Acid Base worksheet - acid base - Critical Thinking Worksheet ... - Free Printable

Absolutely! Let’s break down this Acid-Base Critical Thinking Worksheet step by step. This is a foundational tool for understanding arterial blood gas (ABG) interpretation — essential in nursing, medicine, and respiratory therapy.

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## ✔ PART 1: Complete the Normal Ranges

These are standard reference values for arterial blood gases:

| Parameter | Normal Range |
|-----------|--------------------------|
| pH | 7.35 – 7.45 |
| PaO₂ | 80 – 100 mmHg |
| SaO₂ | 95% – 100% |
| PaCO₂ | 35 – 45 mmHg |
| HCO₃⁻ | 22 – 26 mEq/L |

> 💡 *Note: PaO₂ and SaO₂ reflect oxygenation; pH, PaCO₂, and HCO₃⁻ reflect acid-base balance.*

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## ✔ PART 2: CO₂ and HCO₃⁻ Roles

This box helps you remember what each component does in acid-base balance:

- CO₂ = Respiratory component and supports ACIDosis
→ High CO₂ = Acidic (respiratory acidosis); Low CO₂ = Alkalotic (respiratory alkalosis)

- HCO₃⁻ = Metabolic component and supports ALKALOSIS
→ High HCO₃⁻ = Alkalotic (metabolic alkalosis); Low HCO₃⁻ = Acidic (metabolic acidosis)

> 🧠 *Remember: CO₂ is controlled by lungs (respiratory), HCO₃⁻ is controlled by kidneys (metabolic).*

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## ✔ PART 3: ROME METHOD

ROME is a mnemonic to help interpret ABGs:

> Respiratory = Opposite
> Metabolic = Equal

| Letter | What Does It Stand For? | pH Value | PCO₂ (Respiratory) | HCO₃⁻ (Metabolic) |
|--------|--------------------------|---------------|--------------------|-------------------|
| R | Respiratory | Opposite to PCO₂ | ↑ if pH ↓ (acidosis)<br>↓ if pH ↑ (alkalosis) | Normal or compensating later |
| O | Opposite | pH and PCO₂ move in opposite directions | e.g., pH ↓, PCO₂ ↑ = Respiratory Acidosis | — |
| M | Metabolic | Same as HCO₃⁻ | Normal or compensating later | ↑ if pH ↑ (alkalosis)<br>↓ if pH ↓ (acidosis) |
| E | Equal | pH and HCO₃⁻ move in same direction | — | e.g., pH ↓, HCO₃⁻ ↓ = Metabolic Acidosis |

> 📌 Example:
> - If pH is LOW and PCO₂ is HIGH → Respiratory Acidosis (R=O: opposite)
> - If pH is LOW and HCO₃⁻ is LOW → Metabolic Acidosis (M=E: equal)

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## ✔ PART 4: Definitions of Compensation

Understanding compensation is key to determining severity and chronicity.

- Uncompensated or Not Compensated =
→ The body has NOT started to correct the imbalance.
→ Only the primary disorder is present (e.g., low pH + high PCO₂, normal HCO₃⁻ = uncompensated respiratory acidosis).

- Partial Compensation =
→ The body is BEGINNING to compensate, but pH is still abnormal.
→ Both PCO₂ and HCO₃⁻ are abnormal, but pH is not yet back to normal.
→ Example: pH 7.30 (still acidic), PCO₂ 50 (high), HCO₃⁻ 28 (high) → partially compensated respiratory acidosis.

- Full or Compensated =
→ The body has successfully corrected pH back to normal range (7.35–7.45), even though PCO₂ and/or HCO₃⁻ are still abnormal.
→ Example: pH 7.40, PCO₂ 55, HCO₃⁻ 30 → fully compensated respiratory acidosis.

> 🧭 *Compensation never overcorrects — pH should return to normal, not go past it.*

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## ✔ PART 5: Place pH Values on the Arrow

You’re asked to visualize where pH values fall on the scale:

```
← Acidic (pH < 7.35) ——— Neutral (7.35–7.45) ——— Alkaline (pH > 7.45) →
```

So:
- Acidic: pH < 7.35
- Neutral: pH 7.35–7.45
- Alkaline: pH > 7.45

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## ✔ PART 6: Fill in the Table for Each Acid-Base Disorder

Here’s the full breakdown using ROME and compensation principles:

| Disorder | pH | PaCO₂ | HCO₃⁻ | Explanation |
|------------------------|----------|-----------|-----------|-----------------------------------------------------------------------------|
| Respiratory Acidosis | ↓ (<7.35) | ↑ (>45) | Normal (uncomp) → ↑ (comp) | Caused by hypoventilation → CO₂ builds up → acidosis. Kidneys compensate by retaining HCO₃⁻. |
| Respiratory Alkalosis| ↑ (>7.45) | ↓ (<35) | Normal (uncomp) → ↓ (comp) | Hyperventilation → CO₂ blown off → alkalosis. Kidneys excrete HCO₃⁻ to compensate. |
| Metabolic Acidosis | ↓ (<7.35) | Normal (uncomp) → ↓ (comp) | ↓ (<22) | Loss of HCO₃⁻ or gain of acid → pH drops. Lungs compensate by hyperventilating (blow off CO₂). |
| Metabolic Alkalosis | ↑ (>7.45) | Normal (uncomp) → ↑ (comp) | ↑ (>26) | Gain of HCO₃⁻ or loss of acid → pH rises. Lungs compensate by hypoventilating (retain CO₂). |

> 🔄 *Note: In compensated states, the “compensating” value moves in the direction that brings pH back toward normal.*

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## 🧾 SUMMARY CHEAT SHEET

✔ Normal Values:
- pH: 7.35–7.45
- PaCO₂: 35–45 mmHg
- HCO₃⁻: 22–26 mEq/L

✔ ROME:
- Respiratory = Opposite (pH vs PCO₂)
- Metabolic = Equal (pH vs HCO₃⁻)

✔ Compensation:
- Uncompensated: Only one abnormal value besides pH
- Partial: pH still abnormal, both PCO₂ and HCO₃⁻ abnormal
- Full: pH normal, both PCO₂ and HCO₃⁻ abnormal

✔ Disorders:

| Disorder | pH | PCO₂ | HCO₃⁻ |
|-----------------------|-----|------|-------|
| Respiratory Acidosis | ↓ | ↑ | N→↑ |
| Respiratory Alkalosis | ↑ | ↓ | N→↓ |
| Metabolic Acidosis | ↓ | N→↓ | ↓ |
| Metabolic Alkalosis | ↑ | N→↑ | ↑ |

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