The inspiratory positive airway pressure (IPAP) is similar to the peak airway pressure in traditional mechanical ventilation. A higher IPAP level would result in a larger tidal volume and minute ventilation.

The expiratory positive airway pressure (EPAP) is the same as PEEP during mechanical ventilation or CPAP during spontaneous breathing. In addition to its ability to improve oxygenation by increasing the functional residual capacity, EPAP also relieves upper airway obstruction with its splinting action.

SpO2, Capnography, PaO2, PaCO2 etc may be used for the titration of appropriate IPAP and EPAP levels.

CPAP (Continuous positive airway pressure) provides positive airway pressure during spontaneous breaths and it does not include any mechanical breaths. For this reason, the work of breathing is entirely assumed by the patient. CPAP is active when IPAP=EPAP. CPAP is the treatment of choice for obstructive sleep apnea without significant carbon dioxide retention. CPAP should not be used in apnea due to neuromuscular causes, if there is progressive hypoventilation or facial trauma

Bilevel PAP (Bilevel positive airway pressure) provides IPAP which controls peak inspiratory pressure during inspiration and EPAP that controls end-expiratory pressure. Indications are acute respiratory failure and acute hypercapnic exacerbations of COPD

In patients with acute cardiogenic pulmonary edema, CPAP or bilevel PAP ventilation has been found to reduce the need for subsequent mechanical ventilation

Inability to protect the airway from secretions or aspiration, apnoea, facial trauma are contraindications for NPPV.