The patient at risk of ventilator dependency

Respiratory failure may result from inadequate cental respiratory drive, excessive respiratory workload, or inadequate respiratory muscle endurance. With the exception of drug overdoses, central causes of respiratory failure are uncommon in the adult, and respiratory failure can be considered an imbalance between workload and endurance. Excessive workload can result from airway obstruction or chest wall or lung restriction. Anything that increases the required minute ventilation will increase the workload proportionately. Inadequate endurance results from neuromuscular disease, malnutrition, and a variety of metabolic factors. In most cases, treatment of the precipitating cause allows weaning from mechanical ventilation. However, when respiratory failure persists, often because the precipitating cause cannot be treated, all possible contributing conditions must be identified and corrected to the greatest possible extent. In that way, many patients with apparently intractable respiratory failure can be weaned. Four new approaches are showing some promise in the treatment of persistent respiratory failure: pharmacologic therapy to strengthen respiratory muscles, periodic respiratory muscle rest, sedation, and inspiratory muscle training.