Effect of Alternating Pressure Overlay on Weight Bearing Tissue Tolerance in People With Spinal Cord Injury
Phase: NA
Conditions: Spinal Cord Injuries, Pressure Ulcer
Sponsor: University of Illinois at Chicago

 
 
 
 
Effect of alternating pressure overlay on weight bearing tissue tolerance in 
people with SCI 
 
 
Principal Investigator: 
Yi-Ting Tzen, Department of Physical Therapy, UIC; 1919 West Taylor St. Rm 506H, 
Chicago IL 60612; (312) 996-1506; tzenyt@uic.edu 
 
Study Location(s): University of Illinois at Chicago, Applied Health Sciences Building, 
1919 W Taylor St., room 272, Chicago IL 60612 
 
Sponsor: Dabir Surfaces Inc. 
 
Version: 2 
Date: April 4, 2017 
 
 

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TABLE OF CONTENTS 
Page 
Table of Contents ............................................................................................................. 2 
List of Abbreviations ......................................................................................................... 3 
1.0 Project Summary/Abstract ....................................................................................... 4 
2.0 Background/Scientific Rationale .............................................................................. 5 
3.0 Objectives/Aims ....................................................................................................... 6 
4.0 Eligibility ................................................................................................................... 7 
4.1 Inclusion Criteria .............................................................................................. 7 
4.2 Exclusion Criteria ............................................................................................. 7 
4.3 Excluded or Vulnerable Populations .............................................................. 7 
5.0 Subject Enrollment ................................................................................................... 8 
6.0 Study Design and Procedures ................................................................................. 9 
7.0 Expected Risks/Benefits ........................................................................................ 11 
8.0 Data Collection and Management Procedures ...................................................... 13 
9.0 Data Analysis ......................................................................................................... 14 
10.0 Quality Control and Quality Assurance .................................................................. 15 
11.0 Data and Safety Monitoring .................................................................................... 15 
12.0 Statistical Considerations ....................................................................................... 16 
13.0 Regulatory Requirements ...................................................................................... 16 
13.1 
Informed Consent ........................................................................................ 16 
13.2 
Subject Confidentiality ................................................................................. 16 
13.3 
Unanticipated Problems .............................................................................. 17 
14.0 References ............................................................................................................. 18 
Appendices .................................................................................................................... 19 
American Spinal Injury Association (ASIA) Impairment Scale ................................ 19 
Form A: confidential info ................................................................................................ 20 
Form B: Demographic Info ............................................................................................. 21 
Form C1 – Self-report Medical History ........................................................................... 22 
Form C2 – Self-report CURRENT MEDICATION .......................................................... 23 
Form D – Self-report SOcial HIstory .............................................................................. 24 
Form E1 – resting vitals ................................................................................................. 25 
Form E2 – ASIA Impairment Scale ................................................................................ 26 
Form E3 – Autonomic function scale ............................................................................. 28 
FORM F – Test Data ...................................................................................................... 29 
FORM G – Compensation .............................................................................................. 30 
 

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LIST OF ABBREVIATIONS  
 
AIS 
 
 
American Spinal Injury Association Impairment Scale 
AP 
 
 
Alternating Pressure 
ASIA  
 
American Spinal Injury Association  
ATP  
 
Adenosine Tri Phosphate 
CTRL  
 
Control  
FDA  
 
Food and Drug Administration 
HH 
 
 
Heat Hyperemic 
IRB 
 
 
Institutional Review Board 
ISCOS 
 
International Spinal Cord Society 
LDF 
 
 
Laser Doppler Flowmetry 
OR        
 
Operation Room 
PI 
            
Principal Investigator 
RH 
 
 
Reactive Hyperemic 
ROM  
 
Range Of Motion 
SBF  
 
Skin Blood Flow 
SCI 
 
 
Spinal Cord Injury 
STFT  
 
Short Time Fourier Transform 
WLRS  
 
White Light Reflectance Spectroscopy 
 
 

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1.0 
Project Summary/Abstract 
Tissue ischemia (lack of blood flow) is one of the main causes of pressure injury. 
It is inevitable during bed-ridden condition or prolonged surgery procedure in the 
operating room. Previous studies demonstrated that the protective mechanisms 
of alternating pressure (AP) on pressure injury include redistribution of surface 
pressure, and allowing more blood supplies while lying on the support surface. 
The Dabir AP overlay is low profile yet possesses similar characteristics as other 
AP mattresses on the market. The objective of this study is to evaluate the 
protective mechanisms of Dabir AP overlay on weight bearing tissue of people 
with chronic spinal cord injury (SCI). Our central hypothesis is that the Dabir AP 
overlay will cause lower amount of interface pressure and allow more skin blood 
flow during weight bearing as compared to regular operation room (OR) overlay. 
In addition, people with SCI will have better tolerance to prolonged weight 
bearing after preconditioned with the Dabir AP overlay. This study will be 
repeated measures design, with subjects acting as their own control. Fifteen 
adults with chronic SCI will be recruited from the Greater Chicago area. Each 
subject will undergo two study protocols: lying on AP overlay followed by OR 
overlay (40 minutes each), and lying on OR overlay for 40 minutes only. Laser 
Doppler flowmetry system will be used to collect data before during and after 
lying on the overlays, and pressure mapping system will be used to measure 
interface pressure. Paired t-tests will be computed to compare the interface 
pressure and skin blood flow before, during and after lying on the overlays. 
Findings of this study will help determine the effectiveness of the Dabir AP 
overlay on pressure redistribution and ischemia preconditioning. 

