In medicine and physiology, Hypovolemia or Hypovolaemia is a condition characterized by significant decrease in the blood volume of an individual. More specifically, the term is used to refer to the condition of decreased blood plasma.
No prevalence statistics are available for this condition as it is generally reported to occur from some causative disease or severe injury rather than the physical state of the patient.
Various medical conditions including excessive bleeding, vomiting, weight loss, protein energy malnutrition, stroke and peritonitis (characterized by the inflammation of the abdominal cavity lining) can lead to a decrease in the blood volume. In some cases, sweating, blood donation and alcohol consumption may also lead to this disorder. Autonomic nervous system dysfunction can cause Hypovolemia. It also commonly occurs during surgery because of the application of anesthetics and in-operation bleeding. Severe burns, causing edema and significant fluid loss can lead to a significant decrease in the blood volume. Following are some of the life-threatening causes of this condition:
- Ectopic pregnancy, in which the fetus grows outside the uterus
- Internal bleeding, generally from gastrointestinal tract (but can also occur elsewhere)
- Ruptured aortic aneurysm
Conditions like Pseudohypoaldosteronism, Naked Brimcap Poisoning and Lassa fever may cause Hypovolemia as a complication. Naked Brimcaps are wild and poisonous brown-colored mushrooms that are highly toxic when they come to direct contact with human body. Pseudohypoaldosteronism is a group of disorders which disrupts the functioning of the kidney, leading to electrolyte imbalances.
Hypovolemia Risk Factors
The risk factors of this disease include many conditions in which an individual is likely to lose significant amounts of body fluids. These include:
- Excessive bleeding
- Donating blood
Hypovolemia Signs and Symptoms
The symptoms of decreased blood volume include:
Pallor of skin
Pale skin is one of the main symptoms of lowered blood volume. One can observe this sign easily by studying the palm, tongue, conjunctiva and oral mucosa.
Increased Heart Rate When Resting
When a person suffers around 15% loss of blood volume (approximately 750 ml in an adult who has an average blood volume of five liters), it causes mild Tachycardia in the individual when resting. It does not cause any serious problems in people who do not have any other serious disorders. But elderly patients and patients who are suffering from debilitating circulatory diseases, such as cardiac failure and high blood pressure, show more severe symptoms of Tachycardia.
Anxiety and Palpitation
People with lowered blood volume often experiences anxiety along with an awareness of their heartbeat. Normally, healthy people do not feel their heartbeat.
Increased Respiratory Rate
The decreased blood supply to various cells and tissues results in tissue hypoxia. This leads to significant increase in respiratory rate for taking in more oxygen.
A Hypovolemia patient’s sympathetic nervous system is activated due to the condition which leads to excessive sweating. Minimized blood supply to various limbs also causes vasoconstriction, which is one of the body’s protective mechanisms. This mechanism ensures that the vital organs get enough blood supply and that blood is not wasted on the peripheral long limbs. Vasoconstriction causes the skin (especially the feet and hands) to become cold and sweaty.
Decreased Blood Pressure
The blood pressure of an individual starts to drop when the protective mechanism of vasoconstriction breaks down either due to the unsupported circulatory system or because of the continuous blood loss suffered by an individual.
Alteration in the Mental Status
Decreased supply of blood received by brain and deprivation of glucose as well as various other nutrients due to the metabolite accumulation in blood may cause an alteration in one’s mental state. Its manifestations include confusion, drowsiness and disorientation. This may even lead to loss of consciousness.
Poor Urinary Output
A gradual decrease in urine output can be noticed. The body of an individual with Hypovolemia will eventually become unable to produce any more urine.
Hypovolemic Shock is an emergency condition in which significant blood as well as fluid loss prevents the heart from pumping the required amount of blood. It can disrupt and stop the functioning of various organs. Hypovolemic Shock occurs due to Hypovolemia and is divided into several stages. Most people classify it into four stages whereas this type of shock can have as many as six stages in some systems. The four stages of Hypovolemic Shock are sometimes collectively called the “Tennis” staging because the four stages of blood loss resemble the scores of a tennis match.
Treating Hypovolemia in an individual makes it possible for the heart to pump enough blood to all parts of the body. This manages to cure the Hypovolemic Shock.
There are no known ways of preventing the lowering of the blood volume due to this disorder. However, it is possible to prevent Hypovolemic Shock by quickly treating the source of bleeding or fluid loss. Seeking first aid on an early basis helps to control the shock.
Hypovolemia and Dehydration
“Hypovolemia” and “Dehydration” are two words that are often synonymously used by medical practitioners and physicians. This common mistake can lead to serious problems when treating patients with these conditions. The two terms represent two completely different health problems.
“Dehydration” denotes “loss of water” from the body while “Hypovolemia” means “decreased blood volume”. Blood comprises of sodium solution, various other salts, proteins and several types of blood cells.
Water is the main fluid that keeps the cells and tissues of the body hydrated. The molecules that are dissolved in the water within the body increase in concentration as the water levels decrease. The potassium levels increase within the cells as potassium molecules are the main positively charged particles inside cells. Sodium molecules are the main positively charged particles outside cells. Due to this reason, dehydration causes the concentration of Sodium to increase. This allows the molecules inside the cells to exchange more easily with the fluids outside cells. Blood test reports showing low levels of Sodium in the serum confirm that an individual is dehydrated.
