Monitoring
Connect the electrodes to the wires of the signal cable. Look at the color of the plastic tips located at the ends of the wires.
Note: Previously released devices were staffed with red and black wires.
Connect the wire with the red tip (or red wire) to the red electrode.
Connect the wire with the black tip (or black wire) to the black electrode. Secure the cable with the screw.
Note: First edition devices are partially staffed with yellow and green electrodes. In this case, the color of the electrodes is not important.
Connect the signal cable to the device.
Note: First edition devices were packaged with a non-detachable signal cable, which has always been connected to the device. Modern devices are equipped with replaceable signal cable with the LEMO socket, Swiss made.
Connect the device to the USB port. Do not use any USB hub. Only direct connection to a USB port on the computer is valid. We remind you that after launching the software you can disable the USB key and use a vacant USB port for connecting the device.
Note: The device has а green LED lamp оп the front panel, indicating the status of the device according to the table:
| Device mode | Description |
|---|---|
|
HR registration mode. The device registers heart rate data and transmits it to the РС.
Indication:the green LED is constantly. |
|
Device configuration mode. The device is waiting commands from the personal computer.
Indication: the green LED is flashing intermittently, duration of on and off periods is equal. |
|
USB configuration mode. The USB interface is self-configuring (device driver is installing). Device enters this mode usually once for the very first connection to the computer and leaves it automatically in а few seconds processing to mode #2. If the device enters this mode frequently and lasts for а long time means а problem with the USB рort, USB cable or the device itself.
Indication: the green LED is flashing regularly with noticeably longer pause between the flashes. |
Put the electrodes on the wrists of the client. The red electrode is put on the right hand, and the black one - on the left hand. Or focus on the color of the wire or plastic tip, depending on what set you have. In electrocardiography, this arrangement of electrodes is usually called the first lead.
To improve the signal, apply a special ECG gel to the metal electrode plates or simply moisten their wrists with water. Do not use distilled water - it is a poor conductor. Better to take regular tap water.
The best position of the client during assessment is lying on a couch. A sitting position in a comfortable chair is also acceptable. Make sure that nothing impedes the quality of contact of the electrodes and the skin surface. For example, if the wrist is too close to the body, the contact can be broken by the slight hand movement. We recommend placing small pads under the forearm so that the electrode does not contact anything: couch, chair arms, body, etc.
During the assessment, the client should avoid the actions likely to have an impact on heart rhythm, such as talking, sneezing, coughing, deep breathing, intentionally changing the respiratory rate via breathing techniques or otherwise, eating, chewing gum, swallowing, and heavy thinking. If any of the aforementioned occurs, stop the recording, delete it, and start a new assessment.
If the assessment is specifically aimed at investigating the effect of a particular factor, the guidelines may be modified accordingly.
Click on the New assessment icon in the main menu. The Monitoring Parameters window will open. You will be asked to select the duration of the recording: automatically or manually.
If you select the manual mode, the recording time is set manually. By default, the software suggests setting 5 minutes. And if the automatic mode is selected, the duration of the recording will be determined by the software during the recording process.
In this case, the number of RR-intervals, and not the time, will be used as the target value by the software. The reason for that lies with the mathematical apparatus used by the software for cardiointervalogram analysis, namely the spectral Fourier transform. To ensure high calculation accuracy, it is preferable that the number of RR-intervals is a power of two, i.e. it belongs to the series 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024 etc. It is also essential that the studied wavelength fits within this number of intervals. So, for instance, while 128 intervals are enough for the HF-range calculations, the LF-range and VLF-range would require 256 and 512 intervals respectively. The issue here is that a standard 5-minute recording doesn’t include enough RR-intervals, which results in a calculation error.
When the user prioritizes the correctness of the results, we recommend the automatic setting for the recording duration. However, keep in mind that the recording duration will then be over five minutes. For example, the recording duration at the average heart rate of 60 bpm will be about nine minutes, and at 80 bpm about 6.4 minutes.
After setting the duration of the recording, click on the Continue button to open the ECG signal registration window.
Pay close attention to the ECG signal on the monitor screen for a while. Make sure that the signal quality is good. If the signal is weak, check if you applied enough gel or water.
If the signal contains a lot of disturbance, then disconnect the laptop power cord and switch to battery power. Do not proceed to the next step until a good signal quality is achieved.
If the signal remains weak and contains a lot of disturbance, use the second lead: the red electrode is placed on the wrist of the right hand, and the black one is on the ankle of the left leg.
