In a nutshell: Abnormal Coagulation Tests and Blood Transfusion

In a nutshell: Abnormal Coagulation Tests and Blood Transfusion 54 year old man • Scheduled for elective hernia surgery
‘…Sir, the anaesthetist has cancelled this case … his bloods are abnormal…may bleed’
How does a patient stop bleeding during surgery (haemostasis)?
1. Vascular smooth muscle contraction 2. Platelet adhesion and aggregation 3. The coagulation system 4. The surgeon
The Haemostasis Screen
• Platelet count
Phospholipid Citrate anticoagulated
TF
HMWK
PK
TF
HMWK
Prolonged PT Normal aPTT
Normal PT Prolonged aPTT
Lupus anticoagulant
Multiple clotting factor deficiencies
The 50:50 Mixing Study
One volume Normal Plasma
Worse case scenario
Clotting factor at 0%
Factor concentrations of 30% or more should give a normal PT/PTT result
Total = 50% In clotting factor deficiencies, the PT or PTT should normalise If PT/aPTT remains prolonged, suspect inhibitors
When is the surgeon likely to encounter an abnormal coagulation
screen? • Pre-admission or pre-operative screening
investigation • As part of investigation for intra or post-op
bleeding that is beyond expected norms
If I were a surgeon, what does an abnormal coagulation profile mean to
me…. • Can I operate? • I need to operate – how can I operate? • I have operated – how will it affect my
operation? • My patient is bleeding and it is making me
look bad – do I need to and how do I correct it?
Is it really necessary to do a pre- operative coagulation screen for all
patients?
Pre-operative coagulation screening .… what you don’t know cannot hurt you!
Chee YL et al. BJH 2008
The pre-operative coagulation screen
• Indiscriminate coagulation screening prior to surgery or other invasive procedures to predict postoperative bleeding in unselected patients is not recommended. (Grade B, Level III).
• A bleeding history including detail of family history, previous excessive post-traumatic or postsurgical bleeding and use of anti- thrombotic drugs should be taken in all patients preoperatively and prior to invasive procedures. (Grade C, Level IV).
• If the bleeding history is negative, no further coagulation testing is indicated. (Grade C, Level IV).
• If the bleeding history is positive or there is a clear clinical indication (e.g. liver disease), a comprehensive assessment, guided by the clinical features is required. (Grade C, Level IV).
Chee YL et al. BJH 2008
Positive predictive value of abnormal coagulation test for post-op bleeding
Poor (inconsistent) predictive value
• In-vitro assays – do not necessarily reflect in- vivo haemostatic response
• Best use as diagnostic tests to confirm the presence of a bleeding disorder – not as screening test to detect a bleeding disorder
• Normal range excludes 2.5% of healthy people whose results may be above normal
The PT and/or aPTT is abnormal
Can I ignore an abnormal PT/aPTT?
• No personal or family history of bleeding • Marginal prolongation of 1-2 seconds beyond
the normal range
Before I call a colleague, what I should probably find out first?
• Known congenital bleeding disorder – Haemophilia A and B – Von Willebrand
• Known acquired bleeding disorder – Acquired factor inhibitors e.g against factor 8 – Drugs – e.g. anticoagulants – Liver disease – Sepsis/acute DIC
• A bleeding history
with known bleeding phenotype
• Prolongation of PT and aPTT common in liver disease
• Isolated prolonged PT seen in early liver disease due to fall in factor VII
• PT and PTT are poor predictors of bleeding • Routine correction of coagulopathy is not
required for non-bleeding patients
The patient on anticoagulant
wear off • If you cannot wait
– Warfarin: IV vitamin K AND 4 factor prothrombin complex (4F-PCC) or FFP
– Heparin/low molecular weight heparin – protamine sulphate
– Non-vitamin K oral antagonist – 4F-PCC
The patient with acquired coagulation factor inhibitors
• PLEASE…. TRY…… NOT TO OPERATE • If you do, be prepared to file for bankruptcy
for patient, doctor and hospital • Use recombinant activated factor VII or FEIBA
till such time when bleeding stops
The case of the lupus anticoagulant positive patient
• aPTT prolonged, PT normal, lupus anticoagulant demonstrated
• Patient is however prothrombotic • No correction of aPTT before surgery • Consider VTE prophylaxis after surgery
What do I give to correct coagulopathy?
• Known single factor congenital deficiency – Haemophilia A: factor VIII concentrates – Haemophilia B: factor IX concentrates – Von Willibrand disease: intermediate purity factor
VIII with high vWF – Factor VII deficiency: recombinant activated factor
VIIa – Others: fresh frozen plasma
Factor inhibitors
• Recombinant activated factor VII (Novo Seven) • FEIBA
Are there numerical guides on when I should correct an abnormal
coagulation profile before surgery? • INR >1.2 for surgery in critical areas • INR > 1.5 for major surgery in non-critical
areas • PT and aPTT > more than 1.5x the mid-point
of the normal range
If I give fresh frozen plasma, how much should be given?
• 10-20 mls per/kg • For the average size individual, at least 750
mls (approx. 3 packs)
The platelet count – what is a ‘safe” number for surgery
• 50 x 109/L for major surgery in non-critical areas
• 100 x 109/L of surgery in critical areas e.g intracranial, spinal, ocular surgery
Packed red cell transfusion
transfusion • Hb<7 gm/dl – beneficial especially when
symptomatic or if there is ongoing blood loss • Hb 7-10gm/dl – individualized. Assess
symptoms and signs, co-morbidities, evidence of ongoing blood loss or potential for blood loss
Singapore Med J 2011; 52(3) : 211
Thank you
The typical case
The Haemostasis Screen
The 50:50 Mixing Study
When is the surgeon likely to encounter an abnormal coagulation screen?
If I were a surgeon, what does an abnormal coagulation profile mean to me….
Is it really necessary to do a pre-operative coagulation screen for all patients?
Pre-operative coagulation screening .…what you don’t know cannot hurt you!
The pre-operative coagulation screen
Positive predictive value of abnormal coagulation test for post-op bleeding
The lowdown on PT and aPTT
The PT and/or aPTT is abnormal
Can I ignore an abnormal PT/aPTT?
Before I call a colleague, what I should probably find out first?
When do I need to give something before surgery?
The case of the patient with liver disease
Slide Number 23
The case of the lupus anticoagulant positive patient
What do I give to correct coagulopathy?
Factor inhibitors
Are there numerical guides on when I should correct an abnormal coagulation profile before surgery?
If I give fresh frozen plasma, how much should be given?
The platelet count – what is a ‘safe” number for surgery
Packed red cell transfusion