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2.0 
Background/Scientific Rationale  
Tissue ischemia is one of the main etiologies of pressure injury.1 It is inevitable 
during bed-ridden and wheelchair bound conditions, such as spinal cord injury 
(SCI), or prolonged surgery procedure in the operating room. Active alternating 
pressure (AP) mattresses are covered by Medicare policy for patients with 
multiple/large stage 2/ stage 3 pressure injuries to relief interface pressure and 
prevent recurrence of pressure injuries.2 Previous studies demonstrated that the 
protective mechanisms of AP on pressure injury include redistribution of surface 
pressure, and allowing more blood supplies while lying on the support surface.3–5 
The Dabir AP overlay (DabirAIRTM, Dabir Surfaces Inc., Hardwood Heights, IL) is 
low profile yet possesses similar characteristics as other AP mattresses on the 
market; it is intended for clinical use, such as operation room (OR) where AP 
mattresses may not be an option. We expect Dabir AP overlay will be beneficial 
to people at risk of pressure injury by maintaining the blood supply during weight 
bearing condition.  
 
In addition to pressure redistribution and increasing blood supplies, we also 
postulate that the if an AP overlay will be beneficial to the weight-bearing skin by 
means of preconditioning the skin with short-term ischemia, i.e. when air cells 
inflate. Ischemic preconditioning is a method used to prevent tissue damage 
caused by ischemic events, such as stroke and myocardial infarction,6 by means 
of slowing down ATP depletion in the short-term subsequent ischemic episodes 
and washing out the harmful catabolites during each short-term period of 
reperfusion. Recently, this method is implemented to heal diabetic foot ulcer by 
remotely precondition the lower limb.7 We hypothesize that the alternating 
pressure characteristics of the Dabir AP overlay could be utilized as a method for 
preconditioning to protect weight-bearing tissue in people with SCI. 
 
To quantify the severity of tissue ischemia, we will collect the non-invasive 
reactive hyperemic response as an outcome. Reactive hyperemia is 
characterized by sudden increase in blood flow after temporary obstruction of the 
blood flow. Previous studies used this response to simulate the tissue response 
toward ischemia in people that are at risk of pressure ulcer, such as spinal cord 
injury.8,9  
People with SCI are at extremely high risk of pressure ulcer formation due to 
immobility and lack of sensation. In addition, this population may also have 
underlying change in vascular control mechanisms. To further quantify the 
vascular control mechanisms in our participants, we plan to use two additional 
protocols to provide objective measurements of blood supplies. The two non-
invasive measurements are heat hyperemia and skin vasomotor response.  

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Heat hyperemia is an objective and non-invasive method to quantify the degree 
of impaired thermoregulation. It is characterized by a biphasic pattern with an 
initial peak (initiated by activity of sensory nerves and modulated by sympathetic 
nerves), followed by a brief nadir and a plateau phase (mediated by local 
production of endothelial nitric oxide).8 A previous study showed that the initial 
peak was diminished significantly at skin sites below level of injury in patients 
with complete SCI.9 Given that increased skin temperature is a well-proven risk 
factor in ulcer formation in addition to prolonged pressure,10 adopting 
measurement of thermoregulatory function may assist in understanding the 
pathological patterns related to ulcer formation. 
Skin vasomotor response is a reduction in SBF induced by standardized 
cutaneous electrical stimulation. It is an objective method to assess the integrity 
of sympathetic pathways,11 and it is a sensitive tool in identifying sympathetic 
function below a spinal cord lesion.12 Measurement of the skin vasomotor 
response may provide us a comprehensive understanding of the changes in 
control mechanisms with the pathological pattern in SBF detected before ulcer 
formation. 
By comparing the skin blood flow responses between using Dabir AP overlay vs. 
standard OR overlay, we might be able to fill the gap of current research by 
determining the potential benefit of Dabir AP overlay on pressure ulcer 
prevention. 
3.0 
Objectives/Aims 
The objective of this study is to evaluate the protective mechanisms of Dabir AP 
overlay on weight bearing tissue of people with chronic spinal cord injury (SCI). 
Our central hypothesis is that the Dabir AP overlay will cause lower amount of 
interface pressure and allow more skin blood flow during weight bearing as 
compared to regular OR overlay. In addition, people with SCI will have better 
tolerance to prolonged weight bearing after preconditioned with the Dabir AP 
overlay.  
 
There are three aims (with related hypotheses) for this study: 
Aim 1: To determine the effectiveness of pressure redistribution with Dabir 
AP overlay.  
Hypothesis 1. Our participants will demonstrate lower interface pressure at 
sacrum and heel when lying supine for 40 minutes on Dabir AP overlay as 
compared to that on regular OR overlay (AliMed®). 
 
Aim 2: To examine the severity of tissue ischemia with the use of Dabir AP 
overlay. 

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Hypothesis 2a. Our participants will demonstrate greater skin blood flow at 
sacrum and heel when lying supine for 40 minutes on Dabir AP overlay as 
compared to that on regular OR overlay. 
Hypothesis 1b. Our participants will demonstrate smaller reactive hyperemic 
response at sacrum and heel after being relieved from 40 minutes of lying supine 
on Dabir AP overlay as compared to that on regular OR overlay. 
 
