Measuring Heart Reserve and Load with Video Camera

Cardio Reserve System

Measuring Heart Reserve and Load with Video Camera

 Purpose of the Software Product Cardio Reserve

The heart is the main organ in our body, thanks to which we live in this World.

It works non-stop as long as we live. And yet we constantly act or do things, which are harmful to our health, and do not think about aftereffects of our actions. And it is the heart that suffers first of all. The thing is that we can’t evaluate the degree of the harm, which our behavior inflicts on our heart and it may result in serious heart condition problems.

Cardiac disease mortality rate is over 60%. As a rule people consult a doctor too late.

To prevent grave cardiac problems it is necessary to regularly check the heart condition and to know permissible levels for the load on the heart and correctly assess the heart reserves.

Today, when computers are so widely used in everyday life, it makes sense to use existing means of information transfer as tools for efficient heart control.

One of such cost-effective tools is the web-camera, which allows pulse stream recording that is graphical display of heart rate values. The use of this device significantly lowers the costs of complex heart-rate measuring systems and makes them affordable for masses of people.

The Cardio Reserve system is designed for recording pulse rate by means of a non-pro web camera and allows monitoring of the heart reserve, as well as the load on the heart, at any time.

 Sphere of Application

The Cardio Reserve system can be used for individual health monitoring as follows:

ü  Daily use after sportive activities such as: morning physical exercises, jogging, swimming, sport games.

ü  In fitness centers after rehabilitation procedures.

ü  After various training sessions.

ü  In the course of rehabilitation treatment after heart disorders.

ü  In the event of stressful situations.

ü  After intake of alcohol or drugs.

 

Methodology for Heart Fitness Evaluation

Heart fitness can be assessed by means of the body functional test under controlled exercise program (stress test). One of the simple test methods for such functional trials: 20 squats during 30 seconds.

Before the test check your pulse at rest.

Upon the startup of the Cardio Reserve program enter your age and the at-rest pulse data into respective fields and measure the cardio reserve.

Then using the seconds hand of the clock squat quickly 20 times (on average 1.5 seconds per each squat) during 30 seconds and immediately check your cardio reserve again.

In healthy but not trained individuals the reserve can reduce to 60% and restores to its initial level during 2 – 3 minutes. In better trained persons the cardio reserve value after controlled stress activity shall be at least 80% and restore up to 95 % within 1 – 2 minutes.

The amount of individual load is set for practically healthy persons, and, if such is the case, the training exercise program shall have the load of 75-85% of the maximal value; however, for individuals with ischemic heart disease the stress load may not exceed 50%.

Generally identification of the load on the heart is based on the following principle:

You prescribe a certain 3-minute exercise program (for example 20 squats) and take measurements before the stress test, right after the exercise and 3 minutes after the exercise.

If the load is under 40%, it is light load, if it is between 40-70%, it is average load, if between 70-90%, it is heavy load. This method is good for dynamic monitoring of your physical fitness and selection of adequate load. It means that if 20 squats result in light load, it can’t be regarded as a good training load. On the contrary, if the load value goes up to100%, it means the stress is too high for you.

 

General Principles and Substantiation of the Registration Technique

 The video camera is an optoelectronic system allowing registration of various non-transparent objects in reflected light. Through the lens the object image is projected to the light-sensitive matrix, from which the signal goes along the USB channel to a PC. The video signal is processed, and the converted image is displayed on the computer monitor.

The camera resolution is constituted of a number of pixels per area unit of the video camera light-sensitive matrix. The more pixels, the higher is the resolution. For our purposes this parameter is not decisive. Moreover, the lower is the parameter the better it is for us, as in this case interference immunity improves and the video file size and its processing time reduce.

More important are the sensitivity factors in the spectral range. The spectral range of visible light is from 400 up to 700 nm. Of interest to us is the red and the near infra-red bands (more than 700 nm).

Practically all cameras have sufficient sensitivity in this band, which means they can be used as pulse-wave sensors.

Let’s focus more on the pulse recording using a camera.

Preliminaries. If to cover a source of bright light by hand in a dark room we see the red contour of fingers as the hand tissue works as a filter letting the red light through. The hand tissue is veined with vessels in which blood circulation responds to heart beat causing the change in the translucent light intensity (modulation).

