What would you do?

[DFIB]

It was drilled into my head during my first EMT-B class that the typical B/P has on average a 40 point 'gap' be tween systolic and diastolic pressures. I was further told that widening B/P gaps signified hypovolemia (whether internal or external) and narrowing pulse gaps were indicators of rising ICP (as from closed head injury/CVA).

Am I remembering this correctly, or has my alzheimers kicked in again?

If I remember correctly systolic pressure is "driven" by cardiac output and diastolic pressure by norepinefrin. In a hypovolemic patient the sympathetic system is hyperactive. Systolic pressure is down because the volume is low but the diastolic is high because of the sympathetic is crazy trying to vaso constrict.

So it would be just the opposite of your post, a narrow pulse pressure would be hypovolemia and a wide pulse pressure would indicate shock by vasodilatation such as anaphylaxis or septic shock.

Edited to check spelling

Edited August 13, 2011 by DFIB

[tniuqs]

Hmmm ... well LS as usual is most correct.

Without getting into a huge post, respectfully, perhaps do a bit of review control of homoeostasis, including pulses paradoxus.

http://en.wikipedia.org/wiki/Pulsus_paradoxus

If I remember correctly systolic pressure is "driven" by cardiac output and diastolic pressure by norepinefrin.

Not really, its not quite as simple as that as baroreceptors, chemo receptors, and then the adrenergic and sypmathetic responses come into play as well as underlying pathology's which make my head explode some days.

In a hypovolemic patient the sympathetic system is hyperactive.

In a manner of speaking "kinda" to a point, when you state hyper active that could indicate an endocrine system involvement, hormonal or adreanal insufficency.

Systolic pressure is down because the volume is low but the diastolic is high because of the sympathetic is crazy trying to vaso constrict.

Nope: The adrenegic system is attempting to "compensate" but with more than 40% circulating volume loss (more or less) the venous return is compromised as a result, therefore the hypovolemic hypotension is a direct result of not enough blood returning to the heart, both systiolic and diastolic will be down.

I remember 3 things in shock the 1-PUMP the 2-FLUID and the 3-CONTAINER.

So it would be just the opposite of your post, a narrow pulse pressure would be hypovolemia and a wide pulse pressure would indicate shock by vasodilatation such as anaphylaxis or septic shock.

Narrowing pulse pressures are a result of (most typically) mechanical in nature as in a pericardial tamponade, or "Obstructive Shock"

Wide pulse pressures is typically observed in head injuries called the Cushing Response although epinephrine is a mediator, in part.

http://en.wikipedia.org/wiki/Cushing_reflex

Anaphylactic Shock and Septic/ Warm Shock are forms of "Distributive Shock" although the mechanisms quite different, histamine in anaphalaxis + SRSA or in septic a "histotoxic" response when pre and post capillary's sphincter fail due to toxins. The C.O in sepsis is very high or "pumping wide open into blood into space" but delivery of O2 to the tissue is the problem.

http://en.wikipedia.org/wiki/Cushing_reflex

I hope that helps

[DFIB]

Hmmm ... well LS as usual is most correct.

Without getting into a huge post, respectfully, perhaps do a bit of review control of homoeostasis, including pulses paradoxus.

http://en.wikipedia....ulsus_paradoxus

Thanks, I had not considered pulses paradoxus. It is a good read if we were talking about systolic presure chages caused by respiration.

Not really, its not quite as simple as that as baroreceptors, chemo receptors, and then the adrenergic and sypmathetic responses come into play as well as underlying pathology's which make my head explode some days.

Very true that the baroreceptors react to the change of pressure in the aortic arch and carotids trigger sympathetic nervous system to initiate a cascade of neural and hormonal responses in an attempt to restore the pressure back to a normal state. But the end result is vasoconstriction.

In a manner of speaking "kinda" to a point, when you state hyper active that could indicate an endocrine system involvement, hormonal or adreanal insufficency.

Kinda is correct. Hyperactive is a poor choice of words. Stimulated seems better. Thanks for pointing it out.

Nope: The adrenegic system is attempting to "compensate" but with more than 40% circulating volume loss (more or less) the venous return is compromised as a result, therefore the hypovolemic hypotension is a direct result of not enough blood returning to the heart, both systiolic and diastolic will be down.

Yep, I made no mention of the level of hypovolemia. If you want to pitch an extreme number out to sustantiate your argument a guess it is you can but from a basic level it is kinda weak.

At 40% blood loss is pretty extreme and most likely decompensated so ... of course, I would expect a decrease in BP diastolic as well. When the diastolic pressure falls the cascade of vasoconstrictive hormones and neurotransmitters could no longer keep up with the blood flow.

My bad ... I was thinking of a hypovolemia caused by less blood loss. I should have been more clear.

Narrowing pulse pressures are a result of (most typically) mechanical in nature as in a pericardial tamponade, or "Obstructive Shock"

Yes this is true especially in pulse paradoxus as seen in your wikipedia reference. It is also present in hypovolemia.

And of course there is vasodilation in septic and anafilactic shock. I only mentioned them as a comparison.

Thanks for the help.

[tniuqs]

No worries mate ... good convo.

[DFIB]

No worries mate ... good convo.

I wasn't trying to be conflictive and I don't think you were either. I simply believe we were thinking in different directions. I guess i could have said that in 10 words or less!

Health,

Grady