Assessing Endothelial Vasodilator Function with the Endo-PAT 2000

Endothelial Vasodilator function is an independent predictor of cardiovascular morbidity and mortality. The endo pat methodology is a simple way to assess the effects of drugs and nutrition on endothelial function. Today we're gonna show you how to use the end methodology in an office-based setting.

Prior to beginning the study, the patient needs to fast for at least four hours and also abstain from caffeine, tobacco, vitamins, or any medications that may affect vascular tone. During the study for at least eight hours, the patient should wear loose fitting clothes and be free of jewelry on the upper extremities. With respect to location, the study should be conducted in a quiet, dimly lit temperature controlled exam room.

Apply a blood pressure cuff to the arm and allow the arm to be supported at the patient's side to allow the patient to reach cardiovascular steady state. They should be relaxed and comfortable in the supine position for at least 15 minutes. Measure the blood pressure in the arm that is not occluded.

During the endo pat study, move the cuff to the non-dominant arm, which will be occluded. It is important to know the blood pressure so that the cuff on the other arm can be inflated to a super systolic pressure during the arterial occlusion phase of the study. To prepare the endo PAT system for acquiring data, open the Endo PAT 2000 software and click on the icon labeled patient information.

In order to create a new patient file, complete the patient information dialogue box by including the patient ID age, gender height, weight, and blood pressure. Entering the patient's name is optional if needed, there is an area to text comments. Next, select two new PAT probes and connect them to the Pneumo electrical tubing by inserting the connector tab into the probe until it clicks.

Finally, insert the probes into the sockets of the arm supports and press the deflate button on the top of the Endo PAT 2000 device. The system is now ready for experimentation, ensuring that it is free from cuts and injury. Select a finger, preferably the index finger for placement of the endo pad probe.

Make sure the fingernail is appropriately trimmed prior to beginning the experiment. Ensure that the study finger is put all the way into the back of the probe. The patient should indicate that they can feel the back of the probe with the tip of their finger.

After about five seconds, push the inflate button on the top of the endo Pat 2000 device. Next, attach a foam anchor ring at the base of the middle finger to its very end, and make sure that the foam ring and the pat probe do not touch. Otherwise, the ring may mechanically interfere with the probe.

Create a seven to 10 centimeter loop with the Pneumo electrical tubing. This loop should extend from the pat probe and return to the foam ring on the adjacent finger and the rest of the tubing pointing out from the middle finger. Then anchor the tubing to the foam ring with the attached clip and gently tape the tubing to the tip of the finger.

Position the patient's arms so that the forearms are supported on the arm supports and the fingers can dangle freely. Make sure the probes are not in contact with any objects, including the arm support foam ring, tubing, the mattress, or any other finger. The pressure cuff will be inflated for five minutes during which time you might experience a slight numbness of the hand.

You can relax and please don't move your fingers. Thank you. Click the standby icon on the Endo Pats computer screen and adjust the time base to one minute.

Next, adjust the signal gain on the screen to maximize signal clarity and inspect the Pats signals from the two probes. Confirm that there are no signal artifacts. If any artifact is present, verify that the probes are not touching anything and that the patient is not moving their fingers.

To begin the trial, click the go icon on the endo Pats computer screen. Start the stopwatch by clicking the start stop timer icon. This will initiate a five minute countdown for the baseline recording period.

After five minutes, stop the stopwatch by clicking the same timer icon. We are going to inflate the cuff for the ocion phase, please. You should stay relaxed and please don't move your fingers.

Okay, thank you. Restart the stopwatch. Then quickly inflate the cuff pressure to 60 millimeters of mercury above the patient's systolic pressure or 200 millimeters of mercury, whichever is higher.

Next, change the time base on the screen to 30 seconds and the gain of the occluded side to 10, 000 and verify that the blood flow to the hand has stopped in this arm by checking for an absence of a pat signal, confirm the occlusion By increasing the gain at the occluded side to 500, the gain from the other arm should not need to be changed. This modification checks for signals at a periodo that matches the signal from the control arm, a pattern indicative of incomplete occlusion. If this is the case, then inflate the cuff further until no signals can be seen, or up to a maximum cuff inflation of 300 millimeters of mercury using the stopwatch function of the software.

Initiate a five minute countdown for the arterial occlusion recording period. Toward the end of five minutes, remind the patient that they should not move their fingers and the cuff will release shortly after exactly five minutes. Deflate the cuff as quickly as possible and click the timer icon to stop the timer.

Click the start stop timer icon again. To initiate a five minute post occlusion recording period, stop the timer after five minutes and click the test stop icon to complete the study. At the end of the study, remove the probes tape and rings from the patient's fingers.

Disconnect the path probes from the Pneumo electrical tubing and discard these probes. To review the data, load the study file to the screen using the load icon To run the automatic analysis, click the magician stick icon. The occlusion period will be marked in blue and the test result will be displayed including the reactive hyperemia index and heart rate in the right hand column of the screen.

If the boundaries of the occlusion are not marked properly, simply move the boundaries by dragging them and rerun the automatic analysis. Again, to review additional data including study parameters, calculated variables, patient information and measures of signal quality, click the open results of last calculation icon. This will open a spreadsheet with study parameters and results for all analyses performed to date with the last line in the table.

Containing data from the most recent analysis here is a representative recording of an individual with normal endothelial vasodilator function, which is characterized by an increase in the signal amplitude after cuff release relative to baseline. This recording is characteristic of an individual with endothelial vasodilator dysfunction. Specifically, the increase in the pulse amplitude with reactive hyperemia is less than normal.

The endo pat is a rapid and operator independent approach to assessing the effects of cardiovascular risk factors on endothelial vasodilator function, and the beneficial effects of drug therapy. After watching this video, you should have a good understanding of how to use the endo methodology to assess endothelial vasodilator function.