2.1 Pathophysiologic Mechanism Flashcards
Nursing Process
Assessment Diagnosis Planning Interventions Evaluation
Hydrostatic Pressure
- Movement of fluid through capillary wall
- Pressure exerted on the walls of blood vessels pushing fluid out
Oncotic Pressure
Colloid Oncotic Pressure - Drawing power of protein in plasma
Draws water back into the intravascular spaces
Passive Transport
- Does not require energy to transport
Diffusion
- Movement of molecules/solutes from high concentration to low concentration
Filtration
- Movement of water and dissolved substances across semi-permeable membrane from area of high hydrostatic pressure to low hydrostatic pressure.
- Example includes blood pressure
Osmosis
- Movement of water across semi-permeable membrane over a solute gradient from low concentration to high concentration
Active Transport
- Example is sodium-potassium pump
- Maintains higher concentration of extracellular sodium and higher concentration of intracellular potassium.
Fluid Gains and Losses
- Intake and output should be basically equal
- Loss of water is mainly through the kidney which is roughly 1mL/kg/hour.
- Skin Sensible Loss - Sweating
- Skin Insensible Loss - Fever, Exercise, Burns
- Lungs lose about 300mL a day
Fluid Imbalances
- Fluid deficit may cause delirium
- Dehydration is common in older adults due to reduced renal function, decreased cardiac reserve, age related thinning of skin, loss of skin strength and elasticity, and decreased extracellular fluid.
Pediatric Fluid Imbalances
- Children and infants have higher body water content
- Children also have higher metabolic rates and increased body surface to mass index
- Because of this infants and children require more water to maintain equilibrium
Fluid Volume Deficit Interventions
- Measure I&O at least every 8 hours, sometimes hourly
- Measure daily weight
- Monitor vital signs (especially BP and HR)
- Assessment of skin and tongue turgor, mucosa, mental status
- Measures to minimize fluid loss
- Oral rehydration (preferred)
- Parenteral fluids (if unable to tolerate oral fluids or if deficit is severe)
Fluid Volume Excess
- I&O
- Daily Weights
- Assess lung sounds, edema, etc
- Monitor responses to diuretics and parental fluids
- Promote fluid restriction adherence
- Teach patient sodium and fluid restrictions
- Avoid sources of excess sodium including medications
- Promote rest
Diuretics
- Reduces fluid volume in the body
Diuretic Pharmacotherapeutics
- Hypertension
- Heart failure
- Cirrhosis (liver damage from alcohol or hepatitis)
- Renal disease
- Increased Intracranial Pressure
- Increased Intraocular Pressure
Diuretic Mechanism of Action
- Blocks sodium and chloride from being re-absorbed
- This prevents passive re-absorption of water
Sites of Action Diuretic
- Loop diuretics affect Loop of Henley
- Thiazide diuretics act on early segment of distal convoluted tubule
- Potassium sparing diuretics act on distal nephron
Examples of Diuretics
Furosemide (Lasix) - Loop (High-Ceiling) Diuretic
Hydrochlorothiazide (HCTZ) - Thiazide Diuretic
Spironolactone (Aldactone) - Potassium Sparing (Aldosterone Antagonist)
Triamterene - Potassium Sparing (Non-Aldosterone Antagonist)
Acetazolamide (Diamox) - Carbonic Anhydrase Inhibitor Diuretic
Mannitol (Osmitrol) - Osmotic Diuretic
Diuretic Effect on Electrolytes
- Affects absorption and excretion of electrolytes, mainly potassium.
- Major adverse effect is electrolyte imbalance
Electrolytes
Sodium - 135-145 Chloride - 98-106 Potassium - 3.5-5.0 Phosphate - 2.5-4.5 Magnesium - 1.8-3.0 Calcium - 8.5-10.5
Urine Specific Gravity
- Normal value is 1.010-1.025
- Measures kidneys ability to excrete or conserve water
- Specific gravity is inversely related to urine volume
- Larger the urine volume, lower the specific gravity is
- Glucose/protein in urine can falsely elevate urine specific gravity
BUN (Blood Urea Nitrogen)
Normal Value 10-20 mg/dL
- End product of muscle and protein being metabolized in the liver.
- Breakdown of amino acids produces ammonia which is converted into urea and excreted.
- BUN is increased by dehydration, diminished renal function, fever, GI Bleeding, increased protein intake and sepsis.
- BUN is decrease by low-protein diet, starvation, end stage liver disease, pregnancy
Serum Creatinine
Normal Level - 0.7-1.4 mg/dL
- End product of muscle metabolism
- Does not vary with protein intake and metabolic state
- Better indicator of renal function than BUN
- Levels depend on lean body mass which varies between individuals.
- Serum Creatinine increases when renal function decreases
Hematocrit
Normal Level (42-52% For Men) (35-47% For Women)
- Measures volume percent of RBC in whole blood
Increase caused by dehydration or polycythemia (condition of increased RBC’s)
Decreased caused by fluid volume excess and anemia
Major Cations
- Sodium
- Potassium
- Calcium
- Magnesium
- Hydrogen Ions
Major Anions
- Chloride
- Bicarbonate
- Phosphate
- Sulfate
- Proteinate Ions