Anyone heard of Diastolic BP being higher than Systolic???

motion+e · Feb 25, 2010

LOL...it could if each contraction of the heart gained more momentum...raising the systolic rate each time...and the diastolic to follow...and then "boom"...no more cousin.

diane227, LPN, RN · Feb 25, 2010

Your cousin is incorrect.

allnurses Guide · Feb 25, 2010

That depends on what you are asking...do I believe that your cousin's reading was correct?...no. Is it possible that the diastolic could be higher than the systolic that supplied it?...yes...and this temporary backward spike may be more common than what we realize. First you have to understand fluid dynamics...that is that fluids can not or nearly can not be compressed...when I say nearly...it takes a great amount of pressure to compress a fluid the tiniest bit...more pressure than we would ever see in the human body...so we will just stick with it being non-compressible in the medical field.
The fact that a diastolic reading indicates a pressure at all is saying that there is a "holding" pressure and this holding pressure could increase if something were to exert a force on it...like the constriction of a vessel...we would not visually be able to see the constriction at this precise moment for it can not compress the blood but yet there is energy being exerted onto the blood supply via the vessel...thus causing an increase in pressure...which in turn could raise above the previous systolic pressure until the valves of the heart open...allowing the vessel to constrict...which we could now see visually etc.
So this actually brings me to another side of this topic...the fact that we are taught that resistance is what causes BP...this is ludicrous...the vascular system is a closed system...meaning that pressure will be equal throughout the body...resistance can cause a back pressure in an open system...but a closed system...nada. Certainly there is resistance...adhesion of molecules...etc...but this is not enough to regulate pressure...it deals more with flow rate than it does actual pressure. Energy exerted on spacial volume change is what would increase or decrease pressure...meaning that adrenaline and noradrenaline regulate pressure for the most part by constricting and dilating vessel diameters. If it were resistance that determined pressure, we would see irregular pressures and flow rates through the entire body...meaning a drop in pressure when the diameter of a vessel goes from small to larger...etc...blood flow return would be erratic in volume and pressure...it just is not feasible...so quit using the term resistance for BP...it is simple principles of displacement. :)

This makes no sense. Flow = delta P/R. Pressure in vessels DOES vary according to the diameter... hence why we dilate people vascularly to reduce BP. Both the neural and hormonal systems primarily effect changes in blood pressure via changes in systemic vascular resistance (paraphrased from: http://www.cvphysiology.com/Hemodynamics/H002.htm)

motion+e · Feb 25, 2010

Thank you for your reply, ghillbert...but I'm going to explain it in a little more detail so that it does make sense...

"This makes no sense. Flow = delta P/R."...this is particularly true in the world of fluid mechanics...where diameters of supply lines and return lines do not vary...pressure of the system is provided by one source...that being a pump or other means that is forcing more fluid into the fixed lines...where resistance is the primary source of pressure. However, if there were a period of "rest" for this type of pump...there would be a pressure drop to zero because the source had been severed. This is not the case of our vascular system...our diastolic pressure does not drop to zero...meaning that pressure is not being applied by resistance but rather the displacement of volume in the system by the constriction of vessels etc...this is what fills the heart during the rest cycle. The equation is right...flow is determined by delta p/r...but it is not the entire equation in the case of the vascular system due to its changing ability of volume.

"Pressure in vessels DOES vary according to the diameter... hence why we dilate people vascularly to reduce BP"...exactly...now you are beginning to understand what I am talking about!...and we would see this drop in pressure throughout the entire body! :)

"Both the neural and hormonal systems primarily effect changes in blood pressure via changes in systemic vascular resistance"...it should read via changes in systemic vascular volumetric displacement. It is true that the heart during its contraction cycle does have resistance to overcome...this is the pressure already established in the diastolic cycle...but that is it for resistance, my friend. I hope I explained it a little better this time around...

motion+e · Feb 26, 2010

When you have a complete understanding of this...I will let you in on one of God's little secrets that will blow your mind...you will never look at the vascular system the same again. :)

motion+e · Feb 26, 2010

Why is it that I want you to throw "resistance" out of the headliner for the explanation of BP?

