BSN 206 Week 12 Lesson Notes 2026: Terms & Complete
Definitions | 100% Correct (Nightingale College)
Fluid volume deficit (FVD) can be caused by:
• Poor fluid intake
• Substantial fluid loss
The severity of fluid loss is dependent on factors such as the patient’s body weight. Because of
this, a child would suffer greater consequences from the same amount of fluid loss in a larger
adult.
The table describes two types of FVD: isotonic fluid deficit and hypertonic fluid deficit.
Isotonic Fluid Deficit Hypertonic Fluid Deficit
• Water and solute (sodium) Fluid loss is made up of more water than solute
(sodium).
are lost together.
Overall circulating volume Decreased intracellular fluid: Increased serum
(intravascular) decreases osmolality causes water to shift out of the cells via
(hypovolemia). osmosis. This causes the cells to shrink and become
Serum osmolality does not dysfunctional.
change. Increased serum osmolality: Greater water loss
than sodium, which increases the serum
concentration of sodium.
Decreased extracellular (intravascular and
interstitial) fluid volume: The same feature as
occurs with isotonic FVD.
Causes of FVD
Knowing the cause of a patient’s hypovolemia or dehydration aids in planning of appropriate,
timely interventions. Decreased thirst sensation in older patients can be a cause of dehydration.
Untreated, dehydration can be life-threatening.
Some medical causes of FVD are as follows: Surgery
Preoperatively
, • Patients are prescribed to have nothing by mouth (NPO) before most major surgeries.
• Patients may be required to use enemas or laxatives before surgery or bowel
procedures.
Intraoperatively
• Extent of blood loss depends on the type and length of surgery.
• Insensible loss occurs from skin and organs being exposed to air.
Postoperatively
• Nausea and vomiting
• Drainage from a nasogastric tube
• Drainage from wounds or chest tubes
Other Causes
Isotonic FVD
• Hemorrhage
• Burns
• Vomiting
• Diarrhea
• Addison disease
• Fever
• Excessive perspiration
Hypertonic FVD
• Diabetes insipidus
• Diabetic ketoacidosis (DKA)
• Osmotic diuretics
• Hypertonic enteral tube feedings
• Hypertonic intravenous (IV) fluids
• Prolonged vomiting and diarrhea
• Decreased oral intake
Isotonic Fluid Volume Excess
• Equal retention of water and sodium
• Results in increased circulating volume with no change in serum osmolality
, Hypotonic Fluid Volume Excess
• Retention of water greater than sodium
• Results in increased circulating volume with decreased serum osmolality (known as
hemodilution)
• Water shifts into cells and causes them to swell
• This can be fatal if untreated as a result of pulmonary and cerebral edema
The table lists some of the underlying causes of the two types of FVE.
Causes of Isotonic FVE Causes of Hypotonic FVE
• Heart failure Excessive water intake
• Oliguric kidney disease Prolonged use of hypotonic IV solutions
• Cirrhosis of the liver with low Syndrome of inappropriate antidiuretic albumin
hormone (SIADH)
Effects
FVE can affect multiple body systems. Patients who develop severe kidney disease may have
decreased urine production and output. This water retention contributes to an increased
circulating volume. Eventually, the increased volume puts a strain on the pumping ability of the
heart. Heart failure can develop with possible pulmonary edema (accumulation of fluid in the
lungs).
Summary
The causes and severity of FVD and FVE are varied. Fluid imbalances are frequently associated
with surgery and IV therapy.
FVD develops when excessive fluid is lost or fluid intake is significantly reduced. Two types of
FVD are isotonic fluid deficit and hypertonic fluid deficit. In isotonic FVD, water and sodium are
lost equally, and serum osmolality is unchanged. In hypertonic FVD, fluid shifts from inside of
the cells to outside of the cells. Water is lost more than sodium and serum osmolality is
increased.
FVE occurs when intake of fluid is greater than output and results in increased circulating
volume. There are two types of FVE: isotonic and hypotonic. In isotonic FVE, there is retention
of both water and sodium, serum osmolality remains unchanged. In hypotonic FVE, the
retention of water is greater than sodium, and there is a decrease in serum osmolality.
