Cardiovascular Endpoints for Obstructive Sleep Apnea With Twelfth Nerve Stimulation (CARDIOSA-12): A Randomized, Sham-Controlled, Double-Blind, Crossover Trial
Phase: NA
Conditions: Obstructive Sleep Apnea
Sponsor: University of Pennsylvania

 
CARDIOSA-12 
 
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Full Study Title 
Hypoglossal Nerve Stimulation for Obstructive Sleep Apnea on Sympathetic and 
Vascular Function 
 
Short Study Title 
CARDIOSA-12 
 
Principal Investigator 
Raj C. Dedhia, MD, MSCR 
Department of Otorhinolaryngology 
 
Co-Investigator 
Erica R. Thaler, MD 
Department of Otorhinolaryngology 
 
Sponsors 
American Heart Association 
American Sleep Medicine Foundation 
 
Protocol Version Number & Date 
Version 3.4 | 09/30/2021 
 
1. Eligibility Criteria: All patients recruited into the study will have already been implanted 
with the Inspire® device. Additional inclusion criteria include: 
 As tolerating the therapeutic level during sleep can take time (weeks to months), all 
patients must be able to use the device at the therapeutic setting (> 20 hours per week for 
> 1 month) prior to enrollment based on compliance data.  
 The patients will be English-speaking and able to give written informed consent.  
 
2. Exclusion Criteria 
 Inspire® remote model 2500 or later is required. Patients with older remotes are not 
candidates due to limited adherence monitoring capabilities.  
 Patients who have fallen asleep while driving resulting in accident or “near miss” accident 
within 1 year prior to HGNS implantation. 
 Pregnant women will be excluded* 
 Actively using positive airway pressure (PAP) therapy for treatment of OSA. 
 Patients in whom the difference between sham and therapeutic voltages is within 0.1 V of 
30% therapeutic voltage. 
* Women of child bearing potential must NOT be pregnant or plan on becoming pregnant. This 
study involves temporarily stopping treatment of obstructive sleep apnea, which may harm the 
fetus. If applicable, the patient will need to take a urine pregnancy test after enrollment (prior to 
washout #1), and again prior to washout #2. 
 

 
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3. Study Objectives 
Primary Outcome Measure:  
 Change in mean 24-HOUR systolic ambulatory blood pressure values 
Aim 1: Determine the impact of hypoglossal nerve stimulation on 24-hour systolic 
ambulatory blood pressure in this cohort of patients with moderate-severe obstructive 
sleep apnea  
Hypothesis: The mean 24-hour systolic blood pressures will be improved at therapeutic 
levels of hypoglossal nerve stimulation and returned to pre-operative levels after 30-day 
sham period 
Secondary Outcome Measures:  
 Change in mean 24-HOUR diastolic ambulatory blood pressure values 
Aim 2a: Determine the impact of hypoglossal nerve stimulation on 24-hour diastolic 
ambulatory blood pressure in this cohort of patients with moderate-severe obstructive 
sleep apnea  
Hypothesis: The mean 24-hour diastolic blood pressures will be improved at therapeutic 
levels of hypoglossal nerve stimulation and returned to pre-operative levels after 30-day 
sham period 
 Change in mean SLEEP systolic and diastolic ambulatory blood pressure values  
Aim 2b: Determine the impact of hypoglossal nerve stimulation on mean sleep systolic 
and diastolic blood pressures in this cohort of patients with moderate-severe obstructive 
sleep apnea  
Hypothesis: The mean sleep systolic and diastolic blood pressures will be improved at 
therapeutic levels of hypoglossal nerve stimulation and returned to pre-operative levels 
after 30-day sham period 
 Change in Pre-Ejection Period (PEP) duration 
Aim 3: Determine the impact of hypoglossal nerve stimulation on pre-ejection period in 
this cohort of patients with moderate-severe obstructive sleep apnea  
Hypothesis: The pre-ejection period will be improved at therapeutic levels of 
hypoglossal nerve stimulation and returned to pre-operative levels after 30-day sham 
period 
 Association of MSNA* and PEP with blood pressure measurements 
Aim 4: Determine if MSNA and PEP are positively associated with blood pressure 
measurements after adjusting for confounders of age, sex, body-mass index, baseline 
systolic BP, baseline diastolic BP, antihypertensive medication use.   
H1: There will be a significant association between alterations in systolic and 
diastolic blood pressure and muscle sympathetic nerve activity 
H2: There will be a significant association between alterations in systolic and 

