A session blog from Day 2 of State of the Art, London December 2015. See the full list.
Blogger: Tom Heaton
Managing coagulation abnormalities in critical care
Jecko Thachil opened the session on bleeding in critical care by providing the perspective of an experienced haematologist. He revisited some of the important physiological basics of haemostasis, noting that it involves the vessel wall, VWBF, platelets and fibrinolysis – i.e. much more than just the coagulation factors. The balance of pro and anti-coagulant factors is complex and often forgotten about.
- Pt and APTT frequently deranged – 84% PT & 40% APTT tests deranged in one study at his unit – but only a 3 of the 58 patients had bleeding.
- Coagulation tests (PT and APTT) are pretty simple and tell us very little about the overall haemostatic picture.
- In critical illness, many clotting factors are deranged and low, but not to the degree that would cause bleeding.
- Balance of clotting factors can actually be pro-coagulant e.g. increased fibrinogen.
- Platelets are often an underrated factor in coagulation.
- Factors in sepsis are often more related to vascular and platelet dysfunction.
- DIC is a dynamic process – not necessarily based on specific values but changing values – e.g a dropping platelet count more relevant.
- Therefore, these tests aren’t useful to predict bleeding – they provide a limited picture.
- Thromboprophylaxis is still important in patients with biochemical abnormality of clotting and should be given in most cases – needs a clinical risk assessment not based purely on PT and APTT.
- Don’t perform clotting tests unless there is bleeding or dropping platelet count – perhaps controversial.
- Coagulation test abnormality often not clinically relevant.
- American Physiological Society. New fundamentals in haemostasis – http://physrev.physiology.org/content/93/1/327
- Critical Care. Point-of-care coagulation management in intensive care medicine – http://www.ccforum.com/content/17/2/218
Bleeding in liver disease
This opening was followed by an exploration of the challenges with coagulation in a common subset of ITU patients; those with severe liver disease.
- Coagulation tests are often deranged in liver disease (prolonged PT and APTT)
- Suggestion would be that they are at risk of bleeding – actually probably pro-coagulant.
- Liver disease affects the whole spectrum of coagulant factors – pro and anti.
- We rarely go looking for the pro-coagulant tests – we look mainly at factors that test for risk of bleeding (mainly just PT and APTT). We therefore have a poor view of the patient’s overall haemostatic state.
- This means we can see very high INRs, but protein C and S etc. are also very low.
- TEG/ROTEM is probably better for providing a more balanced picture – not perfect though as doesn’t take into account vascular or VWBF component.
- Suggestion is that we are moving towards anticoagulation in these patients – there is probably only a small subset of acute liver failure patients who do have the increased bleeding risk.
- Additional caveat- liver disease patients appear to have an increased incidence of HIT – beware the falling platelet count in these patients.
- The message is: Treat active bleeding – but prevent thrombosis.
- Liver International. Prophylactic anticoagulation for VTE not associated with high rates of GI bleed – http://onlinelibrary.wiley.com/doi/10.1111/liv.12211/abstract
- World Journal of Gastroenterology. Coagulopathy in liver disease. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4572787/
- NEJM – Coagulopathy in CLD – http://www.nejm.org/doi/full/10.1056/NEJMra1011170
Blood and plasma: learning from the prehospital setting
The session was wrapped up by David Naumann exploring the latest thoughts on the blood products in the prehospital setting. He started with a description of the changing thoughts on this through history, particularly influenced by the different military conflicts.
- Opening question: Why bother with prehospital blood products?
- Blood products better than crystalloid in hospital – so why not bring this out to prehospital arena?
- Crystalloid restriction is currently en vogue, again why not bring this to the pre-hospital setting?
- But transfusion is not without its risks e.g. transfusion reactions.
- Also some big logistical issue – e.g. costs, wastage.
- But if prehospital blood improves patient outcome, then it should be used for all patient –this needs to be evidence based though.
- Described a systematic review of the evidence – 28 studies looking at this question – mainly poor quality and only one prospective study.
- Patients receiving blood often sicker patient/worse injuries
- Overall: No mortality benefit, no benefit to early mortality, improvement in shock index – but sicker patients.
- In general the data is poor and doesn’t really answer question – 28 studies which are heterogeneous and poor quality.
- However there are 4 RCTS recruiting now to look at this – RePHILL study the UK one.
- Therefore little to add at this time– we really need to await results of RCTs.
- Prehospital Emergency Care – Prehospital transfusion in trauma patients – http://www.ncbi.nlm.nih.gov/pubmed/24932734
- University of Birmingham – the RePHILL study – http://www.birmingham.ac.uk/research/activity/mds/trials/bctu/trials/portfolio-v/Rephill/index.aspx
- Study protocol for systematic review on prehospital transfusion – http://www.systematicreviewsjournal.com/content/3/1/123