Aim 3: To assess the feasibility of utilizing Dabir AP overlay for ischemic 
preconditioning for prolonged weight bearing condition. 
Hypothesis 3. With 40 minutes of preconditioning using the Dabir AP overlay, 
our participants will demonstrate smaller reactive hyperemic response at sacrum 
and heel after being relieved from the regular OR overlay as compared to that 
without preconditioning. 
4.0 
Eligibility 
Twenty people with chronic SCI will be recruited from the Greater Chicago area. 
The eligibility of the subjects will be determined by the study team based on the 
following criteria. 
 
4.1 Inclusion Criteria 
• Males and females 18-64 years old 
• have had spinal cord injury for more than one year 
• have injury level at T10 or above 
• not ambulatory and use a wheelchair for mobility 
• non smokers or able to refrain from smoking four hours prior to and during 
the study 
 
4.2 Exclusion Criteria 
• current pressure ulcer 
• history of diabetes mellitus 
• history of cardiovascular diseases 
• history of hypertension 
• history of pulmonary diseases 
• pregnant women (based on screening and pregnancy testing) 
• non-English speakers 
 
4.3 Excluded or Vulnerable Populations 
No vulnerable population will be included in the study. Since all key 
investigators are fluent only in English language, non-English speaking 
subjects will not be included.  
 

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5.0 
Subject Enrollment 
Subjects will be eligible to participate in this study if they meet the study criteria 
as determined by the telephone screening and face-to-face screening 
procedures.  
 
Telephone Screening Procedure (approximately 15 minutes) 
Subjects will be recruited from the Greater Chicago area through study flyers. 
The PI or key personnel will recruit the eligible subjects when potential subjects 
call in response to the flyer. Questions regarding the inclusion and exclusion 
criteria will be asked to determine the eligibility based on the telephone screening 
script. Results of the telephone screening will be documented in Forms A, B, C1, 
C2, and D. If the potential subject is not eligible, results and confidential 
information will be destroyed immediately. All potential subjects will be scheduled 
to a study visit at the UIC Applied Health Sciences Building room 272 for further 
screening. Subjects will be asked to fast and refrain from smoking four hours 
prior to and during the study, and refrain from consuming any caffeinated 
foods/drinks for 12 hours prior to the study.  
 
Face-to-face Screening Procedure (approximately 30 minutes) 
Upon arrival for the study visit, the PI or key personnel will inform the potential 
subject of the study procedures and risks and benefits of the study. A consent 
form with details of all procedures, risks and benefits will be provided to the 
potential subject. Once the PI or key personnel receive the signed consent form, 
the subject will proceed to face-to-face screening. During the face-to-face 
screening procedure, the PI or key personnel will measure the resting heart rate 
and blood pressure with heart rate monitor and blood pressure cuff respectively 
and documented in form E1. The PI or key personnel will also examine the 
remaining motor function, sensation and autonomic function after spinal cord 
injury. The remaining sensation, motor, and autonomic function are standard 
physical examination for people with SCI in the clinic. The remaining sensation 
will be tested with the key personnel performing light touch of the skin below the 
level of injury (as the picture shown in form E2), and the motor function will be 
tested with the key personnel instructing subject to perform joint movement 
below the level of injury. Results of the remaining sensation and motor function 
will be documented in form E2. The autonomic function will be tested by asking 
subject questions regarding their ability to sweat, ability to sense the changes in 
temperature, bladder function, bowel movement and sexual function, and results 
will be documented in form E3. If the subject demonstrates normal heart rate and 
blood pressure, the subject will proceed with the study procedures. Women of 
childbearing age will also be screened for pregnancy using a urine pregnancy 
test strip.  Women who are pregnant will not be eligible to participate. 

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6.0 
Study Design and Procedures 
Study Design. This study uses a repeated measures design, and each subject 
will act as his/her own control. Each subject will undergo the two protocols in the 
experimental procedures: AP protocol and Control protocol. To ensure the order 
of the two protocols are randomized, the order of AP and Control protocols will 
be determined by drawing one envelope from the envelope pool. We will start 
with a pool of total 20 envelopes (10 envelopes indicating AP protocol first, and 
10 envelopes indicating control protocol first). Once the envelope is drawn from 
the pool, it will not return to the pool.  
Study Procedures (Research purpose). After enrollment, subjects will proceed 
to the following procedures: 1) experimental procedures, 2) vascular control 
measures, 3) pressure mapping of wheelchair and 4) blood withdraw. 
1) Experimental procedure (approximately 4.5 hours) 
Each subject will undergo two study protocols: AP and control (figure 1), and 
the order of the protocols will be randomized as described previously. A 30-
minute washout period will be provided in between the two protocols. Two 
Laser Doppler flowmetry (LDF) flat probes (moor instrument, Wilmington, DE) 
will be taped to the sacrum and one heel to collect the skin blood flow 
response throughout both AP and control protocols. A whole body pressure 
mapping system (Xsensor, Xsensor Technology Corp., Alberta, Canada)  will 
be used between the subject and the overlay to collect the inter pressure 
data. For the AP cycle, we will use four 10-minute cycles (5 minutes of high 
pressure and 5 minutes of low pressure). 
AP protocol: The subject will first lie on his/her side quietly for 10 minutes to 
collect the baseline skin blood flow, followed by lying supine on the Dabir AP 
overlay for 40 minutes, and then side lying for 30 minutes to collect the first 
reactive hyperemic response. To test the effect of preconditioning, the subject 
will then lie supine on the OR overlay for 40 minutes followed by side lying for 
30 minutes for the second reactive hyperemic response.  
Control protocol: The subject will first lie on his/her side quietly for 10 
minutes to collect the baseline skin blood flow, followed by lying supine on the 
OR overlay (AliMed®) for 40 minutes, and then side lying for 30 minutes to 
collect the reactive hyperemic response for control protocol. 

