ABSTRACT
The use of mechanical aids to assist patients with chronic respiratory insufficiency, especially those with neuromuscular diseases, has increased over the past few years. Initially, patients were ventilated with negative pressure tanks, which were quite popular during the polio epidemics (I). With the development and increasing sophistication of positive pressure ventilators and the concerns about their effects on upper airway function (2-4), negative pressure ventilators were either discarded or delegated to storage. Positive pressure ventilation via tracheostomy became the method of choice for chronic conditions; but during the last 20 years, the use of the "old style" techniques of negative pressure ventilation and the acceptance of positive pressure ventilation without the need for a tracheostomy or an endotracheal tube have been reexamined.
