Hypovolemic Shock

Symptoms include [6]:

•  Anxiety
•  Low or no urine output 
•  Profuse sweating
•  Dizziness
•  Confusion
•  Loss of consciousness
•  Chest pain
•  Tachycardia with weak pulse
•  Hypotension
•  Decreased urine output

Other signs may be:

•  Abdominal pain (in case of internal hemorrhage)
•  Melena and/or hematuria (in case of internal hemorrhage)
•  Progressive weakness leading to unconsciousness 
•  Peripheral and central cyanosis 

Work up consists of a detailed history and physical examination.

Laboratory Tests

• Complete blood count
• Serum electrolytes 
• Kidney function tests
• Urinary catheterisation and urine output checking 
• Blood sugar levels 
• Arterial blood gases
• Prothrombin time and APTT

Imaging Studies

• Echocardiogram to assess heart function
• ECG
• Ultrasound
• X-ray
• CT scan of head, chest and abdomen to check for internal bleeding

Test Results

On the basis of history, physical assessment of the patient and test results, a diagnosis of hypovolemic shock can be made and intensive treatment should be immediately begun.

Control Bleeding

The cause of bleeding should be immediately identified and treated. Treatment could be surgical or via medications, depending upon the cause.

Treatment of burns

If the hypovolemia is due to severe burns, the primary goal of treatment should be to replace the lost volume.

Treating other underlying cause

If the cause of hypovolemia is due to a pregnancy-associated condition, or due to gastrointestinal disturbances or disease, or due to any other cause, that underlying cause should be identified and promptly treated.

Fluid resuscitation

Many fluids have been studied for use in resuscitation; these include isotonic sodium chloride solution, lactated Ringer solution [7], FFP, hypertonic saline, dextran 70, albumen, etc. The loss of blood volume should be recompensed with appropriate fluids to avoid systemic effects.

Oxygen

Emergency oxygen should be immediately employed to increase the efficiency of the patient's remaining blood supply. This intervention can be life saving [8].

Transfusions

Blood should be matched and transfusions should be performed to replace the lost blood volume.

Medications

Vasopressers and thrombogenic drugs may be administered if needed, to prevent further episodes of bleeding.

Prognosis depends upon how early treatment is begun. If patients are brought to the emergency and treated accordingly, prognosis is excellent. However, if the hypovolemia has extended to multiorgan failure, death may ensue.

Complications

Possible complications include the following:

•  Myocardial infarction
•  Cardiac arrest or fatal arrhythmias
•  Brain damage
•  Kidney damage
•  Multiorgan failure
•  Gangrene of extremities 
•  Coma
•  Death 

Hypovolemic shock results from low cardiac output due to the loss of blood or plasma volume, such as can occur with massive hemorrhage or fluid loss from severe burns [1]. Hemorrhage is the most common cause of hypovolemic shock.

Less common causes include plasma loss in severe burns, or into the abdominal cavity in acute pancreatitis, inappropriate vasodilatation in bacteraemic shock and anaphylactic shock, and excess urinary fluid loss as in diabetic ketoacidosis [3].

Excessive diarrhea and severe vomiting may also cause hypovolemic shock. Pregnancy associated conditions such as ectopic pregnancy rupture or placenta previa may cause hypovolemia, and so can arteriovenous malformations, gastrointestinal disturbances such as Mallory-Weiss tears, esophageal varices and peptic ulcers.

Incidence

More than 1 million patients present in shock or develop shock in the US hospitals each year, at an annual cost of more than $100 billion [2].

Sex

It has no known gender prevalence.

Age
Hypovolemic shock may occur at any age, depending upon the underlying etiology. It may occur in young children who have suffered severe burns or it may occur in adults who have had a serious accident leading to heavy blood loss. 

As discussed in the previous section, the commonest cause of hypovolemia is hemorrhage. Hemorrhage decreases the filling pressure of the circulation and, as a consequence, decreases venous return. As a result, the cardiac output falls below normal and shock may ensue [4]. Hypovolemia occurs so commonly due to hemorrhage that the term hypovolemic shock is sometimes used interchangeably with hemorrhagic shock.

