Anthony Holley, a world famous transfusion and coagulation guru, draws on his military, ED and ICU experience and talks about the most recent blood transfusion guidelines. They are a great resource and can be downloaded here. This talk is different to the last one he gave at Bedside Critical Care 2012!
3. Exsanguination
Haemorrhage remains a major and potentially
reversible cause of all trauma deaths.
More pronounced in the setting of penetrating
trauma.
Current literature from the Afghanistan and Iraq
conflicts report that as many as 15% of casualties
require massive transfusions
Mortality in this group is 20-50%
Bedside Critical Care 2012
4. Classically Trauma-induced
Coagulopathy
Bleeding Coagulopathy
Acidosis Hypothermia
Kashuk JL, Moore EE, Millikan JS, Moore JB. Major abdominal vascular
trauma—a unified approach. J Trauma 1982; 22:672-679.
Bedside Critical Care 2012
5. TOWARDS A DEFINITION, CLINICAL AND
LABORATORY CRITERIA, AND A SCORING SYSTEM
FOR DISSEMINATED INTRAVASCULAR COAGULATION
The consensual definition of DIC as proposed by the ISTH
“DIC is an acquired syndrome characterized by the
intravascular activation of coagulation with loss of
localization arising from different causes. It can originate
from and cause damage to the microvasculature, which if
sufficiently severe, can produce organ dysfunction”
Fletcher B. Taylor et al on behalf of the Scientific Subcommittee on Disseminated
Intravascular Coagulation (DIC) of the International Society on Thrombosis and
Haemostasis (ISTH) 2001
6. Diagnostic algorithm for the diagnosis of overt DIC
1.Risk assessment: Does the patient have a underlying disorder known to be
associated with overt DIC? If yes: proceed; If no: do not use this algorithm;
2. Order global coagulation tests (platelet count, prothrombin time (PT),
fibrinogen, soluble fibrin monomers or fibrin degradation products)
3. Score global coagulation test results
platelet count (>100 = 0; <100 = 1; <50= 2)
elevated fibrin-related marker (e.g. soluble fibrin monomers/fibrin degradation
products) (no increase: 0; moderate increase: 2; strong increase: 3)
prolonged prothrombin time (< 3 sec.= 0; > 3 sec. but < 6 sec.= 1; > 6 sec. = 2)
fibrinogen level (> 1.0 gram/l = 0; < 1.0 gram/l = 1)
4. Calculate score
5. If > 5: compatible with overt DIC; repeat scoring daily
If < 5: suggestive (not affirmative) for non-overt DIC; repeat next 1-2 days
Bedside Critical Care 2012
7. Clinical conditions that may be associated with overt DIC
1.sepsis/severe infection (any micro-organism)
2.trauma (e.g. polytrauma, neurotrauma, fat embolism)
3.organ destruction (e.g. severe pancreatitis)
4.malignancy
- solid tumors
- myeloproliferative/lymphoproliferative malignancies
5.obstetrical calamities
- amniotic fluid embolism
- abruptio placentae
6.vascular abnormalities
- Kasabach-Merrit Syndrome
- large vascular aneurysms
7.severe hepatic failure
8.severe toxic or immunologic reactions
- snake bites
- recreational drugs
- transfusion reactions
- transplant rejection
Bedside Critical Care 2012
8. Diagnostic algorithm for the diagnosis of overt DIC
2. Order global coagulation tests (platelet count, prothrombin time (PT),
fibrinogen, soluble fibrin monomers or fibrin degradation products)
3. Score global coagulation test results
platelet count (>100 = 0; <100 = 1; <50= 2)
elevated fibrin-related marker (e.g. soluble fibrin monomers/fibrin degradation
products) (no increase: 0; moderate increase: 2; strong increase: 3)
prolonged prothrombin time (< 3 sec.= 0; > 3 sec. but < 6 sec.= 1; > 6 sec. = 2)
fibrinogen level (> 1.0 gram/l = 0; < 1.0 gram/l = 1)
