Abstract
Noninvasive ventilation refers to techniques of augmenting alveolar ventilation without an endotracheal airway. Such techniques are, of course, not new. Attempts at assisting alveolar ventilation long antedated the development of endotracheal tubes. Descriptions of negative pressure ventilators (NPV) may be found in the medical literature dating back to the 1830s (1). A century later, these ventilators, in particular the iron lung, served as the mainstay of ventilatory support during the polio epidemics (2). The large number of patients in need of acute and chronic ventilatory support during these epidemics stimulated the development of other so-called body ventilators including the rocking bed, pneumobelt, poncho wrap, and chest shell (3).