42 | Help, my patient has no platelets! How to care for thrombocytopenic patients

HaematologyNursingEmergency and Critical CarePodcast
Written By Laura Jones

Picture this: you’re working the Saturday morning shift, you’re wrapping things up ready to close, and your vet brings through a patient from consults.

 

The patient is a 6-year-old cocker spaniel, and they’ve got a history of lethargy and exercise intolerance, progressing to melena, haematuria and bruising in the last 2 days. You examine them with the vet and find they’re dull, tachycardic and have bounding pulses.

What’s going on, and most importantly, what are you going to do about it? Well - they have some kind of bleeding disorder, and based on these signs, there’s a good chance they have very low platelet levels. 

But why does this happen, and how can we support these patients? We’ll dive into all of that in this episode of the Medical Nursing Podcast.

But before we do that…

Before we dive into the episode, I have an exciting update for you! I am SO excited to let you know that I’m delivering a free, on-demand webinar on October 14th about how to give better care to your patients in less time. The webinar will be sent straight to your email inbox, along with tips, tricks, and support to help you implement this care to your own patients. To watch the session, simply pop your email address in the box below.

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With all that said, let’s get right into what thrombocytopenia is and its consequences for our patients.

So what IS thrombocytopenia?

Thrombocytopenia is a decrease in circulating platelet levels. Platelets are the first line of defence against bleeding—when the body detects a blood vessel injury, our platelets create a plug to cover the site temporarily. Our clotting factors turn this plug into a more stable, long-lasting blood clot.

When platelet levels are low, there are not enough platelets to create this plug and bleeding results. Spontaneous bleeding can occur when platelet levels become very low—less than 40,000 platelets per microlitre.

What causes thrombocytopenia in our patients?

There are a few causes of thrombocytopenia, including decreased platelet production inside the bone marrow, platelet consumption or loss, and platelet destruction.

Platelet production issues are commonly seen in patients receiving cytotoxic medications, patients with viral infections (e.g., parvovirus and FeLV), and patients whose immune systems attack the platelet precursor cells in the bone marrow.

Platelet loss occurs secondary to haemorrhage. Thankfully, this usually causes a low-grade thrombocytopenia, which resolves when the bleeding stops.

Platelet consumption, on the other hand, occurs when our platelets become used up. The example everyone thinks of is disseminated intravascular coagulation (DIC), where platelets and clotting factors are used to form microthrombi, leaving the patient at risk of bleeding.

And then there’s destruction…

Platelet destruction is the most common cause of thrombocytopenia in our patients. It’s usually caused by the immune system, much like IMHA, and so, for the rest of this episode, we’ll be chatting about nursing patients with immune-mediated thrombocytopenia or IMTP.

What is immune-mediated thrombocytopenia?

Immune-mediated thrombocytopenia (IMTP) occurs when the immune system destroys platelets within the circulation. Like IMHA (which we chatted about in episode 41), IMTP can be a primary (aka non-associative) or secondary (associative) disease.

Most cases are primary, though IMTP secondary to infections, neoplasia, or certain medications can also be seen.

What signs do we see in these patients?

Patients with thrombocytopenia typically present with evidence of bleeding and signs associated with haemorrhage. These include:

  • Petechiation – pinpoint haemorrhage on mucous membranes

  • Ecchymoses – small skin bruises, classically seen on the ventral abdomen

  • Scleral haemorrhage

  • Melena

  • Epistaxis

  • Haematuria

  • Gingival bleeding

  • Lethargy

  • Exercise intolerance

  • Anorexia

  • Weakness

  • Collapse

Other clinical signs may also be seen depending on the location and severity of the bleeding. For example, one of my recent IMTP patients had such severe haematuria she developed a large blood clot in her bladder, which caused a urinary tract obstruction and an acute kidney injury. So, on top of her signs of bleeding, she had stranguria, dysuria and pollakiuria, too.

If a patient’s thrombocytopenia causes significant bleeding, they’ll develop anaemia, too. Alternatively, immune-mediated haemolytic anaemia may be seen alongside IMTP as part of Evan’s syndrome, which we discussed in episode 41.

Severe anaemia will cause hypovolaemia and a lack of oxygen delivery to tissues. So, assess your patient’s cardiovascular system carefully, looking for signs of hypovolaemia. Bounding or poor pulses, pale mucous membranes, prolonged CRT, tachypnoea, and either tachycardia or bradycardia are all signs your patient may be transfusion-dependent.