This is the picture we obtain when using a video camera.  If to close the video camera lens by a finger, and the camera is on, on the display we see an unevenly glowing red square with different light intensity in different parts. This is pulsation of blood in the maniphalanx.

Video recording or image registration with video camera has specifics. First of all before the video recording it is necessary to provide the right illumination of the object. It mustn’t be too bright or too dim.

As a rule, cameras have automatic light intensity control, and therefore the output signal can change significantly in the course of time. Because of slow response of the device the changes are intermittent and occur with a delay in time.

These factors must be taken into consideration in the course of pulse stream registration.

Let’s go back to registration of pulsation brightness of the light flux in the camera.

The pixel brightness is a function of three colors: red, blue and green. Their values can be set programmatically. It should be noted that minor pulsations of brightness are recorded against the background of much interference and noise. Special enhancement and filtration techniques are used to extract signals. Then a part of the image is isolated, size10 х 10 pixels, for example, and cumulative indicator of brightness is calculated for each shot of the video recording. At the same time the signal is filtered and smoothed. In case the recording includes registration of brightness of each shot, we obtain a pulsogram allowing computation of the basic heart beat parameters.

This is the essence of the technique, which forms the basis for the software of the CardioReserve system.

System Operation Manual.

Required equipment:

  1.  PC of average efficiency;
  2. OS –Windows XP, Windows 7;
  3. Webcam Backlit
  4. Software VideoPuls.exe (supplied as archive PaketPulsVideoKontrol.).

  Preparation for measurement

Before commencement of measurement:

  1. Install the softwareVideoPuls.exe on the computer  (unpack the archive Paket PulsVideoKontrol.rar into your  file);
  2. . Check the operation of the camera – turn on the camera, close the lens index finger and turn on the backlight. On the screen you should see a red square (Fig. 1);

 

Fig. 1

  1. Close the camera operation-check program.
  2. Display the system clock data on the screen, and move the clock icon to the upper right corner of the screen.

Please, note: During measurement keep hands and the body still, do not change the strength of the finger pressing, no external disturbances allowed, breathe evenly, hands must be warm, body relaxed. Measurement time – 30 seconds.

 

Step-by-step actions in the course of measurement

  1. Start the program VideoPuls.exe, the master form must open. Relocate the form to the upper left corner of the screen (Fig.2) so that to be able to see the seconds hand on the system clock.

 

Fig. 2

 

  1. Before taking the first measurement click the button Identif and log in your data: pulse rate at rest and age. Press the SAVE button (Fig. 3) and close the REGISTR. Form.

 

 Fig. 3

 

  1. Turn on the backlight. Close the camera with his left hand, left elbow to keep on the table. Press the right-hand button on the main form of Camera, Camera Control form appears (Figure 4).;
  2. Press the OpenVidio button on the Camera form; after 1-3 seconds one big and three small red squares will appear on the form (Fig. 5).
  3. Decide the position of his hands so that you can see a big red box of medium brightness. High brightness and low light will not allow a measurement. Usually in this case, instead of pulsogram the screen will go straight. When you see the confirmation message select video sources – press OK.
  4. Note. Measurements can be taken anywhere on the body with enough blood supply.

Warning: Button pressing mustn’t be too quick, the recommended interval is 1 second; if faster, the video recording will be disrupted.

                                 Fig. 4                                               Fig. 5

 

  1. At the first start-up press the FormVideo button and install minimal resolution. Exit the FormVideo.
  1. Press the Exit button to close the Camera form.
  1. Press the Video button to start the measuring procedure. The sand-glass cursor will appear (Fig. 6). To get reliable data meet the above requirements during the measurement.
  1. Remember the readings of the seconds hand on the system clock. Measurement duration shall be about 30 seconds.

 

 

Fig.6

  1. Click twice the left key of the mouse. Sand-glass will disappear after 1-2 seconds. Put the cursor on the Finish button and click.
  2.  Upon automatic reset of the screen the measuring procedure is over and the screen will display the Pulstream (Fig. 7).

 

Fig.7

  1.  After the pulstream on the screen will appear calculation results, and under the control panel there will be three action buttons START, Check and Calc (Fig.8).

 

  Fig.8

 

  1. The START, Check and Calc buttons allow to repeat step-by-step the calculation and data display.

              Please, note: A new measurement can be started only upon closure of the program master form.

 

 

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