Liquid Meal Test
What is a liquid meal challenge?
A non-invasive diagnostic procedure used to examine the effects of food on blood pressure (BP), heart rate (HR) and / or symptoms.
A liquid meal is used as the effects on BP and HR can be observed after a 45 minute period. Solid foods can take a lot longer to digest (up to 7 hours). There are two options for the liquid meal:
- complan (original flavour) + glucose + milk
- glucose + water
Most patients will have option 1 during the test. However, please notify a member of the testing team if you are lactose intolerant and option 2 will be used. We are unable to substitute the milk for soya / almond or other milk substitutes as the complan contains powdered semi skimmed milk. If you have diabetes, the glucose can either be reduced or omitted from the meal option 1. Both meal options are suitable for vegetarians and are gluten free.
At your appointment, you will be asked to lie flat on an examination couch for 10 minutes or until a baseline of your BP and HR are established. You will then have a tilt table test. You will be asked to rest again prior to ingestion of a liquid meal. Once a baseline has been re-established, you will drink the liquid meal whilst lying flat and then rest for 45 minutes. During the 45 minute rest period, your BP and HR will be monitored continuously. You will need to rest during this time and will not be allowed to read or listen to music. After 45 minutes, you will have another tilt test to see if there have been any changes to BP and / or HR following the meal.
How do I prepare for the test?
Please do not eat for 4 hours prior to testing. You may drink water only in the lead up to the test. Please do not drink alcohol & do not carry out heavy exercise 12 hours prior to your appointment.
Please wear loose fitting clothing on the day of your appointment. We recommend a loose fitting T-shirt and loose fitting trousers or shorts.
What equipment will be used during the test?
For the test, you lie down on an examination couch. A Clinical Autonomic Scientist will do the following to prepare you for the test:
Electrodes will be placed on your chest, legs and arms. The electrodes are connected by wires to an electrocardiogram (ECG) machine that monitors your heart rate during testing.
A mini finger cuff will be attached to one of your finger and a larger blood cuff is fitted to the upper part of the same arm to continuously measure the beat to beat changes in your blood pressure during testing.
A disposable blood pressure cuffs fitted one of your arms (usually the right arm) to do periodic checks of your blood pressure during testing.
How will I feel during the test?
You may experience symptoms of Orthostatic Intolerance (OI), pre-syncope or syncope during the tilt. Typical symptoms include, but are not limited to; dizziness, palpitations, nausea, blurred vision and / or episodes of syncope. You are able to terminate the tilt test at any time by informing the Clinical Autonomic Scientist (CAS) performing the test. The tilt test may be terminated early by the CAS if they observe any marked falls in BP and / or HR that could be suggestive of imminent syncope. If you do have an episode that results in loss of consciousness, the CAS will return you to either a horizontal position or head down position. You will be monitored until fully recovered. Full recovery of symptoms is usually instantaneous upon returning to a horizontal position. Continuous monitoring of BP and HR will occur until resting levels have stabilised.
What are the risks?
The exercise test is generally safe, and complications are rare. But, as with any medical procedure, it does carry some risks. All patients will be asked to fill out a pre-assessment questionnaire, which will further assess an individual’s risk factors. If any known risk factors are highlighted, the test will be modified to minimise the risk.
There is a very small risk of an allergic reaction to the meal. Please inform the staff of any known allergies. The complan is suitable vegetarians and is gluten free. The liquid meal does not contain any traces of nuts but please be aware that the meal is prepared in an area where other nut products might be handled. Please inform the staff member of any nut allergies.
What happens if I have questions?
If you have any questions or concerns, please ask the clinical autonomic scientist before signing the consent form for the procedure. If you are not happy to proceed with the test, please inform a member of the testing team. Even after signing the consent form, you may withdraw your consent at any time during the test.
When will I get my results from the test?
We are unable to provide results of the test on the day of your appointment. All results will be sent to Professor Mathias. You will need to arrange a follow up appointment with Professor Mathias to discuss the results of the test(s). Please email email@example.com to arrange the appointment.