An ABG report shows PO2 89 mm Hg, PCO2 35 mm Hg, and pH 7.37. These findings indicate which condition?

An ABG report shows PO2 89 mm Hg, PCO2 35 mm Hg, and pH 7.37. These findings indicate which condition?

• A. Respiratory alkalosis
• B. Poor oxygen perfusion
• C. Normal acid-base balance
• D. Compensated metabolic acidosis

Answer: (D)

In interpreting ABG, look at pH first to see the net acid-base status, then examine the primary disturbance and the compensatory response. A pH of 7.37 sits within the normal range, which suggests there’s compensation balancing an underlying issue rather than a simple normal state or a primary disturbance with an unchanged pH. The PCO2 is 35 mm Hg, which is lower than normal, showing the respiratory system is actively blowing off CO2. When the body faces metabolic acidosis, it compensates by making the breaths deeper and faster to reduce CO2, helping raise the pH toward normal. Seeing a normal pH with a low PCO2 points to metabolic acidosis that has been compensated by the respiratory system. Oxygenation appears adequate with a PO2 of 89 mm Hg, so the issue isn’t a problem with oxygen delivery. Putting this together, the pattern best fits compensated metabolic acidosis: a metabolic disturbance with respiratory compensation that brings the pH back toward normal. The other patterns don’t fit as well: respiratory alkalosis would have a high pH with low CO2; poor oxygen perfusion would show reduced PO2; normal acid-base balance would not involve a lowered PCO2.

In interpreting ABG, look at pH first to see the net acid-base status, then examine the primary disturbance and the compensatory response. A pH of 7.37 sits within the normal range, which suggests there’s compensation balancing an underlying issue rather than a simple normal state or a primary disturbance with an unchanged pH.

The PCO2 is 35 mm Hg, which is lower than normal, showing the respiratory system is actively blowing off CO2. When the body faces metabolic acidosis, it compensates by making the breaths deeper and faster to reduce CO2, helping raise the pH toward normal. Seeing a normal pH with a low PCO2 points to metabolic acidosis that has been compensated by the respiratory system.

Oxygenation appears adequate with a PO2 of 89 mm Hg, so the issue isn’t a problem with oxygen delivery. Putting this together, the pattern best fits compensated metabolic acidosis: a metabolic disturbance with respiratory compensation that brings the pH back toward normal. The other patterns don’t fit as well: respiratory alkalosis would have a high pH with low CO2; poor oxygen perfusion would show reduced PO2; normal acid-base balance would not involve a lowered PCO2.