Hypovolemia: Definition, Causes & Treatment

In today’s micro lecture, Australian Paramedical College Hon. Snr. Lecturer Sam Willis discusses hypovolemia; “hypo” meaning low, “volemia” meaning volume,  in terms of blood or any other fluid.

In today’s micro session, we’re going to talk about hypovolemia.

Hypovolemia means low volume. Hypo meaning low, volemia meaning volume.

Usually, when we think about hypovolemia, we think about low blood volumes, but to be honest, it can be any type of fluid in the body that is low. Remembering that the body is consistent of blood and water and plasma and a range of other fluids.

Hypovolemia is a life-threatening condition when you’re losing large volumes of fluid or blood. Now, when you arrive on scene at somebody who has what we call catastrophic hemorrhage, in other words, somebody who’s been stabbed, or shot, or hit by a car, or fallen from a great height, and there’s clearly excessive, catastrophic hemorrhage. It’s so important that you do address that bleeding before you do anything else.

Arresting major external hemorrhage is so important. That means getting your tuff cut scissors out, cutting clothes off, making sure you find the source of the bleeding and stop the bleeding straight away. Low volume doesn’t just mean low external hemorrhage.

For example, somebody hit by a car or fallen from a height can absolutely have internal bleeding. The paramedic won’t be able to see that directly, but instead what they will do is they will use a range of other signs or symptoms to identify that low blood volume. That includes looking at the patient’s levels of consciousness. Looking at the patient’s pallor. Are they pale? Are they sweaty? Is the color normal? Are they well perfused?

We’ll also be thinking about their vital signs. If somebody is looking a little bit confused. They had lower GCS and you feel for their heart rate and the heart rate is fast and their breathing is fast, that person is in a state of shock.

Recognizing low blood volume is really, really important. Something we don’t tend to think of low blood volume with is conditions of burns. Remembering that when a patient is burnt, you have movement of fluid. When a person has a movement of fluid from an intracellular space to an extracellular space or an extravascular space, your patient is going to be hypovolemic, because the fluid has moved from one space where it should be to another space where it shouldn’t be.

That’s why when we’re treating a patient with burns, we don’t just focus our treatment around pain management, cooling the burns, our usually primary surveys, we also need to think about shock and levels of shock. How badly our patient is shock in a state of clinical physical shock.

In this micro lecture, we’ve defined what hypovolemia is. We’ve recognised a number of causes and sources of hypovolemia, and we’ve talked briefly about treating hypovolemia. Now, just be mindful that with administering fluids in a trauma patient, ambulant services moved away from giving every trauma patient fluids many, many years ago in line with new evidence.

Most guidelines today are focused around giving trauma patients fluids only if there’s an absence of a radial pulse. Of course, if there’s a head injury, then you’re looking to maintain a systolic blood pressure of between 1900, but apart from that, if a patient has a sustained trauma and they do have a radial pulse, we are tending to hold off giving fluids. You can take a look at your local ambulance guidelines and the local evidence as well, which is where the guidelines take their information from to quantify that.

I hope you’ve enjoyed this micro lecture on hypovolemia.

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