This document discusses acid-base disorders including metabolic acidosis, metabolic alkalosis, and mixed acid-base disturbances. [1] Metabolic acidosis is caused by an increase in acids other than carbonic acid in the extracellular fluid or a loss of bicarbonate, with symptoms affecting the cardiovascular, respiratory, central nervous and gastrointestinal systems. [2] Metabolic alkalosis occurs when hydrogen ions are lost or bicarbonate increased, commonly seen with hypokalemia, and causes symptoms like hypertension, dysrhythmias, and gastrointestinal issues. [3] Mixed acid-base disturbances involve two or more concurrent disorders that can balance or exacerbate each other, requiring treatment

1. Acid – Base Part 2
Nurse 158
Winter 2009

2. Metabolic Acidosis
• pH decreases/HCO3 decreases
• Acids (other than carbonic acid) increase in ECF
{AG > 14 mEq/L}
• Or loss of HCO3 {normal AG}
• Rarely spontaneous
• Usually accompanied by other problems
• Renal disease
• GI losses
• Poisoning

3. Signs/symptoms Metabolic Acidosis
– Cardiovascular – hypotension, dysrhythmias
peripheral vasodilation, warm/dry skin then
cold/clammy skin
– Respiratory – rapid, shallow then deep,
Kussmaul
– CNS – headache, confusion, drowsy,
lethargy, weak
– GI – NVD, abd. pain

4. Diagnostic findings metabolic acidosis
– pH < 7.35
– HCO3 < 22 mEq/L
– Hyperkalemia common
– ECG changes
– Increased AG
– Calcium increased
– Magnesium decreased
– Base excess decreases

5. Base excess (BE)
– The amount of HCO3 in ECF
– Normal range -3.0 to +3.0
– If above +3.0, metabolic alkalosis
– If below -3.0, metabolic acidosis

6. Compensation Metabolic Acidosis
– Lungs eliminate CO2
– Kidneys conserve HCO3
– Urine pH <6
– PaCO2 starts decreasing

7. Interventions Metabolic Acidosis
– ABGs
– I&O, edema
– Weights
– VS
– LOC
– GI
– ECG
– Labs (esp. K)
– Protect
– Meds/IVs/possible dialysis

8. Medications Metabolic Acidosis
– If ketoacidosis =
– If diarrhea =
– NaHCO3

9. Metabolic Alkalosis
• Increase pH/ increase HCO3
• Occurs when H is lost
• Or increase in HCO3
• Or both
• Common with hypoK (thiazides,
furosemide), also with hypoCl, hypoCa
• Antacids

10. Signs & Symptoms Metabolic Alkalosis
– Cardiovascular – hypertension, tacky,
dysrhythmias
– Respiratory – hypoventilation, resp failure
– CNS - dizzy, confusion, tremors, irritable,
nervous, cramps, hyperreflexia, tetany,
paresthesia, seizures
– GI – NV, anorexia, paralytic ileus if hypoK

11. Diagnostic findings metabolic alkalosis
– pH >7.45
– HCO3 > 26 mEq/L
– Hypokalemia
– Hypocalcemia
– Hyponatremia
– Hypochloremia
– Chloride responsive/resistant
– Base excess increases

12. Compensation Metabolic Alkalosis
– lungs retain CO2
– Kidneys conserve H
– Kidneys excrete HCO3
– PaCO2 increases
– Urine pH >6

13. Interventions Metabolic Alkalosis
– Correct underlying cause
– Provide sufficient chloride
– Restore normal fluid balance
– Assess LOC
– VS, O2 sats, I&O,
– Protect from injury
– Monitor ECG’s and ABG’s and lytes
– Weights
– Maximize lung expansion with positioning

14. Medications Metabolic Alkalosis
– Normal saline IV replacement
– K supplement if hypoK
– Histamine-2 receptor antagonists
– If chloride responsive – acetazolamide
(Diamox)
– If chloride resistant – supplement to correct K
and Mg

15. Mixed Acid-Base Disturbances
• Two or more disorders at a time
• pH is dependent on the type of each
• Resp acidosis and alkalosis can’t
• Treat underlying cause of EACH disorder
• Mathematical formulas can help ID
• Anion gap and urine pH help with ID

16. • Mixed metabolic acidosis and respiratory
acidosis
– Acute pulmonary edema
– Cardiac arrest: inadequate ventilation
– pH value decreases and more pronounced
(HCO3 decreases while CO2 increases)

17. • Mixed metabolic alkalosis and respiratory
acidosis
– COPD with K wasting diuretics, V, diarrhea
– COPD with quick improvement in ventilation
– pH values balances (HCO3 and CO2 both
increased)

18. • Mixed metabolic acidosis and respiratory
alkalosis
– Due to rapid correction of metabolic acidosis
– Salicylate intoxication
– Gram negative septicemia
– pH values balanced (HCO3 and CO2
decreased)

19. • Mixed metabolic alkalosis and respiratory
alkalosis
– Postop severe hemorrhage
– Received massive transfusions
– Excessive NG drainage
– pH values increased and more pronounced
(HCO3 increased with CO2 decreased)

20. • Mixed metabolic acidosis and metabolic
alkalosis
– Gastroenteritis, V/D
– Usually no change in values
– Hypovolemia

21. • Chronic and acute respiratory acidosis
– Can lead to increased CO2 levels!!!!
– Close monitor by pulmonologist
– Respiratory therapy involved