Continuous Positive Airway Pressure
Priya Prashad, MD, and Nadav Traeger, MD, FAAP, FCCP, DABSM
Continuous positive airway pressure (CPAP) is a form of noninvasive respiratory support that delivers a constant positive pressure via an interface that covers the nose and/or mouth at a pressure sufficient to maintain a patent airway and thus eliminate snoring and obstructive sleep apnea (OSA). Other indications are listed in the following section.
CPAP is used for treatment in the following ways.
• As a secondary treatment modality for patients with clinically significant residual OSA after adenotonsillectomy or other upper airway or craniofacial surgery
• As a primary treatment modality for OSA in patients who are not surgical candidates because of other medical issues (eg, severe obesity, bleeding diathesis, atlantoaxial instability) and/or who have small tonsils and/or adenoids • For OSA when either the patient or the parents prefer a nonsurgical option • For hypoventilation and/or OSA caused by neuromuscular weakness rather than an anatomic issue (bilevel positive airway pressure [BiPAP] is more commonly used for this purpose; see Chapter 115).
•For preterm neonates whose lungs have not fully developed, who have respiratory distress syndrome, or who have bronchopulmonary dysplasia
•For patients who have clinically significant lower-airway obstruction due to tracheomalacia or bronchomalacia who may benefit from using CPAP to stent these airways open
•For patients with a variety of chronic obstructive lung diseases for lung recruitment and to aid with airway clearance of secretions
•CPAP machines can be set at 1 single pressure, typically between 4 and 20 cm H20. Typically, the machine is set at the lowest pressure that resolves all obstructive events, as well as snoring.
•Expiratory positive airway pressure is the background pressure applied at a continuous rate (eg, 9 cm H20).
• O2 is the amount of oxygen that can be added to the inspired air. For most patients with OSA syndrome, supplemental O2 is not needed. This parameter may be displayed in liters per minute or as a fraction (as in the fraction of inspired oxygen) or a percentage.
•Humidification refers to the relative amount of humidity added to inspired air, adjusted for comfort.
•The CPAP machine (pressure generator) is connected to an interface via tubing. It blows air and thus creates positive pressure air through the interface into the nose and/or mouth, thus preventing the upper airway from collapsing during sleep.
•The most effective way to determine the correct pressure and mask is an in-laboratory overnight sleep study (CPAP titration).
•Interface options for CPAP include nasal masks, full-face masks that cover the nose and mouth (see Figures 114-1 and 114-2), total face mask (which covers the entire face), nasal pillows, and oral masks. These are available in a variety of sizes, shapes, and styles.
Figure 114-1. Full-face mask.
Figure 114-2. Nasal mask.
•Increasingly, medical device manufacturers have begun designing smaller masks for pediatric patients.