ABSTRACT
Prolonged Ventilator Dependence Approximately 10% of patients placed on mechanical ventilation require prolonged venti latory assistance. A number of factors contribute to ventilator dependence, including he modynamic instability, persistent lung disease, psychological dependency, malnutrition, and unresolved medical problems. Many times there is an imbalance between the patient’s ventilatory capability and the demand imposed by both the minute ventilation requirement and the elastic and resistive load on the respiratory muscles. Malnutrition, corticosteroids, and metabolic abnormalities contribute to muscle weakness and limited endurance. Minute ventilation requirements will be higher if there is elevated C 0 2 production secondary to fever, metabolic acidosis, excessive caloric intake, or increased dead-space ventilation from lung disease. Lung diseases also decrease lung compliance and increase airway resis tance. All of these potential factors must be sought for and corrected, if present, before any mode of ventilatory withdrawal is likely to be successful.
