Blood Gas INTERPRETATION

Clinical Picture

• 64-year-old male presenting with severe abdominal pain
• Patient is alert and responds appropriately, but is in visible discomfort
• Known history of diverticular disease
• Tachycardic, tachypneic, hypotensive, and febrile

Findings

• Sample type: Arterial
• FiO2: 21%
• pH: 7.30
• paCO2: 38 mmHg
• paO2: 90 mmHg
• HCO3: 18
• Base excess: -8
• Acid-base balance: Abnormal
• Other parameters: Elevated lactate

Summary 

• pH, HCO3, and base excess are not within normal limits on this blood gas. Lactate is not within normal limits (acidotic).
• The acidotic bicarbonate (HCO3) and base excess match with the acidotic pH, consistent with a metabolic acidosis. The normal PaCO2 indicates compensation has not yet occurred; therefore, this is an uncompensated metabolic acidosis, such as that commonly found in acute sepsis or lactic acidosis.

Further reading

• Arterial Blood gas (ABG) interpretation guide