PERMISSIVE HYPOTENSION
IN HYPOVOLEMIC SHOCK
RESUSCITATION
CDR GIRARD POIRIER MC USN
Brief Review

Shock - Inability of the body to adequately perfuse end organs
which can lead to irreversible damage and death

Hypovolemic shock from hemorrhage is common with severe injury
and must be assumed until ruled out.

The numbers: 10% of all trauma patients present with immediate
post traumatic hypotension.

Presence of shock in the pre-hospital setting is a strong predictor of
mortality
Prehospital Hypotension Predicts
Mortality
%Mortality
70
60
Blunt
50
Penetrating
40
30
20
10
0
120 +
120-90
90-60
60-0
SBP
Classes of
Hemorrhagic
Shock
Class I 750 mL (15%)
●
Slightly anxious
●
Normal blood pressure
●
Heart rate < 100 / min
●
Respirations 14-20 / min
●
Urinary output 30 mL / hour
●
Warm skin, Normal Cap Refill
Class II 750-1500 mL (15-30%)
●
Anxious
●
Normal blood pressure
●
Heart rate > 100 / min
●
Decreased pulse pressure
●
Respirations 20-30 / min
●
Urinary output 20-30 mL / hour
●
Pale, Cool, Cap Refill Delayed
Class III 1500-2000 mL (30-40%)
●
Confused, anxious
●
Decreased blood pressure
●
Heart rate > 120 / min
●
Decreased pulse pressure
●
Respirations 30-40 / min
●
Urinary output 5-15 mL / hour
●
V. Pale, Sweaty, Cap refill V Delayed
Class IV >2000 mL (>40%)
●
Confused, lethargic
●
Hypotension
●
Heart rate > 140 / min
●
Decreased pulse pressure
●
Respirations >35 / min
●
Urinary output negligible
Not All Trauma Patients are Alike

Division into 3 categories
 Blunt
 Penetrating
 TBI
/ Head injury
Not All Trauma Patients are Alike

The very young and very old may present differently.

Children have a very large reserve capacity

Elderly may be on medications that blunt normal
responses. Also may be unable physically to mount a
tachycardic response. Finally, many elderly are
hypertensive and may present as “normotensive.”
Resuscitation History

Goal was to normalize HR and BP

Animal models of the 1950’s and 60’s showed benefit of aggressive
fluid resuscitation.

Subsequent review of methods showed numerous flaws


Testing did not accurately reproduce the pathophysiology of an actual
exsanguinating trauma patient

Bleeding was tightly controlled as well as BP
Overall paucity of controlled trials during that time.
Resuscitation History

Animal models in the 80’s and 90’s better designed.

Improved physiologic modeling of actual trauma patients.

Volume and duration of hemorrhage now dependent on animals
physiological responses and not the operator. (thrombus formation as
well as vasoconstriction)

Experiments with this design showed harm with aggressive fluid
resuscitation.

Thought that aggressive fluid mgmt. led to clot disruption, dilution of
clotting factors, and reversal of natural vasoconstriction.
Historical Management

2 large bore IV’s

2 liters or saline or LR wide open

Continue replacement / maneuvers until normalization of BP and HR


MAST trousers, legs up in Trendelenburg, vasopressors
Control bleeding
The question of possible harm with aggressive resuscitation was
actually broached during WWI by US Army Surgeon Cannon and
published in JAMA 1917.
Current ATLS Mgmt

Identify and control source of bleeding (direct pressure, tourniquet,
suture ligation, or surgery)

Access (2 large bore periph IV’s, IO, CVL)

2 liters of warmed crystalloid initially if hypotension is present
followed by fluids at a 3:1 ratio to accommodate fluid shifts into the
interstitial spaces.

Blood products only if no response to initial fluid bolus

Prevent Hypothermia
Choice of Fluid


Crystalliod : LR vs NS. LR may be beneficial
due to its buffering ability in acidosis and
lessening risk of hyperchloremic acidosis.
(studies show this benefit only in massive
transfusions. No benefit with minimal
replacements). Risk of hyperkalemia with use
of LR, especially those with renal disease.
Choice of Fluid

Colloid : Theoretically a good idea. Rapidly expands circulating
volume and stays in the circulation longer therefore much less third
spacing of fluids. However, multiple studies have shown no benefit

2002 Cochrane Review actually showed increased RR of death in those
receiving albumin

Saline vs Albumin Fluid Evaluation (SAFE) showed no benefit using
albumin.

