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Frequently Asked Questions (FAQ)
4. Are ANSWatch tests accurate?

To confirm the accuracy and repeatability of ANSWatch tests, several human clinical
trials were conducted.  In the period of 2004 and 2005, four separate studies were for
Performance and Longevity, Holladay, Utah, another one by William C. Orr, Ph.D. at
Lynn Health Science Institute, University of Oklahoma Health Sciences Center,
Oklahoma City, Oklahoma, another one by Terry B. J. Kuo, M.D., Ph.D. at Tzu-Chi
University Hospital, Hualian, Taiwan, and another one by YF Lin, M.D. at Tri-service
General Hospital, Taipei, Taiwan.  In these IRB-approved studies, blood pressures
measured by an U-300 Spygmomanometer (mercury-based; hand-operated; Registered
Number FI 0156269, Bureau of Standards, Metrology & Inspection, M.O.E.A., Taiwan)
were compared with those obtained by ANSWatch (see standard protocol at Ref. 3). In
addition, heart rate and HRV parameters obtained from a Hewlett-Packard ECG (Model
Agilent A3) and ANSWatch conducted simultaneously were compared.  A total of 103
volunteers were tested.  The summary of the results are presented in Tables 1 through
3 below.  An example of correlation plot of peak-to-peak intervals between ECG and
ANSWatch from a representative volunteer is shown in Figure 2.

Table 1: Comparison of blood pressures between sphygmomanometer and ANSWatch
                             Min. Error        Max. Error        Ave. Error        Stand. Dev.
Systolic Pressure (mmHg)         0                      10                  1.36                   6.02
Diastolic Pressure (mmHg)        0                      10                 -1.22                   5.01
Hear Rate (beat/min)                 0                        2                  0.06                   0.74


Table 2: Comparison between ECG and ANSWatch for HRV parameters and heart rate
Parameters        
                              Min. Error        Max. Error        Ave. Error        Stand. Dev.
HRV (ms)                                 0.3                    1.7                   0.4                  1.2
HF(%)                                      0                       -4                    -1.5                  1.7
LF(%)                                      0                        4                     1.8                  1.7
LF/HF                                      0.0                     0.5                  0.15                0.22
Heart Rate (/min)                     0                         -1                  -0.3                  0.5

Table 3: Linear correlation coefficient of peak-to-peak intervals between ECG and
ANSWatch
Min Corr. Coef.        Max. Corr. Coef.        Ave. Corr. Coef.        Stand. Dev.
0.989                        0.996                         0.993                     0.03

Figure 2: Correlation plot of peak-to-peak intervals between ECG and ANSWatch (X-
axis: ECG; Y-axis: ANSWatch or Pulse)


































From the above tables and figure, a high level of accuracy and repeatability was
indicated for ANSWatch when compared to HP’s ECG.  It is important to note that the
former relies on pulse signals from the radial artery, while the latter analyzes electrical
signals produced by the heart.  

A recent clinical trial was started in 2010 by YH Chang, M.D., Ph.D. at Graduate
Institute of Acupuncture Science, China Medical University, Taichung, Taiwan.  This
study (still ongoing) recruited not only healthy volunteers but also patients with cardiac
arrhythmias. Again, the HP’s ECG (Model Agilent A3) and ANSWatch were operated
simultaneously and post-analyzed by the same software (ANSWatch Manager) for heart
rate and HRV parameters.  A total of 50 cases (39 healthy and 11 with arrhythmias)
have been collected and analyzed.  For the 11 arrhythmic cases, ANSWatch Manager
successfully detected and marked all irregular heartbeat locations in the 5-min test
period (the same period for HRV test), as confirmed case by case using human eyes.  
Irregular peak intervals were removed by ANSWatch Manager before time- and
frequency-domain HRV analyses, as required in 1996 HRV International Standard.  
Tables 4 and 5 present the summary of heart rate and HRV parameters by both
methods and their comparisons.

