FVD occurs when the body loses more fluids than it takes in. The most common way this occurs is through excessive sweating, vomiting, diarrhea, or excessive urination. 

When the body loses fluids, it loses both water and electrolytes, such as sodium, potassium, and chloride. Electrolytes are essential for maintaining proper fluid balance and cellular function.

The loss of fluid and electrolytes can cause a decrease in blood volume, leading to a decrease in blood pressure. In response, the body activates the renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system. 

The RAAS is responsible for increasing sodium and water reabsorption in the kidneys, while the sympathetic nervous system constricts blood vessels to increase blood pressure. These compensatory mechanisms help to maintain blood pressure and blood flow to vital organs, but they can also lead to further fluid loss if not corrected.

Fluid Volume Deficit Signs and Symptoms

• HYPOvolemia
• LOw fluid volume
• LOw & Little Body
• Weight Loss = Water Loss

Cardiovascular

• Low blood pressure DEADLY
• Orthostatic hypotension
• (light-headed & dizziness upon standing)
• Decreased central venous pressure CVP
• Weak, thready pulses
• Flat neck & hand veins
• Tachycardia (pulse over 100)

Integumentary (skin)

• Sunken eyes
• Dry skin (Poor turgor & tenting)
• Dry mucous membranes (MM)
• Increased body temp

Neuromuscular

• Lethargy (which can progress to a coma)
• Weakness 

Urine (High when Dry) 

• Increased urine specific gravity
• High 1.005 (Normal 1.005 – 1.030)
• High gravity = High Concentration

Renal & Urinary

• Increased urine output initially &
• Decreased urine output (at the end)

Respiratory

• Rapid DEEP respiratory rate

Gastrointestinal

• Decreased motility – Constipation
• Diminished bowel sounds

Lab Values (Appear High when Dry)

• Increased Osmolality
• Increased Hematocrit (HCT)
• Increased Blood Urea Nitrogen (BUN)
• Increased Electrolytes
  • High Sodium Na+
  • Hypernatremia (over 145 mEq/L)
  • Risk for brain bleeding 

Fluid Volume Deficit Causes

FVD can occur for several reasons. The most common causes include:

• Blood loss – This can occur due to injury or surgery, or in some cases, due to underlying medical conditions such as bleeding disorders.
• Burns – Severe burns can cause fluid loss due to damage to the skin and underlying tissues.
• Excessive sweating – This can occur due to exercise or hot weather.
• Certain Medications – Some medications, such as diuretics, can cause fluid loss.

FVD Compensation

The body has several compensatory mechanisms to help maintain blood pressure and blood flow to vital organs during FVD. These mechanisms include:

• Activation of the RAAS – The RAAS system helps to increase sodium and water reabsorption in the kidneys, leading to increased blood volume.
• Activation of the sympathetic nervous system – The sympathetic nervous system constricts blood vessels, increasing blood pressure.
• Release of antidiuretic hormone (ADH) – ADH helps to increase water reabsorption in the kidneys, leading to increased blood volume.
• Thirst – Thirst is stimulated when there is a decrease in blood volume, leading to an increase in fluid intake.
• Redistribution of fluids – In some cases, the body may shift fluids from one area to another to help maintain blood pressure.

Why does diabetic ketoacidosis cause dehydration?

Diabetic ketoacidosis (DKA) is a serious complication of diabetes that occurs when there is a shortage of insulin in the body. This can lead to the breakdown of fats for energy, which produces ketones. The buildup of ketones can lead to an acidic environment in the body, causing a range of symptoms, including FVD.

When there is a shortage of insulin, the body cannot properly use glucose for energy. As a result, the body begins to break down fat for energy. This process produces ketones, which can cause a buildup of acid in the blood. The acidic environment can cause the body to lose fluids and electrolytes, leading to FVD.

Additionally, DKA can cause frequent urination and vomiting, and significantly losing fluids and electrolytes. Losing fluids and electrolytes can lead to decreased blood volume and blood pressure, further exacerbating FVD.

Treatment for DKA involves rehydration and electrolyte replacement. In addition, intravenous fluids are given to replace the lost fluids and electrolytes, while insulin is given to lower blood glucose levels and prevent the breakdown of fats. 

It’s important to monitor clients with DKA for signs of FVD, such as decreased urine output and dry mucous membranes, and to provide appropriate fluid and electrolyte replacement as needed.

Dehydration Diuretics

Diuretics are medications that help to increase the excretion of urine from the body. These medications are commonly used to treat conditions such as hypertension and edema. However, they can also cause fluid loss and FVD if not properly monitored.

There are several types of diuretics, including loop diuretics, thiazide diuretics, and potassium-sparing diuretics. Loop diuretics are the most potent and can cause significant fluid loss. 

Thiazide diuretics are less potent and often used with other medications. Potassium-sparing diuretics are the least potent and are often used to prevent hypokalemia.

Fluid Volume Deficit Nursing Interventions

• Assess urine output – Urine output should be monitored to determine the client’s fluid status. A decrease in urine output may indicate FVD.
• Administer intravenous fluids – Intravenous fluids are given to replace lost fluids and electrolytes. The type and amount of fluid given will depend on the underlying cause of FVD and the client’s condition.
• Monitor electrolyte levels – Electrolyte levels should be monitored regularly to ensure proper balance. If electrolyte imbalances are detected, appropriate interventions should be implemented.
• Provide oral care – clients with FVD may have dry mucous membranes, making them more susceptible to oral infections. Regular oral care should be provided to prevent complications.
• Educate clients on fluid intake – clients should be educated on the importance of maintaining proper fluid intake and ways to increase fluid intake, such as drinking water and consuming foods with high water content.