Author Question: Does Blood Loss Effect Fever?

Fraidy Asks:

I was wondering how blood loss would effect a fever? The character is ill with strep throat (or a stomach bug) and a fever that makes her want to cover up under layers of warmth. This is before an accident involving shattered glass and deep cuts and moderately serious blood loss. Would her fever be brought down due to the blood loss or would it complicate things more?

Jordyn Says:

Hi Fraidy! Thanks so much for sending me your question.

In your question, you don’t specify whether or not the patient/character has received treatment for the cause of her fever. In the case of strep throat, they should have been prescribed an antibiotic, and should be feeling markedly better in 24-72 hours. There can still be fever, but it should not be as high as the days go on if the antibiotic is working against the bacteria that is growing.

If this accident occurred say after three days, I would imagine she should be fever free by that time.

However, let’s say the character was just diagnosed and still has increased fever related to the illness.

I would theorize that a high fever, 102 degrees and higher, could cause your character to have some exacerbated symptoms related to additional blood loss. A high fever will naturally increase a patient’s heart rate— and so does blood loss. There could also be a concern that an untreated infection could cause the patient to go into septic shock, of which one complication of sepsis is lowered blood pressure. Low blood pressure is also a symptom of blood loss— if the patient bleeds out enough.

The combination of these two things, low blood pressure and increased heart rate, in light of a patient with a high fever and blood loss can paint a complicated picture for the medical team. They may not know which (blood loss or infection) is making their patient so sick so they would take a dual approach to their treatment which could entail the following.

1. Drawing labs that look at blood counts, blood chemistries, but also those that would address sepsis concerns like blood cultures. Also type and cross for blood. Initially, for symptoms of low blood pressure and tachycardia, the patient will usually receive fluid boluses of normal saline IV.

If the patient is really hypotensive (low blood pressure) and tachycardic (increased heart rate) and is not improved from the IV fluid, the medical team might choose to give O negative blood instead of waiting for a formal type and cross to come back. If the patient is actively bleeding and the bleeding is hard to control, they could opt to start giving blood right away.

2. Consider antibiotics early in the course of treatment once any body fluids are cultured the provider thinks necessary to determine the source of infection. It is helpful if a family member could offer insight into what infection the patient might have or the symptoms they were experiencing before the accident.

3. If the blood pressure remains low despite fluid boluses IV and perhaps blood, then patients are generally placed on a vasopressor which is a class of medications given as a continuous infusion IV to help raise blood pressure.

4. Treat the fever with a fever reducing medicine like acetaminophen or ibuprofen. If the patient is headed to surgery to treat wounds from the car accident, then acetaminophen (or Tylenol) might be preferred.

Hope this helps and best of luck with your story!

When Does a Person Require Blood Transfusion?

Sometimes, it’s hard to know when writing a scene when to pull the big guns out. If you have a character that is bleeding a lot (by whatever mechanism) when should you think about giving them blood? Or, better yet, when will the lack of blood begin to hamper their ability to function.

Fairly consistent among resources, hemorrhagic shock (shock related specifically to blood loss) is a life-threatening condition that results when you lose more than 20% or 1/5th of your blood supply. Patients will feel lightheaded, dizzy. Their respiratory rate and heart rate will be elevated. Their blood pressure might be low. They’ll look pale, pasty. Their skin might feel cool, clammy, dough-like.

But exactly how much blood does that translate to? I actually found this nifty little calculator that will give you a person’s estimated blood volume based on their age, sex, and weight. For instance, a man weighing 100 kg has an estimated blood volume of 7,500 ml. So losing 20% of his blood volume would be 1,500 ml of blood or approximately 3 pints of blood. A pint of whole blood (what you would donate) is approx 500 ml. A woman of the same weight has only 6,500 ml of circulating blood. An infant weighing 10 kg has only 800 ml of blood. You can see how that 20% translates much differently depending on the characters age, sex and weight.