Non-invasive positive pressure ventilation (NIPPV) is a respiratory technique validated for several years in intensive care units, which has became a standard of care in emergency units in recent years. The best indications for NIPPVare patients with chronic obstructive pulmonary disease (COPD) exacerbation and those with acute congestive heart failure (CHF). The two ventilatory modes usually used are spontaneous modes: the bi-level positive airway pressure (BiPAP) and the continuous positive airway pressure (CPAP). BiPAP is the only mode indicated for COPD decompensation, whereas CPAP or BiPAP can be used in CHF. BiPAP has been proposed in case of other indications such as preoxygenation technique before tracheal intubation, in case of acute respiratory failure and in patients with “do not intubate” status. In emergency medicine, NIPPV should be started as earlier as possible either in the prehospital setting or at the patient’s arrival in the emergency department. New ventilators are small with high performance capacities and are equipped with batteries which allow NIPPV to be started in the prehospital setting by the mobile medical units.