What is Hypovolemia?

Hypovolemia Definition

Hypovolemia literal meaning stands for  “low volume of blood”. However, in clinical terms, it often refers collectively to two different and distinct disorders, namely: volume depletion and dehydration. In case of volume depletion, there is a loss of essential salts mostly sodium from the extracellular spaces which may be caused by conditions like diarrhea; vomiting; diuresis; gastrointestinal haemorrhage, etc.

While in dehydration, there is total body water loss along with intracellular water loss which results in high plasma sodium concentration; cellular desiccation and osmolality. Thus, hypovolemia, in general, refers to a sudden loss of blood or whole blood plasma, with or without total body water depletion. While in dehydration, there is a loss of water leading to increased salt content.

Further hypovolemia may be of two different types: relative and absolute. In absolute hypovolemia, there may be a sudden loss of fluid in the circulatory system due to loss of fluids from the body like haemorrhage, diarrhoea, vomiting, etc. While in relative hypovolemia there is a loss in the fluid in circulatory system; but not because of the loss of fluid from the body. In relative hypovolemia, the blood amount may become less or insufficient because of the vasodilation after neurogenic shock or if the fluid gets accumulated in other parts of the body like in the abdominal cavities as in conditions like ascites.

Symptoms of Hypovolemia

Hypovolemia may develop suddenly or gradually in stages. Apart from the loss of body fluids, there are various other symptoms which may suggest hypovolemia. Various mild initial symptoms of hypovolemic include:

• Blue or purple colour of the nails and lips due to the decreased blood flow.

• Decrease in urine output or no output at all.

• Virtigo, dizziness along with chest pain (possibility of impending heart attack)

• Confusion, agitation and anxiety.

• Increase in the rate of respiration.

• Lower blood pressure.

• The skin becomes pale or yellowish, clammy and cold, profuse sweating.Tachycardia or increased heart rate.

• Decreased or negligible pulse rate.

• Loss of consciousness or Coma.

In extreme cases, hypovolemia may be life threatening and the symptoms shall not be ignored. Some of the other symptoms which may relate to hypovolemia and needs immediate attention are as below:

• Palpitations, Sudden pain in chest or tightness in the chest.

• Increased heart rate (tachycardia)

• Increased rate of breathing or respiration (tachypnea)

• Unresponsiveness, Reduced levels of consciousness or alertness.

• Excessive blood loss during pregnancy.

• Accidental injury, trauma.

• Blood clotting disorders.

• Heavy bleeding or haemorrhage.

• Vomiting blood, or uncontrolled vomiting or blood while passing stool or rectal bleeding.

• Excessive menstrual bleeding.

• Pain in the abdomen.

• Excessive swelling in various body parts.

What causes Hypovolemia?

Hypovolemia may be caused by any condition in which there may be an excess loss of body fluids, plasma and sodium or the fluid may get accumulated at some other place than the circulatory system. The condition may arise due to several factors like excessive bleeding after injury, blood donation, uncontrolled vomiting, nervous system dysfunction and much more. Few of the main causes for hypovolemia may be listed as below:

• Vasodilation i.e. expansion of blood vessels can lead to dysfunction of nerves causing the inability of the vasomotor centre of the brain to function,  which often result in hypovolemia. The vasodilation may be caused due to external medicines like certain vasodilators used for treating hypertension or may be caused due to external trauma.

• Hypovolemia often results due to the reduced fluid intakes. Decreased fluid intake may be caused due to several conditions like as mild as environmental conditions, psychiatric illness, dysphagia etc.

• Many a time internal bleeding or external injuries may lead to excessive blood loss from the body.

• Gastrointestinal disorders; renal dysfunction; excessive use of laxatives or diuretics, uncontrolled vomiting, polyuria or frequent episodes of fever or infections are few other important reasons for the loss of both plasma and sodium salt from the body leading to hypovolemia.

• Very often the fluid loss may not be out of the body, rather the fluid gets accumulated in the third space, causing an insufficient amount of fluid in the circulatory system leading to hypovolemia condition. Oedema; intestinal obstructions; ascites; effusions or pancreatitis are many of the few conditions where these kinds fluid shifts may be observed.

• Complications during pregnancy like ectopic pregnancy or excessive bleeding may result into hypovolemia. Hypovolemia in pregnant ladies can lead to premature births, fetal growth retardation and hypertension. Hypovolemic pregnant mothers are often found to be more prone to heart failures due to nerve dysfunction and vasodilation.

Diagnosis Of Hypovolemia

In most of the cases, the patient may not start showing any early symptoms until they lose at least 15-20% of the total blood volume of the body. Change in the colour of the skin reduced blood pressure, an abnormal increase in heart beat are a few of the common signs suggesting lowered blood volume. Various diagnostic tools are employed to ascertain the condition of Hypovolemia which may be listed below:

  • CT-scan or X-ray or Ultrasound or all in combination may be used to scan the suspected area.
  • Total blood count.
  • Endoscopy or endocardiogram may be done.
  • Tests related to kidney malfunction or tests, studying the blood chemistry may be performed.
  • Checking the concentrations of urine chloride may also help.
  • Catheterization of right heart or Urinary catheterization may also be used in some cases.

Very often the early symptoms of hypovolemia may be confused with other related ailments or disorders and injury. Doctors must ensure that the exact cause of the problems faced by patients is due to hypovolemia and not another related disorder. Few of the disorders which may often be confused with symptoms of hypovolemia are: Fractures in femur bone or pelvic area; Gastric and peptic ulcers; Abrupt rupture of placenta; ectopic pregnancy; placenta previa; hemorrhagic shock or Iron toxicity.

Treatment and management for Hypovolemia

No time shall be wasted once the diagnosis for hypovolemia has been confirmed. In the case of early detection, replenishing the loss of body fluid becomes easy, because of the lesser amount of fluid and salt loss. In initial stages, body fluids may be restored by giving oral fluid supplements having moderate amounts of salts, sugars and necessary minerals or electrolytes. A healthy blood donor may be required for levelling up the blood levels in the body. In the case of advanced stages of hypovolemia, the patient may be required to spend a long time in hospitals. Various intravenous fluids and medications may be required to bring back the normal heart rate in the patient. Few of the common medications used in such cases are epinephrine, norepinephrine, dobutamine or dopamine.

Organ failures like kidney, heart or liver dysfunction are many times accompanied with advanced stages of hypovolemia. Death and decay of tissue or gangrene may be caused sometimes, which may also require amputation of the affected area or limb. Post care and management of the patient also becomes important in the case of hypovolemia. A constant check on the blood levels has to be monitored along with a healthy supervised diet and medication.

Hypovolemic Shock

Hypovolemic shock is a life-threatening condition where there is a sudden loss of blood or body fluids and it becomes difficult for the heart to pump the required amount of blood in the body. This condition appears when there is an almost loss of 10-20% of blood volume (approx 0.5-1 litres of blood). This may result in the malfunctioning of various organ system of the body. Usually, hypovolemic shock occurs in four different stages often termed as Tennis staging due to the resemblance of the blood score like tennis matches.

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