Nursing Knowledge
Acid-base disorders involve imbalances in the body's pH levels, often categorized as acidosis (low pH) or alkalosis (high pH). These disorders can be respiratory or metabolic in origin, and they are commonly identified through arterial blood gas (ABG) analysis.
Uncompensated:
Opposite system is not responding, pH remains imbalanced.
Partial compensation:
Opposite system is working to correct the imbalance, pH not yet normalized.
Full compensation:
Homeostasis achieved, all lab values return to normal.
Respiratory alkalosis is a decrease in carbon dioxide levels due to increased excretion by the lungs. Excess carbon dioxide leads to pH imbalance.
The most common cause of respiratory alkalosis is hyperventilation.
| Normal values | Respiratory alkalosis | |
| pH | 7.35–7.45 | Increased |
| CO2 | 35–45 mm Hg | Decreased |
| HCO3- | 22–26 mmol/L | Normal or decreased |
Nursing tip: Kussmaul breathing is an abnormal rapid, deep breathing pattern that helps the body blow off extra CO2; often seen in DKA.
Reviews definition, causes and lab values and treatment of respiratory alkalosis
Respiratory acidosis is an accumulation of carbon dioxide in the body due to decreased excretion by the lungs. Decreased carbon dioxide levels lead to pH imbalance.
The most common causes of respiratory acidosis are:
| Normal values | Respiratory acidosis | |
| pH | 7.35–7.45 | Decreased |
| CO2 | 35–45 mm Hg | Increased |
| HCO3- | 22–26 mmol/L | Normal or decreased |
Reviews definition, causes and lab values and treatment of respiratory acidosis
Metabolic alkalosis is an accumulation of bicarbonate in the body caused by loss of stomach acid. Excess bicarbonate leads to pH imbalance. Metabolic alkalosis is usually accompanied by hypokalemia.
The most common cause of metabolic alkalosis is a loss of stomach acid, caused by excessive NG suction or vomiting.
| Normal values | Metabolic alkalosis | |
| pH | 7.35–7.45 | Increased |
| CO2 | 35–45 mm Hg | Normal or increased |
| HCO3- | 22–26 mmol/L | Increased |
Reviews definition, causes and lab values and treatment of metabolic alkalosis
Metabolic acidosis is an accumulation of acid in the body caused by either increased acid generation, loss of bicarbonate, or diminished renal acid excretion. Excess acid and decreased bicarbonate lead to pH imbalance.
The most common causes of metabolic acidosis are:
| Normal values | Metabolic acidosis | |
| pH | 7.35–7.45 | Decreased |
| CO2 | 35–45 mm Hg | Normal or decreased |
| HCO3- | 22–26 mmol/L | Decreased |
Reviews definition, causes and lab values and treatment of metabolic acidosis
| Disturbance | pH | CO2 | HCO3- |
| ??? | 7.48 | 27 | 19 |
Answer: Metabolic acidosis partially compensated.
| Disturbance | pH | CO2 | HCO3- |
| ??? | 7.30 | 55 | 25 |
Answer: Respiratory acidosis uncompensated.
| Disturbance | pH | CO2 | HCO3- |
| ??? | 7.47 | 47 | 30 |
Answer: Metabolic acidosis partially compensated.
| Disturbance | pH | CO2 | HCO3- |
| ??? | 7.25 | 32 | 18 |
Answer: Metabolic acidosis partially compensated.
Mixed acid-base disorders occur when a patient has more than one primary acid-base imbalance simultaneously. For example, a patient could have both respiratory acidosis and metabolic alkalosis. These disorders are often more complex to diagnose and manage, requiring careful interpretation of arterial blood gas (ABG) results alongside clinical assessment.
| Normal | Respiratory acidosis | Respiratory alkalosis | Metabolic acidosis | Metabolic alkalosis | |
| pH | 7.35–7.45 | Decreased | Increased | Decreased | Increased |
| CO2 | 35–45 mm Hg | Increased | Decreased | Normal or decreased | Normal or increased |
| HCO3- | 22–26 mmol/L | Normal or decreased | Normal or decreased | Decreased | Increased |
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