Where these signs are seen, we’ll need to prioritise getting a whole blood transfusion underway—ideally, a fresh one since this is a more reliable source of platelets. But we’ll chat more about transfusions in a later episode in this series.

So you think your patient has IMTP. What’s next?

We need to perform diagnostic tests to confirm our suspicions - and there are lots of nursing skills we can use whilst doing this, including:

  • Careful venepuncture (avoiding the jugular vein, using small needles, good draws, and lots of pressure afterwards)

  • Haematology sample processing and handling and interpretation

  • Blood smear preparation and examination to count the patient’s platelets

  • Assessing the patient’s buccal mucosal bleeding time

  • Infectious disease testing to look for underlying causes of associative IMTP

  • Obtaining chest x-rays

  • Assisting with or obtaining abdominal ultrasound images for interpretation

We might also perform coagulation testing in these patients, as we need to investigate the reason for their bleeding. And if your patient is showing signs of concurrent IMHA, we’ll need to do additional tests to confirm this, such as an in-saline agglutination test (as we chatted about in episode 41).

And what about treatment and nursing care?

Once your patient has a diagnosis, it’s time to discuss treatment. Treating non-associative IMTP involves suppressing the immune system to prevent it from attacking the body’s platelets. 

Let’s talk immunosuppression

Just like with IMHA, there are lots of drugs we can use to do this, and we usually use combination therapy to minimise the doses needed and, therefore, the side effects seen of any one agent. 

Common medications include prednisolone +/- mycophenolate, ciclosporin, azathioprine or cyclophosphamide. By adding a second immunosuppressive, we can (hopefully) reduce our prednisolone dose, meaning our patients hopefully are less PU/PD as a result!

Since some of these medications are cytotoxic, they require careful handling and administration, both within the clinic and at home - and veterinary nurses and technicians are ideally placed to advise and support clients with this.

Alongside advising clients on handling these medications, patients receiving them should be carefully managed in the hospital, including their saliva and eliminations.

What else can we do for these patients?

Vincristine, as well as being used to manage common cancers, can also be used in low doses to stimulate platelet release from the bone marrow - and we commonly do this in patients with severe thrombocytopenia! 

Even though we’re using it at lower doses, we still need to handle and administer vincristine carefully. It should be prepared within a secure area, and full chemotherapy PPE should be worn during handling, preparation, and administration.

 A closed system transfer device should be used for administration to prevent environmental contamination with a cytotoxic drug, and a new, first-stick IV catheter should be placed ahead of vincristine administration because vincristine is a vesicant and can cause severe irritation and necrosis when extravasation occurs.

Just like IMHA, human intravenous immunoglobulin (hIVIG) has been used as a salvage procedure in patients not responding to immunosuppression and vincristine. Success rates in humans with IMTP are high, but more studies are needed in veterinary patients.

And what about blood transfusions?

Patients who present with severe bleeding secondary to thrombocytopenia may need a blood product transfusion. 

We have a few options for this: 

  • Whole blood (which will replace the red blood cells and plasma lost +/- reliably provides platelets, depending on how fresh the blood has been collected)

  • Packed red blood cells (which will increase oxygen carrying capacity and correct anaemia, but not improve platelet levels)

  • Platelet concentrate (which will stop bleeding but not replace the lost red blood cells or plasma)

What else do we do to support patients with IMTP?

It really depends on the individual patient and their clinical signs. Many patients benefit from supportive treatments such as fluid therapy, antiemetics and gastroprotectants. If a patient has severe haematuria causing dysuria and there is concern for obstruction, then a urinary catheter will be needed - though we need to bear in mind that catheterisation itself comes with a high risk of bleeding in these patients.

Our approach is really aimed at suppressing the immune system to stop the ongoing platelet destruction and prevent further bleeding and then to provide supportive care and stabilisation whilst those drugs take effect. These patients are often challenging to nurse and require careful handling and sampling to prevent further bleeding and administration of blood products as needed. However, they’re also very rewarding - there’s nothing like seeing those platelets come up with each blood smear examination you do, seeing your patient’s bruising resolve, and then seeing them finally get to go home.

So, that’s an overview of treating and managing thrombocytopenia in our patients. Our role as nurses is vast, and we get to put lots of skills to the test with these patients—so the next time you see one, don’t be afraid to get stuck in!


Did you enjoy this episode? If so, I’d love to hear what you think. Take a screenshot and tag me on Instagram (@vetinternalmedicinenursing) so I can give you a shout-out and share it with a colleague who’d find it helpful!

Thanks for learning with me this week, and I’ll see you next time!

References and Further Reading

Laura Jones
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