Noninvasively applied positive airway pressure therapy (PAP) is available in 3 basic modes: continuous positive airway pressure (CPAP), bi-level positive airway pressure (BPAP), and adaptive servo-ventilation. These are in widespread use in home and hospital settings to treat a variety of disorders of ventilation or gas exchange, including obstructive sleep apnea, sleep-related hypoventilation, periodic breathing, acute and chronic hypercapnic respiratory failure, and acute respiratory failure. They are increasingly being used perioperatively to prevent or treat upper airway obstruction, hypoventilation, and periodic breathing, and they have been found to improve postoperative outcomes in the case of obstructive sleep apnea. An impediment to their use in this setting is a lack of familiarity with their application by hospital clinical staff. This review describes the modes of PAP therapy available, their indications, how therapy is initiated, how efficacy is assessed, common problems encountered with its use, and how these problems can be addressed. Key words: PAP therapy; respiratory compromise; obstructive sleep apnea; opioids; sleep-disordered breathing; adaptive servo-ventilation; CPAP; BPAP; hospital; adult. [Respir Care 2018;63(4):479–487.