respiratory failure
Summary
Respiratory failure is the inability of the respiratory system to maintain adequate gas exchange, defined as PaO2 <60 mmHg (Type I/hypoxemic) or PaCO2 >50 mmHg with pH <7.35 (Type II/hypercapnic). It represents a life-threatening condition requiring immediate intervention and mechanical ventilation support.
Detail
Respiratory failure occurs when the lungs cannot adequately oxygenate blood or remove carbon dioxide. Type I (hypoxemic) failure results from ventilation-perfusion mismatch, shunt, or diffusion impairment, commonly seen in pneumonia, ARDS, or pulmonary edema. Type II (hypercapnic) failure involves inadequate ventilation due to respiratory muscle weakness, CNS depression, or severe airway obstruction, as in COPD exacerbations, neuromuscular diseases, or drug overdoses. Clinical presentation includes dyspnea, tachypnea, accessory muscle use, altered mental status, and cyanosis. Arterial blood gas analysis is diagnostic, showing hypoxemia (PaO2 <60 mmHg) and/or hypercapnia (PaCO2 >50 mmHg with respiratory acidosis). Treatment involves addressing underlying causes, supplemental oxygen, and often mechanical ventilation. Complications include organ dysfunction from hypoxemia, cor pulmonale from chronic hypoxia, and respiratory acidosis leading to cardiovascular collapse.
Sources
- Harrison's Principles of Internal Medicine
- First Aid for the USMLE Step 1
- Murray and Nadel's Textbook of Respiratory Medicine
- UpToDate Clinical Decision Support
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