The overall goal of this non-invasive, tonometry-based procedure is to collect good quality carotid to femoral pulse wave velocity data from human patients. Carotid to femoral pulse wave velocity and pulse wave data is collected using a non-invasive evaluation. A standard protocol is crucial to obtain an accurate value, especially when there are multiple operators.
The implications of this technique extend towards the therapy and diagnosis because pulse wave velocity values increased with arterial stiffening. Though this method can provide insight into arterial stiffness, it can also be applied to other cardiovascular phenotypes, such as central blood pressure. Visual demonstration of this method is critical.
The wave recording steps are difficult to learn because the tonometer must be correctly positioned over the artery fluctuation point. Make sure to practice this method before using it. The participant's cooperation is crucial, so explain the procedure well before gaining their consent.
Conduct this procedure in a quiet room with a stable ambient temperature. Start with measuring the height and weight of the participant. Next, have the participant lie supine with their hands next to their body.
Then, connect the three ECG leads to smooth, dry skin for an undisturbed ECG signal. Position the three electrodes according to the diagram. If, during the procedure, the patient's skin gets damp with sweat, wipe the skin dry.
Have the patient rest for at least five minutes, and then measure the patient's blood pressure with a semiautomatic oscillometric device. Peripheral vascular dilation caused by artery occlusion when measuring brachial artery blood pressure will change the brachial artery pulse transmission. Resting is essential to avoid excessive deviation.
Next, have the patient rest two minutes or longer, staying supine. Meanwhile, update the measurement device with the patient's information. Then, manually measure the distance from the SSN to the remote detection point.
Next, determine the distance from the SSN to the proximal detection point, and then measure the distance between the two detection points. At the computer, select the PWA mode. Then, enter a value, ideally zero, for the SSN-carotid distance.
Then, for the SSN-femoral distance, enter 0.8 times the carotid-to-femoral distance plus the SSN-carotid distance value. Now, start capturing data. Next, to measure the central blood pressure, put the tonometer on the radial artery fluctuation point, one to two centimeters above the radial styloid process.
This is where fluctuations are often most strong and stable. Now, keep a stable grip on the tonometer, so it stays perpendicular to the skin. Once the quality and reproducibility of the tonometry measurements reach the standard, the signal recording will automatically stop.
Next, at the computer, change the mode to PWV. Then, collect data with the tonometer, as before. After recording a stable waveform for 15 to 20 seconds, manually stop the recording.
Measurements taken with the described method were compared to brachial-ankle PWV measurements collected using the conventional approach. Data was collected from 2, 098 participants. Both data sets were subjected to the same logistic regression model, with age and gender adjusted.
The result shows that carotid-femoral PWV data was significantly associated with increased carotid intima-media thickness and arterial plaque, but the brachial-ankle PWV data was not. This supports the improvement of the described method over the conventional method. After watching this video, you should have a good understanding of how to obtain a standard PWV value to evaluate arterial stiffness.
Once mastered, this technique can be done in 15 minutes if it is performed properly. While attempting this procedure, it's important to remember to make sure the participants meet the inclusion and exclusion criteria.
