Examkin

Question

Difficulty: MediumPhysiological Adaptation

A client is brought to the emergency department unresponsive with a respiratory rate of 6 breaths per minute. Initial arterial blood gas (ABG) analysis reveals a pH of 7.25, PaCO2 of 65 mm Hg, and HCO3 of 24 mEq/L. If this acid-base imbalance continues, which compensatory physiological mechanism will the client's body utilize?

  1. Increased renal reabsorption of bicarbonate and excretion of hydrogen ionsAnswer
  2. B
    Increased alveolar ventilation to eliminate excess carbon dioxide
  3. C
    Increased renal excretion of bicarbonate and retention of hydrogen ions
  4. D
    Shift of hydrogen ions from the intracellular fluid into the extracellular fluid

Answer

The client's body will compensate through increased renal reabsorption of bicarbonate and excretion of hydrogen ions.
The client is in uncompensated respiratory acidosis, caused by severe hypoventilation and carbon dioxide retention. Because the respiratory system is the source of the problem, it cannot compensate. Instead, the physiological adaptation relies on the renal system. Over hours to days, the kidneys will compensate by increasing the reabsorption of bicarbonate (base) into the bloodstream and excreting excess hydrogen ions (acid) into the urine, which helps restore the blood pH toward normal.

Step-by-Step Solution

1
Analyze the initial ABG values to determine the primary acid-base imbalance.
pH is 7.25 (acidosis), PaCO2 is 65 mm Hg (acidosis), and HCO3 is 24 mEq/L (normal). The primary imbalance is uncompensated respiratory acidosis.
Identifying the primary disturbance is required to determine which organ system will initiate compensation.
2
Determine the cause of the imbalance based on the clinical presentation.
The respiratory rate is 6 breaths per minute, indicating severe hypoventilation causing carbon dioxide retention.
Understanding the source of the problem confirms that the respiratory system cannot fix the imbalance itself.
3
Identify the correct compensatory mechanism for the primary imbalance.
Because the lungs are failing to ventilate adequately, the kidneys must compensate by adjusting acid and base elimination.
The renal system compensates for respiratory acidosis by retaining bicarbonate (to increase buffering capacity) and excreting excess hydrogen ions in the urine.

Key Concept

Acid-Base Compensation Mechanisms
Rate this question

Topics

Physiological Adaptation

More questions from this topic