Examkin

Question

Difficulty: EasyPhysiological Adaptation

A nurse is reviewing the arterial blood gas (ABG) results of a client who has been experiencing severe, frequent diarrhea for the past three days. The ABG results show a pH of 7.317.31, a PaCO2PaCO_2 of 39 mm Hg39\text{ mm Hg}, and an HCO3−HCO_3^- of 18 mEq/L18\text{ mEq/L}. Based on these findings, which of the following acid-base imbalances is the client experiencing?

  1. A
    Respiratory acidosis
  2. Metabolic acidosisAnswer
  3. C
    Respiratory alkalosis
  4. D
    Metabolic alkalosis

Answer

Metabolic acidosis
The client's pH is below the normal range (7.357.35-7.457.45), indicating acidosis. The bicarbonate level (HCO3−HCO_3^-) is also below the normal range (2222-26 mEq/L26\text{ mEq/L}), which points to a metabolic origin for the acidosis. The PaCO2PaCO_2 is within the normal range (3535-45 mm Hg45\text{ mm Hg}), indicating that no respiratory compensation has occurred yet. Additionally, lower gastrointestinal fluid is rich in base, so severe diarrhea classically causes a loss of bicarbonate, validating the diagnosis of metabolic acidosis.

Step-by-Step Solution

1
Evaluate the pH value to determine if the client is experiencing acidosis or alkalosis.
The pH is 7.317.31, which is less than the normal range, indicating acidosis.
The normal pH range for arterial blood is 7.357.35 to 7.457.45. Values below 7.357.35 indicate an acidic state.
2
Evaluate the PaCO2PaCO_2 (respiratory component) value.
The PaCO2PaCO_2 is 39 mm Hg39\text{ mm Hg}, which is within the normal range.
The normal PaCO2PaCO_2 range is 3535 to 45 mm Hg45\text{ mm Hg}. Because it is normal, the primary imbalance is not respiratory.
3
Evaluate the HCO3−HCO_3^- (metabolic component) value.
The HCO3−HCO_3^- is 18 mEq/L18\text{ mEq/L}, which is below the normal range, matching the acidic pH.
The normal HCO3−HCO_3^- range is 2222 to 26 mEq/L26\text{ mEq/L}. A decreased bicarbonate level indicates a metabolic primary cause for the acidosis.
4
Synthesize the ABG interpretation with the client's clinical history.
The low pH and low HCO3−HCO_3^- confirm metabolic acidosis, which is consistent with the loss of bicarbonate from severe diarrhea.
Lower gastrointestinal fluids are rich in base (bicarbonate). Excessive diarrhea leads to the loss of this base, directly resulting in metabolic acidosis.

Key Concept

Basic Arterial Blood Gas (ABG) interpretation for primary acid-base imbalances
Rate this question

Topics

Physiological Adaptation

More questions from this topic