Chart — Acid-Base
Acid-Base Disorder Comparison Chart
Side-by-side comparison of all four primary acid-base disorders — respiratory acidosis, respiratory alkalosis, metabolic acidosis, and metabolic alkalosis — with ABG values, causes, and clinical symptoms.
Educational use only. ABG interpretation must occur in clinical context alongside patient assessment. Critical values require immediate provider notification. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
ABG Values by Disorder
| Parameter | Respiratory Acidosis | Respiratory Alkalosis | Metabolic Acidosis | Metabolic Alkalosis |
|---|---|---|---|---|
| pH | ↓ < 7.35 | ↑ > 7.45 | ↓ < 7.35 | ↑ > 7.45 |
| PaCO₂ | ↑ > 45 (Primary) | ↓ < 35 (Primary) | ↓ < 35 (Compensatory) | ↑ > 45 (Compensatory) |
| HCO₃¹ | ↑ > 26 (Compensatory) | ↓ < 22 (Compensatory) | ↓ < 22 (Primary) | ↑ > 26 (Primary) |
| Primary cause | CO₂ retention (hypoventilation) | CO₂ loss (hyperventilation) | HCO₃¹ loss or acid gain | HCO₃¹ excess or acid loss |
Compensatory values shown reflect partially or fully compensated states. In uncompensated (acute) disorders, the compensatory component remains within normal range.
Common Causes
| Disorder | Common Causes |
|---|---|
| Respiratory Acidosis | COPD exacerbation, opioid/sedative overdose, severe asthma, neuromuscular disease (GBS, MG), airway obstruction, obesity hypoventilation, chest wall restriction, inadequate ventilator settings |
| Respiratory Alkalosis | Anxiety and pain, hypoxemia (hypoxic drive), early sepsis/fever, mechanical over-ventilation, pregnancy (normal physiologic), salicylate toxicity (early), liver failure, CNS disorders, high altitude |
| Metabolic Acidosis | DKA, lactic acidosis (shock/sepsis), renal failure, severe diarrhea (HCO₃¹ loss), RTA, ingestions (ASA, methanol, ethylene glycol), starvation ketoacidosis |
| Metabolic Alkalosis | Vomiting or NG suction (HCl loss), loop/thiazide diuretics, hyperaldosteronism, excessive sodium bicarbonate, prolonged corticosteroid use, antacid overuse |
Clinical Symptoms
| Disorder | Key Symptoms |
|---|---|
| Respiratory Acidosis | Slow/shallow respirations, hypoxemia, confusion to coma (CO₂ narcosis), headache, flushed skin, diaphoresis, cyanosis (severe) |
| Respiratory Alkalosis | Tachypnea, light-headedness, perioral/extremity tingling (paresthesias), muscle cramps, carpopedal spasm, anxiety, positive Chvostek's/Trousseau's (from ionized hypocalcemia) |
| Metabolic Acidosis | Kussmaul respirations (deep, rapid), headache, confusion to coma, nausea/vomiting, hypotension, arrhythmias, hyperkalemia (acidosis-driven K⁺ shift), fruity breath (DKA) |
| Metabolic Alkalosis | Hypoventilation (shallow breathing), muscle cramps, tetany, nausea, confusion, irritability, hypokalemia (often co-present), cardiac arrhythmias (from hypokalemia) |
Compensation Summary
| Disorder | Compensation System | Compensation Mechanism | Speed |
|---|---|---|---|
| Respiratory Acidosis | Kidneys (metabolic) | Retain HCO₃¹, excrete H⁺ | 3–5 days |
| Respiratory Alkalosis | Kidneys (metabolic) | Excrete HCO₃¹, retain H⁺ | 3–5 days |
| Metabolic Acidosis | Lungs (respiratory) | Hyperventilate, blow off CO₂ | Minutes to hours |
| Metabolic Alkalosis | Lungs (respiratory) | Hypoventilate, retain CO₂ | Minutes to hours (limited) |
Related Resources
Standards & sources
Fact-checked Jun 21, 2026This page is written to align with AARC Clinical Practice Guidelines. It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →