Fluid, Electrolyte, and Acid/Base Balance Worksheet (Physiology/Biology) - Free Printable

To determine the primary acid-base disorder for each set of arterial blood gas (ABG) values, we need to analyze the pH, pCO₂, and HCO₃⁻ levels. Here's a step-by-step explanation of how to approach this:

Key Concepts:

1. pH:
- Acidemia: pH < 7.4
- Alkalemia: pH > 7.4

2. pCO₂:
- Respiratory Acidosis: pCO₂ > 40 mmHg
- Respiratory Alkalosis: pCO₂ < 40 mmHg

3. HCO₃⁻:
- Metabolic Acidosis: HCO₃⁻ < 24 mEq/L
- Metabolic Alkalosis: HCO₃⁻ > 24 mEq/L

4. Compensation:
- In respiratory disorders, the kidneys compensate by adjusting HCO₃⁻.
- In metabolic disorders, the lungs compensate by adjusting pCO₂.

Steps to Solve:

1. Identify the primary disorder based on pH, pCO₂, and HCO₃⁻.
2. Check for compensation to confirm the primary disorder.
3. Rule out mixed disorders if necessary.

Analysis of Each Case:

#### Case 1: pH = 7.27, pCO₂ = 34, HCO₃⁻ = 15
- pH: Acidemia (pH < 7.4)
- pCO₂: Normal (34 mmHg)
- HCO₃⁻: Low (15 mEq/L)
- Primary Disorder: Metabolic Acidosis (low HCO₃⁻)
- Compensation: pCO₂ is slightly low, which is expected in metabolic acidosis as the body tries to compensate by hyperventilating.

Conclusion: Metabolic Acidosis

#### Case 2: pH = 7.34, pCO₂ = 50, HCO₃⁻ = 26
- pH: Acidemia (pH < 7.4)
- pCO₂: High (50 mmHg)
- HCO₃⁻: Normal (26 mEq/L)
- Primary Disorder: Respiratory Acidosis (high pCO₂)
- Compensation: HCO₃⁻ is slightly high, which is expected in respiratory acidosis as the kidneys try to compensate by retaining bicarbonate.

Conclusion: Respiratory Acidosis

#### Case 3: pH = 7.45, pCO₂ = 48, HCO₃⁻ = 32
- pH: Alkalemia (pH > 7.4)
- pCO₂: High (48 mmHg)
- HCO₃⁻: High (32 mEq/L)
- Primary Disorder: Mixed disorder (both respiratory and metabolic alkalosis)
- Explanation: High pCO₂ suggests respiratory acidosis, but high HCO₃⁻ suggests metabolic alkalosis. This could be a case of compensated metabolic alkalosis with superimposed respiratory acidosis or vice versa.

Conclusion: Mixed Alkalosis (Respiratory Acidosis + Metabolic Alkalosis)

#### Case 4: pH = 7.32, pCO₂ = 28, HCO₃⁻ = 14
- pH: Acidemia (pH < 7.4)
- pCO₂: Low (28 mmHg)
- HCO₃⁻: Low (14 mEq/L)
- Primary Disorder: Mixed disorder (both respiratory and metabolic acidosis)
- Explanation: Low pCO₂ suggests respiratory alkalosis, but low HCO₃⁻ suggests metabolic acidosis. This could be a case of compensated metabolic acidosis with superimposed respiratory alkalosis or vice versa.

Conclusion: Mixed Acidosis (Respiratory Alkalosis + Metabolic Acidosis)

#### Case 11: pH = 7.45, pCO₂ = 18, HCO₃⁻ = 12
- pH: Alkalemia (pH > 7.4)
- pCO₂: Very low (18 mmHg)
- HCO₃⁻: Low (12 mEq/L)
- Primary Disorder: Respiratory Alkalosis (very low pCO₂)
- Compensation: HCO₃⁻ is low, which is expected in respiratory alkalosis as the kidneys try to compensate by excreting bicarbonate.

Conclusion: Respiratory Alkalosis

#### Case 12: pH = 7.25, pCO₂ = 14, HCO₃⁻ = 8
- pH: Acidemia (pH < 7.4)
- pCO₂: Very low (14 mmHg)
- HCO₃⁻: Very low (8 mEq/L)
- Primary Disorder: Mixed disorder (both respiratory and metabolic acidosis)
- Explanation: Very low pCO₂ suggests severe respiratory alkalosis, but very low HCO₃⁻ suggests severe metabolic acidosis. This is a case of severe mixed acidosis.

Conclusion: Severe Mixed Acidosis (Respiratory Alkalosis + Metabolic Acidosis)

#### Case 13: pH = 7.32, pCO₂ = 46, HCO₃⁻ = 26
- pH: Acidemia (pH < 7.4)
- pCO₂: High (46 mmHg)
- HCO₃⁻: Normal (26 mEq/L)
- Primary Disorder: Respiratory Acidosis (high pCO₂)
- Compensation: HCO₃⁻ is slightly high, which is expected in respiratory acidosis as the kidneys try to compensate by retaining bicarbonate.

Conclusion: Respiratory Acidosis

#### Case 14: pH = 7.28, pCO₂ = 68, HCO₃⁻ = 36
- pH: Acidemia (pH < 7.4)
- pCO₂: Very high (68 mmHg)
- HCO₃⁻: High (36 mEq/L)
- Primary Disorder: Mixed disorder (both respiratory and metabolic alkalosis)
- Explanation: Very high pCO₂ suggests severe respiratory acidosis, but high HCO₃⁻ suggests metabolic alkalosis. This could be a case of compensated metabolic alkalosis with superimposed respiratory acidosis or vice versa.

Conclusion: Mixed Alkalosis (Respiratory Acidosis + Metabolic Alkalosis)

Final Answers:

1. Metabolic Acidosis
2. Respiratory Acidosis
3. Mixed Alkalosis (Respiratory Acidosis + Metabolic Alkalosis)
4. Mixed Acidosis (Respiratory Alkalosis + Metabolic Acidosis)
11. Respiratory Alkalosis
12. Severe Mixed Acidosis (Respiratory Alkalosis + Metabolic Acidosis)
13. Respiratory Acidosis
14. Mixed Alkalosis (Respiratory Acidosis + Metabolic Alkalosis)

\boxed{
\begin{aligned}
1. & \text{Metabolic Acidosis} \\
2. & \text{Respiratory Acidosis} \\
3. & \text{Mixed Alkalosis (Respiratory Acidosis + Metabolic Alkalosis)} \\
4. & \text{Mixed Acidosis (Respiratory Alkalosis + Metabolic Acidosis)} \\
11. & \text{Respiratory Alkalosis} \\
12. & \text{Severe Mixed Acidosis (Respiratory Alkalosis + Metabolic Acidosis)} \\
13. & \text{Respiratory Acidosis} \\
14. & \text{Mixed Alkalosis (Respiratory Acidosis + Metabolic Alkalosis)}
\end{aligned}
}