 
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diastolic blood pressure and pre-ejection period duration 
*Note: MSNA was part of Emory University protocol and will not be performed at the 
University of Pennsylvania. 
 Change in Flow-mediated Dilation (FMD) 
Aim 4a: Determine the impact of hypoglossal nerve stimulation on flow mediated 
dilation in this cohort of patients with moderate-severe obstructive sleep apnea  
Hypothesis: The flow mediated dilation parameters will be improved at therapeutic 
levels of hypoglossal nerve stimulation and returned to pre-operative levels after 30-day 
sham period 
 Change in Pulse Wave Velocity (PWV) 
Aim 4b: Determine the impact of hypoglossal nerve stimulation on pulse wave velocity 
in this cohort of patients with moderate-severe obstructive sleep apnea  
Hypothesis: The pulse wave velocity parameters will be improved at therapeutic levels 
of hypoglossal nerve stimulation and returned to pre-operative levels after 30-day sham 
period 
 Change in Digit Symbol Substitution Test (DSST) score 
Aim 5: Determine the impact of hypoglossal nerve stimulation on digital symbol 
substitution test score in this cohort of patients with moderate-severe obstructive sleep 
apnea 
Hypothesis: The digital symbol substitution test score will be improved at therapeutic 
levels of hypoglossal nerve stimulation compared to after 30-day sham period 
 Change in Psychomotor Vigilance Test (PVT) score 
Aim 6: Determine the impact of hypoglossal nerve stimulation on psychomotor vigilance 
test score in this cohort of patients with moderate-severe obstructive sleep apnea 
Hypothesis: The psychomotor vigilance test score will be improved at therapeutic levels 
of hypoglossal nerve stimulation compared to after 30-day sham period 
 
4. Procedures and Data Collection 
4A. Pre-Study Procedures: All patients in the cohort will have undergone implantation of HGNS 
for OSA at the University of Pennsylvania or Thomas Jefferson University as part of their 
ongoing care for their OSA. HGNS therapy is not experimental and is not under investigation 
per se for efficacy in this study.  Figure 3 shows the study flow. Patients will receive 
compensation for travel and time spent in the study ($100 per visit, plus $10 parking 
reimbursement for each cardiovascular measurement visit; total=up to $520).  Reimbursement 
for parking may also be available.  Compensation will be pro-rated, and will be in the form of 
mailed checks and/or ClinCards. 
 
Figure 3: Study Flow 

 
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Note: We will leave +/- 14 days at each step to accommodate for scheduling issues, etc. 
 
1. HGNS Device Implantation: Under general anesthesia, the HGNS device is implanted 
via 3 incisions: right neck (stimulation lead), right upper chest (pulse generator) and 
right lower chest (respiratory sensor). The incisions are connected via a tunneling 
device, integrating the system components. The pulse generator, using technology from 
cardiac pacemakers, utilizes the signal from the pressure sensor for timing of 
stimulation to the tongue nerve. Patients are monitored in post-anesthesia recovery until 
stable for discharge. The device remains “off” for 1 month to allow for adequate healing. 
2. HGNS Device Activation (1-month post-op):  As part of usual care, patients return to the 
Otorhinolaryngology clinic 1 month post-operatively to undergo activation of the 
implanted device. At this visit, a functional threshold (in volts) is obtained based on 
tongue motion during device stimulation. The patient is provided detailed instructions on 
self-adjustment of stimulation levels using the remote control. For the next month, the 
patient will have steadily increased stimulation strength by 0.1V every 2-3 nights within 
the preset range until the upper limit is reached. The patient has the full support of the 
clinic nurse during this month to troubleshoot any issues.  
3. Polysomnography (PSG) Titration (2-months post-op):  Also as a component of usual 
care, two months after surgery, a level-I PSG (in accordance with 2014 American 
Academy of Sleep Medicine Manual for the Scoring of Sleep and Associated Events) is 
performed at the Sleep Center with standard parameters. Once asleep, the patient 
undergoes device titration of the HGNS starting at 0.2V below functional threshold. The 
voltage is sequentially increased by 0.1V until control of sleep-disordered breathing is 
achieved, providing “therapeutic amplitude” (treatment). 
 
4B. Recruitment into the Cardiovascular Outcomes Study (variable months post-op):  There 
are two different methods for recruitment: 
1. An IRB-approved recruitment letter will be mailed to eligible HGNS patients, which will 
have contact information for the study team. If interested, the patient will reach out to 
the PI or the research study coordinator (RSC) who will mail or email (patient 
preference) a copy of the ICF for review. If contacted by the patient, RSC will obtain 
verbal consent and will coordinate an in-person visit with the patient at the Penn 

 
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Otorhinolaryngology clinic. This visit will include informed consent and visit day one 
procedures. See 4C below. 
2. At the patient’s follow-up appointment, Dr. Dedhia will mention the study to the patient 
and provide a copy of the consent form.  Informed consent discussion will be performed 
at this time. If the patient consents, study day 1 procedures will take place. See 4C 
below. 
 Table 1: Age, gender, race, BMI, smoking status, Pre-op AHI, pre-op ODI, post-op AHI, 
post-op ODI, Months since implant, Hours of usage since activation, average weekly 
therapy use since last visit, diabetes status, HTN status, anti-HTN medications. 
 Eligibility Source documents: Initial consult note, pre-implant sleep study, pre-implant 
DISE report, HGNS titration report, HGNS efficacy sleep study report (if applicable), 
current medications list (reconciled), all Inspire® therapy reports leading up to 
enrollment.  
 
