included. Patients in this database will only be 
identified via a unique study ID number. This study ID number will link the electronic data set of each 
patient to their PHI that will be stored separately in the research study binder.  
 
Subject Safety  
Subject safety is of utmost importance throughout this study. The use of oxygenation devices such as the 
incentive spirometer has not been associated with pulmonary complications or other adverse events. 
Nonetheless, patients with history of chronic obstructive pulmonary disease or those at risk of developing 
barotrauma will be excluded from this study. 
 
Adverse Events 
Patients will be assessed for the following adverse events: 
1. Hypoxia (O2 saturation <85%) 
2. CO rise 20% over baseline  
3. Increasing O2 requirement (non-rebreather mask, biflow, BIPAP requirement) 
4. Reintubation  

 
 
 
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5. Pneumothorax  
 
All serious adverse events will be assessed and reported per the Emory IRB Policies and Procedures. 
 
Data Collection and Monitoring 
Study data will be collected from the patient’s electronic medical records and from the local Society of 
Thoracic Surgeons (STS) clinical outcomes database. All information will be entered in a de-identified 
fashion into a password protected Microsoft Excel spreadsheet created for the study.  All study data will 
be coded using indirect identifiers consisting of a unique numeric study ID code linked to each study 
participant’s name to enable verification of study data against source data, as needed.  
 
Study data, including Protected Health Information (PHI), will be obtained with the patient’s direct 
authorization through the consent form in accordance with HIPAA policy. PHI will be obtained via patient 
medical records and the STS database as noted above. Permission for use or evaluation of PHI will be 
limited to the principal investigator, and research study staff. The PHI will be a part of the clinic record 
and patient study binder. The binders will be kept in a secure location when not being used by the research 
staff. The PHI collected will be used by the PI and research staff for study tracking purposes, to link and 
confirm study data with the information located in the patient’s clinical record, and if patient safety 
necessitates, to communicate relevant findings with the patient’s healthcare providers. The PHI will be 
destroyed using the institution’s official recycling system once the study is completed. The PI and staff will 
maintain the records of the study including all correspondence, the study protocol with any/all 
amendments, all correspondence with and approval from the Emory IRB, and signed informed consent 
forms in the Regulatory Binder. All these materials, along with individual patient files, data collection 
forms and source data will be stored and maintained, along with a record of the location of storage, for 
up to 1 year after the completion of the study.  Records will be destroyed using the official institutional 
recycling system. 
 
Data Management 
Upon study completion the final data set will be provided to Sponsor and stored within the secure server 
in the Houston Plastic Craniofacial and Sinus Surgery office (9230 Katy Freeway, Houston, TX 77055). All 
non-identifiable patient data collected will be stored on a password encrypted Microsoft Excel document 
on the same server. No information will be transmitted electronically outside of the server nor will any 
data be stored off of the server on any portable type media storage device. All study participant PHI and 
personal contact information will be securely stored in a study binder at Emory Saint Joseph’s research 
office. 
 
A data safety monitoring plan is not necessary for this minimal risk study. 
 
Facilities 
The surgical procedure and postoperative care will take place at Emory Saint Joseph’s Hospital, Atlanta, 
Georgia.  
 
Funding Source 
Funding for the study will be provided by PEEP Medical, LLC. Bidirectional oxygenation mouthpieces will 
be provided by the Sponsor. Incentive spirometers will be provided by the hospital as part of the routine 
postoperative respiratory therapy.  
 
 

 
 
 
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Appendix A 
Instructions for Patients Assigned to the Incentive Spirometer 
 
Thank you for participating in the GO2 PEEP research study.  You have been assigned to the study group 
using the incentive spirometer. 
1. To use the incentive spirometer, sit up as far as you can in bed and hold the incentive 
spirometer 
2. Take a deep breath in and then blow out all the way through your mouth with pursed lips. 
3. Put the mouthpiece in your mouth.  Seal your lips tightly around it. 
4. Breathe in slowly through your mouth as deep as possible.  The blue disc will rise toward the 
top of the column. 
5. Keep the blue indicator on the right side between the arrows.   
6. Open your mouth and then breathe out, allowing the blue disc to fall to the bottom of the 
column.   
7. Rest for a few seconds and repeat steps above at least 10 times every hour while you are 
awake.  If you feel dizzy, slow your breathing down.   
8. Move the arrow on the left side of the spirometer to show the highest number you reached. 
9. After each set of 10 deep breaths, practice coughing to be sure your lungs are clear.  You may 
use the device additionally if desired.   
10. Place a pillow firmly against incision area to ease any discomfort while coughing. 
 
Practice this 4-6 times each day before your surgery. 
 
If there are any issues or problems contact Dr. Jeffery Miller or the research coordinator at 678-843-
6092 as soon as possible.  
 
 
 
 

 
 
 
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Instructions for Patients Assigned to the Bidirectional Oxygenation Mouthpiece 
 
Thank you for participating in the GO2 PEEP research study.  You have been assigned to the study group 
using the bidirectional oxygenation mouthpiece.  
 
1. To use mouth piece, place the device inside the mouth, loosely biting down on the bite plate.  
Allow your lips to surround the lip flange.   
 
2. Breathe in as deeply as you can in a steady manner.  Exhale through the device as completely 
and forcibly as possible. 
 
3. Repeat the process, breathing as deeply as possible and exhaling for 2.5 minutes, rest for 10 
minutes and then repeat another 2.5 minutes.  Complete this every hour while awake.   
 
4. After using mouth piece each hour, practice coughing to be sure your lungs are clear.  You may 
use the device additionally if desired.   
 
5. Place a pillow firmly against incision area to ease any discomfort while coughing. 
 
Practice this 4-6 times each day before your surgery. 
If there are any issues or problems contact Dr. Jeffery Miller or the research coordinator at 678-843-
6092 as soon as possible.  

 
 
 

 
 
 
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Table 1 
 
 
Table 1. Risk Factors for PPCs 
 
Preoperative 
Postoperative 
Age > 50 
Type of surgery*  
Congestive heart failure 
Neuromuscular blocking agents 
Cigarette and/or alcohol abuse 
Perioperative blood transfusions 
COPD 
Operative time longer than 3 hours 
Corticosteroids use 
General anesthesia 
 
Emergency surgery 
 
 
*Thoracic, upper abdominal, head and neck, neurosurgery, open aortic resection  
 
 

 
 
 
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