Clinical meaning
Arterial blood gas analysis measures acid-base status and oxygenation. pH is maintained by the bicarbonate buffer system (H2CO3/HCO3-), regulated by lungs (CO2) and kidneys (HCO3-). Henderson-Hasselbalch equation: pH = 6.1 + log(HCO3/0.03 x PaCO2). Respiratory compensation is rapid (minutes), metabolic compensation is slow (hours-days). The anion gap [Na - (Cl + HCO3)] helps identify the cause of metabolic acidosis (normal 8-12).
Diagnosis & workup
Diagnostics & workup: - Order ABG for acid-base assessment and oxygenation status - Order Modified Allen test before radial artery puncture - Order metabolic panel for correlation with ABG findings - Order lactate level for tissue perfusion assessment - Order co-oximetry for carboxyhemoglobin or methemoglobin if indicated - Order venous blood gas as alternative when arterial access is difficult
Risk factors: - Negative Allen test (inadequate collateral circulation) - Coagulopathy - Arterial insufficiency - Local infection - Severe peripheral vascular disease - Anticoagulant therapy