A Pilot Feasibility Study of an Ambulatory Multi-Vital Signs Monitor in Perioperative Patients
Phase: NA
Conditions: Perioperative/Postoperative Complications
Sponsor: Wake Forest University Health Sciences

Protocol version: 05032023 
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Official Title: A Pilot Feasibility Study of an Ambulatory Multi-Vital Signs Monitor in 
Perioperative Patients 
NCT05562011 
IRB-Approved Date:  5/3/2023 

Protocol version: 05032023 
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Study Title:  
A Pilot Feasibility Study of an Ambulatory Multi-Vital Signs Monitor in Perioperative Patients  
 
Principal Investigator, Co-investigator(s): Timothy N. Harwood, MD, Ashish Khanna, MD 
 
Sponsor or funding source: Caretaker Medical, Inc. 
 
Background, Rationale and Context 
 
Mounting evidence indicates that preoperative vital signs measurements can reflect undesired 
perioperative events. However, we rarely measure patients’ vital signs in a thorough manner. We 
generally take a single snapshot and use those values for judging physiologic fitness for surgery and 
anesthesia. 
 
The Third Perioperative Quality Initiative has identified that ambulatory measurement is the optimal 
method to establish baseline arterial pressure.i Another group determined that preoperative heart rate 
variability assessment is an objective and useful instrument for identifying patients with low autonomic 
physiological reserves and high risk of poor post-operative course.ii Likewise, Reich et al determined that 
intraoperative tachycardia was associated with adverse outcome in noncardiac surgery.iii Foëx et al found 
that a preoperative fast heart rate was a harbinger of perioperative adverse cardiac events. Among patients 
in the INPRESS study who were predominantly undergoing abdominal surgery who were at increased 
postoperative risk, management targeting an individualized systolic blood pressure, compared with 
standard management, reduced the risk of postoperative organ dysfunction.iv  
We believe safer care can be achieved by focusing on patients in whom ambulatory vital signs indicate 
severe pathophysiology. 
 
Objectives 
Using a portable,wireless multi-Vital Sign (VS) monitoring system developed by Caretaker Medical, we 
have several objectives: 
 
• 
Primary:  
o Assess the feasibility of placing a Caretaker monitor on subjects scheduled for surgery for an 
18-24 hour preoperative ambulatory monitoring session.  
o Assess the feasibility of placing a Caretaker monitor on subjects scheduled for surgery for the 
perioperative period defined as 18-24 hour intraoperative and postoperative ambulatory 
monitoring session.  
o Quantitate the data capture rate (estimated at over 99% in the company’s prior studies) in this 
setting and how reliable our monitor return rate is in this setting. 
• 
Secondary:  
o Assess the prevalence of alterations in VS (HR, RR, SaO2, BP, Cardiac Output, Stroke 
Volume, and HRV preoperatively) in a group of our highest acuity patients (top quartile of 
risk score) undergoing non-cardiac surgical procedures requiring at least a 2-day admission. 
o Assess any correlation of concerning ambulatory preoperative VS to postoperative VS. 
 
We estimate that the percent of time the patient experiences these concerning 
preoperative VS values will correlate with a higher risk for a similar range of VS 
postoperatively, as well as undesired outcomes. 
• 
Undesired outcomes are defined as a) 30-day mortality, b) longer length of 
stay, c) higher ICU transfer, and 4) RRT calls). 
 

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Methods and Measures 
 
Design 
The Caretaker device is a wrist device that has a version that has already been approved by the 
FDA for use amongst medical professionals.   For the conduct of this protocol we propose to use 
a newer version of the device called VitalStream, which has been cleared for use by the FDA.   
The New Caretaker device being used in the study has successfully passed all safety and accuracy 
tests by an independent lab, which have been submitted to the FDA already (see attached 
Declaration of Conformity).  
We plan to monitor ambulatory preoperative CareTaker VS (HR, RR, SaO2, BP, Cardiac Output, 
Stroke Volume, and HRV) in random patients who meet our inclusion criteria for 18-24 hours, 
beginning during their preoperative (Preoperative Assessment Clinic, PAC) visit then overnight 
after they leave. Postoperatively, we will measure these VS in the same patients for 
approximately 24 hours postoperatively.  
These monitors transmit VS to a data cloud, where we will be able to store and then later analyze 
the VS data. Clinical data will be collected from our EPIC Information System in order to provide 
pre- and postoperative information to examine corresponding risk factors and provide 
demographics. 
 