The whole ideology behind the resistance perspective automatically suggests that a systolic pressure of 120 would move more of a volume of blood than the diastolic of 80...making a hell of a volume fluctuation between each cycle...fast release and a slower fill rate...this in turn would throw every system in the body out of calibration.

My model actually suggests that the vascular system is perhaps one of the most complex fluidized timing systems known to mankind...also suggesting that a diastolic pressure of 80 will move the exact same amount of blood volume as that of the systolic of 120 in the same given time frame. Sound impossible? Well, it is not...and I will first explain this in a mechanical format so that it is simpler to grasp. Let us say that we want to move a volume of 10 cubic inches in a distance length of 10 inches with two different pressures but that they both have to move the 10 cubic inches within the exact same time span. We will start with our systolic pressure in this machine at say 200 psi and the diameter of our line is 0.798. Now in order for our diastolic pressure of 100 psi to move 10 cubic inches in a distance of 10 inches within the same time period of the 200 psi at a diameter of .798...the diameter of our diastolic line would have to increase to 1.128...but as you can see, diameter differences indeed allow for this to take place.

Now this becomes a little more complicated in our circulatory system...and to understand it, we have to understand the relationship between adrenaline and noradrenaline. During the systolic cycle our BP of 120, the head of the blood flow pushes threw a constricted vessel, with noradrenaline being released within this flow, causing the vessel to slowly dilate as more blood and noradrenaline pushes through it...opening the vessel up for the diastolic cycle...which at the tail end of the systolic cycle, adrenaline is released. The adrenaline causes the vessel to constrict (preparing it for the systolic cycle)...pushing blood flow ahead of this constriction wave to fill the heart...and these two cycles move the same amounts of volume within the same amount of time. These vessel fluctuations are very minor as it does not take much to move a non-compressible fluid and therefore may not be visible to the naked eye for the most part.

The interesting thing about this model is that if we know the BP and at least one of the diameters of either the constricted or dilated vessels...we could calculate the other diameter by the ratio difference of the systolic and diastolic pressures. :)

An interesting thing about us aging is that dopamine levels begin to decrease...which is where adrenaline and noradrenaline are derived from...and as we age our heart rates begin to drop...and our circulatory system is not as responsive as it once was...due to the lack of adrenaline and noradrenaline I assure you.

sunnycalifRN · Feb 26, 2010

I have a cousin that was talking with her mom today and was insisting her BP was 130's/150's. I told her that was impossible, I have never encountered that, nor heard of that, but she kept insisting that was correct. She even said that's how it was in her MD's office today... Has anyone here ever seen a diastolic larger than a systolic??? Or is my cousin slightly confused over her bp reading...

Hahaha! Yes, that is possible only if your cousin lives in Bizarro World, where everything is backward!!

blondy2061h, MSN, RN · Feb 26, 2010

Only in Australia.

pca_85 · Feb 26, 2010

I'm thinking she is seeing a digital readout and mistaking the slash between the two numbers for a one. Otherwise, she is defying logic and science.

HeatwaveRN · Feb 26, 2010

the BP machine is broken--send it and have it fixed!

or maybe....

her systolic range is 130s to 150s--

We shouldn't make fun of your cousin for not knowing this. The primary care provider or someone taking care of her from the clinic should have clarified this for her.

emtb2rn, BSN, RN, EMT-B · Feb 26, 2010

In the words of that great philosopher Ralph Wiggum, "that's unpossible".

My mom told me essentially the same thing, that she had just come from her doc and her bp was "perfect, 62 over 110". It wasn't until I took it myself that I could convince her that she transposed the numbers.

motion+e · Feb 26, 2010

"We shouldn't make fun of your cousin for not knowing this. The primary care provider or someone taking care of her from the clinic should have clarified this for her."...I agree with this 100%...it is very unprofessional and personally I wouldn't want someone caring for me that made fun of me because I lacked knowledge in their specific line of work.