4C. Study Timeline – Pages 5 to 10 
 Enrollment (Study Day 1): HGNS therapy will be deactivated (set to 0.0 V) for one week. 
Sham threshold determination may be done during this visit, or during randomization 
visit (see below – study week 2). RSC will schedule cardiovascular and sympathetic 
testing, if possible. The patient will also be instructed about neurobehavioral testing and 
will perform a practice administration of the DSST and PVT. Form 1 will be completed 
by RSC (remote #, current therapy status, non-dominant arm diameter, WatchPAT digit 
determination, medication reconciliation, sham threshold determination (volts), and 
active therapy setting (volts)). If needed, the patient will contact RSC after the 
appointment to provide the remote number. The patient will also be given an “on-study 
card” containing contact information for the research coordinator. The patient will be told 
to contact the coordinator if any health care providers intend to make changes to the 
patient’s blood pressure medication. An enrollment questionnaire will be completed by 
the patient: 
o Do you take any medications or substances to improve daytime alertness? 
o Do you take any medications or substances to improve sleep quality? 
o How many hours do you sleep each night, on average? 
o ESS, ISI, FOSQ, Snoring VAS 
 Washout Period 1 (Study Week 1): The patient will not use HGNS for 1 week 
 Randomization Visit (Study Week 2 with RCD and RSC):  
a. Patient will fill out “washout questionnaire”: 
o Patient attestation statement about therapy non-use 
o Have you taken any substance to increase daytime alertness (e.g. caffeine)? 
o Have you taken any substance to improve sleep quality (e.g. alcohol)? 
o Have you had any episodes of falling asleep while driving? 

 
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b. Sham Threshold Determination (Consent or Randomization Visit): 
Mouth open, nose breathe only, stimulation from 0.1V up by 0.1-0.2V at same electrode 
configuration as at last clinic visit, level at which bulk tongue motion detected without 
obvious protrusion. This process is repeated and the average value is used to 
determine “sham-HGNS”. This threshold will be used to define “sub-therapeutic 
amplitude” (sham). The electrode configuration will remain consistent between the 
patient’s therapeutic and sham thresholds. 
c. Randomization: The research coordinator will program the device at the specified 
amplitude level: either “sham-HGNS” as above, or “therapeutic HGNS,” depending on 
which is assigned first (see part d below). The “therapeutic HGNS” setting will be the 
patient’s incoming amplitude on enrollment day which will have been predetermined as 
part of routine clinical care prior to enrollment in the study. The patient control range will 
be deactivated for consistency, i.e. there will only be one allowable setting. The 
research coordinator will instruct the patient to use therapy the same night, and for 
every night until the next washout after cardiovascular test day (study week 6). 
 
d. Randomization technique: Both patients and investigators will remain blinded 
regarding patient intervention (sham or treatment HGNS). Only the research coordinator 
will remain unblinded; he will randomize the patients using a simple scheme 
(sealedenvelope.com) and will not take part in any assessments. Block design (block 
size = 10 with 10 units per block) for total of 100 potential subjects. Number 1 = Sham 
First, Number 2 = Treatment First.  
 
 Blinding Adequacy Phone Call (Week 2, Day 2) 
A blinded member of the study team, as delegated by the PI, will contact the patient and 
perform a verbal questionnaire: 
1. Do you think you are on “low” or “regular” treatment, or do you not know? 
2. Why you do think so? 
a. Increased snoring per bed partner 
b. Increased fatigue 
c. Morning headache 
d. Nighttime awakening 
e. Other _____________ 
 
 Weekly Check-In Phone Call (Week 3, Week 4, Week 5) 
RSC weekly call with patient re: usage. Goal is to encourage use (>20h/week) 
RSC will document changes in blood pressure medication, if applicable.  
RSC will remind the patient to consistently take the blood pressure medication. Any 
questions, comments, concerns, or AEs will be documented at this time as well. 
 
 Overnight testing: 24-hour Ambulatory Blood Pressure Testing (Study Week 6, Day 0-
1), and WatchPAT (Study Week 6, Night 1) 

 
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1. The patient will be mailed a pre-programmed 24-hour ambulatory blood pressure 
monitor (ABP) and WatchPAT home sleep test, scheduled to arrive between 2-7 
days before physiology testing. For convenience and/or patient preference, the 
patient may also meet in person with RSC to pick up this equipment. RSC will 
ensure that ABP, WatchPAT and Inspire® device times are synchronized. Each test 
will have comprehensive instructions along with a questionnaire (start time, 
approximate sleep time, wake time, stop time, note anything that may affect the 
tests). A “blood pressure medication witness” statement will be included in the 
instructions to ensure that the patient takes the medication on the day of ABP. 
 
2. ABP will be measured using a noninvasive, portable, validated recorder (Spacelab 
90227; SpaceLabs Medical; Redmond, WA). The patient will wear the device for 24 
hours and asked to perform daily activities as usual. The monitor is programmed to 
record blood pressure every 30 minutes during the day, and every 1 hour at night. 
Data are considered valid if at least 50% of the readings over the 24 hours are 
adequate, with at least 16 hours of use, or at the discretion of the PI. The patient will 
be asked to record bedtime and wake time to corroborate the sleep and wake time 
from the recorder. The following night, the patient will perform the WatchPAT test. 
The patient will be advised not to use both at same time. The patient must use 
HGNS at same time as WatchPAT. RSC will follow up with patient to ensure both 
were completed to best of subject’s ability. 
 
