What is the interpretation and management of an adult patient with an arterial blood gas showing slight alkalosis, normal pCO2, slightly low HCO3, elevated pO2, and mild base excess?

Arterial Blood Gas Interpretation

This ABG demonstrates a normal acid-base status with appropriate oxygenation and no intervention is required.

Systematic ABG Analysis

pH Assessment

• pH 7.43 is within normal range (7.35-7.45), indicating neither acidemia nor alkalemia 1
• The pH is in the upper half of normal, but this alone does not constitute alkalosis requiring treatment 2

Respiratory Component

• pCO2 37 mmHg is normal (34-46 mmHg), ruling out any respiratory acid-base disturbance 1
• This normal pCO2 confirms there is no primary respiratory acidosis or alkalosis, and no respiratory compensation is occurring 3

Metabolic Component

• HCO3 24.9 mEq/L is normal (24-31 mEq/L), indicating no metabolic acidosis or alkalosis 4
• Base excess (BE) +1.4 is within normal range (-2 to +2 mEq/L), confirming no significant metabolic derangement 5
• The slightly positive BE of 1.4 is physiologically insignificant and does not represent true metabolic alkalosis 5

Oxygenation Status

• pO2 139.2 mmHg is elevated above normal (>80 mmHg), indicating the patient is likely receiving supplemental oxygen 6
• This degree of hyperoxemia is common in patients on supplemental oxygen and does not require intervention unless the patient has chronic hypercapnic respiratory failure 6

Clinical Interpretation

No acid-base disorder exists. The ABG shows:

• Normal pH (7.43) 1
• Normal pCO2 (37 mmHg) 1
• Normal HCO3 (24.9 mEq/L) 4
• Normal base excess (+1.4) 5

The elevated pO2 simply reflects supplemental oxygen administration and is not pathological 6.

Management Recommendations

Oxygen Therapy Adjustment

• If the patient is on supplemental oxygen and has normal lungs, target SpO2 94-98% 6
• Consider reducing FiO2 to achieve target saturation range, as excessive oxygen provides no additional benefit 6
• If the patient has risk factors for hypercapnic respiratory failure (COPD, obesity hypoventilation), target SpO2 88-92% 6

Monitoring

• No repeat ABG is indicated based on these normal values unless clinical deterioration occurs 6
• Continue pulse oximetry monitoring to maintain appropriate SpO2 targets 6

Common Pitfalls to Avoid

• Do not treat the slightly elevated pH (7.43) or positive BE (+1.4) as metabolic alkalosis, as both values are within normal physiological range 2, 5
• Do not restrict oxygen to "normalize" the pO2, as the elevated pO2 is benign in patients without contraindications to supplemental oxygen 6
• Do not order unnecessary repeat blood gases when values are normal and the patient is clinically stable 6