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AHII - Chapter 14
Concepts of Acid-Base Balance
Question | Answer |
---|---|
Acid-base balance | Maintenance of arterial blood pH between 7.35 & 7.45 through regulation of hydrogen ion production & elimination |
Acids | Substances that release hydrogen ions when dissolved -> increasing the amount of free hydrogen ions in that solution |
Bases | Bind free hydrogen ions in solution & lower the amount of free hydrogen ions in solution (Most common: bicarbonate aka HCO3) |
Buffers | Substances that can react as either an acid or base when dissolved, just depends on the fluid's pH |
Normal ranges | pH: 7.35 - 7.45 (Anything lower = acidic; anything higher = basic) CO2: 35 - 45 (Respiratory) HCO3: 21 - 28 (Metabolic) |
Carbon dioxide (CO2) | Carbon dioxide content of a fluid is directly related to the amount of free hydrogen ions in that fluid; therefore, eliminating extra CO2 during exhalation can bring hydrogen levels back to normal |
Defense | Buffers: 1st line of defense; respiratory: 2nd line of defense by breathing (hyperventilation or hypoventilation); kidneys: 3rd line of defense by movement of bicarbonate |
Compensation | The body adapts to attempt to correct changes in blood pH & maintain acid-base balance |
Acidosis vs. alkalosis | Acidosis: imbalances in which blood pH is below normal; alkalosis: imbalances in which blood pH is above normal. No specific disorders that cause overproduction of bicarbonate -> health probs are more likely to cause acidosis |
Relative acidosis | Amount of acids does not increase; the amount or strength of the bases decreases (base deficit) |
Common causes of acidosis | Metabolic: overproduction of hydrogen ions, underelimination of hydrogen ions, underproduction of bicarbonate, overelimination of bicarbonate Respiratory: underelimination of hydrogen ions |
S/S of acidosis | Cardio: ranges from bradycardia - heart block, tall T waves, widened QRS complex, thready peripheral pulses, & hypotension CNS: depressed activity Neuromuscular: hyporeflexia, muscle weakness, & flaccid paralysis Resp: Kussmaul respirations |
S/S of acidosis | Integumentary: warm, flushed, dry skin (metabolic); pale-to-cyanotic, dry skin (respiratory) Psychosocial: cognitive changes may be the 1st signs Labs: important to distinguish metabolic vs. respiratory for treatment |
Metabolic acidosis interventions | Hydration & drugs or treatments to control the problem causing the acidosis (Bicarbonate is given only if serum bicarbonate levels are low & the pH is less than 7.2) |
Respiratory acidosis interventions | Drug therapy, oxygen therapy, pulmonary hygiene, & ventilatory support |
Relative alkalosis | The actual amount of bases does not increase, but the amount of the acids decreases, creating an acid deficit |
S/S of alkalosis | CNS: increased activity, anxiety, irritability, tetany, seizures, positive Chvostek sign, positive Trousseau sign, & paresthesias Neuromuscular: hyperreflexia, muscle cramping & twitching, muscle weakness |
S/S of alkalosis | Cardio: increased HR, normal or low BP, & increased digoxin toxicity Resp: hyperventilation (respiratory) & decreased respiratory effort associated with skeletal muscle weakness (metabolic) |
Alkalosis interventions | Drug therapy & ***prevention of injury from falls due to hypotension & muscle weakness symptoms |