The severity of hypovolemia can be staged. The stages include the following:

Stage I

• Blood loss up to 15% of total blood volume
• Normal or slightly low blood pressure 
• Normal mental status
• Normal respiratory rate 
• Normal urine output [5]

Stage II

• Blood loss up to 20-30% of total blood volume
• Increased diastolic blood pressure, systolic pressure maintained 
• Tachypnea 
• Mild anxiety
• Urine output of 20-30 millilitres/hour [5]

Stage III

• Blood loss up to 30-40% of total blood volume
• Hypotension
• Tachycardia
• Tachypnea 
• Altered mental status 
• Urine output 20 millilitres/hour

Stage IV

• Blood loss >40% of total blood volume
• Extreme tachycardia with weak and faint pulse 
• Extreme tachypnea
• Unconsciousness/coma
• Very little urine output

It can be prevented by emergency medicine provided as early as possible. First aid is critical in the prevention of hypovolemic shock.

Shock is characterised by systemic hypotension due either to reduced cardiac output or to reduced effective circulating blood volume [1]. Hypovolemic shock occurs due to a rapid fall in blood volume resulting in life threatening hypotension and may lead to multi organ failure, and ultimately, death.

Definition

Hypovolemic shock is a potentially life threatening condition that occurs when around 20% of the body's fluid volume is lost.

Cause

Common causes of hypovolemia are [9]:

• Plasma loss
• Blood loss (external or internal bleeding or blood donation [10])
• Vasodilation
• Loss of electrolytes like sodium
• Pregnancy-associated conditions
• Severe diarrhea and vomiting

Symptoms

Symptoms and signs may include:

• Light headedness
• Dizziness and lethargy
• Anxiety
• Increased heart rate with decreased pulse
• Hypotension
• Chest pain
• Unconsciousness

Diagnosis

Diagnosis is made by evaluating a combination of factors like history, physical examination and laboratory tests.

Treatment

Treatment includes fluid replacement, blood transfusions, oxygen and sometimes, surgical repair.

Prevention

Hypovolemic shock can be prevented by giving first aid on development of symptoms and admitting the patient to a hospital as soon as possible.

1. Robbins and Cotran. Pathologic Basis of Disease, 8th ed. Pa:Saunders Elsevier. Ch.4 p129
2. Rivers E. Approach to the patient with shock. In: Goldman L, Schafer L, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 106
3. Guyton and Hall. Textbook of Medical Physiology. 12th ed. Ch.24. Pa: Sanders Elsevier
4. Davidson's Principles and Practice of Medicine. Christopher RWE, Ian ADB, eds. 16th ed. Ch.8 p282 
5. Elizabeth D Agabegi; Agabegi, Steven S. (2008). Step Up To Medicine (Step-Up Series). Hagerstwon, MD: Lippincott Williams and Wilkins. ISBN 0-7817-7153-6
6. Rachel N, reviewed by Brenda B. Spriggs. Hypovolemic Shock. June 22, 2012. Retrieved on 17th Sept 2014. 
7. Ghafari MH, Moosavizadeh SA, Moharari RS, Khashayar P. Hypertonic saline 5% vs. lactated Ringer for resuscitating patients in hemorrhagic shock. Middle East J Anesthesiol. Oct 2008;19(6):1337-47 [Medline]
8. Takasu A, Prueckner S, Tisherman SA, Stezoski SW, Stezoski J, Safar P. (2000), Effects of increased oxygen breathing in a volume controlled hemorrhagic shock outcome model in rats. PMID 10959021. 
9. Sircar, S. Principles of Medical Physiology. Thieme Medical Pub. ISBN 9781588905727. 
10. Danic B, Gouezec H, Bigant E, Thomas T (June 2005). "[Incidents of Blood Donation]". Transfus Clinic Biol (in French) 12 (2):153-9. doi:10.1016/j.tracli.2005.04.003 PMID 15894504.