Setting 
The subjects will be recruited in the PAC, where their monitoring period will start, and will 
continue at their residence (or wherever they decide to stay that night). They will return the 
monitor with them into the holding area on the day of their surgical procedure. We will replace 
their monitor on them in the Post-Anesthesia Care Unit (PACU) where it will remain with the 
patient for 24 hours +/- 6 hours continuously monitoring. 
 
Subjects selection criteria 
• 
Inclusion Criteria 
o Age>18 years 
o Scheduled for surgery from an outpatient setting and scheduled for a pre-
admission PAC appointment 
o Risk stratification placing them in the top 25th percentile using our internally-
validated PAC Risk Score. 
• 
Exclusion Criteria 
 
o Surgery on the day of admission (same-day surgery) 
o Any upper extremity surgery 
• 
Sample Size 
o Our power analysis indicates that we need a total number of 150 patients to 
have at least 90% power in detecting a change in VS assuming a mean 
population VS (HR or BP) change of 12% from Phase 1 to Phase 2. We 
estimate a standard deviation of 10%, a type I error rate (2-sided) of 5%, 
and 1% missing follow-up data.  We may have to consent up to 200 subjects 
in order to obtain the 150 evaluable subjects. 
o We estimate this study lasting up to 12months. 
 
Interventions and Interactions 
The essential features of interventions and interactions used to generate data for the study should be 
described. 

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• 
Each participant will have the study summary discussed with them, then allowed to read and 
sign the informed consent after having the chance to interact with the study equipment and 
ask questions. This will occur in the PAC prior to their preoperative visit. 
• 
Participants who agree with entering the study will then have the CareTaker monitor placed 
on their left wrist and calibrated prior to them leaving the PAC.  
• 
No surveys or questionnaires will be administered to subjects. 
• 
An information sheet about the Caretaker device along with an emergency contact number 
will be given to the study subject at the time the device is placed. 
• 
A description of the monitoring device is located in Appendix B. 
• 
Phase I (preoperative phase) Participants will wear the CareTaker monitor for at least 12 
hours (up to 24 hours) in their place of residence during the immediate time period after their 
initial monitor placement. 
• 
The participants will be asked to remove the monitor and ship it back to us using pre-printed 
packaging or bring it with them on their day of surgery and admission to the hospital, 
whichever they prefer. 
• 
For Phase II (intraoperative and postoperative phases) of the study, the participants will then 
have a monitor placed back on them for intraoperative and postoperative monitoring. The 
monitor will remain on them for up to 24 hours postoperatively, at which time a member of 
the research staff will remove the monitor. 
• 
Thus, the total length of time participants will undergo active CareTaker monitoring will be 
24-48 hours, divided between pre-and intra- and postoperative phases. 
• 
Participants who complete the entire study will be compensated $50  for their time and 
efforts.   
 
Table 1. Intervention Events According to Timeline 
EVENT 
PAC VISIT 
DAY AFTER PAC VISIT 
DAY OF 
ADMISSION 
POSTOPERATIVE 
DAY 1 
Recruitment 
X 
 
 
 
Consent 
X 
 
 
 
Placement of 
monitor 
X 
 
X 
 
Monitor 
removal 
 
X 
 
X 
 
Outcome Measure(s) 
• 
Primary outcomes:  
o Phase I: Quantitate the data capture rate and how reliable our monitor return rate is in this 
setting. 
o Phase 2: Quantitate the data capture rate in this setting for the perioperative period. 
• 
Secondary:  
o Assess the prevalence of alterations in VS (HR, RR, SaO2, BP, Cardiac Output, Stroke 
Volume, and HRV preoperatively) in a group of our highest acuity patients (top quartile of 
our internal PAC risk score) undergoing non-cardiac surgical procedures requiring at least an 
overnight admission. See Table 2 for ranges. 
 

