Chronic ventilatory failure (CVF) is a devastating condition that recognizes multiple etiologies and is associated with many different pathophysiologic findings. From the point of view of the patient, it is a frightening, relentlessly progressive disease that affects one of the most fundamental needs, the ability to breathe without discomfort.
The list of individual illnesses that may precipitate CVF is considerably long, and it is always worthwhile remembering that the primary organ or system affected by the disease is not necessarily the lung. Degenerative neurologic processes, such as multiple sclerosis or amyotrophic lateral sclerosis, or muscoloskeletal defects, such as severe kyphoscoliosis, may be as likely causes of CVF as COPD, cystic fibrosis, or usual interstitial pneumonitis. Accordingly, though some of the most important clinical endpoints, such as hypercapnia and hypoxemia, are usually shared by all manifestations of the disease, the road leading to them may be quite different. Thoracopulmonary compliance, airway resistance, bronchoalveolar time constant, and static and dynamic pressure-volume curves may exhibit very different, even opposite, characteristics, depending on the conditions of the lungs and chest cavity.