What to Expect in the 4 Stages of Blood Loss

Posted by Nate Jones on Jun 18th 2024

What to Expect in the 4 Stages of Blood Loss

Most of us are acutely aware of the fact that we could bleed to our deaths. Maybe you are not thinking about it often, but with the right injury it usually will jump to the forethought of our minds. I have found though, that it is a whole other thing for us to understand why. I often ask in Stop the Bleed classes, “why do we care about stopping bleeding?” Most are surprised that I would ask such a basic question, that they would have to justify that bleeding to death is a bad thing. It’s not a question I ask to insult anyone’s intelligence, but to rather begin our conversation from the same foundation. What about blood makes it so vital? Well there are actually a plethora of reasons for this, but to simplify I’ll pick the one I think about the most. I care about the blood because it carries the oxygen. Most of us are also pretty aware that without oxygen we tend to die rather quickly.

When we breathe in, oxygen enters our lungs. It then moves from our lungs into our bloodstream. The red blood cells containing hemoglobin pick up the oxygen in our lungs and carry it to different parts of our body. Imagine our red blood cells as little buses, and hemoglobin as the passengers. These buses travel through our bloodstream, and as they pass by our body's tissues and organs, they drop off oxygen molecules. This is how oxygen gets to all the cells in our body. If red blood cells are quickly spurting outside our body we find ourselves with less and less buses to transport the oxygen.

Blood Loss Leading to Shock

Now many of you are likely familiar with the term “shock.” The first rule of every discussion is to define your terms so I want to do that before we continue. I was always surprised by the wide range of answers Combat Medics would give me when I was an instructor so this is worth the digression. If when you think of shock you think of someone who is so hurt they are wide eyed, unresponsive and “shocked,” this is also worth clarifying. Many medics would describe what they were trained to look for, “Blood pulling from the extremities.” Which to me was more the physiological process of “shunting.” Lose enough blood and your body starts having to make some tough decisions. Many other Medics would ask which type of shock I was referring to. Luckily we do not have to dig into each kind of shock to know though what the threat is. Shock, essentially is a lack of perfusion.

Blood, and therefore oxygen are not getting to the tissue at adequate levels to maintain function.

I hear “shock” used a lot be people, and they way they keep using the word, it doesn’t mean what they think it means. Inconceivable, I know.

As it pertains to bleeding to death though, let’s focus on “what is Hypovolemic Shock?” Hypovolemic shock is a medical emergency that occurs when the body loses a significant amount of blood or fluid, leading to a decrease in blood volume. This can cause vital organs to fail due to lack of oxygen and nutrients. Good news is that hypovolemic shock can occur gradually or suddenly (that’s the bad news), depending on the cause and severity of the blood loss. I ask the question of students often in training, “how long does it take for you bleed out?” A variety of answers from students are inevitable, but answer is always “it depends.” Like most things that is the most accurate way to describe it because it falls somewhere on a spectrum.

Instead of giving you a ballpark of seconds and minutes though, let’s focus on how your body responds to losing blood volume. The average human has about five liters of blood volume. If you are a smaller than average human you likely have a little less and if you are a larger than average human you likely have a little more. As previously mentioned, this process bleeding to our deaths can occur gradually or suddenly. There are a few ways we can conceptualize this, I like to use two. An airplane plummeting to the earth and car speeding down a road towards a cliff.

Stage One Blood Loss

Stage one, which is up to fifteen percent of your total blood volume, roughly 750ml. You are flying high at thirty thousand feet in a craft with multiple engines and you hit whatever you would need to hit to rupture your fuel tank. This causes a disruption in the engines, but they can largely compensate for what has happened and you don’t lose much altitude. Im not actually positive this would impact aircraft engine function but bear with me. In the first stage of blood loss, the body can compensate for the blood loss by increasing heart rate and constricting blood vessels to maintain blood pressure. However, you may start to experience symptoms such as mild shortness of breath, increased thirst, and fatigue.

Stage Two Blood Loss

Stage two kicks in when you are have lost between fifteen and thirty percent of your total blood volume. Thirty percent will be roughly around 1500ml, a liter and a half. In the second stage of blood loss, the body's compensatory mechanisms become overwhelmed, and the blood pressure drops. This can lead to symptoms such as rapid heartbeat, pale skin, confusion, and cool extremities. In general, losing about 15-30% of your blood volume can cause you to pass out. However, it's important to note that this can vary depending on the individual and their circumstances. Your airplane is beginning to feel heavy and you are red lining your engines capabilities to maintain altitude.

Stage Three Blood Loss

Stage three our bodies have to start making some tough decisions. After losing thirty to forty percent of our total fuel, your body can either run a pair of engines or none of them. In the third stage of blood loss, the body's compensatory mechanisms are no longer able to maintain blood pressure, and vital organs start to fail. This is between 1500ml to 2000ml of blood loss. Here we may start to see symptoms such as shallow breathing, severe confusion, and a weak or rapid pulse. You are truly beginning your nose dive when you lose compensatory abilities. The reason I use this image of a plane falling to earth is one, it’s terrifying, two is because of how an aircraft flies. The higher an airplane climbs, the thinner the air gets and the more efficiently it can fly. This in reverse, means the more you lose altitude the less your engines can function efficiently. Our bodies are similar when we compare this to what is known as the “lethal triad.” Hypothermia, coagulopathy, and acidic blood create a self perpetuating system that causes the body to spiral downwards and operate less and less efficiently.

Stage Four Blood Loss

Stage four is our last stage. After losing forty percent or more of our blood volume we are worried about a dive that we may not be able to pull out of. There is a decent likelihood that we are beyond a point that we are able to do much to help ourselves. Immediate medical treatment will be needed. At this stage of blood loss, there are so few hemoglobin buses in our blood vessels that important parts of our body is likely not getting adequate perfusion. If this condition is prolonged, the damage may not be something that we get to walk away from. Receiving blood products to replace the oxygen carrying capability to our blood quickly, is essential. This leads me to my car driving off the cliff visual I mentioned earlier. How fast we are speeding through each phase will provide limited opportunity to effectively hit the brakes with enough stopping distance to not fall off the cliff. First we need speedy intervention to stop the bleeding. If that took too long we will need blood products from a medical treatment facility quickly to prevent irreversible damage. If you need a visual to help conceptualize this, dump out a two liter of soda.

After that two liter is dumped out, have a family member lay in it for a feeling exercise. I’ll say it time and time again, the best medicine is preventative. Anything and we can do to mitigate risk to ourselves and loved ones is likely worth the effort. As the old saying goes, “do what your rank can handle.” Planning for elements outside our control and having contingencies are just as important. Invest in life saving equipment and become proficient with them. Learn a good patient assessment to help you effectively find and treat injuries with that equipment. Hoping that nothing will happen isn’t a solid plan. Believing that you’ll be able to spring into action without any training isn’t impossible, but it isn’t probable either. Last thing you want is your loved one laying in two liters of soda, or worse and to feel helpless. Come learn how to be helpful.