Current opinion in pulmonary medicine
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Alveolar hypoventilation associated with neuromuscular disease can occur in acute and chronic forms. In the acute form, progressive weakness of respiratory muscles leads to rapid reduction in vital capacity followed by respiratory failure with hypoxemia and hypercarbia. Symptoms are those of acute respiratory failure, including dyspnea, tachypnea, and tachycardia. ⋯ For chronic but stable diseases such as old polio, quadriplegia, or kyposcoliosis, mechanical support of minute ventilation can reverse symptoms. For chronic and progressive disease such as muscular dystrophy and amyotrophic lateral sclerosis, mechanical support of minute ventilation provides only symptomatic relief and is usually associated with deterioration to the point of complete ventilator dependency for survival. For the chronic progressive forms of alveolar hypoventilation, there is currently a need for quality randomized controlled clinical trials to define physiologic indicators and appropriate timing for mechanical support of minute ventilation.
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The ventilatory drive is affected by several factors such as chemosensitivity, basal arterial oxygen or carbon dioxide tension, mechanical impedance, and respiratory muscle dysfunction. Blunted ventilatory drive or a decrease in the perception of dyspnea in bronchial asthma and chronic obstructive pulmonary disease (COPD) could lead to a decrease in the alarm reaction to dangerous situations such as severe airway obstruction, severe hypoxemia, or severe hypercapnia. ⋯ The ventilatory drive to chemical stimuli can be altered by a beta-2-agonist, oxygen administration; and lung volume reduction, and an increased dyspnea sensation may be improved by corticosteroid, chest wall vibration, or lung volume reduction. The ventilatory drive has been found to play a key role in determining the severity of asthma and COPD.