Lecture on Isotonic, Hypotonic, and Hypertonic Solutions

Introduction

• Presenter: Sarah from register nurse rn.com
• Key objectives:
  • Understand what happens to cells under different tonic conditions
  • Identify fluids administered for each condition
  • Key concepts for exams including NCLEX
  • Free quiz available on website

Understanding the Cell and Osmosis

• Cell composition:

  • Intracellular: Inside cell, composed of organelles and electrolytes
  • Extracellular: Surrounds cell, also contains electrolytes

• Osmosis:

  • Movement of water from less concentrated to more concentrated area through a semi-permeable membrane
  • Sodium and water relationship: Water follows sodium

Isotonic Solutions

• Definition:

  • "ISO" = equal; equal concentration inside and outside the cell

• Types of Isotonic Fluids:

  • 0.9% Saline
  • Dextrose 5% in water (D5W)
  • 5% Dextrose and 0.225% Saline
  • Lactated Ringers (LR)

• D5W Special Note:

  • Initially isotonic, but becomes hypotonic after metabolism

• Uses:

  • Increase extracellular fluid volume
  • Conditions: blood loss, dehydration, surgery

Hypotonic Solutions

• Definition:

  • "Hypo" = under; lower concentration outside the cell

• Effects:

  • Fluid moves into cell, causing cell swelling (lysis)
  • Risk of hypovolemia in circulatory system

• Types of Hypotonic Fluids:

  • 0.45% Saline (Half Normal Saline)
  • 0.225% Saline (Quarter Saline)
  • 0.33% Saline (Third Saline)

• Uses:

  • Hydrate dehydrated cells
  • Conditions: Diabetic ketoacidosis (DKA), hyperosmolar hyperglycemia

• Contraindications:

  • Increased intracranial pressure, burns, trauma

Hypertonic Solutions

• Definition:

  • "Hyper" = excessive; higher concentration outside the cell

• Effects:

  • Fluid moves out of the cell, causing the cell to shrink

• Types of Hypertonic Fluids:

  • 3% Saline
  • 5% Saline
  • 10% Dextrose in water
  • 5% Dextrose in 0.9% Saline
  • 5% Dextrose in half normal saline
  • 5% Dextrose in LR

• Uses:

  • Reduce cell swelling
  • Conditions: cerebral edema, hyponatremia

• Administration:

  • Often requires central line
  • Usually administered in ICU due to risk of fluid overload

Conclusion

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