bruce cartwright: blood conservation
DESCRIPTION
Bruce Cartwright speaks about surgical, peri and post-op methods blood conservation for patients undergoing surgery.TRANSCRIPT
BLOOD CONSERVATION Bruce Cartwright Royal Prince Alfred Hospital
Status quo? • Cardiac surgery consumes 15-20% of blood product
supply • RBC transfusion rate 5-80%; platelets up to 40%
• Up to 20% of cardiac surgical patients have a preoperatively identified risk factor for bleeding
• Around 5% of patients return to the OR for investigation of bleeding • “Microvascular coagulopathy” is diagnosed in >50%
The cardiac dilemma • Don’t transfuse
• Re-exploration for bleeding increases morbidity and mortality up to 3 to 4 times
• Acute bleeding causes haemorrhagic shock, tamponade and cardiac decompensation
• Return to ICU after re-exploration is associated with higher rates of infective complications, arrhythmias and prolonged pulmonary support and complications
• Do transfuse • Risk especially with platelets • TRALI, allergy, allommunisation, GVHD, renal failure, volume
overload (TACO), immunosuppresion/immunomodulation • Increasing COST
Normal perioperative course
Normal cardiac course HAEMODILUTION ACTIVATION CONSUMPTION CPB Prime - crystalloids/colloids
Contact Activation - XIIa, kallikrein and
bradykinin
Thrombin and Plasmin mediated
Cardioplegia Tissue factor activation - Tissue injury - Monocyte related - Pericardial blood
Inflammation mediated - Elastase - Complement - Leukocyte-platelet
complexes Cell Salvage - Loss of platelets and coagulation factors
Activation of fibrinolysis - Increased tPA via
endothelial cells and pericardial cavity
- Intrinsic activation - Heparin and
protamine effects
Mechanical (ECC) - Oxygenator - Cardiotomy suction
and vents - Filters - Centrifugal and roller
pumps
Coating the Circuit
Edmunds, L. H. (2004). Cardiopulmonary bypass after 50 years. New England Journal of Medicine, 351(16), 1603–1606
What do we do to address this? Key components
• Attentive preoperative assessment • Surgical approaches to limit periop bleeding • Strategies to limit haemodilution, activation and
consumption associated with extracorporeal circulation • Systemic and topical pharmacological agents • Point of care testing to target blood product therapy and
recently use of factor concentrates • Post operative fluid management and transfusion
thresholds to limit unnecessary blood product use
Preoperative assessment • Current Strategies
• identification of at-risk patients • cessation of over the counter supplements and all herbal remedies • timing of surgery with clopidogrel cessation according to platelet
aggregometry threshold • investigation of preoperative anaemia
• Considerations for the future: • screening for anaemia in preop clinic with subsequent
administration of IV iron +/- erythropoietin
Surgical Strategies • IMA bed haemostasis prior to retractor removal • immediate bandaging of vein harvest sites • attention to sternum, ITA bed, pericardial edges and aortic
adventitia prior to sternal closure • topical haemostatic agents • topical tranexamic acid on pericardium prior to closure • cell salvage especially for OPCAB and redo sternotomy • stratification to OPCAB where antiplatelet therapy
inappropriate for cessation if possible
Perioperative Perfusion Strategies • Current strategies
• Pre bypass fluid limited to 500ml crystalloid • Retrograde autologous priming in all patients • Transfusion trigger based on DO2i rather than Haematocrit alone
together with supportive evidence of VCO2i, SvO2, lactate and adequacy of regional circulation where available such as NIRS
• Normovolaemic haemodilution in selected cases • Shear force and blood air interface management: pump sucker
activated only on demand, minimisation of air entrainment into vents
• Future considerations • biocompatible circuits, heparin alternatives, platelet anaesthesia • quarantining of cardiotomy blood • modified ultrafiltration
Systemic pharmacological agents Current practise • Tranexamic acid • No routine use of starch solutions Future directions • Aprotinin returns? • Cangrelor platelet anaesthesia • Direct thrombin vs indirect thrombin inhibition
Point of Care Testing Multifaceted approach • Viscoelastic testing
• Need to utilise full capacity of technology • Rapid TEG, heparinase TEG, functional fibrinogen, platelet
mapping where appropriate • ROTEM: ExTEM, FIbTEM, InTEM, hepTEM, ApTEM
• Platelet aggregometry • Multiple electrode aggregometry (Multiplate)
• Activated Clotting time • low range vs high range, heparinase
• Prothrombin complex assessment • Coagucheck with Quick estimation
• Rapid turnover platelet count and fibrinogen level
Post operative management • Crystalloid resuscitation in preference to HES & 4%
Albumex • no fluid challenge use for treatment of isolated low CVP or
low urine output where all other signs point to adequate cardiac output
• no empiric blood product transfusion • red cell transfusion trigger: Hb <70 unless evidence of
cardiogenic shock, severe vasoplegia or end organ dysfunction
• protamine where heparin rebound has been documented • early take back where point of care testing rules out
microvascular coagulopathy
Results • All case transfusion rate: steady fall from 65% to 35%
0
10
20
30
40
50
60
70
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
Results – average usage
0
0.5
1
1.5
2
2.5
3
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
Red Blood Cells
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
Platelets
0
0.5
1
1.5
2
2.5
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
Fresh Frozen Plasma
0 0.5
1 1.5
2 2.5
3 3.5
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
Cryoprecipitate
Results – cost reductions
0.00
0.02
0.04
0.06
0.08
0.10
0.12
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
Activated Factor 7
$0
$500
$1,000
$1,500
$2,000
$2,500
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
Total cost per patient
$0
$200,000
$400,000
$600,000
$800,000
$1,000,000
$1,200,000
$1,400,000
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
At 600 per year
Elective Coronary Surgery
0
10
20
30
40
50
60
70
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
Elective Surgery – other benefits
• average decrease in 4 hour blood loss of 31% • reductions in ICU length of day by 25 hours when not
transfused (vs transfused) • reduction in length of hospital stay by 1 day when not
transfused
Current Challenges
0
10
20
30
40
50
60
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
Non Elective Coronary
0 10 20 30 40 50 60 70 80 90
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
Aortic Surgery
Future directions • Preoperative Fe +/- EPO • Circuit Modifications
• biocompatible circuits, heparin alternatives, platelet anaesthesia • quarantining of cardiotomy blood, MECC • modified ultrafiltration
• Aprotinin or alternatives • Integrated electronic data collection • Tranfusion trigger assessment • Refining POC algorithms • State/Nationwide/International colloboration • Factor Concentrates