The overall goal of this procedure is to assess arterial stiffness through the use of pulse wave velocity measurements. This is accomplished by first measuring the patient's central blood pressure by pulse wave analysis In the second step, three, ECG electrodes and leads are attached to the patients in a modified lead to configuration. Next carotid pulse wave forms and e femoral wave forms are acquired using a tonometer.
Finally, custom designed computer software analyzes the speed with which the pressure waves travel through the aorta. Ultimately, the speed with which a pressure wave travels through the aorta can be used to demonstrate the degree of arterial stiffening. Though this method can provide insight into cardiovascular disease, it can also be applied to other areas of study such as cognitive disorders, renal disease, diabetes, and arthritis.
After opening the software, click patient to activate the patient's screen. Then to enter a new patient into the database, click the new button in the patient search area, and click yes to confirm the new patient information will be entered. Next, enter the patient details such as last name, first name, date of birth, and gender.
Then click save. Now measure the distance from the manubrium to the radial artery, the umbilicus to the femoral artery, and then the and hip circumference, and record these values for entry. Now select the pulse wave analysis or pulse wave velocity button to begin measuring these parameters.
If the pulse wave analysis mode was chosen, click study to enter the patient's brachial pressure as taken from a calibrated Figma manometer, and any other details pertinent to the study. Then click capture data to proceed with a measurement. Next, attach the three ECG electrodes and leads to the patient in a modified lead two configuration.
Now palpate the patient's radial artery located lateral two and immediately above the wrist joint near the base of the thumb by using the middle and index fingers. To gently press the artery against the underlying bone, place the tonometer over the strongest pulse point, and then gently press the instrument down until a consistent pressure waveform is displayed on the data capture screen To manually save the measurement for analysis, step on the foot switch. If a repeat measurement is required with the same study parameters, click repeat to return to the capture data screen.
To perform a measurements on a new patient, click on the patient button and confirm that a new patient will be entered into the system. If the pulse wave velocity mode was chosen, click study and then enter the brachial pressure as taken from a calibrated figma manometer. Next, enter the distance measured for the distal S super sternal notch to femoral pulse and the proximal super sternal notch to carotid pulse sites.
Fill in the medication notes and operator fields as desired at this time as well. Then click capture to proceed with the measurement, ensure the ECG signal is of acceptable quality, and then palpate the carotid artery pulse located between the larynx and the sternal cidal mastoid muscle on the neck by pushing the muscle to one side and pressing the artery against the larynx. Next, place the tonometer on the carotid artery gently pressing the instrument down until a consistent pressure waveform is displayed on the data capture screen.
When a minimum of 13 seconds of consistent waveforms has been observed, press on the foot switch and then palpate the femoral artery pulse located over the ventral thigh. Halfway between the pubic synthesis and the anterior superior iliac spine. Now place the tonometer on the femoral artery, gently pressing the instrument down until a consistent pressure waveform is displayed on the capture screen.
When a minimum of 13 seconds of consistent waveforms has been observed, press on the foot switch. Now place the tonometer on the radial artery, again located lateral to and immediately above the wrist joint near the base of the thumb by using the middle and index fingers to gently press the artery against the underlying bone. The report can now be reviewed in the monitor automatically.
To perform a measurement on a new patient, click the study button and repeat the procedure or use the search feature to search for an existing patient. The software automatically saves all the reports to close the software, click on system from the main menu, and then click exit. Clean the probe with an alcohol swab, and then place the tonometer in the module tray for storage.
Pulse wave velocity results are produced in meters per second and healthy subjects. These speeds can range from an average of 6.2 meters per second at subjects under 30 to 10.9 meters per second in subject 70 and older. When performing the exam, the standard deviation must be under 10%in order for the results to be considered accurate.
Here, waveforms from carotid and femoral arterial sites are displayed. The foot of each waveform and corresponding R wave are marked with a dot, and then used to calculate the time delay and the mean pulse wave velocity calculations For the waveforms. In this example, the pulse wave velocity is 6.0 plus or minus 0.3 meters per second with a standard deviation of 4%representing a fairly consistent reading.
Here, the captured radial waveforms are displayed as well as the computer generated ascending aortic pressure tracing. The central clinical parameters derived from this wave are displayed here and the accuracy of the waveform is displayed in the operator index. An operator index of 100 is desired, however, anything greater than 75 is acceptable.
Once mastered, this technique can be completed in 40 minutes if performed properly.