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2) Vascular control measures (approximately 30 minutes) 
The PI, or key personnel will then collect the vascular control measures, 
including the heat hyperemic (HH) blood flow response, and the skin 
vasomotor response. A non-invasive combined laser Doppler and white light 
reflectance spectroscopy (LDF-WLRS) probe (CP2T-1000, Moor Instrument, 
Wilmington, DE) will be used for both measures.  
HH blood flow response will be measured at the sacrum and one heel while 
the subject is in side-lying position. Figure 2 demonstrates the HH 
measurement setting. HH will be induced with the heater at the tip of the 
probe head (41°C for 5 minutes). This HH measure will take approximately 7 
minutes (2 min-baseline, 5 min-heating) per location. In total, the HH 
measures will take up to 15 minutes to complete. 
The skin vasomotor response will be induced using cutaneous electrical 
stimulation (3-10 mA, 0.2-1.0 ms pulses at 20 Hz, 1 s trains) delivered via 1 
cm Ag-AgCl surface electrodes applied bilaterally (4 cm apart) to the forehead 
(above lesion) and the abdominal wall (below lesion) while the subject is in a 
semi-reclined position.12 For each site, 5-8 stimuli will be delivered randomly. 
CP2T-1000 probe will be used to collect SBF and tissue oxygenation data at 
pulp of the second finger and toe. Subject will be in a semi-reclined position 
(about 30° from horizontal plane) during this protocol, and it will take up to 15 
minutes to complete this protocol. 
 
AP 
Baseline 
(10 min) 
AP overlay 
(40 min) 
RH 1 
(30 min) 
OR overlay 
(40 min) 
RH 2 
(30 min) 
 
 
 
 
 
 
Ctrl 
Baseline 
(10 min 
OR overlay 
(40 min) 
RH 
(30 min) 
 
 
 
Figure 1. Illustration of the full course of the experimental protocols: Alternating 
pressure (AP, top panel) and Control (Ctrl, bottom panel). 
 
Figure 2. (A) hand held LDF-WLRS probe with heater ring, (B) HH measure. 

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3) Pressure mapping of wheelchair (approximately 10 minutes) 
The subject will be asked to transfer back to his/her wheelchair with the 
pressure mapping system placed between the wheelchair and the subject to 
collect the interface pressure data. The pressure mapping system is the same 
as that used between the subject and overlay to collect the interface pressure 
data. 
4) Blood withdraw (approximately 15 minutes) 
The key personnel will draw venous blood samples (total 20 mL) via 
venipuncture for standard blood tests, including glycated hemoglobin 
(HbA1C), plasma glucose, lipid and lipoprotein concentrations (i.e. total-
cholesterol, low-density lipoprotein, triglycerides, and high-density 
lipoprotein). The rationale for making these measurements is to collect 
potential covariates that might affect skin blood flow responses. Blood 
samples not used to probe for blood sugar and lipid profile tests will be stored 
up to five years (or until exhausted) for further analyses, since latest trend in 
literatures demonstrated metabolic syndrome after spinal cord injury had an 
effect on pressure ulcer formation.13 
7.0 
Expected Risks/Benefits 
Expected Risks 
Overall, potential risks associated with participation in the study are unlikely and 
of low risk. Subjects will be advised to speak with the PI if they believe they have 
been hurt by the study. Potential risks associated with the non-invasive protocols 
of our study are as followed: 
1) Emotional stress: The risk of having emotional stress with our telephone 
screening procedure and examination of remaining sensation, motor and 
autonomic function is no more than minimal. Participants may feel 
uncomfortable 
answering 
personal 
health 
related 
questions. 
The 
examinations of remaining sensation, motor and autonomic function are 
regularly performed at the physician’s office. Participants may feel 
uncomfortable that he or she could not feel or move the body below the level 
of injury. In addition, female subjects may feel added emotional stress if their 
screening pregnancy test results are positive and they were unaware that 
they were pregnant.   
2) Discomfort: The risk of having discomfort with our heart rate, blood pressure, 
exams is no more than minimal. These examinations are regularly performed 
at the physician’s office. Participants may feel discomfort caused by the blood 
pressure cuff and heart rate monitor belt. 
3) Localized Ischemia. The risk of tissue ischemia associated with reactive 
hyperemia (caused by lying on OR or AP overlays) is low. Reactive 

