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English Captions by Zero Mella MD
Produced by Zero Mella MD
Have you ever had an instance when the nurse or medical clerk left the BP cuff inflated
and told you that it was a "test for Dengue" and they left you for a good amount of time
or until you told them that it was starting to hurt or your hands are going numb?
Well that's a Tourniquet Test and I'll show you why and how it's properly done.
[INTRO Reel]
Starring Zero Mella
Marcus Zachary Mella
Special Thanks to Afable Medical Center
Special Thanks to Olongapo City Health Department
Well, we are now in the fourth episode of the Zero MD show and I'm glad to announce I have a new co-host.
Well, Marcus, why don't you say Hi!
Well if you might remember from my first episode, I was just talking about naming my first child Marcus.
Well, here he is!
My bundle of joy was born October 14, 2013 and as promised on my show, I named him Marcus.
I was so proud of him that I already gave him a YouTube debut only after a few days.
OK, So now let's go to the "Tourniquet Test"
Now, before we start this show, I want to clear up a few things.
The official pronounciation is toor-nee-kay
Doctor's keep correcting each other but the alternative pronounciation toor-nee-ket is also valid
toor-nee-ket is used in the US
toor-nee-key everywhere else, OK?
So during this show, I'll be using toor-nee-kay
So now, let's discuss why we do the Tourniquet Test
Dengue is a common disease in a tropical island like the Philippines.
It used to be seasonal with the peak at June, which is why the Department of Health of the Philippines
calls June the Dengue Awareness Month.
However, 2 years ago, the DOH announced that Dengue is now a whole-year phenomenon around the country.
There are of course areas, like Bataan, with really low prevalence rates.
We don't know why yet but for most urbanized cities like Manila and Olongapo,
Dengue is diagnosed left and right.
Dengue is diagnosed clinically and one of the procedures done is the Tourniquet Test.
The Tourniquet test is a test done to check the fragility of the circulatory system.
In Dengue, the virus is not the one responsible for much of the symptoms we see in this disease.
It's actually the antibodies formed to attack this Dengue virus
that is responsible for much of what we see in Dengue.
The antibodies are produced by the patient's immune system in response to the Dengue infection.
They are designed to attack the virus.
However, much of the design mimics a receptor found in the body's capillary system. [Simplified, see disclaimer on the description]
Imagine that your capillaries are small rubber tubes with holes.
The holes are actually controlled by switches or receptors found in the capillaries. [Simplified, see disclaimer on the description]
The body maintains a certain number of holes to be open at a certain period of time
to maintain pressure and prevent cells and fluid in the blood to go out of the circulatory system.
What happens in Dengue is that antibodies unnecessarily turn all the switches open or in the open position
so that blood products do go out of the circulatory system.
And this is responsible for most of the symptoms of Dengue.
A test devised years ago was the capillary fragility test or the Tourniquet Test or the Rumpel-Leedee test.
The problem in the early phases of Dengue is that not all of the switches are in the OPEN position so there is not much symptoms in the start of the disease.
But if you force pressure in a certain capillary for example like milking it or adding pressure to it,
you can find that the holes open easily hence the term "capillary fragility."
Applying a tourniquet to the upper arm doesn't actually stop blood flow to the rest of the arm UNLESS you apply pressure enough in the tourniquet to obstruct the brachial artery.
What a tourniquet does (in this test) instead is to decrease the flow of blood returning to the heart.
You can use any tourniquet.
You can use a rubber tourniquet, an elastic bandage or even a piece of clothing.
In standardized versions of the Tourniquet test though, we use a blood pressure apparatus or a sphygmomanometer.
Well, the word sphygmomanometer is a frequent spelling bee clincher
and when you ask elementary students what it is, they usually have no idea or they have difficulty pronouncing it.
I mean try saying it (fast) five times. Sphygmomanometer, sphygmomanometer, sphygmomanometer, sphygmomanometer, sphygmomanometer
This is why people keep referring to it as a BP app or BP apparatus.
The first step is to actually take the BP of the patient.
You then add the systolic blood pressure measurement to the diastolic blood pressure value then divide by 2 to get the mean.
Now this is when Internal Medicine consultants would then terrorize medical clerks or fourth year medical students to answer the inevitable question:
WHY? Why get the mean?
Clerks will then come up with some ridiculous explanations
and some would reason that this is a standard arbitrary point made by the original study researchers Dr Rumpel and Dr Leedee.
Why they chose that point would be beyond understanding?
Actually, no.
Keeping the pressure in that point meant that the arteries are guaranteed to be open but the veins closed.
This means that blood is going to the hand but it is not coming back to the heart for the duration of the test.
The pressure increases venous capacitance.
If the pressure is enough and there are some Dengue antibodies in the capillaries 0:06:29.000,0:06:35.000maintaining some of the holes to be opened, blood will come out in the form of tiny red dots or petechiae.
The test is done for only 5 minutes and the tourniquet or bp cuff is removed.
I repeat, 5 minutes only.
After that time period, the patient starts to feel pain which increases in intensity as time flies.
How'd I know?
I once had a senior resident who made me do it in a dengue suspect patient for 30 minutes.
Oh it was a positive result as we had a lot of petechiae and the resident was happy to report to his colleagues that he was really good at Tourniquet tests.
But the patient was not a very happy Dengue patient afterwards and directed all his resentment towards me.
So much for following orders.
A positive test is getting 10 petechiae in a coin-sized circle area of about 2.5 cm in diameter.
I use a marker or ballpen and encircle an area in the antecubital crease near the bp cuff.
Original researchers of the method did this to create a standard area for measuring. WHY?
Because as a physician you want to remove bias in all your test and create standards to increase test quality.
Unfortunately, following proper guidelines in doing the tourniquet test has resulted in a poor sensitivity
or poor positivity rate of 30% in actual Dengue patients.
Most physicians have largely abandoned this test in favor of new rapid diagnostic techniques
that have greater sensitivity in diagnosing Dengue.
But the Tourniquet test is an important tool in low-resource setting, like in rural areas who have poor access to medical facilities.
Also, it is for patients who cannot afford the new tests.
Remember if there are signs and symptoms, a negative Tourniquet test does not mean the patient does not have Dengue.
However, a positive test does confirm positive capillary fragility and supports a probable Dengue infection.
The patient has to be treated accordingly.
And now, for some news...
Last week I, along with everybody in the Olongapo City Health Office
We took part in a coastal clean up, to clean up part of the Subic Bay beach
in the Parola area in Kalaklan
Here's a clip...
Also, this weekend, I posted a little sketch
about an Englis-Tagalog translation joke
You can watch the video here
And lastly, if you do have Twitter, follow me at twitter.com
My Twitter handler is @zeroMD
And like me on facebook at facebook.com/zeromella
And also follow me on my blog zeromd.wordpress.com
And my other blog public health resources.blogspot.com
If you like this video and if you like arequest for a diagnostic test be demystified, do so in the comments section below.
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