3. The following day, the patient will return to the lab to return the ABP and WatchPAT 
equipment and undergo vascular, sympathetic, and neurobehavioral measurements. 
If any of the ABP or WatchPAT data is invalid or incomplete, the patient may be 
asked to repeat these tests, at the discretion of the PI. Therefore, the patient will 
remain at the current setting and will return to have their HGNS reset for therapy 
washout. 
 
 Vascular Testing (Study Week 6, Day 2): RSC will download therapy compliance data 
from the patient’s remote. Prior to the testing, subjects will have been informed of the 
pre-visit protocol: no food >6 hours before testing (in the event of afternoon testing, a 
light, low fat breakfast is permitted); withhold all cardiac and blood pressure medications 
on the day of testing; no caffeine or alcohol >12 hours before testing; avoid exercise on 
morning of testing; refrain from cigarette smoke exposure >12 hours before testing; and 
abstain from vitamin supplementation >72 hours before testing. Upon arrival, the subject 
will undergo an intake exam including height, weight, vitals, and current medications. 
1. Flow-mediated dilation (FMD) testing. The brachial artery of the non-dominant 
arm is imaged using a high-resolution 10 MHz ultrasound transducer (Acuson, 
Siemens AG, Munich, Germany). A blood pressure cuff on the forearm is inflated 
to suprasystolic pressures to produce 5 min of ischemia. On cuff deflation, 
imaging is performed to measure FMD. Arterial diameter is measured using a 
validated software program. Brachial artery FMD is calculated as (post-ischemia 
diameter − baseline diameter) / (baseline diameter) x 100. The absolute and 

 
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percentage increase in brachial diameter in relation to the baseline diameter are 
examined.    
2. Pulse Wave Velocity (PWV) Testing. Following a rest period of 10 minutes with 
subjects in a supine position in a quiet, temperature-controlled room, the 
Sphygmocor device® (Atcor Medical, Sydney, Australia) will measure Pulse 
wave velocity (PWV), augmentation index (AIX), and subendocardial viability 
ratio (SEVR). The PWV is determined by acquiring waveforms at the carotid and 
femoral arterial sites with electrocardiogram gating. Velocity (distance/time in 
m/s) is calculated by measuring the time interval between electrocardiogram R-
wave and the recorded waveforms at each site, whereas distance between sites 
is measured manually. Reproducibility studies at the Emory vascular laboratory 
on 9 subjects on consecutive days have demonstrated a coefficient of variation of 
3.8%, 13.8%, and 20.3% for PWV, SEVR, and AIX, respectively. 
3. 24-hour ambulatory blood pressure (ABP). This test will be done prior to study 
week 6, day 2 (sympathetic and vascular testing day). The patient will return 
the ABP monitor on vascular testing day. 
 
 Sympathetic Measurements (Study Week 6, Day 2): The patient will be laid supine in a 
comfortable position prior to testing. The 15-minute protocol will involve pre-ejection 
period (PEP) testing by impedance cardiography. 
 
Prior to the testing, subjects will have been informed of the pre-visit protocol: no food >6 
hours before testing; withhold all cardiac and blood pressure medications on the day of 
testing; no caffeine or alcohol >12 hours before testing; avoid exercise on morning of 
testing; refrain from cigarette smoke exposure >12 hours before testing; and abstain 
from vitamin supplementation >72 hours before testing. 
 
Pre-ejection Period (PEP): Each patient will be fitted with the Biopac NICO100C 
Impedance Cardiography (ICG) Noninvasive Cardiac Output Module (Biopac, Goleta 
CA USA). This device will record the ECG and the ICG continuously during a 10-minute 
period through eight, disposable, pre-gelled Ag/AgCl electrodes. PEP will be calculated 
as the average interval (milliseconds) from the onset of left ventricular depolarization, 
reflected by the Q-wave onset in the ECG to the opening of the aortic valve, reflected by 
the B-point in the ICG signal.  
o At the end of this visit, the patient will be set to 0.0V for washout period 2. 
o Procedure Day Questionnaire: Therapy attestation statement, medication 
reconciliation, caffeinated beverages per day, sleep-promoting substance use 
(e.g. alcohol), ESS, FOSQ, ISI, Snoring VAS. 
 
 Neurobehavioral Measurements (Study Week 6, Day 2): The patient will perform 
neurobehavioral tests on a designated laptop in a quiet room at the Otorhinolaryngology 
clinic. Each subject will perform a unique version of the digital symbol substitution test 

 
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and psychomotor vigilance test. The laptop is calibrated for timing precision. All patients 
will be monitored by a trained study staff member to ensure adherence to test 
procedure protocol. 
 
Prior to testing, subjects will have been informed of pre-visit protocol: abstain from 
testing if sick; abstain from testing if <1 hour of waking up; and abstain from testing if 
>16 hours of being awake. 
 
 Washout Period 2 (Study Week 6-7): The patient will not use HGNS for 7 days. 
 
