Introduction to Nursing Care:
Complex Fluid Balance Alterations
Fluid and electrolyte imbalances are among the most encountered
problems in critically ill clients and are associated with increased
morbidity and mortality.
Disorders such as severe burns, trauma, sepsis, kidney disease, and heart
failure potentially disrupt the finely balanced mechanisms that control
fluid and electrolyte balance. Supporting treatments, such as mechanical
ventilation and medications, may also affect fluid balance.
Monitoring and careful management of electrolytes and fluid balance
are integral parts of assessing and caring for a critically ill client.
Supporting Increased Cardiac
Output
The nurse is caring for a client experiencing hypovolemia. Which action will support an
increased preload and improve cardiac output?
Administer intravenous bolus 0.9% normal saline
Increased intravenous (IV) fluid administration will increase preload, which
will increase cardiac output.
,Fluid Balance and Mechanical
Ventilation
The nurse is caring for a client diagnosed with acute respiratory distress syndrome (ARDS).
Which factor contributes to fluid retention during mechanical ventilation?
Decreased renal perfusion with release of renin
Mechanical ventilation causes fluid retention because decreased cardiac
output is associated with positive pressure ventilation and positive end-
expiratory pressure (PEEP) results in decreased renal perfusion, release of
renin, and increased aldosterone secretion.
Fluid Volume Deficit
An older adult client with severe dehydration is admitted to the intensive care unit (ICU) after
being found unconscious on the floor of the home.
Laboratory results include:
sodium 122 mEq/L
hematocrit 56%
blood urea nitrogen (BUN) 38 mg/dL
The provider orders intravenous administration of D5W at 200 ml/hour to treat hypovolemia.
Several hours after the infusion is started, the client has a generalized seizure. Which statement
most accurately describes the cause of the seizure?
Administration of sodium-free fluids causes cerebral cellular swelling.
Dextrose in water causes fluid to shift from the extracellular space into
the cells, which caused cerebral cellular swelling and led to seizure activity.
,Fluid Homeostasis
The human body strives to consistently achieve fluid balance
(homeostasis). There are hundreds of feedback mechanisms in place to
ensure homeostasis is maintained. However, fluid and electrolyte
imbalances are prevalent in clients with critical illnesses or injuries,
because illness disrupts normal homeostatic mechanisms.
Many factors contribute to the shifting of fluids and electrolytes among
critically ill clients, which compromises their clinical status and adversely
affects outcomes. The shifts occur due to underlying chronic diseases and
acute conditions, which often occur during the client’s hospitalization.
Fluids must be in equilibrium within the intravascular, interstitial, and
intracellular spaces. Intracellular fluid volume is relatively stable, whereas
intravascular fluid fluctuates in response to fluid intake and loss.
Interstitial fluid is the reserve fluid, replacing intravascular and
intracellular volume as needed.
Hormonal Influences on Fluid
Balance
Kidneys are the primary organ responsible for the absorption,
distribution, and excretion of water and its particles. Electrolyte
homeostasis is regulated by the kidney and its response to hormones
such as aldosterone, anti-diuretic hormone, and natriuretic peptides
which work specifically on the renal tubules.
Aldosterone
Aldosterone promotes sodium retention while increasing urinary loss of
potassium. Severe hypotension and hypovolemia trigger the release of
aldosterone.
Antidiuretic Hormone (ADH)
Antidiuretic hormone (ADH) triggers the renal tubules to reabsorb water and return it to the
intravascular space. Hypovolemia and increased blood osmolarity cause ADH to be released.
, Conditions such as diabetes insipidus and syndrome of inappropriate ADH secretion (SIADH)
affect the release of this hormone.
Natriuretic Peptides
Natriuretic peptides (atrial natriuretic peptide) are released from the heart
in response to chamber stretching and overfilling. Increased renal
excretion of sodium, water, and increased glomerular filtration rate occur
in response to natriuretic peptide release.
Maintaining Fluid Balance
The pituitary gland is responsible for the production and release of antidiuretic hormone (ADH).
ADH causes renal cells to reabsorb
water. This action decreases urine output, concentrating the urine while diluting the
blood.
In fluid volume deficit, urine specific gravity is increased
and in fluid volume overload, urine specific gravity is
decreased.
A medication given as a replacement for ADH is desmopressin.
The posterior pituitary gland releases antidiuretic hormone (ADH), causing
renal cells to reabsorb water which decreases urine output, concentrating
the urine, and diluting the blood.
The normal urine specific gravity is 0.010–0.030. Decreased specific gravity
indicates fluid volume overload. Increased specific gravity indicates
dehydration.
Desmopressin is a synthetic form of ADH administered intranasally,
subcutaneously, or intravenously.
