Acute respiratory failure in COPD

Acute respiratory failure in COPD


In patients with essentially normal lung tissue, acute respiratory failure (ARF) usually means a partial pressure of arterial carbon dioxide (PaCO2) greater than 50 mm Hg and a partial pressure of arterial oxygen (PaO2) less than 50 mm Hg. These limits, however, don’t apply to patients with chronic obstructive pulmonary disease (COPD), who commonly have a consistently high PaCO2 and low PaO2. In COPD patients, only acute deterioration in arterial blood gas (ABG) levels and corresponding clinical deterioration indicate ARF.


ARF may develop in COPD patients from any condition that increases the work of breathing and decreases the respiratory drive. Such conditions include respiratory tract infection (such as bronchitis or pneumonia), which is the most common precipitating factor; bronchospasm; or accumulating secretions secondary to cough suppression. Other causes include:

  • central nervous system (CNS) depression—head trauma or injudicious use of sedatives, narcotics, tranquilizers, or oxygen

  • cardiovascular disorders—myocardial infarction, heart failure, or pulmonary emboli

  • airway irritants—smoke or fumes

  • endocrine and metabolic disorders—myxedema or metabolic alkalosis

  • thoracic abnormalities—chest trauma, pneumothorax, or thoracic or abdominal surgery.

Signs and symptoms

In COPD patients with ARF, increased ventilation-perfusion mismatching and reduced alveolar ventilation decrease PaO2 (hypoxemia) and increase PaCO2 (hypercapnia). This rise in carbon dioxide tension lowers the pH. The resulting hypoxemia and acidemia affect all body organs, especially the central nervous, respiratory, and cardiovascular systems. Specific symptoms vary with the underlying cause of ARF but can include any of the following:

Jun 16, 2016 | Posted by in GENERAL & FAMILY MEDICINE | Comments Off on Acute respiratory failure in COPD

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