TBI patients at much higher risk of harm using albumin.
Finfer S, Bellomo R, Boyce N, et al. A comparison of albumin and saline for fluid resuscitation in the intensive care unit. N Engl J Med
2004;350(22):2247–56
Choice of Fluid

Hypertonic Saline.

Osmotic agent that can reduce cerebral edema in TBI

Stays intravascular for longer period therefore decrease risk of lung injury
and abdominal compartment syndrome (ACS)

Human trials to date are inconclusive in showing benefit in the prehospital and initial treatment phases.

Subgroup analysis: Blunt trauma receiving massive transfusion did show
decreases risk of ARDS.
TBI patients showed no changes in outcomes.
Signif increase in mortality in trauma patients who did not receive blood
transfusion in the first 24hrs.
Kobayashi L. Hypovolemic Shock Resuscitation. Surg Clin N Am 92 (2012) 1403–1423
Choice of Fluid

LR and transfusions: Currently not advised by the American Board
of Blood Banks due to possibility of clot formation in lines. (calcium
in LR may bind with Citrate preservative therefore increasing risk of
clotting.)

However, recent studies have shown this not to be the case
especially in those receiving massive / rapid transfusions. Risk is
greater with slower transfusion rates.

New preservatives also in PRBC’s (AS-3)
Michael Vlessides. Study: Ringer’s Lactate Does Not Trigger Clotting Cascade. Clinical Anesthesiology. OCTOBER
2008 | VOLUME: 34:10
Problems with Traditional Mgmt.

Immediate and aggressive fluids to normalize BP with increase blood
flow and perfusion pressures to injured areas.

This may disrupt clot formation

Will lead to significant third spacing of fluids leading to pulmonary as
well as intestinal edema. Also, increased risk of abdominal
compartment syndrome and ARDS

Dilutional coagulopathy: starts at about 750ml of cystalloid admin.
Uncontrolled Hemorrhage :
Is Normal Blood Pressure the Target ?
Roberts et al Lancet 2001
Bleeding
or
Re-bleeding
Mechanic effect
on vascular clot
SAP
Increase
Agressive
Volume
Loading
Hemodilution
Anemia
Hypothermia
Hypoxemia
Coagulation
disorders
Normal blood pressure is not the target !
Normotensive or hypotensive
resuscitation ?
A meta analysis
Mapstone J, Roberts I, Evans PH , J TRAUMA 2003, 55 , 571
Favour hypotensive
Favour normotensive
Permissive hypotension improve survival !
What About Human Studies

Landmark Study by Bickel and colleagues most cited.

Compared immediate with delayed fluid resuscitation in
penetrating trauma to the abdomen

One group received standard fluid mgmt. while the other was
delayed until reaching the OR.
Std group received on avg about
2L of saline. Delayed group received 100-200cc)

Overall survival of the Delayed group 70% vs 62% for Standard grp.

Also noted was an increase in ARDS, pneumonia, sepsis, and
coagulopathy in the standard group.
Bickell WH, Wall MJ Jr, Pepe PE, et al. Immediate versus delayed fluid resuscitation for hypotensive patients with penetrating torso
injuries. N Engl J Med 1994;331(17):1105–9
What About Human Studies

Study By Owens and Colleagues

Restrictive fluid resuscitation model following traumatic amputation
significantly increased survival.
Owens TM, Watson WC, Prough DS, et al. Limiting initial resuscitation of uncontrolled hemorrhage reduces internal bleeding
and subsequent volume requirements. J Trauma 1995;39(2):200–7 [discussion: 208–9]

Study By Morrison and Colleagues

Evaluated differences between intra-operative MAP of 50 vs the
standard of 65 in guiding resuscitation.

