NEGATIVE-PRESSURE VENTILATION IN THE TREATMENT OF ACUTE RESPIRATORY-FAILURE - AN OLD NONINVASIVE TECHNIQUE RECONSIDERED

Noninvasive mechanical ventilatory techniques include the use of negat ive and positive pressure ventilators, Negative pressure ventilators, such as the ''iron lung'', support ventilation by exposing the surface of the chest wall to subatmospheric pressure during inspiration; wher eas, expiration occurs when the pressure around the chest wall increas es and becomes atmospheric or greater than atmospheric. In this review , after a description of the more advanced models of tank ventilators and the physiological effects of negative pressure ventilation (NPV), we summarize the recent application of this old technique in the treat ment of acute respiratory failure (ARF), Several uncontrolled studies suggest that NPV may have a potential therapeutic role in the treatmen t of acute on chronic respiratory failure in patients with chronic obs tructive pulmonary disease and restrictive thoracic disorders, reducin g the need for endotracheal intubation. In the paediatric field, after substantial technical improvement, NPV has been successfully reintrod uced for the treatment of ARF due to neonatal distress syndrome and br onchopulmonary dysplasia, and for the weaning from positive pressure v entilation in intubated patients. The positive results of these report s need to be formally confirmed by further prospective and controlled studies before recommending the generalized use of negative pressure v entilation in acute respiratory failure as a standard of care.