Intubation and mechanical ventilation are well-established techniques in the management of patients with acute respiratory failure; however, there are situations in which these procedures cannot be used safely for various reasons. A recently described noninvasive technique, nasal positive-pressure ventilation (NPPV), has been developed for home ventilation of certain patients with chronic ventilatory insufficiency. We hypothesized that NPPV could be used in selected patients in whom intubation and mechanical ventilation were clearly indicated, but not immediately possible, or even contraindicated. Six patients were treated with NPPV during an episode of acute respiratory failure and enrolled in a prospective study. We found that NPPV was successful in avoiding intubation, but only in the three patients suffering from a restrictive pulmonary disorder, whereas the procedure was unsuccessful in patients with obstructive disorders. Moreover, in every patient, acute NPPV was very time-consuming for the nursing staff: in patients with restrictive disorders, a nurse had to monitor a patient submitted to NPPV during 41 +/- 9 percent of the duration of ventilation and during 91 +/- 9 percent of the NPPV time in patients with obstructive disorders. We conclude that acute NPPV may be attempted in selected patients with acute respiratory failure, predominantly patients with restrictive respiratory disorders, but that this procedure is very time-consuming for nurses.