 Crossover Visit & Therapy (Study Week 7): The patient will be switched to the other 
intervention arm (treatment to sham vs. sham to treatment) for 28 days, or for the 
duration spent on the previous intervention arm. The research coordinator will program 
the device at the specified amplitude level, per Form 1. 
 
Patient will fill out “washout questionnaire #2”: 
o Patient attestation statement about therapy non-use.  
o Have you taken any substance to increase daytime alertness (e.g. caffeine)? 
o Have you taken any substance to improve sleep quality (e.g. alcohol)? 
o Have you had any episodes of falling asleep while driving? 
 
The research coordinator will reprogram the patient’s HGNS to the amplitude the patient 
was using prior to study participation. The research coordinator will instruct the patient 
to use therapy the same night. 
 
 Blinding Adequacy Phone Call (Week 7, Day 2) 
Phone call: second morning questionnaire: 
1. Do you think you are on “low” or “regular” treatment? 
2. Why you do think so? 
a. Increased snoring per bed partner 
b. Increased fatigue 
c. Morning headache 
d. Nighttime awakening 
e. Other _____________ 
 
 Weekly Check-In Phone Call (Week 8, Week 9, Week 10) 
RSC weekly call with patient re: usage. Goal is to encourage use (>20h/week). 
Document any changes in blood pressure medication. 
Document any AEs, issues or concerns. 
 
 24-hour Ambulatory Blood Pressure & WatchPAT (Study Week 9, Night 1):   
The patient will be programmed and mailed 24-hour ambulatory blood pressure testing 
(ABP) and WatchPAT, scheduled to arrive between 2-7 days before physiology testing. 

 
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RSC will ensure that ABP, WatchPAT and Inspire® times are synchronized. For 
convenience and/or patient preference, the patient may meet with RSC in person to pick 
up the equipment. 
 
 Sympathetic, Vascular, & Neurobehavioral Measurements & Wrap-Up (Study Week 10, 
Day 2):  
1. RSC will download therapy compliance data from the patient’s remote. 
2. The patient will undergo the same set of testing as above. 
3. If any of the ABP or WatchPAT data is invalid or incomplete, the patient may be 
asked to repeat these tests, at the discretion of the PI. In this case, the patient will 
remain at the current setting and will need to return to have their HGNS reset to 
the pre-study amplitude. 
4. Procedure Day Questionnaire: Therapy attestation statement, medication 
reconciliation, caffeinated beverages per day, sleep-promoting substance use, 
ESS, FOSQ, ISI, Snoring VAS.  
5. Exit Questionnaire 
6. The patient will resume usual care: the RSC will reprogram the patient’s HGNS to 
the pre-study therapeutic amplitude and will reactivate the stimulation control 
range. The patient will be encouraged to contact the study team to address any 
problems or questions. 
 
5. Variables:  
Medical Chart: age, sex, race, smoking status, hypertension status, diabetes status, apnea-
hypopnea index (AHI) from pre-operative sleep study, ODI from pre-operative study, pre-
operative DISE report, history of PAP intolerance   
Study Data (Clinical): body-mass index, current medications (recorded each study visit), 
therapy usage (hours/week) 
Study Data (Experimental): mean systolic and diastolic blood pressures over 24 hours, 
mean systolic and diastolic blood pressures during sleep, WatchPAT ODI and AHI from both 
sham and active therapy tests, pre-ejection period (milliseconds), flow-mediated dilation, 
peripheral arterial stiffness (PWV in m/s, AIX, SEVR), Snoring Visual Analog Scale (VAS), 
Epworth Sleepiness Scale (ESS), Insomnia Severity Index (ISI), Functional Outcomes Sleep 
Questionnaire (FOSQ-10) 
 
6. Analysis 
The overall analysis plan is to examine changes in all cardiovascular endpoints over time 
(i.e., sham to treatment or treatment to sham) as well as internal correlation of these 
endpoints. Sex, a relevant biological variable, is a covariate in all analyses. 
 
For Aim 1, we will perform a paired t-test to compare sham and active therapy 24-hour 
systolic ambulatory blood pressure values. Improvement in AHI will be calculated as the 

 
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difference between pre-operative and post-operative AHI. Multivariable linear regression 
models will be used to estimate associations between blood pressure reduction (outcome 
variable) and improvement in AHI (main effect variable) Final models will include age, sex, 
body-mass index, baseline systolic BP, baseline diastolic BP, antihypertensive medication use. 
 H1: Therapeutic levels of HGNS will reduce mean 24-hour systolic pressures 
H2: Therapeutic levels of HGNS will further reduce mean sleep systolic and diastolic 
pressures 
For Hypotheses 1 & 2, for the purposes of sample size estimation, we are using t-test 
(bivariate) calculation rather than multivariate analysis. Historical data from an OSA cohort 
demonstrated an overall 24-hour mean systolic pressure of 133mmHg, with a standard 
deviation=11. 40  We estimate a clinically significant difference in systolic blood pressure to be 
4mmHg41 which, at the population level, reduces mortality from stroke by 10-40% and mortality 
from ischemic heart disease or other vascular causes by 7-10%.42 With significance level α = 
0.05 (two-tailed) and power 1-β = 0.80, to test a difference in blood pressure of 4mmHg 
between two repeated measures, a sample of n=60 would be needed.    
 
