Damage control resuscitaion and Endpoints of Resus

What is damage control surgery?

• Operations performed in patients whose condition is in extremis due to bleeding, severely injured patients are unable to withstand prolonged procedures and physiological insults associated with definitive repair.

• Involves rapid control of bleeding and contamination

What is the time limit for DCS?

-90 min

What are the three steps of DCS?

1) Bleeding and contamination control and temporary abdominal closure

2)Critical care for restoration of physiology

3) Definitive surgery

What does damage control resuscitation entail?

• Critical care approaches correcting trauma induced coagulopathy and provide optimal resus

  Including: (5)

  • Permissive hypotension to prevent clots from dislodging

  • Minimal crystalloid use

  • Hemostatic resuscitation

  • Body warming

  • Early hemorrhagic control

Why is definitive management delayed in DCR?

• Aggressive definitive surgery results in worsening acidosis and hypothermia.

What is the lethal diamond and why is it termed lethal? (HHCA)

• Hypothermia

• Hypocalceamia

• Coagulopathy

• Acidosis

Set of physiological derangements that if not corrected will result in death

Discuss Trauma induce coagulopathy.

• Coagulopathy occurring very early on in injury, within 30min of injury, prior to significant dilution.

• ¼ of pts

• Higher mortality than those with normal clotting functions

How is TIC thought to occur?

• Pathophysiology not fully understood

• Thought to occur following injury and hypoperfusion

• Activation of protein c causing anticoagulant and fibrinolytic effects by inhibiting plasminogen activator inhibitor 1 (pai1)

Define permissive hypotension.

• AKA hypotensive resuscitation

• Restricting amount of resc fluids and vasopressors to maintain blood pressure lower-than-normal until bleeding is controlled.

• If BP is normal to high, clots that have formed will be dislodged and bleeding may increase.

What is the target systolic BP in permissive hypotension?

• 80-90mmHG

What is the downside of permissive hypotension?

• Prolonged hypotension can cause ischemic damage to end-organs and worsen lactic acidosis

What is the contraindication to permissive hypotension?

• Severe TBI: Target MAP >80 mm Hg

What is the ATLS recommended amount of crystalloids to be given in hemorrhagic shock?

• 1L- including any amount given pre-hospital setting

What are the risks of excessive crystalloid use?

• Dilutional coagulopathy

• Hypothermia

• Acute lung injury

• Abdominal compartment syndrome

• Immunological and inflammatory disorder

What is hemostatic resuscitation?

Transfusion of blood products: pRBC’s, FFP’s, Platelets, that approximates whole blood.

A high plasma-to-RBC ratio is independently associated with survival benefits

Early and aggressive plasma transfusion is associated with reduced mortality.

What is the optimal RBC-FFP and RBC-plasma ratio ?

Unknown

But RBC:FFP 1:1:1 ratio recommended within the 1st 6 hours reduces risk of death

What are the recommended ratios?

• 1:2 of FFP:RBC and Platelets:RBC ratios

What are causes of hypothermia in in trauma patients?

• Admin of large fluids and blood products

• Exposure of body

• Surgical intervention

• Alcohol and drugs use

Why is hypothermia a problem in hypovelamic resuciation?

• Platelet and enzyme dysfunction

• Function of clotting factors sensitivity decreased by at temps rangin 37-25 by 10% degrees even if no loss of clotting factors.

What are some rewarming modalities?

What must you think if hypothermia persists?

• Infusion of fluid at 40-42 deg

• Heated air inhalation

• Body cavity or gastric lavage with warm fluids

• Temp in emergency room/operating room raise to thermally neutral 28-29 deg

If hypothermia ongoing despite efforts: ongoing hemorrhage and unresolved tissue hypoperfusion and hypoxia should be suspected

Hemorrhagic shock causes a metabolic acidosis due to poor tissue perfusion and lactic acid production, how does the low pH affect coagulation factors?

• Low pH ;decrease from 7.4-7.0; decreases activity of factors by 70-90%

How is metabolic acidosis reversed in trauma pts?

• Fluid, blood resusc and vasopressor support.

• Surgical control of hemorrhage, revere shock and restore tissue perfusion

• Endpoints of resus and end organ perfusion: Base deficit and lactate

What is tranexamic acid and why is it recommended DCR?

What trial recommends TXA use?

• Hyperfibrinolysis contributes to TIC

• Anti-fibrinolytic, interferes with binding of plasminogen to fibrin.

• TXA (theoretically) prevents clot breakdown

• CRASH 2 trial in 2011- pts receiving TXA had 5.3% mortality, placebo group received had 7.5% mortality

On a TEG, what triggers tranexamic use?

• Increased clot lysis

When should tranexamic acid be given? Dose?

Between 1-3 h of injury

When given >3hours after injury, no decrease in mortality noted.

Dose: 1g iv or intraosseously mixed with 100ml N/saline for 10min followed by 1g steady drip over 8h

What is the rationale in giving fibrinogen concentrates?

