ABG Interpreter
Enter pH, PaCO₂, and HCO₃⁻ for a stepwise interpretation — primary disorder, compensation, and the expected-compensation math.
Written by Apex Respiratory Editorial Team
Enter pH, PaCO₂, and HCO₃⁻ to interpret the gas.
How the interpretation works
The interpreter follows the classic sequence: classify the pH, identify which system (respiratory or metabolic) explains it, then compare the other system against its expected compensation — Winter’s formula for metabolic acidosis, the 1/3.5 per 10 mmHg HCO₃⁻ rules for respiratory acidosis, and their alkalosis counterparts. A measured value outside the expected band flags a possible second disorder.
Real gases can be messier than rules — mixed and triple disorders, lab error, and chronicity ambiguity all happen. When the tool flags a result as mixed or inconsistent, correlate clinically before acting on it.
Educational use only. Acid-base interpretation depends on the clinical context — this tool sees only three numbers. This material supports respiratory therapy education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional protocols, or physician orders. Always follow facility policies and current provider orders, and verify calculations independently before clinical use.
Sources
- Kacmarek RM, Stoller JK, Heuer AJ. Egan's Fundamentals of Respiratory Care. 12th ed. Elsevier; 2021. Acid-base balance chapters.
- Albert MS, Dell RB, Winters RW. Quantitative displacement of acid-base equilibrium in metabolic acidosis. Ann Intern Med. 1967;66(2):312-322.