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Table 2. Data Sorted into Ranges for each parameter 
Heart rate 
(bpm) 
Systolic Blood 
pressure 
(mmHg) 
Diastolic 
Blood Pressure 
(mmHg) 
RR (bpm) 
<50 
<90 
<50 
<8 
51-70 
91-100 
51-65 
9-12 
71-90 
101-120 
65-80 
13-16 
91-100 
121-140 
81-90 
17-20 
101-110 
141-160 
91-100 
21-25 
>110 
>160 
>100 
>25 
 
o Assess any correlation of range data of ambulatory preoperative VS to postoperative VS. 
o Determine if specific VS ranges are associated with undesired outcomes (defined as 1) 30-
day mortality, 2) hospital length of stay, c) ICU transfer rate, and 4) Rapid Response Team 
calls). 
 
 
Analytical Plan   
• 
For the feasibility portion of the study, we will describe descriptive results of subjects’ 
time of use of the monitor, their description of ease of use (difficult or easy), and the 
quantity of non-artifactual VS data. 
• 
Results will be analyzed initially using descriptive statistics (percent of time VS remained 
in one of the ranges listed in Table 2) and means/standard error. 
• 
We will compare relative incidence with matched cohort undergoing surgery using 
univariate analyses (categorical variables: chi-­‐square test, continuous variables: 
Student’s t-­‐test or Mann–Whitney U test). We will use multivariable Cox proportional 
hazards regression modeling to assess VS risk factors associated with the postoperative 
undesired outcomes mentioned in outcome measures above.  
• 
Statistical methods data will be expressed as mean ± SD, number (percentage), odds ratio, 
and 95% CI. All P values will be two-tailed, and a P value less than 0.05 is considered 
significant. 
 
 
Human Subjects Protection 
 
Subject Recruitment Methods 
Subjects scheduled for surgery and to have a preoperative visit in our Preoperative Assessment Clinic 
(PAC) will be identified using their medical information in our EHR (Epic) to see if they fit our study 
criteria, and interviewed by research staff in the PAC. We ensure equal access to participation among 
women and minorities because we see both who fit our study criteria adequately on a daily basis.  We will 
protect the privacy of potential subjects during recruitment by not using names or date of birth, and we 
will assign a unique study identifier to their medical record number.  
 
• 
We do not plan to use recruitment flyers and advertisements. 
• 
We will use limited PHI to identify subjects via medical records search.  
o We will use only the minimum amount of PHI necessary to review eligibility criteria and 
method to contact potential subjects.  The information we plan to collect for this purpose 
includes: 
 
Medical history 
 
Planned surgical procedure 

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 
Age 
 
PAC appointment time 
Confidentiality/privacy will be protected prior to ascertaining desire to participate.  Subjects who appear 
to be eligible for the study on the PAC appointment list will be marked for a conversation with a member 
of the study staff that will occur during their PAC visit. If they do not wish to participate, any record of 
their PHI will be immediately erased if electronic or shredded if on paInformed Consent 
Signed informed consent will be obtained from each subject by a member of the study staff while the 
patients are present in the PAC. 
 
Confidentiality and Privacy 
Confidentiality will be protected by collecting only information needed to assess study outcomes, 
minimizing to the fullest extent possible the collection of any information that could directly identify 
subjects, and maintaining all study information in a secure manner.  To help ensure subject privacy and 
confidentiality, only a unique study identifier will appear on the data collection form.  Any collected 
patient identifying information corresponding to the unique study identifier will be maintained on a 
linkage file, store separately from the data.  The linkage file will be kept secure, with access limited to 
designated study personnel.  Following data collection subject identifying information will be destroyed 
by securely wiping data 3 years after closure of the study, consistent with data validation and study 
design, producing an anonymous analytical data set.  Data access will be limited to study staff.  Data and 
records will be kept locked and secured, with any computer data password protected.  No reference to any 
individual participant will appear in reports, presentations, or publications that may arise from the study. 
 