• Bridges activated platelets and works as substate of thrombin to generate fibrin mesh.

• Fibrinogen decrease rapidly under low concentrations than other factors.

• Does not improve 30day mortality, improves 6 hour mortality

What is prothrombin complex concentrate?

• Contains factors 2,7,9,10.

• Used with TEG when clotting factors are indicated

• Fibrinogen alone or used in combo with PCC, showed significant improvement in fibrin polymerisation and shorter clotting time

In most centers, PCC is not approved for use in trauma, what is the alternative?

• Cryoprecipitate: Contains high concentration of fibrinogen

What is the drawback with cryoprecipitate?

• There are no reports on positive effects of cryo in the exsanguinating patient.

• Relatively unavailable

• Allogenic drawbacks

• Need blood typing

• Time consuming thawing

• Indications administration unclear

What is the advantage of using PCC and fibrinogen concentrate in coagulopathy?

• Transfusion of FFP and cryoprecipitate avoided in most pts

Why is calcium NB in bleeding pt?

• Calcium is a cofactor in coag cascade

• Blood products have citrate that chelate calcium

What is the preferred calcium preparation to manage hypocalcemia?

• 10% Calcium chloride -contains 270mg of elemental calcium/10ml

• 10% Calcium gluconate contains 90mg of elemental calcium/10ml

What is the recommended calcium level to maintain coagulation and cardiac contractility?

0.9 mmol/L

What are the defintions of massive transfusion? (24-3-1)

• 10 packed red cells within 24h of injury

• Replacement of 50% of blood volume in 3h

• Transfusion of >4 units in 1h with anticipation of more transfucion

What are the types of bloods to be given once MBT protocol is activated?

• Cooled O neg RBC’s

• Type AB FFP

• Platelets

What are the two components being replaced in transfusion?

• Intravascular volume

• Blood components

What is the diff between DIC and TIC?

TIC

• Triggered usually by severe trauma, due to hypoperfusion and with lethal lethal diamond.

• Characterised initially by hyper coagulopathic state then by hypocoagulation due to depletion of factors and fibrinogen

DIC

• Triggered by variety of conditions

• Widespread activation of coag cascade leading to microthrombi formation and consumption of clotting factors and platelets leading to excessive bleeding

• Prolonged PT and aPTT, LOW FIBRINOGEN, elevated d-dimer.

-ENDPOINTS OF RESUS-

What are the main targets of resuscitation?

• Metabolic endpoints

• Hemodynamic endpoints

• Regional perfusion endpoints

What equations are used to assess hemodynamic endpoints?

• Fick’s equation: Balance between DO2 and oxygen Consumption (vo2)

• DO2= CI x 1.34 x Hb x SaO2

• VO2= CI x 1.34 x Hb x (Sa-SvO2)

What parameters are used to asses for hemodynamic endpoints?

• MAP: DBP+1/3(SBP-DBP)

• CVP

• Mixed and central venous O2 sats( SvO2 and ScvO2)

• Echo

What are the targets of MAP?

• No consensus of target map in patients with non traumatic brain injury

• Severe TBI- MAP>85

• Permissive hypotension in most pt is allowed until control is bleeding is achieved

• Military uses fluid boluses only when radial pulses diminish or when mental status

What are target CVP readings and what are drawbacks of using CVP to asses CO?

• Target 18-20 mmHG in 1st 6h of resus(Surviving sepsis guidelines)

• Does not correlate with actual intravascular vol ro Right ventricular vol

• Altered in mechanical vnt and pulm hypertension

• Pursuit of cvp can result in over resuscitation

What do SvO2 and ScvO2 measure?

• Oxygen extraction by tissue

• ScvO2 of >70% is goal in resus

What IVC measurement defines hypotension?

• Measurement of < 2cm (flat)

What are parameters under metabolic endpoints?

• Lactate

• Base excess

• pH

How does lactate come about in shock?

• Shock results in regional hypoxia because of impaired DO2

• Anaerobic metabolism results in production of 2 ATP molecules and pyruvate instead of 36 ATP +CO2+ H2O produced in aerobic metabolism.

• Pyruvate is converted to lactic acid

What is the lactate level associated with poor outcome?

• 3.4mmol/L or >

What is a Base deficit?

• The amount of base required to increase 1L of whole blood to normal pH

Quantify Mild,Mod and Severe Base deficit.

• Mild 2-5 mmol/L

• Mod 6-14 mmol/L

• Severe >15 mmol/L

Why is base deficit a better measure of metabolic acidosis that pH?

• There are compensatory measures in place to maintain normal pH and bicarb values

• Predictive of transfusion requirements

What are some modalities used to asses for regional endpoints?

• Near-infrared Spectrometry NIRS- Measures StO2. Spectrometer placed on thenar eminence of hand.

• NIRS values are shown to be very low in trauma pts with severe shock