For Aim 3, we will perform paired t-tests to compare sham and therapy values for both 
MSNA bursts/minute and pre-ejection period duration. Note that MSNA will no longer be 
performed at the University of Pennsylvania. 
H1: Therapeutic levels of HGNS will reduce muscle sympathetic nerve activity, a direct 
measure of sympathetic activity 
H2: Therapeutic levels of HGNS will increase the duration of the pre-ejection period, an 
indirect measure of sympathetic activity 
For the purposes of sample size estimation for H1, in a published study of OSA patients 
measuring baseline MSNA, mean MSNA was 39 bursts/min (s.d. = 4). 33  While MSNA is not a 
commonly used clinical outcome measure, we estimate a significant difference in MSNA to be 
5 bursts/min, based on documented effect of CPAP therapy on MSNA. 14 With significance 
level α = 0.05 (two-tailed) and power 1-β = 0.80, to test a difference in MSNA of 5 bursts/min 
between two repeated measures, a sample of n=11 would be needed.     
For Hypothesis 2, published PEP values in a cohort of OSA patients had a mean of 93 
milliseconds (s.d.=17.3). 36 Based on comparative data between untreated apneics and non-
apneics, we estimate a significant difference in PEP to be a 10 millisecond increase from 
baseline. 36 With significance level α = 0.05 (two-tailed), power 1-β = 0.80, to test a difference 
in PEP of 10 milliseconds, a sample of n=47 would be needed. 
 
For Aim 4, we will perform linear regression with MSNA bursts/min and PEP duration as 
outcome variable and systolic and diastolic blood pressures as main effect variables. We will 
determine if MSNA and PEP are positively associated with blood pressure measurements 
while adjusting for confounders of age, sex, body-mass index, baseline systolic BP, baseline 
diastolic BP, antihypertensive medication use.   
H1: There will be a significant association between alterations in systolic and diastolic 

 
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blood pressure and muscle sympathetic nerve activity 
H2: There will be a significant association between alterations in systolic and diastolic 
blood pressure and pre-ejection period duration 
With n=45, we would exceed 95% power to detect effects in the moderate to large range (r2 
> 0.25) assuming a two-tailed α = 0.05. With smaller effects (r2 > 0.16) power drops somewhat 
(78%) but still affords a reasonable opportunity to reject the null hypothesis of an association 
among these various measures of sympathetic function. 
 
For Aim 5, we will perform a paired t-test to compare sham and active therapy DSST 
scores. Improvement in DSST score will be calculated as the difference between the score at 
therapeutic levels and the score after 30-day sham period. Multivariable linear regression 
models will be used to estimate associations between DSST score (outcome variable) and 
improvement in AHI (main effect variable). Final models will include age, sex, body-mass 
index, baseline DSST. 
H1: DSST score will increase during therapeutic levels of HGNS compared to after the 30-
day sham period. 
 
For Aim 6, we will perform a paired t-test to compare sham and active therapy PVT 
reaction time scores. Improvement in PVT reaction time score will be calculated as the 
difference between the score at therapeutic levels and the score after 30-day sham period. 
Multivariable linear regression models will be used to estimate associations between PVT 
score (outcome variable) and improvement in AHI (main effect variable). Final models will 
include age, sex, body-mass index, baseline PVT. 
H1: PVT reaction time score will decrease during therapeutic levels of HGNS compared to 
after the 30-day sham period. 
 
7. Risk / Benefit 
Potential study risks:  Patients will undergo laboratory testing of their cardiovascular system 
following each intervention arm.  They will undergo pre-ejection period, by which an external 
chest monitor and electrocardiogram are used to calculate the time between electrical and 
mechanical motion of the heart.  While muscle sympathetic nerve activity represents an 
invasive procedure, microneurography is a safe, well-tolerated, standard human research 
procedure that has been used in multiple studies with a range of patient diagnoses – greater 
than 200 procedures performed at Emory University by Dr. Jeanie Park, collaborating 
investigator, without complication.  Approximately 7% of subjects have discomfort, including 
tingling, soreness at the electrode insertion site, or muscle weakness in the leg 1 to 2 days 
following the procedure; this usually resolves within a week.  There are no known long-term 
risks.  Participants are free to discontinue microneurography at any time for any reason. 
As part of the experimental study design, the subject will be assigned to a 4-week sham 
intervention period during which they will most likely experience a recurrence of symptoms of 
OSA that may have been alleviated by the HGNS during clinical care.  As only patients who 

