CPR First Aid

Does Low Blood Volume Cause Low Blood Pressure

Does Low Blood Volume Cause Low Blood Pressure?

Many people think of blood as the fuel that powers our bodies. The truth is that food is the closest thing to fuel we have. 

If we want to be technically accurate, blood acts as the postman that delivers all the essential nutrients throughout our body. Without these nutrients, we won’t be able to experience the beauty of life, let alone function. 

With how important blood is, blood volume must be kept at an optimal level. If enough blood is lost, many problems and conditions come about. 

If a person’s body has low blood volume, does it automatically equate to low blood pressure? That is what we’re here to find out. 

The Levels of Blood in Our Body

Before we get into whether hypotension is associated with having the amount of blood we have, let’s familiarise ourselves with the concept first. 

What Is Blood Volume? 

As the name indicates, the volume refers to the total amount of blood we have circulating throughout our bodies. It takes into consideration those within our veins, the chambers of the heart, and the capillaries just to name a few.

This isn’t just isolated to the red blood cells. White blood cells, plasma, and even platelets comprise this level as well.

The total amount of blood circulating in a body is dependent upon the weight and size of the person. On average though, an adult will have approximately five litres circulating within them. Women have a lower volume than men, but it increases by half when pregnant. 

What Determines the Volume?

The volume of blood in our bodies is dependent upon the amount of water and sodium that we take in. However, this is only one half of the coin. If something comes in, it must also come out. In terms of blood, without an exit, the volume will continuously rise. 

The path of exit for the volumes of blood lies in the lungs, the skin, and through the kidneys just to name a few. 

The kidney, for example, plays a central part in keeping levels equal. If too much water and sodium are ingested, the kidneys respond by filtering it out through the urine. 

What Does It Do For Us?

The volume of blood is particularly important. Having the right levels at all times is necessary to keep all tissues in the body bathed and wet. This is called perfusion. 

This is needed to provide essential nutrients to all parts of the body, At the same time, it also assists in the removal of cellular waste. 

Without proper perfusion, important issues will not be in optimal health. In addition, it could also decrease how tissues repair and their resistance to infections. 

What Happens if the Level of Blood is Not Equal?


If the volume of blood within a body gets too high, it causes a condition called hypervolemia or fluid overload. 

This condition can affect anyone. However, it can occur more likely in people who have heart conditions, pregnant women, those experiencing hormonal changes, and people who have an increased amount of salt in their diets. 

Statistics are muddled on this as some people experience mild cases of hypervolemia and resolve it all on their own. 

A person experiencing hypervolemia will feel significant swelling and bloating. People will similarly gain weight quickly. At the same time, it will also hamper people from going about their day. 


On the opposite end of the spectrum, hypovolemia is when the volume of blood in the body gets too low. This occurs when a person has lost at least 15% of volume. 

Additional causes of the condition include wounds where people bleed out, diarrhoea, vomiting, and internal bleeding. 

When levels are this low, people will typically feel a slew of symptoms. These include being dizzy, cramps in muscles, fatigue, and having urine with a darker colour. More serious symptoms include excessive sweating, shortness of breath, and becoming unconscious.

In its most extreme form, people will go into hypovolemic shock which if left untreated, may result in organ failure and eventually, death.

Can Low Blood Volume Result In Low Blood Pressure?

There is a strong relationship between the volume of blood in a body and blood pressure. Interestingly enough, hypovolemic shock causes blood pressure reactions in people.

As the shock sets in, blood pressure will first rise via the rising of the diastolic pressure. Then, if enough volume is lost, the systolic pressure decreases, thereby lowering the blood pressure. 

So, to address the question, the answer is yes. Low volume of blood results in lower blood pressure. 

Interestingly enough, studies have also shown that in some situations, certain hypovolemic treatments also cause hypertension. This shows how interconnected blood volume and blood pressure really are. 

How to Avoid Lower Blood Volumes?

In truth, it is unrealistic to avoid any and all factors that could result in this type of blood volume. The next best thing then is to ensure that you know what to do if things happen.

Treat Illnesses and Injuries Immediately

For starters, if any injuries or illnesses are received, they must be treated immediately. This goes double for any infections in the body. 

Serious wounds will have blood coming out of the body at alarming rates and must be stifled as soon as possible. For illnesses, some of them may make people vomit and expel waste that affects the volume. 

Sweat in Moderation

At the same time, it is best to be cautious around any activities that make them sweat in excessive amounts. It is particularly difficult to select activities on 

If it is unavoidable though, make sure to hydrate as much as possible.

Also, when working in particularly hazardous work environments, wear the right protective equipment to avoid any injuries.

How To Treat Lower Blood Volumes?

If for any reason hypovolemia reaches serious levels, then immediate care must be administered. This can be done in a number of ways, with the treatment depending on the cause of the loss of volume. 

For instance, if a person is bleeding out, the first thing a doctor would do is to stop the bleeding. Afterwards, an IV drip will help replace the lost blood volume with the use of crystalloids. These saline solutions help to refill the volume of the blood, but they may decrease platelets and other components in the blood.

When this happens, doctors can introduce more transfusions using plasma and red blood cells, depending on what is lacking. 

How Long does treatment Last?

The length of treatment is dependent on many factors as well. With how serious hypovolemic shock is, the first thing a doctor looks at is if any serious damage has occurred due to the condition. These could include severe damage to the brain and kidneys.

Thus, replenishing the volume becomes critical. With that said though, not everybody refills blood at the same rate, even with IV solutions. This could be due to how severe the hypovolemic shock is, the amount of blood loss, the extent of the injury, and other pre-existing medical conditions that could hinder it. 

Balance in All Things

Low blood volume is a serious condition. The loss of volume leads to many symptoms, with low blood pressure being one among many. 

As with all things, one should always strive for balance. This includes the volume of blood. A touch too high or too low could introduce complications to a person that could result in death. 

While treatment is available, there is a big element of risk involved. The best thing to do is to check in with a doctor immediately if any symptoms show up.

The knowledge of blood volume is important, but it must also be balanced with the right actions. Learn all about potentially life-saving first aid practices through CPR First Aid’s Liverpool course today. 

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