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hyperemia is a normal physiological response induced by short-term non-
damaging ischemia of the loaded area. The amount of pressure expected on 
sacrum and heels is very low (~60mmHg) and for a short period of time (40 
minutes), which simulates the amount of pressure lying or sitting on a 
mattress or seat cushion. The amount, duration and area of localized 
pressure on the skin is within the current clinical practice guideline of 
pressure ulcer prevention, which is making turning the patient in bed every 
two hours. The skin breakdown risk associated with lying on OR or AP 
overlay is considered as rare (less than 1 out of 100 people). 
4) Localized Heating. The risk of burn associated with heat hyperemia is low. 
Heat hyperemia will be induced by short-term heating of the skin. The 
temperature of heating is very low (41°C or 106°F) and for a short period of 
time (5 minutes). This temperature and duration is far lower and shorter than 
the therapeutic hot packs used regularly in clinic (45-54°C) for more than 10 
minutes covering the whole joint or lower back. Previous published literatures 
that investigated microcirculatory response in people with SCI induced heat 
hyperemia with 20-30 minutes heating at 41°C. No tissue burn or damage to 
the skin was noted in these published studies. The amount and duration of 
localized heating of the skin is far shorter than that causing burn of the skin. 
The skin breakdown risk associated with the heating protocol is considered as 
rare (less than 1 out of 100 people). 
5) Electrical Stimulation. The risk of skin or muscle damage associated with 
electrical stimulation is low. The skin vasomotor response will be induced 
using cutaneous electrical stimulation (3-10 mA, 0.2-1.0 ms pulses at 20 Hz, 
1 s trains) delivered via 1 cm Ag-AgCl surface electrodes applied bilaterally (4 
cm apart) to the forehead (above lesion) and the abdominal wall (below 
lesion). This is a standard protocol used to measure the sympathetic outflow 
of the microcirculatory response. The same protocol was used in previous 
studies on chronic spinal cord injury patients, and no damage to the skin or 
underlying muscle was noted. Electrical stimulation at a higher intensity and 
duration (10-50mA for 10 minutes) is one of the standard clinical practice 
protocol in nerve stimulation and pain reduction for patients with SCI. 
Therefore the skin or muscle damage associated with electrical stimulation is 
considered as rare (less than 1 out of 100 people). 
6) Skin Blood Flow (SBF) and Tissue Oxygenation Testing will be performed 
using an FDA cleared non-invasive device.  The amount of energy used with 
the laser light during the measurement is similar to that of a bar code 
scanner, and the white light is similar to that of ordinary daylight. 
7) Bruising and swelling with venipuncture The risks of drawing blood from a 
vein includes discomfort at the site of the needle stick, possible bruising and 
swelling around the site of the needle stick is minimal. The risks of infection is 
very rare, and feeling faint from this procedure is uncommon. 
8) Bare skin measurements. Bare skin measurements will be collected during 
this study. Some of the locations for the measurements, such as the sacrum 

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(low back) is very private, so the subject may feel embarrassed.  A bed sheet 
will be provided to cover the subjects upon request. 
9) Breach of confidentiality. The risk of breach of confidentiality is minimal since 
the only key to link subject ID and confidential information is locked in the file 
cabinet of the PI’s locked office. The key will only be accessible to the PI’s 
team. All other data is only coded with a subject ID in hard copy and 
electronic files. All hard copy files with subject ID only will be stored in a 
locked cabinet in the PI’s locked laboratory, which is three floors away from 
the PI’s office. All electronic data do not contain any confidential information, 
and they will be stored on the laptop used to collect data, and the hard drive 
located in the PI’s Laboratory. Both computers are password protected, and 
the data are only accessible to the PI’s team. All study personnel are trained 
in the maintenance of security and confidentiality of research data. 
Benefits.  
There is no direct benefit for the participants in this study, however findings from 
these participants will help us understand the potential benefit of the Dabir AP 
overlay as compared to the regular OR overlay, and the potential use of Dabir AP 
overlay on ischemia-preconditioning. 
8.0 
Data Collection and Management Procedures 
Three sets of data (and one biological sample) will be collected from the 
subjects. The following listed the details of data procurement, storage, and 
encryption: All data will be stored at UIC, and data will not be shared or stored at 
Schwab. 
1) Confidential information (hard copy only): Confidential information that 
includes direct identifiers such as name, date of birth and phone number will 
be recorded on Form A. A subject ID (code) will be assigned to the subject by 
PI upon study enrollment for the purpose of protecting the confidentiality of 
the subject data for analysis purpose. Form A will serve as the key to the 
code. Form G is the compensation form.  Participants will be asked to sign 
the form once the payment is received. Form A and G will be stored in a 
locked file cabinet in PI’s locked office (UIC Applied Health Science Building, 
Rm 506H).  Only the PI will have access to this locked file cabinet. A portable 
lock cash box will be used to transport Form A and G between the DHSP 
building and Department of Physical Therapy. Form A and G will be stored up 
to five years and destroyed afterwards so that all data will be de-identified for 
future analyses only. 
 
2) Paper-based data (hard copy and excel spread sheet) will be coded using the 
subject ID on forms: B, C, D, E and F. These forms will be stored in a locked 
file cabinet in PI’s locked laboratory (UIC Applied Health Science Building, 
Rm 272; different from the room that stores Forms A and G). The PI’s team 
will be responsible for incorporating data on these forms to an excel 

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spreadsheet for further statistical analyses. Two layers of encryption will be 
used to ensure the security of excel file. These coded data will be stored up to 
seven years after completion of this study. 
 