Renal Function
Complex Fluid Balance Alterations
Fluid and electrolyte imbalances are among the most encountered
problems in critically ill clients and are associated with increased
morbidity and mortality.
Disorders such as severe burns, trauma, sepsis, kidney disease, and heart
failure potentially disrupt the finely balanced mechanisms that control
fluid and electrolyte balance. Supporting treatments, such as mechanical
ventilation and medications, may also affect fluid balance.
Monitoring and careful management of electrolytes and fluid balance
are integral parts of assessing and caring for a critically ill client.
Supporting Increased Cardiac
Output
The nurse is caring for a client experiencing hypovolemia. Which action will support an
increased preload and improve cardiac output?
Administer intravenous bolus 0.9% normal saline
Increased intravenous (IV) fluid administration will increase preload, which
will increase cardiac output.
,Fluid Balance and Mechanical
Ventilation
The nurse is caring for a client diagnosed with acute respiratory distress syndrome (ARDS).
Which factor contributes to fluid retention during mechanical ventilation?
Decreased renal perfusion with release of renin
Mechanical ventilation causes fluid retention because decreased cardiac
output is associated with positive pressure ventilation and positive end-
expiratory pressure (PEEP) results in decreased renal perfusion, release of
renin, and increased aldosterone secretion.
Fluid Volume Deficit
An older adult client with severe dehydration is admitted to the intensive care unit (ICU) after
being found unconscious on the floor of the home.
Laboratory results include:
sodium 122 mEq/L
hematocrit 56%
blood urea nitrogen (BUN) 38 mg/dL
The provider orders intravenous administration of D5W at 200 ml/hour to treat hypovolemia.
Several hours after the infusion is started, the client has a generalized seizure. Which statement
most accurately describes the cause of the seizure?
Administration of sodium-free fluids causes cerebral cellular swelling.
Dextrose in water causes fluid to shift from the extracellular space into
the cells, which caused cerebral cellular swelling and led to seizure activity.
,Fluid Homeostasis
The human body strives to consistently achieve fluid balance
(homeostasis). There are hundreds of feedback mechanisms in place to
ensure homeostasis is maintained. However, fluid and electrolyte
imbalances are prevalent in clients with critical illnesses or injuries,
because illness disrupts normal homeostatic mechanisms.
Many factors contribute to the shifting of fluids and electrolytes among
critically ill clients, which compromises their clinical status and adversely
affects outcomes. The shifts occur due to underlying chronic diseases and
acute conditions, which often occur during the client’s hospitalization.
Fluids must be in equilibrium within the intravascular, interstitial, and
intracellular spaces. Intracellular fluid volume is relatively stable, whereas
intravascular fluid fluctuates in response to fluid intake and loss.
Interstitial fluid is the reserve fluid, replacing intravascular and
intracellular volume as needed.
Hormonal Influences on Fluid
Balance
Kidneys are the primary organ responsible for the absorption,
distribution, and excretion of water and its particles. Electrolyte
homeostasis is regulated by the kidney and its response to hormones
such as aldosterone, anti-diuretic hormone, and natriuretic peptides
which work specifically on the renal tubules.
Aldosterone
Aldosterone promotes sodium retention while increasing urinary loss of
potassium. Severe hypotension and hypovolemia trigger the release of
aldosterone.
Antidiuretic Hormone (ADH)
Antidiuretic hormone (ADH) triggers the renal tubules to reabsorb water and return it to the
intravascular space. Hypovolemia and increased blood osmolarity cause ADH to be released.
, Conditions such as diabetes insipidus and syndrome of inappropriate ADH secretion (SIADH)
affect the release of this hormone.
Natriuretic Peptides
Natriuretic peptides (atrial natriuretic peptide) are released from the heart
in response to chamber stretching and overfilling. Increased renal
excretion of sodium, water, and increased glomerular filtration rate occur
in response to natriuretic peptide release.
Maintaining Fluid Balance
The pituitary gland is responsible for the production and release of antidiuretic hormone (ADH).
ADH causes renal cells to reabsorb
water. This action decreases urine output, concentrating the urine while diluting the
blood.
In fluid volume deficit, urine specific gravity is increased
and in fluid volume overload, urine specific gravity is
decreased.
A medication given as a replacement for ADH is desmopressin.
The posterior pituitary gland releases antidiuretic hormone (ADH), causing
renal cells to reabsorb water which decreases urine output, concentrating
the urine, and diluting the blood.
The normal urine specific gravity is 0.010–0.030. Decreased specific gravity
indicates fluid volume overload. Increased specific gravity indicates
dehydration.
Desmopressin is a synthetic form of ADH administered intranasally,
subcutaneously, or intravenously.
Renal Function
