BGA-Interpreter
Systematische arterielle Blutgasanalyse mit schrittweiser Säure-Basen-Interpretation. Identifiziert primäre Störungen, bewertet Kompensation und berechnet A-a-Gradient.
Eingaben
Disclaimer: Nur für Bildungszwecke. Kein Ersatz für klinische Beurteilung.
Über dieses Tool
Was ist eine arterielle Blutgasanalyse (BGA)?
An arterial blood gas is a blood test performed on arterial blood that measures pH, partial pressure of carbon dioxide (pCO₂), partial pressure of oxygen (pO₂), and bicarbonate (HCO₃⁻). It is the gold standard for assessing acid-base status and oxygenation. ABGs are essential in the evaluation of respiratory failure, metabolic derangements, and critically ill patients. The measured values — together with calculated parameters like the A-a gradient — allow clinicians to identify the type and severity of acid-base disorders and to guide treatment.
Systematischer Ansatz zur BGA-Interpretation
A reliable interpretation requires a stepwise approach: (1) Assess the pH to determine if the patient is acidemic or alkalemic. (2) Identify the primary disorder — respiratory (driven by pCO₂) or metabolic (driven by HCO₃⁻). (3) Evaluate compensation using expected formulas to determine whether a second (mixed) disorder is present. (4) Calculate the A-a gradient if oxygenation data is available. This systematic method prevents errors and ensures that mixed acid-base disturbances are not overlooked.
Kompensation: Was zu erwarten ist
The body compensates for primary acid-base disorders to minimize pH changes. Metabolic disorders trigger respiratory compensation (fast, within hours), while respiratory disorders trigger renal compensation (slow, taking 3–5 days for full effect). Winter's formula (Expected pCO₂ = 1.5 × HCO₃ + 8 ± 2) is used to check respiratory compensation in metabolic acidosis. If measured pCO₂ falls outside the expected range, a mixed disorder is present.
🔑 Klinische Hinweise
- Compensation never fully corrects the pH back to 7.40 — a "normal" pH with abnormal pCO₂ and HCO₃ strongly suggests a mixed disorder.
- Respiratory compensation for metabolic disorders is rapid (hours); renal compensation for respiratory disorders is slow (3–5 days). Distinguishing acute from chronic respiratory disorders is critical for selecting the correct compensation formula.
- A normal A-a gradient in a hypoxic patient points to hypoventilation or low FiO₂ as the cause, not a parenchymal lung process.
- Always correlate ABG findings with clinical context, electrolytes (anion gap, potassium, chloride), and the patient's clinical trajectory.
- Venous blood gases (VBG) can estimate pH (add 0.03–0.05) and pCO₂ (subtract 3–8 mmHg) but cannot assess oxygenation.
Wichtige Referenzen
- Albert MS, Dell RB, Winters RW. Quantitative displacement of acid-base equilibrium in metabolic acidosis. Ann Intern Med. 1967;66(2):312–322.
- Narins RG, Emmett M. Simple and mixed acid-base disorders: a practical approach. Medicine. 1980;59(3):161–187.
- Berend K, de Vries APJ, Gans ROB. Physiological approach to assessment of acid-base disturbances. N Engl J Med. 2014;371(15):1434–1445.
Formel zuletzt überprüft: Februar 2026