Outline

History of fluid resuscitation Clinical trial

Animal studiesHuman studies

Guideline Controversies Conclusion

Trauma Trauma had long been a major cause of preventable

deaths worldwide.

One-third of trauma deaths because the victims bleed to death within the first several hours

Lethal triad In the past, high volume resuscitation strategies was

used to reverse haemorrhagic shock

However, still a number of patient develop lethal triad and leads to mortality

Acidosis, hypothermia, coagulopathy

Can be due to the injury, or due to resuscitation

History of Fluid resuscitation Controlled hemorrhage animal models in

1950s.

Wiggers insert a IV catheter, allow the animal to bleed and maintain a predetermined level of hypotension

Fluid deficit was corrected with crystalloid 3 times the blood loss

Lead to traditional fluid replacement regimen of 3:1 crystalloid: blood

Wiggers’ model may not be accurateBlood pressure is controlled by investigator

by controlling the blood loss through the iv catheter

Aggressive fluid resuscitation Early aggressive fluid resuscitation was

used routinely in Vietnam War in 1970s

Coincidentally, ARDS was commonly described

1980s Uncontrolled haemorrhagic models were

developed to simulate blunt traumamaximal vasoconstrictionthrombus formation

Animal study : Aggressive resuscitation with isotonic crystalloidIncrease blood pressure and increase blood

lossDid not reduce mortality

Hypotensive Resuscitation In haemorrhagic shock patient, hypotension and

vasoconstriction help to stalilized the clot

Increasing the blood pressure places additional stress on formed clot

Blood pressure greater than 90mmHg associated with higher risk of re-bleeding

Hypotensive resuscitation aim at keeping the blood pressure low enough while maintaining perfusion of end organ.

Hypotensive Resuscitation Walter Cannon proposed it in 1918

“If the pressure is raised before the surgeon is ready to check any bleeding that may take place, blood that is sorely needed may be lost”○ The preventive treatment of wound shock○ JAMA 70:618-621

George Higginson Professor of PhysiologyWho invented the word ‘homeostasis’

MAP 0

MAP 80

MAP 40

By AortotomyMAP 40mmHg group had better survival than MAP 80mmHg groupMap 40mmHg group also had less blood loss

2003 Hypotensive resuscitation improved

mortality compared to traditional resuscitation

How about Human Studies?

Prospective controlled trial

Single centre

Penetrating torso injury with SBP < 90mmHg○ Exclude: pregnant, age <16, revised trauma score 0, fatal

gunshot to head, not requiring operation

Immediate Resuscitation (309)•traditional resuscitation with crystalloid

Delayed Resuscitation (289)•Withhold IV Fluid until arrival to operative theatre

VS

Delayed resuscitation:•Less fluid and packed cell given

Delayed resuscitation: pre op•Lower SBP•Better Hb, plt, clotting profile

Delayed resuscitation:•Improved survival

•(62% vs 70%)•Shorter length of stay

Delayed resuscitation:•Trend of less ARDS

Randomized controlled trial

Single centre

Trauma patient with SBP <90mmHg Exclude: pregnant, CNS injury/ impaired consciousness, age >55, history

of DM/ IHD

Target SBP > 100mmHg (55) VS Target SBP 70mmHg (55) Titrating Crystalloid or blood product Fluid restriction to lower BP Until active bleeding was stopped

SBP 114 +-12 VS SBP 100 +- 17 Similar survival: 92.7%

Cochrane Review Timing and volume of fluid administration for patients

with bleeding (2003)

We found no evidence from randomized controlled trials for or against early or larger volume of intravenous fluid administration in uncontrolled haemorrhage.

While increasing fluids will maintain blood pressure, it may also worsen bleeding by diluting clotting factors.

That was 10 years ago

Few more studies published recently

Retrospective cohort study

Single centre

Including patient with emergent damage control laparotomy Exclude: age <18, pregnant, die on scene or during OT

VSNormotenive group (282) Hypotensive group (108)

Hypotensive group:• Better:

• temp, heart rate, plt, INR, fibrinogen, pH, base value, lactate

• Fluid:• Less fluid given (13.9L vs 5L)• Less RBC, plasma, platelet transfusion

• Survival:• 24hr survival ( 97% vs 88%)• 30day survival ( 86% vs 76%)

Ongoing RCT

Single centre

Trauma patients with SBP <90mmHg need laparotomy or thoracotomy Exclude: age >45, <14, pregnant, history of IHD/CVA, head injury

Minimum blood pressure to trigger further resuscitation If spontaneously MAP higher than target, no further action

VSTarget Intra-opMAP 50mmHg

Target Intra-op MAP 65mmHg

Survival

MAP 50mmHg had better 24hr survivalreduced transfuion requirementLess coagulopathy

So Which way is correct

Consequences of aggressive fluid resuscitation and bursting the clot

Consequences of hypotension and decreased organ prefusion

Different Parties have different practice

ATLS

Everyone gets 2 liters of crystalloid initiallyRespondersTransient responders

○ rebolus or blood for ongoing bleedingNon-responders

○ blood for serious ongoing bleeding

NICE guideline

Recommendation on traumaAdults and older children

○ IV fluid should not be administered if radial pulse is present

○ 250ml IV fluid should be given if pulse cannot be felt

○ Burns, Blast injuries, Head injuries exception to permissive hypotension

US Army

Stop bleeding 500ml fluid if

○ No radial pulse or○ Decrease mental status

If positive response, stop fluids

Something is still missing

Unsolved problems

Concept of hypotensive resuscitation is clear

But the definition is not!○ Different studies use different definition

SBP? MAP? Limit crystaloid? Complete withhold or titrate against target BP?

Unsolved problems

Application in concomitant head injury patient?

○ Need to maintain CPP

Unsolved problemsApplication in concomitant head injury

patient?○ Lack of human study on this area○ Animal study: Stern 2000

Swine model on uncontrolled haemorrhage and brain injury- MAP 60 vs 80- Survival: MAP 60 better and MAP 80- Similar ICP and cerebral blood flow

Draw back: no long term neurological outcome

Unsolved problems

Duration of hypotensive resuscitation before irreversible damageLack of consensus

○ In Dutton’s studiesMean duration is 2.57 hourSimilar survival between 2 group

Difficult area for research Heterogeneous definition of hypotensive

resuscitation

Heterogeneous group of trauma patientsUS: both penetrating and blunt traumaUK: most blunt trauma and head injury

Ethical issue, difficult to recruit trauma patient

Limited paper focus on this topic

Conclusion Aggressive fluid resuscitation in trauma case may not be

totally beneficial

Multiple animal studies demonstrate benefits of hypotensive resuscitation

Equivocal result from human studies. Yet more recent studies demonstrate beneficial effect of hypotensive resuscitation

Different parties had different practice worldwide

Ongoing RCT may help to provide more evidence in near future