4. Calculate score
5. If > 5: compatible with overt DIC; repeat scoring daily
If < 5: suggestive (not affirmative) for non-overt DIC; repeat next 1-2 days
Bedside Critical Care 2012
9. A Time to Consider
1.Mechanism of coagulopathy
2.Tranexamic acid
3.Product ratios
4.Activated factor VII
5.Best modality to assess
coagulopathy
Bedside Critical Care 2012
10. Dilution?
Little or no dilutional effect of crystalloid therapy
on the standard tests of coagulation either in vitro
or in healthy volunteers
Colloid vs Crystalloid
Coagulopathy was present in 10% of patients who
received less than 500 ml of fluid
? Alternative mechanism
Bedside Critical Care 2012
11. Hypothermia?
Moderate/severe hypothermia present < 9% of
trauma patients
Relationship between hypothermia, shock and
injury severity is a weak independent predictor of
mortality (OR 1.19)
Very little effect of moderate hypothermia on
coagulation proteases.
Significant effects on function and clinical bleeding
only at temperatures < 33°C.
Bedside Critical Care 2012
12. Acidaemia?
Effects of IV HCL acid on human volunteers.
Definite dose–response of acidaemia on clotting
function by thromboelastometry.
Little clinically significant effect on protease
function down to a pH of 7.2 in in-vitro studies
Animal studies: pH of 7.1 produces only a 20%
prolongation of the PT & APTT.
Bedside Critical Care 2012
13. Consumption?
Consumption regarded as a primary cause of traumatic
coagulopathy
Little evidence for consumption of clotting factors as a
relevant mechanism
In patients without shock coagulation times are never
prolonged, regardless of the amount of thrombin
generated
Bedside Critical Care 2012
14. Time to Challenge the
Dogma?
“None of these appears to be responsible
for acute coagulopathy, and it appears that
shock is the prime initiator of the
process!"
Bedside Critical Care 2012
16. Drivers of Traumatic
Coagulopathy?
Shock and systemic hypoperfusion?
Dose-dependent prolongation of clotting times
with increasing systemic hypoperfusion.
Base deficit (BD) as a surrogate for perfusion
2% of patients with a BD < 6 mEq/l had
prolonged clotting times
20% of patients with a BD > 6 mEq/l.
Bedside Critical Care 2012
17. Mechanism of Acute
Traumatic Coagulopathy
Acute coagulopathy in massive transfusion appears to be due to
activation of anticoagulant and fibrinolytic pathways.
Thrombomodulin–protein C pathway is implicated.
Bedside Critical Care 2012
18. Procoagulant Antifibrinolytic
activity
Activity
Thrombus Normal
Haemostasis Bleeding
fibrinolytic Anticoagulant
activity Activity
Bedside Critical Care 2012
19. Protein C Activation
With tissue hypoperfusion the endothelium
expresses thrombomodulin which complexes with
thrombin.
Less thrombin is available to cleave fibrinogen
Thrombin complexed to thrombomodulin activates
protein C, which inhibits cofactors V and VIII
Bedside Critical Care 2012
21. Biological Response Pathological
in Shock
Tissues subjected to low-flow states generate
an anticoagulant milieu
Avoids thrombosis of vascular beds.
Bedside Critical Care 2012
22. Hyperfibrinolysis
Trauma is associated with increased fibrinolytic
activity.
Tissue plasminogen activator (tPA) is released from
the endothelium following injury and ischaemia.
Local control mechanism to reduce propagation of
clot to normal vasculature
Bedside Critical Care 2012
23. Hyperfibrinolysis
APC
Reduction in plasminogen activator inhibitor-1 (PAI-1) levels
in tissue hypoperfusion
24. A new understanding of coagulopathy in trauma:
potential therapeutic implications. 2012 Yearbook
of Intensive Care and Emergency Medicine.
Edited J.-L. Vincent. Springer. Read M, Holley A
25. Tranexamic acid
Effects of tranexamic acid on death,
vascular occlusive events, and blood
transfusion in trauma patients with
significant haemorrhage (CRASH-2): a
randomised, placebo-controlled trial
CRASH-2 trial collaborators. The Lancet. 2010;376:23-32
Bedside Critical Care 2012
28. The Study
Prospective double blind
274 hospitals
40 countries
n=20211
Tranexamic (n=10 060) acid vs placebo (10115)
1 g over 10 minutes then 1 g over 8 hours
Primary outcome: in hospital four week mortality
Bedside Critical Care 2012
31. But............
Entrance criteria soft (HR>110 bpm, SBP<90
mmHg)
70% of patients SBP > 90 mmHg
Only 16% of patients SBP <75 mmHg
No reduction in blood transfusion observed
Median no. of RBC units transfused = 3 in both
groups
Needs to be given within three hours of injury
Bedside Critical Care 2012
32. Tranexamic acid safely reduces the risk of
death in bleeding trauma patients!