Table 4: Comparison between ECG and ANSWatch for HRV parameters and heart rate
Parameters                ECG        ANSWatch        Ave. Error        Linear Corre. Coefficient
HRV (ms)                   47.1            45.4                 - 1.7                              0.99
LF (ms**2)                 564             540                  - 24                                1.0
HF (ms**2)                 601             538                  - 63                                0.99
LF/HF                        1.55            1.74                 0.19                                1.0
Heart Rate (per min)  70.5          70.5                    0                                    1.0

Table 5: Linear correlation coefficient of peak-to-peak intervals between ECG and
ANSWatch
Min Corr. Coef.        Max. Corr. Coef.        Ave. Corr. Coef.        Stand. Dev.
0.939                           0.999                     0.960                       0.039

Again, from the small average errors and high levels of linear correlation coefficients, it
is concluded that ANSWatch tests were accurate and reproducible for both healthy
volunteers and patients with irregular heartbeats.

The above clinical studies have been published in peer-reviewed journals and
conferences:

Wen Chieh Liang,  John Yuan, Deh Chuan Sun, Ming Han Lin, Changes in Physiological Parameters Induced
by Indoor Simulated Driving: Effect of Lower Body Exercise at Mid-Term Break, Sensors 2009, 9, 6913-
6933

Liang, W.C., Yuan, J.,Sun, D.C., Lin, M.H., Changes In Physiological Parameters Induced By Simulated
Driving Tasks: Morning Vs. Afternoon Session,  J. Chin. Inst. of Industrial Eng., 25(6), 457-471, 2008

Wen Chien Liang, John Yuan, D.C. Sun, Ming Han Lin, Variation in Physiological Parameters Before and
After an Indoor Simulated Driving Task: Effect of Exercise Break, 2007 International Conference on
Gerontic Technology and Service Management (ICGTSM), Nantou County, Taiwan, March-26-2007

Wen Chien Liang, John Yuan, D.C. Sun, Ming Han Lin, Variation in Physiological Parameters Before and
After a Simulated Driving Task (Part 2) The 14th Annual Meeting, Ergonomics Society of Taiwan, March 31,
2007 / Wufong, Taichung County

Wen Chien Liang, John Yuan, D.C. Sun, Ming Han Lin, Variation In Physiological Parameters Before And
After An Indoor Simulated Driving Task In The Afternoon, 2006 Biomedical Engineering and Technology
Conference, Taichung, Taiwan


D.C. sun, Y.I. Kuo, Y.H. Liang,  S. H. Tang, Y.F. Lin, Y.H. Chang, J.K, Lin,  Introduction to a New Wrist
Patient Monitor - ANSWatch and its Clinical Applications,  9th Conference on Engineering Technology and
Applications of Chinese and Western Medicine, Taichung, Taiwan, Conference Proceeding, Page 33-38
More Resources



Back to FAQ
Do you have     
hypertension?
- are you monitoring   
frequently?
- are you taking
prescription drugs?
- are you aware of drug
side effects on ANS?
- self-improvement tips
Read more......
Feeling dizzy      
or even fainted?
- are you low in blood
pressure or heart rate?
- are you taking
prescription drugs?
- You may experience
Baroreflex failure
Read more......
Irregular heartbeats?
- often noticing abnormal
heartbeats (missing,
uneven, or super-fast)?
- Yo might have cardiac
arrhythmias
- Most sudden death
events are preceded by
irregular heartbeats
Read more......
Mitral Valve Prolapse?
- Mitral valve is the
bicuspid valve between left
atrium and ventricle
- If mitral valve is not
closed properly (called
mitral valve prolapse
MVP), the blood may
backflow during pumping
- there is a strong
connection between panic
attackes and MVP
- How to detect it?
Read more......
Am I having   
dysautonimia?
- autonomic nervous
system works to fine tune
body conditions depending
on physiological needs
- ANS consists of two
branches: sympathetic and
parasympathetic
- do you have balanced
ANS?
- what are the symptoms of
dysautonomia?
Read more......
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