Help, my patient is bleeding! the veterinary nurse's guide to coagulation: part 2
Do bleeding patients increase your blood pressure, or are you a dab hand at nursing these patients?
In this post, we’re continuing our focus on bleeding and clotting! If you’ve not read part 1 of this post make sure you catch up on it here. By the end of this post, part 2, you’ll understand the common coagulation disorders we see, and how to nurse the bleeding patient.
If you want to learn even more about these patients, join me in a few weeks for the haematology nursing workshop on July 18th. We’ll work together to plan care for these patients, calculate and administer transfusions and much more! You’ll also get a free copy of the VIMN haematology guide for signing up!
Coagulopathies
Coagulopathies are disorders of clotting (secondary haemostasis).
They can be seen due to congenital clotting factor deficiencies, or acquired, due to toxin ingestion or hepatic dysfunction.
Inherited Coagulopathies
The most common inherited coagulopathies include haemophilia A, haemophilia B and factor XII deficiency.
Haemophilia A and B
Haemophilia A is the most common canine coagulopathy.
It occurs due to a deficiency in factor VIII, which is part of the intrinsic clotting pathway.
It is most commonly seen in large breed dogs, particularly German shepherd dogs.
Haemophilia B is the second most common coagulopathy, and this occurs due to an inherited deficiency in factor IX.
This, like factor VIII, is part of the intrinsic coagulation pathway. It is seen more commonly in male dogs, and Labrador retrievers are overrepresented.
Clinical Signs
The clinical signs of these conditions are similar to von Willebrand’s disease, as these patients cannot form blood clots.
Though platelet function is unaffected (because it's a clotting factor disorder, not a platelet disorder), because the platelet plug does not last long, haemorrhage continues.
As haemophilias are genetic conditions, affected animals should not be bred.
Feline Congenital Coagulopathies
Factor XII deficiency is a common inherited coagulopathy affecting cats.
It most commonly affects Siamese cats and has no sex predilection.
Patients with factor XII deficiency show no clinical signs and do not require any treatment.
Acquired Coagulopathies
Acquired coagulopathies are normally to do with the vitamin K-dependent clotting factors.
Deficiencies in these can be seen due to toxicity (usually anticoagulant rodenticides), or due to hepatic disease.
Anticoagulant Rodenticide Toxicity
Rat poisons typically contain warfarin, bromadiolone or brodifacoum.
These substances are vitamin K antagonists – they reverse the action of vitamin K. Without sufficient vitamin K, the body cannot synthesise clotting factors (specifically our Vitamin K-dependent factors, II, VII, IX and X), leading to haemorrhage.
Hepatic Disease
Patients with severe acute or end-stage liver disease may also present with coagulopathies.
This occurs due to the liver’s vital role in synthesising coagulation factors.
The result of hepatic-associated coagulopathy is a syndrome similar to anticoagulant rodenticide toxicity.
Diagnostics
The most common diagnostics performed in the coagulopathic patient are clotting times. There are two parameters we commonly measure in practice – APTT and PT.
APTT is activated partial thromboplastin time. It tells us about the intrinsic clotting pathway. The normal range is approximately 90-120 seconds.
PT is prothrombin time. This test assesses the extrinsic and common coagulation pathways. The normal range for PT is typically 10-20 seconds.
Other diagnostics include testing for specific coagulation factors where a deficiency is suspected.
These are submitted to an external laboratory and often have specific sample collection and handling requirements, so it is worth double-checking with the laboratory how they would like the sample collected, before going ahead with sampling.
Some laboratories will accept whole blood in sodium citrate anticoagulant; others want frozen citrated plasma. When collecting samples for coagulation testing, the following considerations are really important:
Collect the sample as quickly as possible (i.e., not allowing the blood to clot in the syringe)
Fill the tube immediately after the sample is collected
Ensure you fill the tube to the line (1.3ml will be needed for a standard tube, not 1ml!)
Rotate the tube thoroughly to mix the blood and anticoagulant
If you’re separating the plasma off for external submission, you need to centrifuge this as soon as possible, then separate the plasma into a plain tube and freeze it.
Treating Coagulopathies
Emergency Stabilisation
Coagulopathic patients frequently present with evidence of haemorrhage. They can be very unstable due to this, with severe signs of hypovolaemia.
On presentation, we need to immediately triage these patients, and stabilise them appropriately based your findings.
This may include:
Fluid resuscitation to maintain perfusion until a blood product is sourced/administered
Respiratory support/oxygen therapy where pulmonary haemorrhage has occurred
Blood Transfusions
Plasma products are generally required to replace the clotting factors not present. Depending on the clotting factor deficient, either fresh frozen plasma or stored plasma should be used.
Patients with haemophilia A require fresh frozen plasma, since factor VIII is a labile factor. Labile clotting factors are generally not reliably present within plasma products as they age.
However, as stored (frozen) plasma contains the vitamin-K dependent clotting factors, it is suitable to use for coagulopathies caused by hepatic disease or anticoagulant rodenticide toxicity.
If the coagulopathy has caused significant haemorrhage, packed red blood cell transfusion may be required to replace the lost RBCs and provide oxygen-carrying support.
Decontamination
Emesis should be induced, and GI decontamination should be performed in the anticoagulant rodenticide toxicity patient, depending on how recently they ingested the toxin.
Vitamin K should also be administered as a priority. This is initially done parenterally, via subcutaneous injection.
After the patient has been stabilised, they can be transitioned to oral vitamin K for an appropriate duration, based on the individual toxin ingested. As vitamin K is a fat-soluble vitamin, we also need to give our patient enough dietary fat intake whilst receiving treatment.
Nursing The Bleeding Patient
In terms of nursing care, all of our haemostasis disorder patients must be handled incredibly carefully due to their risk of haemorrhage. In addition to general nursing care, specific areas to consider include:
No jugular venepuncture – peripheral veins only, with pressure bandages and small needles
No neck leads – harness walk only if possible
No IM (+/- SC) injections
No urinary catheters – due to the risk of haematuria
No cystocentesis sampling
No nasal feeding tubes – due to the risk of epistaxis
No dry food – due to the risk of gingival bleeding
Gentle handling – utilise anxiolytic drugs or sedation if a patient is stressed or challenging to restrain, to minimise injury or the need for excessive restraint
Resting the patient and carrying them out to the toileting area where possible
Monitoring the patient’s vital signs at appropriate intervals
Transfusion preparation, administration and monitoring
Closely monitoring any surgical or venipuncture sites for ongoing haemorrhage
That brings us to the end of our coagulation posts - as you can see, there’s a lot to think about when nursing these patients! From preparing and administering blood products, to resting them and careful handling, there is a lot we can do to show off our nursing skills.
Want to know more about how to select, calculate and administer blood products, and plan nursing care for your haematology patients? Don’t forget to join me on July 18th for our interactive haematology workshop! If you’ve not got your ticket yet, grab it here.
Do you see many bleeding patients? How do you nurse them? Be sure to DM me on instagram and let me know! I can’t wait to hear from you.
References
Day, M. and Kohn, B. 2012. BSAVA Manual of Canine and Feline Haematology and Transfusion Medicine. Gloucester: BSAVA.
Merrill, L. 2012. Small Animal Internal Medicine for Veterinary Technicians and Nurses. Iowa: Wiley-Blackwell.