Hypotonic FVE results in fluid moving into cells, causing them to swell.
Definitions | 100% Correct (Nightingale College)
Fluid volume deficit (FVD) can be caused by:
• Poor fluid intake
• Substantial fluid loss
The severity of fluid loss is dependent on factors such as the patient’s body weight. Because of
this, a child would suffer greater consequences from the same amount of fluid loss in a larger
adult.
The table describes two types of FVD: isotonic fluid deficit and hypertonic fluid deficit.
Isotonic Fluid Deficit Hypertonic Fluid Deficit
• Water and solute (sodium) Fluid loss is made up of more water than solute
(sodium).
are lost together.
Overall circulating volume Decreased intracellular fluid: Increased serum
(intravascular) decreases osmolality causes water to shift out of the cells via
(hypovolemia). osmosis. This causes the cells to shrink and become
Serum osmolality does not dysfunctional.
change. Increased serum osmolality: Greater water loss
than sodium, which increases the serum
concentration of sodium.
Decreased extracellular (intravascular and
interstitial) fluid volume: The same feature as
occurs with isotonic FVD.
Causes of FVD
Knowing the cause of a patient’s hypovolemia or dehydration aids in planning of appropriate,
timely interventions. Decreased thirst sensation in older patients can be a cause of dehydration.
Untreated, dehydration can be life-threatening.
Some medical causes of FVD are as follows: Surgery
Preoperatively
, • Patients are prescribed to have nothing by mouth (NPO) before most major surgeries.
• Patients may be required to use enemas or laxatives before surgery or bowel
procedures.
Intraoperatively
• Extent of blood loss depends on the type and length of surgery.
• Insensible loss occurs from skin and organs being exposed to air.
Postoperatively
• Nausea and vomiting
• Drainage from a nasogastric tube
• Drainage from wounds or chest tubes
Other Causes
Isotonic FVD
• Hemorrhage
• Burns
• Vomiting
• Diarrhea
• Addison disease
• Fever
• Excessive perspiration
Hypertonic FVD
• Diabetes insipidus
• Diabetic ketoacidosis (DKA)
• Osmotic diuretics
• Hypertonic enteral tube feedings
• Hypertonic intravenous (IV) fluids
• Prolonged vomiting and diarrhea
• Decreased oral intake
Isotonic Fluid Volume Excess
• Equal retention of water and sodium
• Results in increased circulating volume with no change in serum osmolality
, Hypotonic Fluid Volume Excess
• Retention of water greater than sodium
• Results in increased circulating volume with decreased serum osmolality (known as
hemodilution)
• Water shifts into cells and causes them to swell
• This can be fatal if untreated as a result of pulmonary and cerebral edema
The table lists some of the underlying causes of the two types of FVE.
Causes of Isotonic FVE Causes of Hypotonic FVE
• Heart failure Excessive water intake
• Oliguric kidney disease Prolonged use of hypotonic IV solutions
• Cirrhosis of the liver with low Syndrome of inappropriate antidiuretic albumin
hormone (SIADH)
Effects
FVE can affect multiple body systems. Patients who develop severe kidney disease may have
decreased urine production and output. This water retention contributes to an increased
circulating volume. Eventually, the increased volume puts a strain on the pumping ability of the
heart. Heart failure can develop with possible pulmonary edema (accumulation of fluid in the
lungs).
Summary
The causes and severity of FVD and FVE are varied. Fluid imbalances are frequently associated
with surgery and IV therapy.
FVD develops when excessive fluid is lost or fluid intake is significantly reduced. Two types of
FVD are isotonic fluid deficit and hypertonic fluid deficit. In isotonic FVD, water and sodium are
lost equally, and serum osmolality is unchanged. In hypertonic FVD, fluid shifts from inside of
the cells to outside of the cells. Water is lost more than sodium and serum osmolality is
increased.
FVE occurs when intake of fluid is greater than output and results in increased circulating
volume. There are two types of FVE: isotonic and hypotonic. In isotonic FVE, there is retention
of both water and sodium, serum osmolality remains unchanged. In hypotonic FVE, the
retention of water is greater than sodium, and there is a decrease in serum osmolality.
Hypotonic FVE results in fluid moving into cells, causing them to swell.
