Permissive Hypotension

[fireflymedic]

Recently while at a conference a respected trauma surgeon in our area made the comment that the accepted permissive hypotension level of 90 systolic while acceptable actual was not the optimal level at which patients survived. Based on the data he showed us (which is far to extensive to link here if you wish for it, please PM me and I will attach) the optimal level of survival was at 110 systolic. Now I know this is still an area of gray and great debate as the arguement still lies between trauma surgeons and neurosurgeons as to the level at which survival is optimal and produces a functional patient in the end. The argument is that we are saving patients but at an increased risk to brain function.

With what was informed to us at this conference, the level of 110 does not significantly increase the risk of bleeding out much more than 90, still adequately perfuses the brain, producing not only an alive patient, but a patient with the greatest chance of recovering function and not having injury due to ischemia.

Granted this was his first go around with this but the information shared was interesting and is really making some of us wonder. This physician is well respected within this area for research so it's posing a question to us is the acceptable level of permissive hypotension really correct or should it be a bit higher? I'm not trying to throw current research to the wind but the current level has both neuros and trauma docs in a debate over who wins - perhaps we raise the level a bit it may reach an agreement between the two and improve patient care? Thoughts?

[Miss Sasha]

With what was informed to us at this conference, the level of 110 does not significantly increase the risk of bleeding out much more than 90, still adequately perfuses the brain, producing not only an alive patient, but a patient with the greatest chance of recovering function and not having injury due to ischemia.

But perfuses it with what? Koolaid?

[fenwayfrankee]

The head trauma surgeon at one of the major teaching hospitals here is Boston was big on permissive hypotension. He did not give us an actual systolic BP to work from but rather he wanted their BP as low as possible while still mentating. Reguardless of the BP, if they are mentating they don't get fluid.

[fireflymedic]

Frankee - that is similar to our mentality, however we are discussing unconscious patients or those on the brink, not conscious mentating patients - that's a whole nother ballgame. Obviously consciousness is the biggest determining factor in how well the brain is being perfused. Thanks !

[mobey]

What your physitian was bringing forth is the newest info/science on permissive hypotension.

If you check out the new ITLS-A and/or ATLS texts they discuss permissive hypotension in the trauma patient.

What you have to consider (and what this surgeon was discussing) is what it takes to perfuse the brain in a head injured patient.

When dealing with anything from a epidural bleed, to a simple cerebral contusion, you are always battling a common denominator..... Cerebral swelling.

I do not have time to research the numbers today.... but I am sure one of my bro's here will.

In fact, it is better for you to reasearch it yourself.

Check out what BP it takes to maintain Cerebral perfusion pressure (CPP) in the brain injured patient. There is lots of info out there.

In the trauma patient without head injury, permissive hypotension of 90 systolic is a good idea so you do not exacurbate any internal bleeding.....

BUT as you will find out during your search, with even slight swelling/edema, it takes more pressure to perfuse the brain properly.

[rock_shoes]

But perfuses it with what? Koolaid?

Funny ha ha. A minimum Blood pressure is still required to maintain adequate perfusion. The minimum BP required to perfuse the brain is dependent on someone’s intracranial pressure which isn't something we can measure in the field. The flipside is that maintaining the lower (90mmHg) systolic is better for major trauma not involving the brain. The higher you keep someone’s BP with fluid resuscitation the faster they are going to bleed out.

Personally I'm looking forward to the days of synthetic blood products when we can eliminate one concern and focus on maintaining an adequate CPP (Cerebral Perfusion Pressure).

[akroeze]

Well looks like in Ontario we are right in the middle of the pack as far as that goes.

When the patient is symptomatically hypotensive/hypovolemic without signs of fluid overload on chest auscultation, and has a systolic BP<100 (or SBP<[2 x patient age + 70] in patient <40kg) the paramedic may:

a. For patients >=40kg: Give an IV fluid bolus to a maximum of 20ml/kg. Repeat vitals and perform a chest auscultations after every 250cc. Return to KVO when bolus completed, SBP is >=100 or chest auscultation reveals crackles.

b. For patients <40kg: Give an IV fluid bolus to a maximum of 20ml/kg. Repeat vitals and perform a chest auscultations after every 100cc. Return to KVO when bolus completed, SBP is >=(2 x patient age + 70) or chest auscultation reveals crackles. In patients <40kg with suspected diabetic ketoacidosis, give IV fluid boluses to a maximum of 10ml/kg.

So basically we are trying to keep them at 100 systolic.

Interestingly our post-arrest protocol calls for maintaining BP >90 systolic.

Edited July 28, 2009 by akroeze

[fireflymedic]

Indeed mobey - but my thoughts are at what point do we decide the patient with decreased or altered mental status is suffering that due to a head injury or lack of brain perfusion? Certain times we are able determine CPP and maintaining the ideal MAP of 50-60 depending upon which text and physician you decide to follow though I have found 60 to be the general accepted number. Within the critical care community you may occasionally transport patients with ICP monitors and thus be able to determine CPP, otherwise as you stated at this point you cannot determine it within the field.

Unfortunately I think at this point, despite the positive evidence that was out for some blood product alternatives the research into that area has been postponed for a good bit. The one area I am curious of is the trial which is using albumin for stroke patients...the military currently to my understanding from a military medic friend of mine is that they are using the very thing which we do not carry for patients with extensive blood loss within the field - dextran seems to be a big choice. They have higher survival rates as it is a volume expander, not replacement as current options we are using (ie LR or NS). Most of our advances have come from military medicine, so perhaps this is the new frontier for us to follow and trucks will begin carrying these within the near future especially as research on blood substitutes such as polyheme are halted for the moment. Though understand the polyheme trial one of the excluding criteria was head injury....

I'm interested to see where this research takes us. Hopefully to great improvements in patient care !

[AnthonyM83]

Did he specifically state SBP of 110 for actively hemorrhaging patients, versus those where they were bleeding and hypotensive but where bleeding is no controlled? Were these studies done in the hospital or prehopsital?

[croaker260]

Three comments:

1- We should really be titrating to a MAP , not systolic B/P

2- The "standard" is nothing more than consensus (read: he who argues longest or loudest, or is most stubborn ...wins) .

3- Differeng standards exist for general trauma and head Injury.

Our guidelines verbally have been 80-90 for general trauma, 100-110 for CHI.