3) Skin blood flow data (electronic text file generated automatically with data 
acquisition system): Skin blood flow data will be collected directly via the LDF. 
These analog signals are automatically stored on the UIC laptop used for 
data collection. Only Dr. Tzen’s team can log on to the password protection 
laptop to collect and access the blood flow and tissue oxygenation data. The 
assigned subject ID will be the only identifier of the data set collected from 
each subject. These coded data will be stored up to seven years after 
completion of this study. 
 
4) Blood sample: The blood samples not used to probe for blood glucose and 
lipid profile will be stored coded at co-investigator Dr. Haus’ lab (UIC Applied 
Health Science Building, Rm 106). Dr. Haus will not have access to the key of 
the code.   
 
5) Urine sample:  Urine will be collected from women of childbearing age for 
pregnancy testing during visit one for eligibility screening.  Any urine 
remaining after the testing will be disposed of. 
 
9.0 
Data Analysis 
The MatLab program (The MathWorks Natick, MA) will be used to process the 
skin blood flow signal. The signals will be analyzed with two signal processing 
methods to characterize the responses in both time and frequency domains. 
Details of both methods were published previously by the PI.14  
1) Exponential curve-fitting technique:  
To select the time-domain parameters of the reactive hyperemia and heat 
hyperemia objectively. A tenth ordered Chebyshev I low pass filter (with cut 
off frequency at 0.15 Hz) will be applied to remove the noise caused by 
respiration and cardiac movement.10 We will use a least squares model to fit 
the filtered reactive and heat hyperemic curves, and all parameters (including 
peak, time to peak, area under curve of reactive hyperemia; and first peak, 
second peak and time to first and second peaks, area under curve of heat 
hyperemia) will be derived from the fit curves. 
2) Time-frequency analysis: 
To further examine the different control mechanisms of SBF by decomposing 
the signal in frequency domain. Short-time Fourier transform will be used to 
decompose the signal by breaking the signal into short-time segments 
(windows), then computed Fourier analysis within each segment to calculate 

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spectral densities. A 256-sample Hanning window (512 seconds) will be used 
to compute the spectrogram. 
Please see section 12.0 for details of all statistical analyses.  
10.0 Quality Control and Quality Assurance 
Dr. Tzen will be responsible for quality control and quality assurance of the data 
collected. Dr. Tzen has more than ten years of experiences in pressure ulcer 
research using non-invasive blood flow measurements, and she will perform the 
protocols in person and shadow her research team on the first two subjects. Dr. 
Tzen will then supervise the data collection on site for the next three subjects 
recruited in this study. Dr. Tzen will check all the data within two days of 
collection (paper and electronic formats). If the study team encounter any issues 
related to data collection, Dr. Tzen is available through phone calls to address the 
concerns. Dr. Tzen will meet with her team every two weeks to check the 
laboratory notes and monitor the study regularly.  
 
11.0 Data and Safety Monitoring 
The PI of this study (Tzen) will be responsible for monitoring the data and safety 
of this study. Dr. Tzen will meet with the research team every two weeks to 
monitor the overall conduct of the study (including issues with safety, ethics, 
recruitment, retention, adequacy of study design to achieve the specific aims) 
and provide feedback to the study team for the possible protocol amendments, 
and input from this study on future studies. Serious adverse events are not 
expected, but all such events will be reported according to the UIC IRB, and will 
be handled with the standard of Good Clinical Practice Guidelines including 
informing the PI, and IRB within 24 hours of the event, following up and reporting 
on the event until resolved, and subsequently reported to the PI. 
The risk of breach of confidentiality is minimal since the only key to link subject 
ID and confidential information is a hard copy of Form A, which is locked in the 
file cabinet of the PI’s locked office. All other data is only coded with a subject ID 
in hard copy and electronic file. All hard copy files with subject ID only will be 
stored in a locked cabinet in the PI’s locked laboratory, which is three floors away 
from the PI’s office. All electronic data are also coded and encrypted using 
Symantec software, and they will be stored on the laptop used to collect data, 
and the hard drive located in the PI’s laboratory. Both computers are password 
protected, and the data are only accessible to the PI’s team. All study personnel 
are trained in the maintenance of security and confidentiality of research data.  

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12.0 Statistical Considerations 
For aims 1 and 2, paired t-tests will be computed to compare the interface 
pressure and skin blood flow during 40 minutes of AP overlay (AP protocol) vs. 
OR overlay (Ctrl protocol). Paired t-tests will also be used to compare the 
reactive hyperemic response during RH1 (AP protocol) vs. RH (Ctrl protocol). For 
aim 3, paired t-tests will be computed to compare the skin blood flow during OR 
overlay (AP protocol) vs. OR overlay (Ctrl protocol), and the reactive hyperemic 
response during RH2 (AP protocol) vs. RH (Ctrl protocol). SPSS will be used for 
all statistical analyses. Since this is a pilot study, we will test the study on 15 
subjects. Results form this study will be used to calculate sample size for future 
studies. In case of dropout or subject decease during this study, we propose to 
recruit up to 20 subjects for this study. 
13.0 Regulatory Requirements 
13.1 Informed Consent  
Oral consent will be obtained by phone during the initial telephone screen.  
Eligible subjects will be scheduled for a study visit where written informed 
consent will be obtained prior to conducting any study procedures. The 
PI’s team is responsible for obtaining the signed consent form. The PI’s 
team members were trained by the PI in obtaining informed consent, 
including thorough explanation of the research protocols and allowing 
potential subjects sufficient amount of time to ask any questions and to 
make the decision in participating in this study. To ensure the quality of 
the informed consent process, the PI will consent the first two subjects by 
herself and shadow her team members, and the PI will supervise her team 
members to consent the next three potential subjects of this study. 
The informed consent documents will be stored in a locked file cabinet in 
PI’s locked office (UIC Applied Health Science Building, Rm 506H), only 
the PI have access to the locked file cabinet. A portable lock cash box will 
be used to transport the signed consent forms from the DHSP building to 
the PI’s office. Only the PI’s team will have access to the consent form.  
Subjects will receive a signed copy. 
13.2 Subject Confidentiality  
As described in 8.0 Data Collection and Management Procedures, the 
only document that contains confidential information is a hard copy of 
Forms A and G. To guard the confidentiality, Forms A and G will be stored 
in a locked file cabinet in PI’s locked office (UIC Applied Health Science 
Building, Rm 506H), only the PI has access to this locked file cabinet. A 
portable lock cash box will be used to transport Form A between DHSP 

