Bilevel Positive Airway Pressure Ventilation

Over the past few decades, invasive positive pressure ventilation, usually applied via an endotracheal tube, has been the standard treatment for acute respiratory failure [1–3]. However, intubation and mechanical ventilation is associated with significant morbidity, including upper airway trauma and infections [4–7]; indeed, it is the single most important predisposing factor for nosocomial pneumonia [7]. In response to the problems associated with intubation, noninvasive positive pressure ventilation (NPPV) has become more common in the treatment of patients with respiratory failure [7,8]. NPPV has the advantages of avoiding endotracheal tube–related morbidity as well as increasing patient comfort and autonomy; it also may be more cost-effective [9–12]. Of the several types of noninvasive ventilation, bilevel positive airway pressure (BiPAP) has become the one most commonly used [13]. BiPAP ventilators (Figure) deliver a positive airway pressure that alternates between a higher pressure during inspiration and a lower pressure during expiration. When the ventilator detects the patient’s inspiration, it increases the inspiratory positive airway pressure (IPAP) to a set level until it senses a drop in the flow rate below a given threshold value (usually 25% of the peak inspiratory flow) or until a certain amount of time elapses (usually 3 seconds). Then, the pressure support ventilation decreases to the expiratory positive airway pressure (EPAP) level, which lasts until the patient’s inspiration is again detected and the cycle repeats. Because BiPAP is a relatively new ventilatory modality, many clinicians may be unfamiliar with its use. This article reviews the utility of BiPAP in acute respiratory failure and provides illustrative examples of its application in patient care.