AbG

ABG, in medical contexts, most commonly refers to an arterial blood gas test. The procedure measures acidity and levels of oxygen and carbon dioxide in arterial blood to assess ventilation and acid–base balance. An ABG is obtained from an arterial puncture or arterial line and analyzed to provide pH, pCO2, pO2, and bicarbonate (HCO3-), plus base excess; lactate may be reported in some settings. Normal values vary by laboratory, but typical ranges are pH 7.35–7.45, pCO2 35–45 mmHg, HCO3- 22–26 mEq/L, and pO2 adequate for the patient.

Interpretation centers on pH to define acidemia or alkalemia, then on pCO2 and HCO3- to identify primary respiratory or metabolic disturbances. Respiratory disorders show abnormal pCO2 with compensatory HCO3- changes; metabolic disorders show abnormal HCO3- with compensatory pCO2 changes. ABG findings are used to assess oxygenation and guide management of ventilation, oxygen delivery, and critical-care decisions.

Clinical indications include acute respiratory failure, shock or sepsis, pulmonary disease, perioperative monitoring, and evaluation of suspected acid–base disorders. Sample handling requires prompt analysis, avoidance of air bubbles, and proper handling to preserve components.

Limitations include that ABG reflects systemic arterial blood and may not reflect tissue-level gas exchange in all settings; venous blood gas or noninvasive methods may complement ABG. Interpretation should consider the overall clinical context and other laboratory data.