Exam 2: Fluids, Electrolytes, and Acid-Base Balance Flashcards
What is the distribution of fluid in the body?
2/3 intracellular, 1/3 extracellular (interstitial and intravascular)
What are the forces affecting fluid distribution?
Osmotic and hydrostatic (capillary and interstitial)
What is osmotic pressure?
pulling pressure, movement of things (lots of sodium in the vessel pulls water in
What is hydrostatic pressure?
pushing pressure, blood against the blood vessel
What are normal and abnormal excretion mechanisms?
Normal: urine, sweat, feces, respiration
Abnormal: vomiting, diarrhea
What causes volume deficit?
vomiting, diarrhea, excessive diuretics, hemorrhage
What causes volume excess?
Iatrogenic, heart failure, renal failure
Clinical manifestations of volume deficient
depends on amount of fluid loss, tachycardia, orthostatic hypotension, dizziness, syncope, dry mucus membranes, skin tenting, prolonged capillary refill
Clinical manifestations of volume excess
edema, JVD (jugular vein distention), dyspnea, orthopnea
What is Hyponatremia?
relative excess of water (decrease sodium concentration)
What is hypernatremia?
relative water deficiency (increased sodium concentration)
Causes of hyponatremia
iatrogenic, water poisoning, SIADH, Diuretics, Replacement of fluids due to vomiting/ diarrhea with water but no salt
Causes of Hypernatremia
Iatrogenic, diabetes insipidus, prolonged vomiting or diarrhea without volume replacement, diaphoresis
How does sodium imbalance impact cells?
Hyponatremia causes cells to expand (decreased osmolality), Hypernatremia causes cells to shrink (increased osmolality)
Clinical manifestations of abnormalities in sodium concentration
headache, nausea/vomiting, CNS dysfunction, confusion, seizures, coma
What system is Sodium imbalance connected with?
Neurological
What system is potassium imbalance connected with?
Muscular (smooth, cardiac, skeletal)
What system is calcium imbalance connected with?
Neuromuscular (less cardiac but still some smooth and skeletal)
What is edema?
swelling caused by excess fluid in tissues
What are normal and abnormal electrolyte excretion mechanisms?
Normal: urine, feces (diarrhea (potassium, magnesium), Fat malabsorption (calcium, magnesium)), sweat
Abnormal: vomiting/diarrhea, fistula/wound drainage, nasogastric suction
What is Hypokalemia? Causes
two little potassium, diarrhea, vomiting, alkalosis, potassium-wasting diuretics, excess insulin
What is Hyperkalemia? Causes
too much potassium, renal failure, iatrogenic (blood transfusion or iv potassium), aldosterone inhibition (medications), insufficient insulin
Hypokalemia clinical manifestations
muscle weakness, cardiac arrythmia, abdominal distention/ ileus
Hyperkalemia clinical manifestations
muscle weakness, cardiac arrythmia, intestinal cramps/diarrhea
What is Hypocalcemia? Causes
too little calcium, dietary insufficiency, vitamin D deficiency, renal failure, fat malabsorption (pancreatitis), large blood transfusions (citrate)
What is Hypercalcemia? Causes
too much calcium, vitamin D excess, Milk-Alkali syndrome, cancer (bone tumors, multiple myeloma, leukemia), Thiazides, Paget disease
Hypocalcemia clinical manifestations
increased neuromuscular excitability (paresthesias, muscle twitching/ cramping, tetany , hyperactive reflexes, Trousseau/ Chvostek signs, cardiac arrhythmias,
Hypercalcemia clinical manifestations
decreased neuromuscular excitability (personality changes/ fatigue, nausea & vomiting, constipation, muscle weakness, diminished reflexes), cardiac arrythmias
What is the normal blood pH?
7.35 - 7.45
Buffer mechanisms of the Acid-Base Homeostasis
carbonic acid, hemoglobin, phosphate
Lung mechanisms of the Acid-Base Homeostasis
exhalation of CO2
Kidney mechanisms of Acid-Base Homeostasis
HCO3-, Phosphate, NH3/NH4+
Renal proximal tubule function???
excretion of metabolic acid. Hydrogen ions secreted into the renal tubular lumen combine with filtered bicarbonate, buffers, or ammonia
Metabolic Acid-Base Disturbances
Acidosis: decrease HCO3-
Alkalosis: increase HCO3-
Respiratory Acid-Base Disturbances
Acidosis: increase CO2
Alkalosis: decrease CO2
What questions to ask when measuring the acid-base imbalance
What is the pH? Acidosis or Alkalosis
What is the PCO2? Does this explain the pH
What is the HCO3-? Does this explain the pH
Causes of metabolic acidosis
DKA, toxin ingestion (ASA/Methanol), severe infection, burns
Causes of metabolic alkalosis
vomiting, intake of bicarbonate (antacids), hypokalemia, hyperaldosteronism
Causes of respiratory acidosis
Opioids, COPD, Asthma, Chest injury
Causes of repertory alkalosis
hyperventilation
