Compensated Shock

[skyemt]

with regards to the body's compensating mechanisms for hypoperfusion...

increased HR, peripheral vasoconstriction, cool clammy skin, increased RR, etc...


with regards to the BP... my understanding is that it is the CO X Peripheral resistance (afterload)... as the CO drops, the body tries to compensate by increasing the afterload... basically, the body's compensating mechanism tries to maintain it's BP...

if my understanding of this is crude, but correct, does it explain why BP is not always a reliable Vital Sign for compensated shock?

 

[firetender]

Relying on BP alone will not get you there.

When you look at the VSs behaving as you stated, then it's a fair bet to suspect compensation going on. The next step is to prepare for the compensation to cease. I would often observe that if the systolic and diastolic numbers got progressively closer together, then I needed to be ready for the blood pressure to plummet. Don't recall the mechanism.

It's important to keep aware of everything going on within the Big Picture.

 

[Ops Paramedic]

I had to read your thread afew times before grasping what I think you asking. My answer is yes. However, BP cannot be a reliable source, on its own. You would have to look at the whole picture as firetender mentioned. The BP will become reliable as a source when used inconjuction with other signs & symptoms.

You also mentioned some aspects of the compensating mechanisms. Some of these are compensating mechanisms, and others would rather be as a result of a compensating mechanism, such as, cold and clammy skin, can be as result of the peripheral vaso constriction. None the less it is something that we can examin on the patient leading us to the direction of compensating shock.

To add to your BP=CO*PR, remember that CO=HR*SV. One of the first reponses to blood loss is vasoconstriction of the peripheries and muscles to supply blood to the vital organs. According to an ATLS text, tachycardia is the earliest vital sign we can measure. For the body to maintain a BP that is compromised the HR will increase, leading to the increase of CO (Should SV not fall). This togther with an increase in the PR should lead to a increase in the BP.

When looking at the different classes of blood & fluid loss, BP will only show a change in class III, which is just prior to being detremental. However a decrease in the pulse pressure can be noted in class II already. Yes, BP is not a reliable source, ON ITS OWN, but should be used together with other signs & symptoms to diagnose compensated shock.

The mechanism behind the decreased pulse pressure is as result of the release of catecholamines. These cause an inscrease in PR, leading to the rise in diastolic pressure.

Hoping it helped a bit...

 

[fma08]

BP is a late sign... here's why. Shock=inadequate tissue perfusion. The body is excellent at compensating, especially kids. The body reacts to shock by shunting blood to the core, in increments. First skin and peripheral tissues first (hence pale skin), next are the guts (nausea/vomiting), next are skeletal muscles (weakness), then everything else except heart, lungs and brain. Thats when the BP starts to noticeably drop. generally at that point the pt. will either be in a coma or have a significant LOC change. Death follows quickly after this point. So you have very little time if any to reverse it.

Hope this helps a bit.

 

[Ridryder911]

I believe that this article covers it, pretty well.

http://ccforum.com/content/8/5/373

 

[fma08]

excellent article, don't suppose you have those on the other types of shock?