 
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had previously untreated OSA therapy are eligible for the study, these patients will experience 
a return to pre-operative symptoms.  We have deliberately excluded patients who were actively 
using CPAP or other OSA therapy prior to HGNS surgery, as placing these subjects through a 
period of inadequate treatment (sham period) bears ethical concern.  Subjects will be advised 
to avoid or exercise increased caution when driving or operating heavy machinery during the 
sham therapy period when they are more likely to feel sleepy.  Additionally, patients will wear a 
blood flow measurement device for 24 hours, which is also well tolerated and does not disturb 
sleep or other daily activities.  Wearing the WatchPAT device while sleeping may result in 
decreased sleep quality during the night of the testing.  However, sleep quality typically returns 
to usual the following night, with no lasting effects noted.   
Potential study benefits:  This study is not designed to benefit subjects directly. However, the 
study results may help doctors to better understand sleep apnea and might be used to help 
people with sleep apnea in the future. 
Risk/Benefit Ratio:  As there are few risks in measuring cardiovascular data apart from 
recurrence of OSA symptoms during the 4-week sham period and there are the possible 
benefits of better understanding sleep apnea and how to treat people with sleep apnea in the 
future, the risks of participating in this study are outweighed by the potential benefits. 
8.  Device Management 
Penn owns WatchPAT and ambulatory blood pressure devices, which will be managed, 
dispensed, and received back from subjects by the study team.  Recordings will be handled 
and scored in accordance with best clinical practices. 
 
9. Feasibility 
Sample Size Feasibility:  We have recruited 17 subjects (16 have successfully completed 
the study) since January, 2018, and plan to complete recruitment in 2020. 
Technical Feasibility:  With regard to Aim 1, 16 subjects successfully completed both sets 
of 24-hour ambulatory blood pressure testing.  
Project execution feasibility:  PI has 50% protected research time through 2021. PI will 
devote 20% of his efforts to ensure the successful completion of this project. 
 
10. Potential Pitfalls, Solutions, and Contingency Plans 
1. Study Design 
a) The study sample reflects a selective subset of patients with moderate-severe OSA, 
limiting the generalizability of these findings. Among others, the inclusion criteria are 1) 
unable to consistently use PAP, and 2) body-mass index < 32 kg/m2.  In clinical practice, this 
represents only 20% of the moderate-severe OSA population as BMI > 32 kg/m2 is an 
exclusion criterion for HGNS and roughly 50% of patients can comply with PAP. From a 
population health perspective, however, this selected group represents a not insignificant 2% 
of the U.S. adult population. 4 Note: since this research protocol was created, BMI was 

 
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removed as an exclusion criteria for HGNS. 
b) We are performing measurements at 2 time points only, immediately after sham and 
treatment interventions.  While we do not capture baseline values, these measures will 
allow us to compare the individual effects of sham and active therapy.  We predict that a 2-
week washout period, in contrast to the 1-week withdrawal period in the STAR trial, 23 will 
provide a return to baseline for ABP at 2 weeks. 31  
c) It is plausible that our hypothesis regarding the positive effect of HGNS on blood 
pressure is not true for two main reasons. First, we are not restricting inclusion for patients 
with normal blood pressure. Normotensive patients have been shown to have less 
improvement in blood pressure, compared to hypertensive patients, after CPAP use. 30 
Secondly, our prospective cohort data suggests roughly 50% of subjects will be on anti-
hypertensive therapy, potentially masking the blood pressure benefit of HGNS. While we 
plan to perform multivariate regression controlling for these variables, the sample size will 
not be sufficient to detect differences in cardiovascular outcomes by subgroup.   However, 
the expected blood pressure values and prevalence of anti-hypertensive medication usage 
are similar to another OSA cohort in which modest, but significant, improvements were 
seen with PAP therapy. 43  In exploratory analyses, we can examine patients with baseline 
hypertension in subgroup analyses. 
d) While we have attempted to blind subjects to each study arm, it is possible that 
experienced HGNS users will recognize the difference between therapeutic and sub-
therapeutic HGNS. However, correct guessing of treatment versus sham will not impact the 
study or the outcomes. Additionally, HGNS users may experience return of untreated OSA 
symptoms and dropout from the study in order to have therapy restored. Patients will have 
been thoroughly educated on this aspect of the study prior to enrollment and, as such, we 
have accounted for 10-15% dropout rate during this period.  
e) We plan to include patients with atrial fibrillation while recognizing the potential 
challenges in measuring pre-ejection period (Aim 2). By using a 10-minute capture period 
(~600 data points), we anticipate that this will minimize sample variability.   
 
2. Study Results 
a) As not all patients will achieve therapeutic success as measured by polysomnography, it 
is possible that the cardiovascular changes will not be seen in these patients. As part of 
Aim 1, we will perform linear regression of change in blood pressure upon change in AHI to 
examine this relationship. As polysomnographic metrics in OSA bear weak a correlation to 
measures of clinical improvement, 44 it is possible that the relationship between AHI and BP 
reduction is also discordant. If, in fact, there is a discrepancy between cardiovascular 
outcomes and polysomnographic outcomes, the findings of this study would challenge the 
current paradigm in outcome measures for OSA.   
b) It is possible that difference between treatment groups is not detected due to the limited 
sample size (Type II error). This statement applies to Aim 1. If we chose a blood pressure 

 
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change of 3mm Hg, instead of 4mm Hg, as a clinically significant difference, our current 
projected sample size of 60 will be underpowered, 1-β = 0.56. It is noteworthy that the 
inputs for the sample size and power calculations rely heavily on clinical judgment as poor 
consensus exists regarding clinically significant differences. 
 