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building and the PI’s office. Form A and G will be destroyed at the end of 
the study so that all data will be de-identified for future analyses only. 
Other data, including Forms B, C, D, E, F, blood flow and tissue 
oxygenation data in text files and excel spreadsheets will only contain an 
assigned subject ID, and Form A is the only document to link the subject 
ID to the subjects’ confidential information. To guard the confidential 
information, Forms B, C, D, E, F will be stored in a locked file cabinet in 
PI’s locked laboratory (UIC Applied Health Science Building, Rm 272; 
different from the room that stores Forms A and G). The PI’s team will be 
responsible for incorporating data on Form B to a excel spreadsheet that 
contains information of all subjects on a password protected desktop 
located in the PI’s locked laboratory. Two layers of encryption will be used. 
The analog signals of blood flow and tissue oxygenation will be stored on 
the password protected UIC laptop used for data collection. Only the PI’s 
team can access the laptop to collect and access data. The assigned 
subject ID will be the only identifier of the data set collected from each 
subject. These coded data will be stored up to seven years after 
completion of this study. The password of the laptop and desktop used in 
this study will be changed quarterly and known only by the PI’s team.  
13.3 Unanticipated Problems 
The PI will be responsible for monitoring and overseeing all procedures of 
the study. With the previous experiences, there should be no 
unanticipated problems with this study. However, should any 
unanticipated problems occur, the incident will be handled with the 
standard of Good Clinical Practice Guidelines including informing the PI, 
and IRB within 24 hours of the event, following up and reporting on the 
event until resolved, and subsequently reported to the PI. 

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14.0 References 
1. National Pressure Ulcer Advisory Panel. Prevention and treatment of pressure 
ulcers: clinical practice guideline. (2015). 
2. HomeStar Meical Equipment & Infusion Services. Summary of medicare coverage 
for medical equipment. 
3. Arias, S. et al. Effects on interface pressure and tissue oxygenation under ischial 
tuberosities during the application of an alternating cushion. J. Tissue Viability 24, 
91–101 (2015). 
4. Jan, Y.-K., Brienza, D. M., Boninger, M. L. & Brenes, G. Comparison of skin 
perfusion response with alternating and constant pressures in people with spinal 
cord injury. Spinal Cord 49, 136–141 (2011). 
5. Masterson, S. & Younger, C. Using an alternating pressure mattress to offload heels 
in ICU. Br. J. Nurs. Mark Allen Publ. 23, S44, S46–49 (2014). 
6. Hausenloy, D. J. & Yellon, D. M. Remote ischaemic preconditioning: underlying 
mechanisms and clinical application. Cardiovasc. Res. 79, 377–386 (2008). 
7. Shaked, G. et al. Intermittent cycles of remote ischemic preconditioning augment 
diabetic foot ulcer healing. Wound Repair Regen. Off. Publ. Wound Heal. Soc. Eur. 
Tissue Repair Soc. 23, 191–196 (2015). 
8. Minson, C. T., Berry, L. T. & Joyner, M. J. Nitric oxide and neurally mediated 
regulation of skin blood flow during local heating. J. Appl. Physiol. Bethesda Md 
1985 91, 1619–1626 (2001). 
9. Nicotra, A., Asahina, M. & Mathias, C. J. Skin vasodilator response to local heating 
in human chronic spinal cord injury. Eur. J. Neurol. 11, 835–837 (2004). 
10. Tzen, Y.-T., Brienza, D. M., Karg, P. & Loughlin, P. Effects of local cooling on sacral 
skin perfusion response to pressure: implications for pressure ulcer prevention. J. 
Tissue Viability 19, 86–97 (2010). 
11. Nicotra, A., Young, T. M., Asahina, M. & Mathias, C. J. The effect of different 
physiological stimuli on skin vasomotor reflexes above and below the lesion in 
human chronic spinal cord injury. Neurorehabil. Neural Repair 19, 325–331 (2005). 
12. Brown, R., Engel, S., Wallin, B. G., Elam, M. & Macefield, V. Assessing the integrity 
of sympathetic pathways in spinal cord injury. Auton. Neurosci. Basic Clin. 134, 61–
68 (2007). 
13. Li, C., DiPiro, N. D., Cao, Y., Szlachcic, Y. & Krause, J. The association between 
metabolic syndrome and pressure ulcers among individuals living with spinal cord 
injury. Spinal Cord 54, 967–972 (2016). 
14. Tzen, Y.-T., Brienza, D. M., Karg, P. E. & Loughlin, P. J. Effectiveness of local 
cooling for enhancing tissue ischemia tolerance in people with spinal cord injury. J. 
Spinal Cord Med. 36, 357–364 (2013). 
 
