Hypercapnic ventilatory failure chronic

Respiratory failure may be classified as hypoxemic (type 1) or hypercapnic (type II or ventilatory failure) (3), either of which may be acute and chronic. Hypoxemic respiratory failure is due to failure of the lungs, caused by acute (cardiogenic pulmonary edema, pneumonia, acute respiratory distress syndrome) or chronic (emphysema, interstitial limg disorders) diseases (Tables 1 and 2). It is characterized by hypoxemia with normocapnia or hypocapnia. In these conditions central respiratory drive is high and there is sufficient alveolar ventilation (VA) to eliminate CO2 and prevent hypercapnia. 

Management of chronic hypercapnic ventilatory failure, including bridging to transplantation and to palliate symptoms... 

Hypercapnic respiratory failure is due to failure of the ventilatory pump caused by acute (drug overdose, acute neuromuscular diseases) or chronic (chest wall abnormalities, chronic neuromuscular diseases) disorders. It is characterized by alveolar hypoventilation, which leads to hypercapnia with coexistent, usually mild, hypoxemia. The central drive may be globally reduced with the fall in Pa02 resulting from the increase in alveolar CO2. More commonly, the drive remains high, but the mechanical load on the respiratory systan is too great or the capacity of the muscles too low to ensure efficient CO2 elimination (Fig. 1). 

The function of the ventilatory pump is critically dependent on three factors the respiratory workload, the respiratory muscle strength, and the ventilatory drive (Fig. 1). Chronic hypercapnic respiratory failure can result from one or more of these abnormalities inadequate ventilatory drive, excessive respiratory load, and inadequate inspiratory muscle... 

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