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Difficulty: MediumPhysiological Adaptation

A nurse evaluates the arterial blood gas (ABG) results for a client admitted with acute respiratory distress secondary to severe pneumonia. The laboratory report shows the following values:

ParameterValue
pH7.30
PaCO262 mm Hg
PaO258 mm Hg
HCO330 mEq/L

Which acid-base imbalance do these findings indicate?

  1. Partially compensated respiratory acidosisAnswer
  2. B
    Uncompensated respiratory acidosis
  3. C
    Fully compensated respiratory acidosis
  4. D
    Partially compensated metabolic acidosis

Answer

The findings indicate partially compensated respiratory acidosis.
The combination of a low pH (acidosis) and a high PaCO2 confirms a primary respiratory acidosis. The elevated HCO3 demonstrates that the kidneys are actively retaining bicarbonate to buffer the excess acid. Because the pH remains outside the normal range (7.35-7.45), this physiological adaptation is defined as partially compensated.

Step-by-Step Solution

1
Analyze the pH to determine if the client is in a state of acidosis or alkalosis.
The pH is 7.30, which falls below the normal range of 7.35 to 7.45.
A pH below 7.35 defines acidemia (acidosis), establishing the primary direction of the imbalance.
2
Evaluate the PaCO2 and HCO3 to identify the primary cause of the acidosis.
The PaCO2 is elevated at 62 mm Hg (normal 35-45 mm Hg), and the HCO3 is elevated at 30 mEq/L (normal 22-26 mEq/L).
Because the PaCO2 indicates acidity and matches the acidic pH, the primary problem is respiratory in nature.
3
Assess the degree of compensation by checking the opposite parameter and the final pH.
The HCO3 is elevated outside its normal range, but the pH remains abnormal.
An elevated HCO3 shows the kidneys are retaining base to compensate for the high acid level. However, because the pH has not yet returned to a normal value, the compensation is only partial.

Key Concept

Interpretation of Arterial Blood Gases (ABGs) and compensatory mechanisms.

Alternative Method

The Tic-Tac-Toe or R.O.M.E. (Respiratory Opposite, Metabolic Equal) method can visually organize these values. For R.O.M.E.: pH is down, PaCO2 is up (Opposite = Respiratory). Since HCO3 is also up (trying to balance the acid) but pH is still abnormal, it is partially compensated.
Estimated Time:1m 0s
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Topics

Physiological Adaptation

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