Overview
This lecture covers fluid volume deficit (dehydration), its causes, key signs and symptoms, and how the body compensates for low fluid levels.
Causes of Fluid Volume Deficit
- Fluid volume deficit means a decrease in body fluids, leading to dehydration.
- Major causes include vomiting and diarrhea from infection or food poisoning.
- Excessive sweating from fever, heat stroke, thyroid crisis, or severe burns causes fluid loss.
- Increased urination (diuresis) also leads to fluid loss.
- The "Three D's" are Diabetes Insipidus (DI), Diabetic Ketoacidosis (DKA), and Diuretics.
Three D's of Clinical Fluid Loss
- Diabetes Insipidus (DI): Causes excessive urination (up to 20 L/day), leading to severe fluid loss.
- Diabetic Ketoacidosis (DKA): High blood sugar from infection increases dehydration, often with rapid breathing (Kussmaul respirations) causing further fluid loss.
- Diuretics (e.g. furosemide, hydrochlorothiazide): Medications that increase urine output, causing both fluid and potassium loss.
Body Compensation Mechanisms
- The body compensates for fluid loss by increasing thirst to boost fluid intake.
- Urine becomes concentrated to conserve water.
- Heart rate increases and blood vessels constrict to maintain blood pressure and tissue oxygenation.
Key Terms & Definitions
- Fluid Volume Deficit — A decrease in body fluids causing dehydration.
- Diabetes Insipidus (DI) — A condition causing excessive urine production and fluid loss.
- Diabetic Ketoacidosis (DKA) — A complication of diabetes with high blood sugar and dehydration.
- Diuretics — Medications that promote fluid loss through increased urination.
- Kussmaul Respirations — Deep, rapid breathing seen in DKA, leading to fluid loss.
Action Items / Next Steps
- List and memorize the major causes of fluid volume deficit, especially the “Three D’s.”
- Review symptoms and compensation mechanisms of dehydration.
- Study the effects and risks of diuretics on fluid and electrolyte balance.