Assessment of Strength Outcomes After Use of the PrimusRS for Specificity of Training in a Cardiac Rehabilitation Setting
Phase: NA
Conditions: Coronary Artery Disease, Valve Disease, Heart
Sponsor: Brandon Hathorn

IRB Number: 015-050
 
Version Date: 08/11/2020
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Baylor Hamilton Heart and Vascular Hospital
(Cardiovascular Rehabilitation Department)
Use of the PRIMUS to Assess Strength Outcomes 
in a Cardiac Rehabilitation Setting
Primary Investigator- Brandon Hathorn, B.S.
                                           

IRB Number: 015-050
 
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1.0
OBJECTIVE
In a prospective study involving 130 cardiac rehabilitation patients muscular strength will 
be measured with a force dynamometer (PRIMUS) on six commonly performed 
activities. During the first session of cardiac rehabilitation, each subject’s date of birth, 
height, and weight will be recorded. To ensure safety, cardiovascular nurse specialists 
and exercise physiologists will monitor the patients for hypertension (blood pressure 
>240/110 mm Hg), arrhythmias, angina, dizziness, pain, shortness of breath, and 
perceived exertion. The subjects will be asked to complete a pre-activity confidence 
survey. On the second day of cardiac rehabilitation, a clinical exercise specialist will the 
PRIMUS equipment to obtain force measurements on the six activities including: rising 
from a bed, rising from a chair, opening a door, lifting an object from the floor and/or 
placing an object overhead. Following the performance of the activities, the patients will 
be asked to complete a post-activity confidence survey.  
1.1
HYPOTHESIS
The purpose of this study is to determine if performed force measurements yield a 
different recommended weight lifted during the sternotomy healing process than the 
traditional gold standard of 5 pounds. A secondary endpoint data obtained will be scores 
from the pre and post-activity questionnaires. 
1.2
STATISTICAL METHODOLOGY 
Continuous variables will be reported as means and standard deviations or medians and 
interquartile ranges, if skewed. Categorical variables will be reported as frequencies and 
per cents. To do so, patients will use the PRIMUS equipment to obtain the maximum 
force pounds performed during six activities. Then, their new recommended weight to lift 
will be 30% and 50% of that maximum. We will use a one sample t-test to determine if a 
difference exists between the gold standard recommendation and the force performed in 
the activities.
With a sample size of 130 subjects, we will have in excess of 90% power to detect a 
difference of 5 pounds from the gold standard recommendation, assuming a standard 
deviation of 5 and a type I error rate of 0.05 in a two-tailed test. With this sample size, the 
data will likely be normally distributed, which is a necessary assumption to perform the 
one sample t-test. However, if the data do not meet this assumption, we will proceed 
using a nonparametric alternative, the Wilcoxon Rank Sum Test.
Additionally, to examine the change in confidence after from performing the 6 activities, 
2 surveys will be administered: 1 prior to treatment and 1 after treatment. In the survey, 
subjects will be asked to rate their confidence using a 7-point Likert scale to perform 
selected daily tasks. Subjects’ perceptions of confidence will be reported and analyzed in 
several ways. We will consider the changes from each of the 7 categories, the change in 

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percent of ‘top box’ responses, and the changes in stratified responses (positive, neutral, 
negative).
2.0
BACKGROUND  
Coronary artery bypass grafting (CABG) and other procedures (VALVE)  involving 
median sternotomy carry the risk of sternal wound complications that can lead to 
increased morbidity, reduced quality of life, prolonged or repeated hospitalization, 
increased health care costs, and, for serious cases, mortality rates of 15% to 40%. 
Because the consequences of sternal complications can be grave, sternotomy patients 
require educational guidance before being discharged from the hospital. 
Authors of the first discharge education materials focused on restricting the loads patients 
could lift for specific time periods that were considered appropriate for sternal healing. 
The resulting sternal precautions likely stemmed from expert opinion or were based on 
anecdotal rather than direct evidence and, consequently, vary widely among hospitals and 
rehabilitation centers around the world. In general, sternal precautions are very restrictive 
and are applied broadly instead of being tailored to the patient. A common example from 
the USA is to avoid lifting more than 5 pounds.  
Sternal precautions are intended to help protect patients after median sternotomy, but 
instead, they may inadvertently impede recovery. A restriction such as “don’t lift more 
than 5 pounds” can reinforce fear of activity, leading to the substantial muscle atrophy 
that occurs during short-term disuse. Worldwide, median sternotomies are performed 
during an estimated 800,000 CABG procedures and an indeterminate number of valve 
surgeries each year, so the potential scope of problems arising from the ongoing use of 
restrictive sternal precautions is sobering. 
Many patients are referred to cardiac rehabilitation programs following sternotomy. 
Cardiac rehabilitation is a program of supervised exercise and risk factor education 
prescribed by the patient’s physician. Traditionally, the exercise prescription comprises 
aerobic activities such as walking and cycling, which utilize large muscle groups in 
rhythmic contractions and improve exercise tolerance and functional capacity. However, 
according to common goals that patients claim, they are more interested in being able to 
return to activities of daily living such as the following: rising from a bed, rising from a 
chair, opening a door, lifting objects from the floor and/or placing objects overhead. 
These movements are reflected in a new philosophy (Keep Your Move in the Tube™) for 
replacement of traditional sternal precautions. The Baylor Institute for Rehabilitation and 
the post-sternotomy surgical unit on 13 Roberts have adopted and currently using the  
Keep Your Move in the Tube philosophy. 
Use of the PRIMUS will enable us to document the force pounds that patients can 
actually lift. If this information was available to cardiac rehabilitation clinicians, specific 
exercise prescriptions could be made to help patients reach their goals and gain 
confidence after a cardiac event. 

