Giving vasoconstrictor drugs in trauma situations

[rhan101277]

I just wanted to ask about this. If you give these drugs due to low blood pressure from massive blood loss. Don't you first have to give normal saline to keep the volume up. If you don't and you administer it anyway, it may cause the blood pressure to come up but it will still cause bad perfusion from not enough blood volume right?

 

[Melbourne MICA]

I just wanted to ask about this. If you give these drugs due to low blood pressure from massive blood loss. Don't you first have to give normal saline to keep the volume up. If you don't and you administer it anyway, it may cause the blood pressure to come up but it will still cause bad perfusion from not enough blood volume right?

Depending on the volume loss even these tools amy not help with BP Aramine (potent alpha agonist - perpiheral vasoconstrictor) is a popular vasoconstrictor used for short term BP manipulation amongst surgeons and anaesthetic staff on multi trauma pts but the use is highly controversial in the field for the same purpose. I don't know of any EMS services that have it in their trauma protocols. (Not so sure about the US)

Volume compensation and tissue/organ perfusion through fluids is another highly controversial area and the subject of much discussion and many many studies over decades.

There's not much point trapping blood volume in the perpihery for the half life of the drug when major organs need perfusion above all other considerations. Volume filling assists with BP but is not an oxygen or tissue nutrient carrying mechanism.

EMS still volume fill and now it seems the debate over plasma volume expanders versus fluids like D5W/Hartmanns etc is over and the fall back position is normal saline. Depending on volume loss - how easy is it to determine this in the field? - fluid volume expansion provides some compensation effects temporarily - its all about time really.

In the end hypovolaemic shock or rather its prevention in the short term requires two managments.

* Prevention of further external blood volume depletion (thats our job through pressure wound dressing and control of sympathetic responses) and
* Surgical repair of internal vessel damage.

Ventmedic is probably the best person to clarify medium term and long term problems like DIC, rebleeding, haemodilution/clotting/lysis/fluid filling interactions in trauma.

So in the end its effective and prompt wound management, control of sympathetics to reduce heart rate; remember the heart moves 70mls of blood with every beat on average - multiply that by a heart rate of 120/min and you can see how fast you can bleed out through a large hole in a major vessel and also why pain management and fluid filling come into play to help stabilise the equation HR x SV = CO.

Good overall packaging (so the pt doesn't do anything that will work the heart) and short scene times with an eye on the best trauma centre destination option to throw in for good measure.

The other side of the coin is to ask why we don't use adrenaline (epi) boluses for trauma pts when they'r flat.

As a final comment - the military and some EMS services are starting to use artifical wound clotting/packing materials that can be used in the field to control external haemorrhage. They look promising and a fair bit of research money is heading in that direction from the public and private sectors.

Trauma management is a great area of interest for ambos - lets hope our role will expand in this area in the future.

MM

 

[MSDeltaFlt]

I just wanted to ask about this. If you give these drugs due to low blood pressure from massive blood loss. Don't you first have to give normal saline to keep the volume up. If you don't and you administer it anyway, it may cause the blood pressure to come up but it will still cause bad perfusion from not enough blood volume right?

Fluid of choice for massive blood loss in the prehospital setting is LR according to the American College of Surgeons. If their BP's real low, then permissive hypotension (70-80 sys) will generally work until you get them to ER. You don't want to give them too much fluid thus diluting their volume decreasing their oxygenation.

If their BP's even lower despite fluid boluses and/or showing serious signs and symptoms of shock, then contact med control because if they're bleeding out that bad, then they'll need enough vasopressors to risk constricting the vessels enough to worsen the tear and make them bleed even more.

There's only one thing that will fix your trauma pt who's bleeding out: hot lights and cold steel... i.e. surgery.

 

[rhan101277]

Thanks for the input, I know this stuff is above my scope but I like to know.

 

[Veneficus]

There has been a lot of research in this field, this is the latest I have heard and suggest.

LR does not have the osmotic qualities of large amounts of NS. In the short term NS is fine. Long term LR is preferred.

Synthetic Colloid solutions seem to have no significant difference in outcome, only the price. For civilian EMS that is not hiking through the wilderness much cheaper to use NS or LR than dextran or the like.(by almost 10x) Otherwise the colloid is lighter in weight.

I have posted it several times, but systolic BP is not a good indicator of perfusion status. In the field and ED pulse pressure is much more accurate.

While I see what Melbourne is trying to say about cardiac output, I personally like to see more cardiac output. (two schools of thought, one not better than the other) But output of crystalloid is basically worthless. The purpose of the crystalloid is to return blood to the heart. No blood, no point. Depending on the level (classification) of hemorrhage crystalloid will be enough, work transiently or have no effect at all. Generally the worse they are, the less crystalloid helps. But a large effect is based off what happens after you plug the leak.

When you have a bleeding trauma patient, the primary goal I think needs to be hemostasis. That could mean mechanical bleeding control (direct pressure) or permissive hypotension. As for maintaining perfusion, massive blood transfusion as close to 1:1:1 as possible is becoming the standard prior to surgical intervention. The problem is this is not really practical for EMS and is a hospital event.

Permissive hypotension has shown to be effective in penetrating injuries, but no statistical advantage with blunt injuries.

As for vasoconstrictors, over the past year a lot of thought has gone into this.(particularly with vasopressin) Some small studies have been done and some larger ones are not published yet. It is shown to have no effect in outcome so far, some are saying the data points to worse outcome. What is done in surgery is a whole different animal, but remember damage control surgery is in and out as quickly as possible, so transient help there makes a difference.

The stats on traumatic arrest show abysmal survival rates. As low as <1%. Epi while increasing vascular constriction, also increases cardiac output, and demand. You cannot meet the demand as it is, so increasing it just makes the discharge to the ECU a bit faster.

Once you get the massively injured to the ICU you then have to start dealing with things like clotting cascades, cytokine release, restoration of organ function, etc. That is when your MODS, DIC, and other complications occur.

Advancing trauma care in the field requires a change in techniques, equipment, and knowledge. I very much doubt anything short of a blood substitute is going to make much difference in the austere environment.

Thanks to vascular surg though, tourniquets are coming back.