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Zorluk: OrtaPhysiological Adaptation

A nurse is evaluating the arterial blood gas (ABG) results of a client who suddenly developed dyspnea and pleuritic chest pain 48 hours after a total hip arthroplasty. The ABG reveals a pH of 7.52, PaCO2 of 28 mm Hg, PaO2 of 65 mm Hg, and HCO3 of 24 mEq/L. Which of the following pathophysiological processes best explains this acid-base imbalance?

  1. Alveolar hyperventilation in response to hypoxemia leading to excessive elimination of carbon dioxideCevap
  2. B
    Impaired gas exchange causing systemic retention of carbon dioxide and hydrogen ions
  3. C
    Tissue hypoperfusion resulting in anaerobic metabolism and the accumulation of lactic acid
  4. D
    Renal retention of bicarbonate ions to compensate for acute pulmonary compromise

Cevap

Alveolar hyperventilation in response to hypoxemia leading to excessive elimination of carbon dioxide
The client's ABG results indicate uncompensated respiratory alkalosis: an elevated pH (alkalemia), a decreased PaCO2 (respiratory origin), and a normal HCO3 (no metabolic compensation yet). The sudden onset of dyspnea and pleuritic chest pain in a post-operative client strongly suggests an acute pulmonary embolism. The resulting hypoxemia and pain trigger tachypnea (hyperventilation), which causes the lungs to exhale excessive amounts of carbon dioxide, leading directly to a decreased PaCO2 and an elevated pH.

Adım Adım Çözüm

1
Analyze the pH value.
The pH is 7.52, which is greater than the normal upper limit of 7.45. This indicates alkalosis.
Determining the primary acid-base state (acidosis vs. alkalosis) is the first step in ABG interpretation.
2
Analyze the PaCO2 and HCO3 values to determine the etiology.
The PaCO2 is 28 mm Hg (decreased from normal 35-45 mm Hg), and the HCO3 is 24 mEq/L (normal range 22-26 mEq/L).
Matching the abnormal parameter to the pH determines if the imbalance is respiratory or metabolic. A low PaCO2 causes alkalosis, which matches the pH.
3
Correlate the findings with the clinical scenario.
The client has sudden dyspnea and chest pain post-operatively, strongly suggesting a pulmonary embolism (PE). The resulting hypoxemia (PaO2 65 mm Hg) and pain cause tachypnea.
Tachypnea (hyperventilation) causes the excessive exhalation or 'blowing off' of carbon dioxide, directly resulting in respiratory alkalosis.

Anahtar Kavram

Respiratory alkalosis occurs when hyperventilation leads to excessive elimination of carbon dioxide, commonly seen as an early sign of pulmonary embolism or acute hypoxemia.
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Physiological Adaptation

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