Working electrical appliances, poor electrical wiring, power cables proximity or a computer with a low noise control might cause electrostatic field to appear, leading to disturbance. Dry air, synthetic or woolen clothing worn either by a specialist or a client, creates an electrostatic field which can also become a source of interference.
Normally, the second lead can increase the signal by 2–3 times. Combined with battery power supply, it allows conducting a high-quality assessment even with a very high level of interference.
The software has two signal recognition modes: automatic and manual. The automatic mode is selected by default. Usually, a few seconds after the signal registration starts, the software automatically adjusts and begins to detect R-waves. In this case, a heart-shaped icon will appear on each peak of the R-wave. Keep track of this process for a few seconds. Make sure the R-waves are recognized correctly. There should be no missing R-waves, and heart icons should not appear on other waves – P or T.
If there are no errors in the recognition of R-waves within 10-15 seconds, then proceed to the recording by clicking on the Start Recording button.
If it was not possible to achieve high-quality recognition of R-waves in the automatic mode, then switch to the manual mode. The mode switch is in the upper right corner of the signal registration window.
By switching to the manual mode, you need to adjust the Threshold value. It is the topmost window in the settings located on the right side of the screen. On the ECG graph along the ordinate, determine the amplitude of the R-wave and roughly divide it by two. Enter the resulting number in the Threshold field. Watch how the software recognizes R-waves. A heart icon should appear on each R-wave.
If the heart icon skips individual R-waves, then you need to decrease the threshold value.
If the heart icon appears on other waves, except for R, then the threshold value should be increased.
The amplitude of the R-wave is determined by individual electrophysiological parameters of a client. If the threshold value has to be lowered below 25 mkV in order to achieve the R-waves detection, then it is time to use the second lead, since this indicates a low signal level, and the risk of artifacts increases. But of course, the main reason for deciding whether to switch to the second lead is the fact whether it is possible or not to adjust the voltage threshold to achieve a stable recognition of R-waves. If, in spite of all the efforts, artifacts appear, then you need to proceed to the second lead. Increasing the useful signal is often easier than dealing with the noise which can cause artifacts. The most important thing to remember is that there is no need to completely eliminate the noise, but it is crucial that this noise does not block the useful signal and does not interfere with the stable recognition of R-waves.
Note: Take your time. Adjust quietly, so as not to affect the emotional state of the client. Before starting recording, the client has to give a few minutes to sit quietly to calm down the heartbeat. But if the specialist hastes and is nervous in preparation for the beginning of the assessment, then his mood can be transmitted to the client. It is important for the specialist to act confidently and calmly to minimize the impact on the client. But don't fall in to another extreme - no need to enable slow meditative music to immerse the client in relaxation artificially. The music has a great influence on people and can considerably change the normal functional state. If the task is to estimate the normal functional state, then eliminate all the factors that can change it. The best time for assessment is the first half of the day, it is undesirable for the client to experience a severe famine. It is also important that the client the day before the survey did not take alcoholic drinks, did not feel any strong emotional and physical exhaustion in the previous days. But if the client has violated any of these terms of preparation for the assessment, but did come, it makes sense to conduct a survey and repeat it in future to be able to compare the results of the assessment in the normal state and under the influence of the corresponding stress factor. This will give additional information to assess the impact of the lifestyle that leads the client, its functional state.
After achieving quality settings of R-wave, you can save the settings by clicking on the button Save settings. Thereby you will simplify configuration when the survey is conducted in this client next time. After saving settings, you can go to the assessment's record.
After adjusting the signal, click on the Start recording button. Then at the bottom of the screen will turn on a timer that displays the recording duration.
Pay attention that below the ECG graph there is a Cardiointervalogram graph, which shows in real-time mode changing of the cardiac cycle's duration.
Observing this graph, a specialist in the process of recording can assess the stationarity of the recording, that is, to assess how stable the functional status of the client is. The monitoring of the recording allows to stop the assessment to eliminate the cause of changes in the functional state of the client. Also, on the graph one can dynamically track the result of any impact on the client. Use this in the case when the purpose of the assessment is not an estimation of the functional condition of the client, but the evaluation of the degree of influencing factor. But remember that if you operate on the client during the recording and change its functional state, these entries will be suitable mainly for visual assessment of the dynamics of cardiointervalogram, but not for automatic HRV-analysis by the software. Because the algorithms of HRV-analysis work only on stationary records, when the client does not change the functional state during the test.
Note: To delete the record, use the command Assessments – Delete assessment.