Re: Write it down, permissive hypotension, Mark the date

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Mark Forrest wrote:

"... then consider the ITU sometime later.....acute lung injury, ARDS..."

and

"There is no audit evidence to suggest an increase in ATN in our units since this 'dry' regime, but even if there was, this is far easier condition to manage and has a better prognosis than severe ARDS."
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Mark,

You seem to be implying that crystalloid infusion either leads to ARDS, increases the likelihood that it will develop, or both.  I think you would agree that volume infusion in a healthy volunteer is unlikely to cause CHF, let alone ARDS… clearly for ARDS to develop there must exist some inflammatory trigger.  The difference between blunt and penetrating may be a difference in the degree of inflammation.  ARDS follows from an inflammatory insult, not just from excessive hydration.  See:

http://books.nap.edu/books/0309064813/html/50.html#pagetop

p. 50 from Pope, French, Longnecker: Fluid Resuscitation: State of the Science for Treating Combat Casualties and Civilian Injuries  (1999)

The Vietnam era observations seem to have been refuted by more controlled studies.  It isn’t the volume that causes ARDS, it is the shock that causes inflammatory response which causes the organ failure and ARDS.

If a patient has hypovolemic shock (hypotensive with evidence of end organ hypoperfusion) from either blunt or penetrating trauma, we have two goals; 1. Bleeding must be controlled or they will die,  2. Shock must be reversed, or they will die. 

Clearly, once bleeding is controlled, volume responsive shock must be treated quickly with volume.  The question remains how aggressively to resuscitate prior to bleeding control.  The question is pretty well answered for penetrating thoracic trauma by Mattox et al. in NEJM 1994 Oct 27;331(17):1105-9.  Not at all until the bleeding is fixed.  

Could the complications in that study (more ARDS, MODS, sepsis, etc.) be secondary to the immumologic effects of PRBC transfusions given to patients who bled more because of the early resuscitation prior to hemostatic control?

Blunt trauma may be different.  Especially the pelvic fracture with slowly expanding retroperitoneal hematoma.  Eventually the veins will have to tamponade themselves.  Too much volume and they may bleed more, too little, then the patient is still in shock and if they’re in shock for long enough, they will die.  Sadly, for some patients, the right amount is neither too much nor enough.

I’ll grant you the clot concerns, but I challenge your implication that it is the fluid resuscitation that independently causes MODS and ARDS later.  The data (see Moss, or Shoemaker) would seem to support that those complications are caused by the tissue trauma, inflammatory mediators and shock, not by the fluid alone.

I’d be interested in literature supporting the crystalloid resuscitation – ARDS connection in blunt trauma.

Regards,

david

J. David Roccaforte M.D.
Dept. of Anesthesiology, NYU
Co-director SICU
Bellevue Hospital

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