Fluid Therapy in Medical Practice

Importance of Fluid Therapy

• Can be life-saving in certain conditions
• Loss of body water can cause problems ranging from mild headache to convulsions, coma, and death

Types of Fluids

Colloid Solutions

• Contain large molecules that don't pass cell membranes
• Expand intravascular volume and draw fluid from extravascular spaces via higher oncotic pressure

Crystalloid Solutions

• Contain small molecules that flow easily across cell membranes
• Increase fluid volume in both intravascular and interstitial spaces

Isotonic Solutions

• 0.9% sodium chloride (Normal Saline)
  • Simply salt water containing sodium and chloride
  • Used for severe diarrhea, vomiting, hemorrhage, fistulas, wounds, shock, mild hyponatremia, and metabolic acidosis
• Ringer's lactate or Hartmann solution
  • Most physiologically adaptable fluid, closely related to body's blood serum and plasma composition
  • Used for burn and injury patients
• Ringer's solution
  • Contains sodium, potassium, calcium, and chloride in similar proportions to LR, but without lactate
• Dextrose 5%
  • Isotonic solution, but becomes hypotonic when dextrose is metabolized, causing fluid to shift into cells

Hypotonic Solutions

• Lower concentration of solutes (electrolytes) compared to isotonic solutions
• Osmolality less than 250 mOsm/L
• Lower serum osmolality, causing fluid to shift from intravascular space to intracellular and interstitial spaces
• Examples: 0.45% sodium chloride, 0.33% sodium chloride, 0.2% sodium chloride, and 2.5% dextrose in water
• Used to treat patients with intracellular dehydration, hypernatremia, diabetic ketoacidosis, and hyperosmolar hyperglycemic state

Hypertonic Solutions

• Higher tonicity or solute concentration
• Osmolarity of 375 mOsm/L or higher
• Draw water out of intracellular space, increasing extracellular fluid volume
• Examples: 3% sodium chloride, 5% dextrose with normal saline (D5NS)
• Used for severe hyponatremia, cerebral edema, and as volume expanders

Colloid Solutions

• Expand intravascular volume by drawing fluid from interstitial spaces
• Require administration of less total volume and have a longer duration of action
• Examples: albumin (Human albumin 5% solution), hydroxyethalstarches

Precautions and Complications

• Hypotonic solutions: decrease in vascular bed volume, worsen hypovolemia and hypotension, and cardiovascular collapse
• Hypertonic fluids: intravascular fluid volume overload and pulmonary edema
• Colloid solutions: interfere with platelet function, increase bleeding times, and anaphylactic reactions
• Complications of fluid therapy: phlebitis, infiltration, extravasation, hemorrhage, local infection, pulmonary edema, and air embolism

Importance of Fluid Therapy

• Can be life-saving in certain conditions
• Loss of body water can cause problems ranging from mild headache to convulsions, coma, and death

Types of Fluids

Colloid Solutions

• Contain large molecules that don't pass cell membranes
• Expand intravascular volume and draw fluid from extravascular spaces via higher oncotic pressure

Crystalloid Solutions

• Contain small molecules that flow easily across cell membranes
• Increase fluid volume in both intravascular and interstitial spaces

Isotonic Solutions

• 0.9% sodium chloride (Normal Saline)
  • Simply salt water containing sodium and chloride
  • Used for severe diarrhea, vomiting, hemorrhage, fistulas, wounds, shock, mild hyponatremia, and metabolic acidosis
• Ringer's lactate or Hartmann solution
  • Most physiologically adaptable fluid, closely related to body's blood serum and plasma composition
  • Used for burn and injury patients
• Ringer's solution
  • Contains sodium, potassium, calcium, and chloride in similar proportions to LR, but without lactate
• Dextrose 5%
  • Isotonic solution, but becomes hypotonic when dextrose is metabolized, causing fluid to shift into cells

Hypotonic Solutions

• Lower concentration of solutes (electrolytes) compared to isotonic solutions
• Osmolality less than 250 mOsm/L
• Lower serum osmolality, causing fluid to shift from intravascular space to intracellular and interstitial spaces
• Examples: 0.45% sodium chloride, 0.33% sodium chloride, 0.2% sodium chloride, and 2.5% dextrose in water
• Used to treat patients with intracellular dehydration, hypernatremia, diabetic ketoacidosis, and hyperosmolar hyperglycemic state

Hypertonic Solutions

• Higher tonicity or solute concentration
• Osmolarity of 375 mOsm/L or higher
• Draw water out of intracellular space, increasing extracellular fluid volume
• Examples: 3% sodium chloride, 5% dextrose with normal saline (D5NS)
• Used for severe hyponatremia, cerebral edema, and as volume expanders

Colloid Solutions

• Expand intravascular volume by drawing fluid from interstitial spaces
• Require administration of less total volume and have a longer duration of action
• Examples: albumin (Human albumin 5% solution), hydroxyethalstarches

Precautions and Complications

• Hypotonic solutions: decrease in vascular bed volume, worsen hypovolemia and hypotension, and cardiovascular collapse
• Hypertonic fluids: intravascular fluid volume overload and pulmonary edema
• Colloid solutions: interfere with platelet function, increase bleeding times, and anaphylactic reactions
• Complications of fluid therapy: phlebitis, infiltration, extravasation, hemorrhage, local infection, pulmonary edema, and air embolism

Learn about the importance and risks of fluid therapy, including types of fluids used in clinical practice, such as colloids, crystalloids, and blood products.