11. Safety and Adverse Events 
1. Definitions 
a) Adverse Event/Adverse Device Effect:  An adverse event (AE)/adverse device effect 
(ADE) is any symptom, sign, illness or experience that develops or worsens in severity 
during the course of the study.  Intercurrent illnesses or injuries should be regarded as 
adverse events.  Abnormal results of diagnostic procedures are considered to be adverse 
events if the abnormality: 
• results in study withdrawal 
• Is associated with a serious adverse event 
• is associated with clinical signs or symptoms 
• leads to additional treatment or to further diagnostic tests 
• is considered by the investigator to be of clinical significance 
 
b) Serious Adverse Event:  Adverse events are classified as serious or non-serious.  A 
serious AE is any AE that is:  
• fatal 
• life-threatening 
• requires or prolongs hospital stay 
• results in persistent or significant disability or incapacity 
• required intervention to prevent permanent impairment or damage 
• a congenital anomaly or birth defect 
• an important medical event 
 
Important medical events are those that may not be immediately life threatening, but are 
clearly of major clinical significance.  They may jeopardize the subject, and may require 
intervention to prevent one of the other serious outcomes noted above.  For example, drug 
overdose or abuse, a seizure that did not result in in-patient hospitalization, or intensive 
treatment of bronchospasm in an emergency department would typically be considered 
serious.  
 
All adverse events that do not meet any of the criteria for serious should be regarded as 
non-serious adverse events. 
 
c) Unanticipated Adverse Device Effect (UADE):  A UADE is any serious adverse effect on 
health or safety, or any life-threatening problem or death caused by, or associated with, a 
device, if that effect, problem, or death was not previously identified in nature, severity, or 
degree of incidence in the investigational plan or application, or any other unanticipated 
serious problem associated with a device that relates to the rights, safety, or welfare of 

 
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subjects. 
 
2. Recording of Adverse Events 
All adverse events occurring during the study period will be recorded.  The clinical course of 
each event will be followed until resolution, stabilization, or until it has been determined that 
the study intervention or participation is not the cause.  Serious adverse events that are still 
ongoing at the end of the study period will be followed up to determine the final outcome.  Any 
serious adverse event that occurs after the study period and is considered to be possibly 
related to the study intervention or study participation will be recorded and reported. 
3. Relationship of AE to Study  
The PI will determine the relationship of each adverse event to the study procedures.  
Relationship will be classified as definitely related, probably related, possibly related, or not 
related. 
4. Reporting of Adverse Events and Unanticipated Problems 
The Investigator will promptly notify the Penn IRB of all on-site unanticipated, Adverse Events 
that are related to the research activity.  Other unanticipated problems related to the research 
involving risk to subjects or others will also be reported promptly.  Written reports will be filed 
using the HS-ERA and in accordance with the Penn IRB timeline of 10 working days.  
5. Follow-up Report 
If an AE has not resolved at the time of the initial report and new information arises that 
changes the investigator’s assessment of the event, a follow-up report including all relevant 
new or reassessed information (e.g., concomitant medication, medical history) should be 
submitted to the IRB.  The investigator is responsible for ensuring that all SAEs are followed 
until either resolved or stable. 
 
12. Management of Multi-Site Research 
1. Study Sites:  
 University of Pennsylvania 
 Thomas Jefferson University 
 
2. Management of Information 
The management of multi-site information will be carried out entirely by the research team at 
the University of Pennsylvania. The research team at Thomas Jefferson University (TJU) will 
simply provide a list of patients implanted with the Inspire® hypoglossal nerve stimulator and 
their contact information. All reporting of unanticipated problems, reporting of interim results, 
and submission of protocol modifications will be executed by the research team at the 
University of Pennsylvania. 
 
3. Management of Study Teams 
The management of study teams will be carried out entirely by the research team at the 

 
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University of Pennsylvania. The research team at Thomas Jefferson University will simply 
provide a list of patients implanted with the Inspire® hypoglossal nerve stimulator and their 
contact information. All subsequent research-related activities (i.e., consent, enrollment, study 
procedures, compensation, etc.) will be carried out by the research team at the University of 
Pennsylvania. For this reason, the research team at the University of Pennsylvania will ensure 
the research team at Thomas Jefferson University has the most up-to-date version of the study 
protocol, consent documents, and other supporting materials; however, no study related 
activities will occur at Thomas Jefferson University.  
 
The only information that will be communicated between the research team at Thomas 
Jefferson University to the research team at the University of Pennsylvania is a list of patients 
implanted at Thomas Jefferson University with an Inspire® hypoglossal nerve stimulator and 
their contact information. This list of PHI will be sent to the research team at the University of 
Pennsylvania with a HIPAA waiver.  
 
The TJU study team roster and their credentials (e.g., CVs, CITI certificates, medical licenses) 
will be collected by the Penn research team and kept on file at Penn. TJU will notify Penn of 
any relevant personnel or credential changes.  
 
Local consent requirements are not expected to vary between study sites, as both sites are 
located in the same city. However, the research team at TJU will notify the Penn research 
team of any relevant changes to institutional policy or site-specific circumstances in a timely 
manner. Penn’s research team will then notify IRB of any resulting changes warranting IRB 
review.