 

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APPENDICES 
 
American Spinal Injury Association (ASIA) Impairment 
Scale 
 
 
A = Complete: No motor or sensory function is preserved in the sacral segments S4-S5. 
 
B = Incomplete: Sensory but not motor function is preserved below the neurological level and 
includes the sacral segments S4-S5. 
 
C = Incomplete: Motor function is preserved below the neurological level, and more than half of 
key muscles below the neurological level have a muscle grade less than 3. 
 
D = Incomplete: Motor function is preserved below the neurological level, and at least half of 
key muscles below the neurological level have a muscle grade of 3 or more. 
 
E = Normal: motor and sensory function are normal.  
 
 

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IRB approval 
FORM A: CONFIDENTIAL INFO 
(to complete during telephone screening) 
 
Name of subject: _______________________________ 
Date of birth: ___/___/____ 
 
Address:  
Street: _______________________________________________________________ 
City: ___________________ State: _________________ Zip Code: ______________ 
Phone: (Work) ________________________  (Home) _________________________ 
E-mail: _________________________ 
 
 
 
 
 
 
 
 
 
Researcher’s Initials:______ 
Date: __________________ 
 

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Subject ID: _________________ 
 
 
 
  
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IRB approval 
FORM B: DEMOGRAPHIC INFO 
(to complete during telephone screening) 
 
• Gender: _____ Male _____ Female 
• Weight: __________ 
 
Height: __________ 
• (Body Mass Index: _____________________ (To be calculated by the investigator) 
• Race/Origin: _____African-American  
_____Asian-American/Asian 
_____Caucasian 
 
 
 
_____Hispanic 
_____Others (please specify________________________________) 
 
 
 
 
 
 
 
 
 

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IRB approval 
FORM C1 – SELF-REPORT MEDICAL HISTORY 
(to complete during telephone screening) 
 
Spinal Cord Injury History 
• Date of injury: _____/_____/_____ 
• Level of injury: Cervical ___ Thoracic___  Lumbar___ 
• AIS: ___ A ___ B___ C 
• Wheelchair: ____ manual ____ power 
 
Pregnant: _______ yes _______ no 
 
Other Medical history 
_____ Cardiovascular Disease 
_____ Hypertension 
_____ Diabetes Mellitus 
_____ Neuropathy 
_____ Lung Disease 
_____ Others, please list 
______________________________________________________________ 
_____ None of above diseases 
 
Pressure Ulcer history 
If had pressure ulcers in the past, please indicate the location and time: 
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________ 

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IRB approval 
FORM C2 – SELF-REPORT CURRENT MEDICATION 
(to complete during telephone screening) 
 
Name of Medication  
Dosage 
 
Frequency 
Reason for Taking 
___________________ 
__________ _________ ________________________ 
___________________ 
__________ _________ ________________________ 
___________________ 
__________ _________ ________________________ 
___________________ 
__________ _________ ________________________ 
___________________ 
__________ _________ ________________________ 
___________________ 
__________ _________ ________________________ 
___________________ 
__________ _________ ________________________ 
___________________ 
__________ _________ ________________________ 
___________________ 
__________ _________ ________________________ 
 
 
 

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IRB approval 
FORM D – SELF-REPORT SOCIAL HISTORY 
(to complete during telephone screening) 
 
Please indicate Yes or No to the following: 
Do you smoke? _____Yes _____No      
If yes, packs per day? ___________  
Number of years? _____________ 
 
Do you exercise on a regular basis? ____Yes ____No 
If yes, describe 
_____________________________________________________ 
_____________________________________________________ 
_____________________________________________________ 
 
 
 
 
 
 
 
 
Researcher’s Initials:______ 
Date: __________________ 

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FORM E1 – RESTING VITALS 
(to complete during face-to-face screening) 
 
Resting heart rate: ________________ 
Resting blood pressure: ________________ 
 
Pregnant: _______ yes _______ no (based on urine test result) 
 

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FORM E2 – ASIA IMPAIRMENT SCALE 
(to complete during face-to-face screening) 
 

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Subject ID: _________________ 
 
 
 
  
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FORM E3 – AUTONOMIC FUNCTION SCALE 
 
(Document!Subject!ID!instead)!

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FORM F – TEST DATA 
_______  Envelope A: CTRL à AP 
Session 
Heart Rate 
Blood Pressure 
Before 
After 
Before 
After 
CTRL 
 
 
 
 
AP 
 
 
 
 
 
 
 
________  Envelope B: AP à CTRL 
Session 
Heart Rate 
Blood Pressure 
Before 
After 
Before 
After 
AP 
 
 
 
 
CTRL 
 
 
 
 
 
 
 
 
 
 
 
(Signature of Investigator) 
 
 
 
(Date) 
 
 

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FORM G – COMPENSATION 
I, ________________________________, acknowledge that I am to receive 
compensation for participating in this study $_____________ on _____/_____/_____. 
 
 
Participant’s signature ______________________Date _____________ 
 
Researcher’s signature _____________________Date______________