Lower group exhibited less blood loss, less transfusion, improved early
survival as well as improved mortality rates at 30 days

Benefits most beneficial in penetrating trauma
Morrison CA, Carrick MM, Norman MA, et al. Hypotensive resuscitation strategy reduces transfusion requirements
and severe postoperative coagulopathy in trauma patients with hemorrhagic shock: preliminary results of a
randomized controlled trial. J Trauma 2011;70(3):652–63
What About Human Studies

Restrictive Fluids in Blunt Trauma

Paucity of studies

Turner and Colleagues compared fluid restriction in the
field vs standard paramedic protocols.
 Significantly
more blood was transfused in the
standard group vs the restrictive group
 Flawed
compliance by paramedics was significant.
Turner J, Nicholl J, Webber L et al. A randomized controlled trial of prehospital intravenous fluid replacement
therapy in serious trauma. Health Technol Assess 2000;4:1-57.
What About Human Studies

Head Injury
 There
are no human studies that have
evaluated hypotensive resuscitation in the
trauma patient with concurrent head injury.
What About Human Studies

Subsequent studies have failed to reproduce consistently these
results.

Active debate continues on the uses of permissive hypotension

Fluids should never be restricted to patients with a MAP of <40 who
are pulseless. These patients have little chance of survival and any
fluid admin to maintain some tissue perfusion outweighs any risk of
increased hemorrhage risk.
Mortality with Blood Transfusion

Data shows a stepwise increase in mortality
Table
2
Stepwise
increase
in mortality
with
transfusion
Mortality
Inaba
PRBCs
( Units
)
1 – 10
Como
et al,
15
22 %
2004
Huber-Wagner
et al,
17
2007
et al,
* Uncross-Matched
<7 5 30 %
14.8 %
>7 5 54 %
11 – 20
30 %
21 – 40
35.1 %
20 – 29 5 53.7 %
50 %
30 5 60.4 %
>40
* This
59 %
study
includes
patients
given
uncross-matched
blood.
142
<15
5 78 %
>15
5 95 %
2008
What is the Target
MAP / SBP
Coronary Autoregulation
50
160
Cerebral Blood Flow Autoreg.
CPP = MAP - ICP
Current Recommendations
On Target MAP

Most recent guidelines are based on expert opinion and results of
animal and human trials.

Goal is to limit the volume of infused fluids and maintain SBP at a
minimum safe level.

Target SBP of 80-90mmHg

If concurrent brain injury is suspected then a goal of 100mmHg is
recommended to ensure adequate perfusion in the face of possible
increased ICP.
Current Recommendations
On Target MAP

Morrison and Colleagues:

Compared MAP of 50 vs 65mmHg (intra-operative)

Showed significant reduction in fluid and transfusion requirements in the
lower MAP group.

Reduced post operative coagulopathy

Statistically lower mortality in the immediate post op phase and trend
toward lower mortality at 30 days
Morrison CA. Hypotensive resuscitation strategy reduces transfusion requirements and severe postoperative coagulopathy in trauma
patients with hemorrhagic shock: preliminary results of a randomized controlled trial. The Journal of Trauma. 2011 Mar;70(3):652-63
Current Recommendations
On Target MAP


Israeli Methods: Commence hypotensive resuscitation when one of
the following is met:

Altered mental status

Loss of radial pulse

SBP < 80
Up to 250ml of fluid are given at a time in order to return mental
state, regain radial pulse, or SBP to 80mmHg
Review

The Bickel paper is the only randomly controlled trial which enables
some conclusions to be drawn on the topic of hypotensive
resuscitation.
Some harm has been shown with aggressive fluid
resuscitation in the field. Hypotensive resuscitation reduces blood
loss and transfusion requirements.

Animal studies consistently show that increased SBP in resuscitation
increases or restarts bleeding.

Evidence for hypotensive resuscitation in blunt trauma or TBI is sparse
and needs further investigation.
Permissive Hypotension in Other
Areas of Medicine

Leaking AAA : normal physiologic response to maint SBP 70-80.
Treatment is to maint hypotension until proximal control achieved.

Dissecting aneurysm : afterload reducing agents to induce
hypotension

Pulmonary contusions treated with fluid restriction

Bleeding Duodenal ulcers treated by lowering BP and holding off on
transfusion if possible until definitive treatment.
Final Thought

"There is nothing more difficult to take in hand, more
perilous to conduct, nor uncertain in its success, than to
take the lead in the introduction of a new order of
things, for the innovator has for enemies all of those who
have done well under the old, and lukewarm defenders
in all of those who may do well under the new.“
- Machiavelli
Questions ?
Anecdotes From
Your Practice ?