Bedside Critical Care 2012
35. Holcomb JB, Wade CE, Michalek JE, Chisholm GB, Zarzabal LA, Schreiber MA, Gonzalez EA,
Pomper GJ, Perkins JG, Spinella PC, Williams KL, Park MS. Increased plasma and platelet to red
blood cell ratios improves outcome in 466
massivelyBedside Critical Care 2012
transfused civilian trauma patients. Ann Surg 2008; 248:447-458 .
36. Product Ratios
Massive data base ~ 25 000
16% transfused
11.4% received massive transfusions
Logistic regression identified the ratio of FFP to
PRBC use as an independent predictor of survival.
Higher the ratio of FFP:PRBC the greater probability
of survival.
The optimal ratio in this analysis was an FFP:PRBC
ratio of 1:3 or less.
Teixeira PG, Inaba K, Shulman I, Salim A, Demetriades D, Brown C,
Browder T, Green D, Rhee P. Impact of plasma transfusion in massively transfused
trauma patients. J Trauma 2009; 66:693-697 .
Bedside Critical Care 2012
37. Practice Point
In patients with critical bleeding
requiring massive transfusion,
insufficient evidence was identified to
support or refute the use of specific
ratios of RBCs to blood components.
Bedside Critical Care 2012
39. Activated Factor VII
Bedside Critical Care 2012 were enrolled. 143 blunt, 137 penetrating.
301 trauma patients
40. Randomized prospective trial
573 patients
No effect on mortality
No effect on thrombotic events
Trial stopped early for lack of efficacy!
Hauser et al. J Trauma. 2010 Sep;69(3):489-
500
Bedside Critical Care 2012
42. Levi M, Levy JH, Andersen HF, Truloff D. Safety of recombinant activated factor VII in
randomized clinical trials. N Engl J Med 2010;363:1791-1800.
Bedside Critical Care 2012
44. Recommendation 2
The routine use of rFVIIa in trauma patients
with critical bleeding requiring massive
transfusion is not recommended because of
its lack of effect on mortality (Grade B) and
variable effect on morbidity (Grade C).
Bedside Critical Care 2012
45. Practice Point Bedside Critical Care 2012
1. An MTP should include advice on the
administration of rFVIIa when conventional
measures – including surgical haemostasis and
component therapy – have failed to control
critical bleeding.
2. NB: rFVIIa is not licensed for this use. Its use
should only be considered in exceptional
circumstances where survival is considered a
credible outcome
3. When rFVIIa is administered to patients with
critical bleeding requiring massive transfusion, an
initial dose of 90 μg/kg is reasonable.
46. Summary
More to coagulopathy than acidosis, hypothermia and
dilution.
Almost certainly hypoperfusion is the principle driver.
Acidosis, hypothermia and dilution certainly contribute.
Despite advances in our understanding we haven’t yet found
the magic bullet.
We will have to wait for the definitive word on product
ratios.
Tranexamic acid given early seems to be safe and effective
and we are unlikely to get better evidence than CRASH2
Bedside Critical Care 2012
In each study, the time from injury to admission was relatively short at a median of 70–75 min. In the London study there was minimal prehospital fluid administration (median 500 ml) and we identified no relationship between fluid administration and the incidence of coagulopathy [6] . Higher volumes of fluid were given in the German study (mean 2200 ml) and there was a clear dilution effect, with coagulopathy present in more than 50% of patients who received more than 3 l of fluid in the prehospital phase [8•] . This may be a result of colloid use in this study as there appears to be little or no dilutional effect of crystalloid therapy on the standard tests of coagulation either in vitro [11] or in healthy volunteers [12] . Coagulopathy was still present, however, in 10% of patients who received less than 500 ml of fluid, suggesting an alternative mechanism is responsible.