Data and Safety Monitoring 
Since this is a feasibility study of the Caretaker monitor, we will disable the data screen from displaying 
vital signs. Stored data will later be analyzed for proximity to standard vital signs measured during the 
subject’s hospital stay. No vital signs from the monitor will be used for actionable interventions. 
The principal investigator will be responsible for the overall monitoring of the data and safety of study 
participants.  The principal investigator will be assisted by other members of the study staff. 
 
Reporting of Unanticipated Problems, Adverse Events or Deviations 
Any unanticipated problems, serious and unexpected adverse events, deviations or protocol changes will 
be promptly reported by the principal investigator or designated member of the research team to the IRB 
and sponsor. 
 
SUBSTUDY 
Since our hypotheses are 1) the percent of time the patient experiences significantly abnormal or 
concerning preoperative vital signs (VS) values will correlate with a higher risk for a similar range of VS 
postoperatively, and 2) undesired outcomes such as myocardial infarction or higher 30-day readmission 
rates, we need to assure that the CareTaker monitors we use have relative accuracy. This will be 
important to help assure that the CareTaker device measures will be generalizable to the current standards 
used in clinics. 
 
In order to investigate the accuracy and precision of heart rate (HR), systolic blood pressure (SBP), 
diastolic blood pressure (DBP), and oxygen saturation (SpO2) measurements of the CareTaker 
monitoring devices we are using, we plan to compare the values obtained by CareTaker devices to 
standard clinic VS measurements. 
 
In order to accomplish this, we will measure VS using  hospital-grade standard monitors at intake into the 
Preoperative Assessment Clinic. We will then discuss the study with the patient. If the patient accepts 
entry to the study, we will then place the CareTaker monitor on the patient and record the VS. We will 
then recheck VS with standard monitors every 20 minutes while the patient is in clinic. Within 60 

Protocol version: 05032023 
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seconds, each VS measure will be immediately followed by recording the VS from the CareTaker 
monitor.  
 
 
 
References 
 
i Perioperative Quality Initiative consensus statement on the physiology of arterial blood pressure control in 
perioperative medicine. Miller, Timothy E., Ackland, Gareth, L.Sanders, Robert, Sessler, Daniel, I.McEvoy, 
Matthew D. et al. British Journal of Anaesthesia, Volume 122, Issue 5, 542 - 551  
 
ii Reimer P, Máca J, Szturz P, Jor O, Kula R, Ševčík P, Burda M, Adamus M. Role of heart-rate variability in 
preoperative assessment of physiological reserves in patients undergoing major abdominal surgery. Ther Clin Risk 
Manag. 2017;13:1223-1231.  
 
iii Reich DL, Bennett-Guerrero E, Bodian CA, Hossain S, Winfree W, Krol M. Intraoperative tachycardia and 
hypertension are independently associated with adverse outcome in noncardiac surgery of long duration. Anesth 
Analg. 2002 Aug;95(2):273-7.  
 
iv Futier E, Lefrant JY, Guinot PG, Godet T, Lorne E, Cuvillon P, Bertran S, Leone M, Pastene B, Piriou V, Molliex 
S, Albanese J, Julia JM, Tavernier B, Imhoff E, Bazin JE, Constantin JM, Pereira B, Jaber S; INPRESS Study 
Group. Effect of Individualized vs Standard Blood Pressure Management Strategies on Postoperative Organ 
Dysfunction Among High-Risk Patients Undergoing Major Surgery: A Randomized Clinical Trial. JAMA. 2017 Oct 
10;318(14):1346-1357. doi: 10.1001/jama.2017.14172. PMID: 28973220; PMCID: PMC5710560. 
 
 
 
 
 
 
Appendix A. 
1. Copies of questionnaire that will be used 
a. Verbal question: Did you find the wearing of the monitor difficult or easy? 
b. Verbal question: If difficult, what exactly made it difficult? 
i. Free text answer: _______________________________________ 
______________________________________________________ 
c.  
 
 
Appendix B. 
CareTaker Monitor brochure is a separate attachment (pdf).