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3.0
PATIENT SELECTION
3.1
Patient Inclusion Criteria 
All participants who are referred to Cardiac Rehabilitation with a qualifying 
diagnosis: CABG or VALVE. A total of 130 male and female volunteers who are 
18 to 80 years of age will be asked to participate in the study. Subjects may be of 
any ethnic background and socio-economic status.
3.2
Patient Exclusion Criteria 
Refusal to participate 
Sternal dehiscence
Permanent pacemaker
Permanent defibrillator
Unstable angina
History of heart transplant
History of hernia
History of aneurysm
Physical disability that limits resistance training
Uncontrolled hypertension (systolic 160 mmHg or diastolic > 100 mmHg)
Symptomatic dysrhythmias
History of aortic dissection
3.3
Inclusion of Women and Minorities
Women
Minorities

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4.0
STUDY PLAN
On day 1 (evaluation day), patients will report to the cardiovascular rehabilitation 
department.  Patients will complete a medical history form and medications will be 
documented. The patient’s case manager will review these documents with the patient, 
describe the cardiac rehabilitation program to the patients, and assess the patient’s resting 
heart rate, blood pressure, height, and weight. During this evaluation session, the study 
will be presented to patients who meet the inclusion criteria. The nurse will conclude this 
session by assessing the patient for signs of edema, incision infection, and any other heart 
or lung problems. 
On day 2 (testing day), to ensure safety, nurses and exercise physiologists will monitor 
the patients for hypertension, arrhythmias, angina, dizziness, pain, shortness of breath, 
and perceived exertion. Patients will be asked to review and sign the informed consent 
and a confidence survey. Thereafter, through use of a stethoscope placed above the 
sternum and clavicle, a cardiovascular nurse specialist will listen and document any 
findings of sternal clicking, moving, or grating as subject performs a repetitive chest fly 
routine. The PRIMUS force dynamometer will then be used to obtain one repetition 
maximum (1RM) strength measurements during the activities including: placing an 
object overhead, picking up object up from the ground, and opening a door. Once a one 
1RM has been determined, the patient will then perform 5-20 repetitions at 30% and 50% 
1RM of the same three exercises. Then, dynamic movements that mimic rising from a 
bed and rising from a chair will be performed three times by pushing against the 
PRIMUS force dynamometer. A post session confidence survey will be filled out by the 
subject. Following completion of the activities, the cardiovascular nurse specialist will 
listen to the sternum for changes in clicking, moving or grating. Final measurements will 
be assessed, including a recovery lead II ECG, heart rate, and blood pressure.  
 5.0
EXPECTED ADVERSE EVENTS
Potential Physical Risks:
Potential risks include: high blood pressure, sternal dehiscence, fast breathing, fatigue, 
muscle soreness, chest pain, heart palpitations, myocardial irritability, syncope, chest 
discomfort and MI.

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Potential Psychological Risks:
            
            Subjects may feel pressure to perform well for the investigators and peers. Patients   
   might feel anxious about performing the specific exercise protocol.
Potential Social Risks:
Subjects may feel self-conscious if unable to perform the specific exercise protocol 
appropriately.
Potential Economic Risks:
None are expected. 
Potential Legal Risks:
There could be the threat of lawsuit if subject experiences harm during participation in 
the specific exercise protocol.
6.0
POTENTIAL BENEFITS
Potential direct benefits to research subjects: 
The subjects may experience mental and social fulfillment as a result of participation in 
this study. 
Potential future benefits to individuals with the condition being studied: 
Professionals rehabilitating cardiac patients will have valuable data that might be used to 
help heart patients safely and confidently return to work and activities of daily living.
            Potential benefits to society in general: 
           
            Patients who have a heart event may be able enjoy their livelihood by returning to work 
            and performing their leisure activities.
  
Potential benefits to others involved in the research: 
            There might be a developed appreciation of the confidence and strength necessary for  
            safe return to work and participation in leisure activities.
Provisions in place to protect confidentiality of research related information:
Only designated research staff will perform the data collection and analysis process.  

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Provisions in place to protect the privacy of the research subjects: 
Additional provisions specific to your department Patient information will be secured in 
research office.
Provisions in place to protect the PHI collected during the study: 
No patient identifiers will be used during statistical evaluation and/or preparation of 
manuscript for publication.
             Risk/benefit ratio:
Well known benefits of cardiac rehabilitation include improved strength and confidence    
anxiety. When considering the benefits of participation in the specific activity   
protocol resistance training activity, the risks identified above seem justified. 
Investigators will also be exceedingly careful and will also explain in detail the 
appropriate method for lifting during the specific activity movements. For those 
who increase their strength earlier in the rehabilitation process, they may gain the 
confidence to perform activities outside of the rehabilitation area in a safe manner. This 
finding would be of great importance to help our patients and we think the risks are worth 
these potential benefits.   

IRB Number: 015-050
 
Version Date: 08/11/2020
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