AcidBase Balance Preclass review materials AcidBase Balance Buffer
Acid-Base Balance Pre-class review materials
Acid-Base Balance Buffer Systems n Respiratory: n n n Blows off C 02 in exchange for 02 Responds immediately to p. H Imbalances (increasing/decreasing respiration) Kidneys: n n Excretes or conserves hydrogen ions (H+) and/or bicarbonate Respond w/in 2 -4 hrs but may take days to become effective in resolving p. H imbalances
Acid-Base Balance Respiratory: n Inadequate respiration: n n n Metabolic: n too fast (blowing off too much C 02= alkalosis) n or too slow/shallow (C 02 accumulates=acidosis) In Acidosis the extra CO 2 molecules combine with water to form carbonic acid which contributes to an acid p. H. Acidosis occurs when metabolism is impaired : n n poor blood supply (ischemic bowel) stops oxidative metabolism and lactic acid forms (acidosis) DKA – break down of fatty acids (acidosis) Alkalosis: n Too much acid removed from body i. e. nasogastric sx, N/V/D
Respiratory Imbalances Respiratory Acidosis n n n Causes: n Hypoventilation n Narcotics n Coma S&S: n CNS depression n Decreased mentation n Restlessness, lethargy, somnolence, coma Treatment: n Reverse narcotics (Increase respiration) n Mechanical ventilation Respiratory Alkalosis n n n Causes: n Hyperventilation n Anxiety/Pain n Over ventilation via mechanical ventilation (i. e. tidal volumes or rate too high) S&S: n Tetany, irritability, disorientation, seizure Treatment: n Rebreath C 02 (paper bag) n Decrease anxiety (medications)
Metabolic Imbalances Metabolic Alkalosis n n n Causes: n Excessive gain of base (bicarb) or loss of acids (hydrogen ions) n Excess antacids n Gastric suctioning, vomiting n Loop diuretics (hypokalemia >H+ excretion) n Diarrhea S&S: n Over-excitability of PNS (tetany, irritability, disorientation, seizures) Tx: tx underlying cause, infusion of hydrochloric acid (HCl) Metabolic Acidosis n n n Causes: n DKA & starvation (fatty acids) n Anaerobic metabolism n Excessive ASA intake n K+ sparing diuretics (hyperkalemia < H+ excretion) S&S n n/v, abdominal pain n Cardiac arrhythmias, n Kussmaul respirations n CNS depression (confusion, drowsiness, lethargy, stupor, coma) Tx: n Tx underlying cause n Infusion of bicarbonate
Anion Gap The Anion Gap is the difference between the sum of the major anions and the major cations: n Gap = Na+ + K+ - Cl- - HCO 3 - n Normal value 8 -14 m. Eq/L Useful in differentiating the potential causes of metabolic acidosis n n Increased AG (>14) indicates > in acid production/load (i. e. lactic acidosis) n Normal AG indicates a loss of base/HC 03, hyperchloremia, acute renal tubular necrosis
Analyzing ABGs Normal Arterial Values 6 Easy Steps: Range: n p. H 7. 35 -7. 45 n p. CO 2 35 -45 n p. O 2 80 -100 n O 2 Sat. 95 -100% n HCO 3 22 -26 n BE +or-2 n n n Is the p. H normal? Is the CO 2 normal? Is the HCO 3 normal? Does the CO 2 or the HCO 3 match the p. H? Does the CO 2 or the HCO 3 go the opposite direction of the p. H? Is the p. O 2 and the Sa. O 2 normal?
Analyzing ABGs Respiratory n n n p. H and C 02 Inverse p. H low – C 02 high n n n (Resp acidosis) p. H high- C 02 low n Metabolic (Resp alkalosis) p. H and Bicarb Parallel p. H low – Bicarb low n n (metabolic acidosis) p. H high – Bicarb high n (metabolic alkalosis) ROME (Respiratory Opposite/ Metabolic Equal) Respiratory Seesaw / Metabolic Elevator
Analyzing ABG’s n n n p. H 7. 30 p. CO 2 58 p. O 2 50 O 2 Sat. 80% HCO 3 26 normal n n Step 1. The p. H is acidotic Step 2. The CO 2 is acidotic Step 3. The HCO 3 is normal Step 4. The CO 2 matches the p. H, therefore the imbalance is respiratory acidosis Step 5. The HCO 3 is normal, therefore there is no compensation Step 6. The Pa. O 2 and O 2 sat are low indicating hypoxemia The full diagnosis for this ABG is: Uncompensated respiratory acidosis.
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