EP 101: Tilt Table Testing
- Posted on: 5/3/08
- 0 Comments
- 7415 reads
The purpose of this article is to provide a simple educational overview for staff members about tilt table testing. Although the specifics of this test can vary from place to place, there are fundamental basics that should be understood. Therefore, our goal is to give a brief outline of what to grasp when performing this test. With the help of the Providence Heart Institute s EP lab team and director Dr. Christian Machado, we will cover the how to of tilting.
What is a tilt table test?
A tilt table test is performed for the study and evaluation of syncope. For patients who have had episodes where they have unexplainably passsed out or lost consciousness, felt nauseated or dizzy, experienced vertigo or lightheadedness, or even blacked out, this test will attempt to understand why. Patients are tilted in an upright position on a table to assess their tolerance to this stress. Documenting blood pressure, level of consciousness, and heart rate consistently throughout the test are very important tools for a full assessment. The time and angle the patient is tilted varies from institution to institution. Medication may also be used, depending on the institution s conception of tilting. It is important to note that the tilt table test is not the only test that should be considered in understanding syncopal episodes.
What can the test show?
This test is designed to see if the physiological systems in your body are working properly. The trigger for patients that causes their episodes may usually be typical and follow a pattern. This includes many activities or anything that causes stress, heat, hunger, or dehydration. Autonomic dysfunction (dysautonomia) and vasovagal syncope have many different ways of revealing themselves.
Neurocardiogenic syncope pertains to the brain, heart and blood flow. If there is not adequate communication between these systems, patients may become symptomatic, which could reveal important information and discovery for understanding what happened during their syncopal episode. At a tilted position, the blood in the body may pool to the extremities (the patient may feel tingling or funny in their arms and legs), and it is the responsibility of the brain to recognize this and tell the heart to work harder. There has to be compensation by the brain and heart to avoid a positive tilt table test for neurocardiogenic syncope. The blood flow has to keep moving and this mechanism needs to respond appropriately. If this is not the case, there will be definite signs and evidence in the patient s intolerance to the test as well as visible changes in their vital signs.
Postural Orthostatic Tachycardia Syndrome (POTS) also deals with a physiologic inability to respond in the standing position. In POTS, you will see a significant increase in a patient s heart rate (greater than or equal to 30 beats per minute [bpm]) within the first 10 minutes of being tilted. So, for example, the patient may have a heart rate of 65 bpm in the supine position, but this could jump to 103 bpm as soon as they are tilted to an upright position. During POTS, the heart rate will remain elevated throughout the duration of the test. Although the patient may not pass out with this jump in their heart rate, they still may become symptomatic. In this case, a physician may recommend treatment for POTS.
How do you do the test?
Patients are secured to a tilting table and IV access is obtained. Vital signs including heart rate and blood pressure should be recorded every two minutes in the supine position for a period of 10 minutes to get a good insight on baseline values before tilting. Once this is completed, the patient can be tilted up and monitored accordingly. Depending on physician or institution preference, the duration and angulation of the table s position will vary along with Spo2 monitoring or arterial access during the test. What is relevant during this test is to monitor and document the patient s mental and physical tolerance to the test. It is important to put the patient at ease by explaining the process of the test and what the significance is in doing a tilt table evaluation. Don t feel like a nuisance by asking the patient How are you feeling? over and over throughout the tilt. This information can give great insight as to what may be coming up for the patient, as there could be an onset of symptoms before the syncopal/near-syncopal event. Document blood pressure levels at least every two minutes and pulse values when the patient is tilted. It is also necessary to verify with evidence any significant changes in these values. The blood pressure and heart rate may change minimally throughout this test, but if there are drastic fluctuations in these values, they must be confirmed and recorded. If the patient tolerates the tilt table test without any symptoms, that s great news. However, if the patient starts to become symptomatic for syncope, don t panic.
How long should the patient be tilted?
That depends. Different institutions follow different guidelines for tilt table testing. At Providence (years ago), we used to tilt for 20 minutes at 70 degrees, bring the patient back down, and than 20 minutes again at 70 degrees with Isuprel administration via the intravenous line. For the past few years, we have not used this protocol. Instead, the patient is tilted for 30 minutes at 80 degrees. There is no Isuprel or any kind of medication administered during our tilts. We feel it is sufficient enough to have the patient tilted for 30 minutes. Therefore, the entire test should take no longer than one hour, including pre- and post-test education.
What to do if the test is positive?
Relax syncopal or near-syncopal episodes can happen during a tilt table test. Make sure that once the patient becomes symptomatic that you record a strip of EKG and blood pressures providing evidence and comparison as to what is actually going on in the patient. There are also many things that you may see. The patient may become diaphoretic (sweaty) and express discomfort with the test. The patient could complain of lightheadedness and/or pass out. The patient may also develop severe hypotension, bradycardia, or even asystole. As soon as confirmation is obtained with those significant fluctuations mentioned above while upright, the patient should be tilted to a Trendelenburg position (supine position). Why? Because the Trendelenburg position will increase venous return. It goes back to the blood needs to be moving idea discussed earlier. The fact that the ventricle is empty creating that vagal response, the Trendelenburg position will aid in alleviating symptoms. In addition, 0.9 NaCl should be opened as fluids are a good minimally invasive asset to reverse a syncopal event. In extreme circumstances of asystole, transient CPR may be required with the use of atropine.
What can be expected if the patient has a pacemaker and becomes symptomatic?
a) A cardioinhibitory response: The pulse will drop and the pacemaker will kick in.
b) A vasodepressor response: The patient will experience hypotension without pacing.
c) A mixed response: The patient will experience a combination of both a & b: low blood pressure with a change to bradycardia, meaning that there will be pacing.
Have you had any unusual results from a test?
There have been many unique cases here at Providence. We do have our straightforward and uneventful tests, but there have also been many interesting tilts. In one case, a patient went into asystole for almost 10 seconds; we moved the patient back into the Trendelenburg position, and the patient woke up unaware of what had just happened. In addition, we have had patients pass out right at the 30-minute mark, moments before the test is completed. There are also always incidents where a patient complains of symptoms and intolerance to being tilted. This is followed by verbalizing fear, anxiety or headaches with absolutely no significant changes in the patient s vital signs. In these circumstances, the physician may speak to the referring doctor and order alternative evaluations. A patient should only be tilted as long as they feel they can maintain themselves in this compromising position. Regardless of the evidence (or lack of), we must give them the benefit of doubt and tilt them back down so they can begin to recover at will.
What do I tell the patient after the test is completed?
Once the patient s symptoms have alleviated, bring them back to the supine position and get some readings of their pressures and heart rate. As soon as it can be confirmed that they are stable, let them sit up. If there are no other scheduled tests following the tilt evaluation, give the patient some water, maybe even some crackers. They should have been NPO for hours before the test, so hydration may help and they ll appreciate it. Have a physician speak to the patient. It is at this time that the results can be studied and analyzed, and the physician can make his decisions for treatment if the test is positive, or recommend other exams if the test is negative.
A tilt table test can make many patients feel nervous. That is why patient education pre- and post-test will help make their experience more pleasant, regardless of the results.
Acknowledgements: This article was written under the guidance of Christian Machado, MD, and the EP staff at Providence Heart Institute: Jack Cain, Manager, John Owings, RN, Jessica Ottino, RN, and Kathy Bell, CVT.