Acid-Base Practice Questions

Acid-Base Disturbances Overview

• Arterial blood gas (ABG) results are crucial for assessing acid-base status.
• Normal pH range is typically 7.35-7.45.

Respiratory Alkalosis

• Identified by high pH (7.45) and low Pco2 (30).
• Indicates decreased carbon dioxide, often due to hyperventilation.
• Compensation occurs when the pH normalizes, indicating the body is adjusting.

Metabolic Alkalosis

• Causes include loss of gastric fluid (suction or vomiting), excessive bicarbonate intake, and conditions like hyperaldosteronism.
• Characterized by an increase in pH due to deficit/loss of hydrogen ions or excess base (bicarbonate).
• Specifically, loss of hydrochloric acid through NG suction leads to this condition.

Metabolic Acidosis

• Occurs from loss of buffer bases or excessive acid retention (e.g., renal failure, diabetic ketoacidosis).
• Involves higher hydrogen ion concentration; loss of intestinal secretions can contribute.
• Results in a lower pH and potentially higher CO2.

Respiratory Acidosis

• Caused by hypoventilation, resulting in increased Pco2 and lower pH.
• Common in conditions that depress respiratory function.

Kussmaul's Respirations

• Characterized by abnormal depth and increased rate of breathing.
• Typically seen in metabolic acidosis, particularly diabetic ketoacidosis as the body attempts to expel CO2 to manage acidity.

Interpretation of ABG Results

• pH, Pco2, and HCO3- values must be analyzed together for accurate diagnosis.
• Conditions can be compensated or uncompensated depending on the body's ability to restore pH balance.

Risk Factors for Acid-Base Disorders

• Nasogastric tube suction leads to metabolic alkalosis.
• Ileostomy patients are at risk for metabolic acidosis due to loss of bicarbonate-rich intestinal secretions.

Example Conditions and Observations

• Respiratory alkalosis (elevated pH, decreased CO2) often results from hyperventilation.
• Metabolic alkalosis (high pH, possibly high HCO3-) can occur due to loss of gastric acids (vomiting, suction).
• Metabolic acidosis (low pH and low HCO3-) develops from various causes including severe diarrhea and diabetic conditions.
• Kussmaul's respirations indicate severe acidosis, requiring immediate assessment and intervention.