Acute respiratory failure is a commonly encountered entity in the emergency department and intensive care unit. Non-invasive positive pressure ventilation (NIPPV) has dramatically changed the management of acute respiratory failure, particularly when chronic obstructive pulmonary disease (COPD) or congestive heart failure is the underlying etiology.1,2 In the case of hypercapnic respiratory failure due to COPD, the NIPPV augments the ability of the patient to ventilate by assisting with the work of breathing and therefore increasing tidal volume and ensuring a minimum respiratory rate. Traditional settings for a bilevel positive airway pressure ventilator (BPAP) include an inspiratory positive airway pressure (IPAP) and an expiratory positive airway pressure. Adjustments in the IPAP change the tidal volume delivered for a given breath. The difference between IPAP and expiratory positive airway pressure is the driving pressure, which, in combination with respiratory rate, determines a patient’s ventilation. The limitations of this device are that it requires frequent attention from the physician or respiratory therapist in order to assure that a patient has an adequate tidal volume. Factors that may influence adequate tidal volumes are dynamic and include level of consciousness, position, and lung compliance. If any of these factors change during a patient’s hospital course, it may reduce the tidal volume and thus ventilation, which can be deleterious to the patient if unrecognized or underrecognized.