Hypovolemia and Pregnancy
Hypovolemia can occur as a complication during pregnancy due to extreme blood loss. Hypovolemic pregnant women have higher risks of fetal growth retardation, premature labor and hypertension. The arterial wave velocity measurements in these women show that those who do not display an increased cardiac performance during pregnancy have higher risks of giving birth prematurely.
Sometimes, Evan’s blue disappearance test done in pregnant women shows a delay in vivo mixing. These women also have an increased cardiac performance and are more likely to develop hypertension.
The symptoms of the disorder are generally not evident in patients until they lose 10% to 20% of their total blood volume. Abnormally rapid heartbeat or Tachycardia, lowered blood pressure and various skin disorders, like pale skin, denoting lowered levels of blood help to recognize lowering of blood volume.
The following diagnostic tests are used for identifying Hypovolemia or Hypovolemic Shock in an individual:
- CBC or Complete blood count
- Blood chemistry including tests to detect any abnormality in kidney functioning
- Ultrasound, x-ray and CT scan of suspected areas
- Urinary catheterization
- Right heart catheterization
In some cases, measuring the concentration of urine chloride in the body of a patient helps to determine whether he or she has Hypovolemia.
Hypovolemia Differential Diagnosis
The following conditions are characterized by symptoms that are similar to Hypovolemia:
- Abruptio Placentae
- Abdominal Aneurysm
- Thoracic Aneurysm
- Femur Fractures
- Pelvic Fractures
- Peptic and Gastritis Ulcers
- Placenta Previa
- Ectopic Pregnancy
- Postpartum Hemorrhage
- Hemorrhagic Shock
- Iron Toxicity
Physicians must ensure that the problems experienced by sufferers are the result of Hypovolemia and not any of the abovementioned conditions.
Hypovolemia Treatment and Management
Minor Hypovolemia caused by a known and completely controlled factor, like blood donation by a healthy individual, can be treated easily by resting for up to 30 minutes. Oral fluids with moderate amounts of electrolytes and sugars are required for replenishing the depleted sodium ions. A blood donor should also follow a healthy diet with plenty of protein rich foods for a few days afterwards to avoid the condition. Healthy people with good physical conditions can tolerate slightly higher amounts of blood loss compared to leaner individuals.
It is advisable to consult a physician in more serious cases of blood loss. Following are the ways how moderate to severe loss of blood volume is treated.
First Aid for Hypovolemia
Applying direct pressure helps to stop external bleeding. One can use a tourniquet in case of serious hemorrhage which cannot be stopped by direct pressure. However, use of tourniquet by less-trained or untrained people is controversial because it can lead to some adverse effects.
Other techniques used for stopping blood loss, including pressure points and elevations, do not work in these cases. First-aid providers should immediately ask for emergency medical assistance if there are signs of internal bleeding.
Field Care for Hypovolemia
A patient should be given oxygen immediately so that the remaining blood in his or her body can be supplied to different body parts. Employing oxygen therapy can save the life of the sufferer.
Using IVs or intravenous fluids can help in compensating for the decreased fluid volume. However, IV fluids are not capable of carrying oxygen in the same way as blood. Due to this reason, scientists are developing blood substitutes that can work like blood. Crystalloid or colloid IV fluid infusion also dilutes the clotting factors in the blood which increases the risks of bleeding. Currently, the best practice is to allow the permissive hypotension in individuals suffering from Hypovolemia because this prevents the over-dilution of the clotting factors and keeps the blood pressure from being raised to a degree where it easily blows off the blood clots that have already been formed.
Hospital Treatment for Hypovolemia
If a medication causes the condition, a doctor may use appropriate antidotes for controlling the blood loss. However, it is very important to monitor the dosage to avoid Hypovolemic Shock. Fluid replacement procedures are beneficial in stage 2 Hypovolemia and are necessary for patients in stages 3 and 4. Loss of blood volume caused by some trauma is generally treated by blood transfusion along with certain surgical methods.
The following interventions are used in hospitals for treating patients with decreased blood volumes:
- Oxygen as required
- IV access
- Surgical repair at locations of hemorrhage
- Fresh frozen plasma or whole blood
- Inotrope therapy (Noradrenaline, Dopamine)
The disorder may lead to Hypovolemic Shock which is associated with various complications such as the impaired functioning of various organs. This condition can interfere with the proper functioning of all the organs in the body as their working depends on a sufficient blood supply which is hampered by Hypovolemia. Due to this reason, an individual with lowered volume of blood may suffer from a heart attack, stroke, kidney disease, kidney failure and liver failure.
The condition generally has a good outcome when the source of bleeding is identified at an early stage and treated promptly. However, it can lead to serious Hypovolemic Shock at advanced stages if not treated immediately. A patient suffers from an irreversible shock if he or she loses more than per cent of the total body fluid. This condition can lead to serious consequences and may even cause the death of the individual.
Hypovolemia and Nephrotic Syndrome
Nephrotic Syndrome, a kidney disease characterized by hypoalbuminemia, proteinuria and edema, can occur along with this condition. The decreased blood volume can complicate Nephrotic Syndrome in newborns and children.
Hypovolemia can lead to serious health problems and even death of an individual if not taken care of at an early stage. In many cases, however, patients can live a long and normal life once the source of blood loss has been treated.