None of the retrospective studies that identified early coagulopathy specifically reported patient temperature on admission. Moderate or severe hypothermia is present in less than 9% of trauma patients [13,14] . Although there is a relationship between hypothermia, shock and injury severity it remains a weak independent predictor of mortality (odds ratio 1.19) [14] . There is, however, very little effect of temperature on coagulation proteases at these temperatures, and significant effects on function and clinical bleeding are observed only at temperatures below 33°C [15–17] .
Acidemia affects the function of the coagulation proteases. Clinically it is difficult to separate the effects of acidemia per se and the effects of shock and tissue hypoperfusion. A recent study [18] examined the effects of intravenous administration of hydrochloric acid on human volunteers. While there was a definite dose–response effect of acidemia on clotting function as measured by thromboelastometry, clotting times were not prolonged. This is consistent with in-vitro studies for which there is little clinically significant effect on protease function down to a pH of 7.2 [16] and in animal studies for which a pH of 7.1 produces only a 20% prolongation of the prothrombin and partial thromboplastin times [17] . Whatever the exact effect of acidemia on coagulation function, it appears not to be reversible by simple correction of the acidosis [19,20] .
Consumption of clotting factors has always been regarded as a primary cause of traumatic coagulopathy [1] . There is little evidence, however, to support consumption of clotting factors as a relevant mechanism for acute traumatic coagulopathy, and nothing to suggest a process of disseminated intravascular coagulation (DIC). There is certainly activation of the tissue-factor dependent extrinsic pathway and a linear relationship between thrombin generation and injury severity [9••] . In patients without shock, however, coagulation times are never prolonged, regardless of the amount of thrombin generated [9••] . Further, fibrinogen levels are rarely decreased in patients with acute traumatic coagulopathy [19] . A commonly held belief is that traumatic brain injury releases ‘thromboplastins’ into the circulation which then lead to a consumptive or DIC-like coagulopathy. Again, however, there is no evidence to support this, and we [21] and others [22] have refuted the presence of a specific brain injury-related coagulopathy.
Shock and tissue hypoperfusion strong independent risk factor for poor outcomes in trauma no patient with a normal base deficit had prolonged prothrombin or partial thromboplastin times, regardless of injury severity or the amount of thrombin generated. In contrast there was a dose-dependent prolongation of clotting times with increasing systemic hypoperfusion. Only 2% of patients with a base deficit under 6 mEq/l had prolonged clotting times, compared with 20% of patients with a base deficit over 6 mEq/l. Higher injury severity increased the incidence and severity of coagulopathy in shocked patients. Fibrinogen and platelet levels were normal in all patients. Shock and systemic hypoperfusion appears to be the key driver of acute traumatic coagulopathy.
We were not able to measure activated protein C levels in this study due to the assay's complexity at the time. The activation of protein C, however, was strongly suggested by a dose-dependent prolongation of clotting times as protein C levels fell below normal. Corroborating this, we found that in the presence of hypoperfusion and increased levels of thrombomodulin, fibrinogen levels remained normal, indicating that less thrombin was available to cleave fibrinogen (as it was complexed to thrombomodulin). Nevertheless, confirmation of the generation of activated protein C in hypoperfusion is required to verify this hypothesis. Intuitively, however, it seems appropriate that
Trauma is associated with increased fibrinolytic activity. Raised D-dimer levels following injury have been identified in many studies [9••,27] . Activation of fibrinolysis occurs as tissue plasminogen activator (tPA) is released from the endothelium following injury and ischemia [28–30] . This is a local control mechanism to reduce propagation of clot to normal vasculature, and our study was consistent with these findings [9••] . We also, however, identified a reduction in plasminogen activator inhibitor-1 (PAI-1) levels in patients with tissue hypoperfusion, who had almost twice the levels of tPA than patients without shock. Activated protein C in excess will consume PAI-1 [31] and thus lead to a ‘de-repression’ of fibrinolytic activity and systemic hyperfibrinolysis ( Fig. 2 ).
Activated protein C in excess will consume PAI-1 and thus lead to a ‘de-repression’ of fibrinolytic activity and systemic hyperfibrinolysis