Critical Care Medicine |
|Chapter 72:||Respiratory Care|
PRINCIPLES OF POSITIVEAIRWAY PRESSURE THERAPY
Positiveairway pressure therapy refers to the application of higher than ambient airway pressures during inspiration and/or exhalation for the purpose of improving pulmonary and respiratory function. Positive pressures applied during inspiration are usually referred to as positive-pressure ventilation (PPV). Positive pressures applied during exhalation are usually referred to as positive end-expiratory pressure (PEEP). Positive airway pressure is an essential component of critical care medicine and represents the single most important area demanding the unique skills and knowledge of the anesthesiologist.
The application of positiveairway pressure therapy to critically ill patients is confusing and controversial because of the following: (1) the physics, physiology, and technology are complex; (2) the terminology is inconsistent and at times contradictory; and (3) prospective conclusive human studies are rare because of multiple variables and the multidisciplinary clinical setting. This discussion is intended to provide a cohesive overview for all anesthesiologists irrespective of involvement in critical care medicine. Table 72–6 lists the definitions used in this chapter. These definitions are as acceptable as any others and are compatible with the published standards of the American College of Chest Physicians, the American Thoracic Society, and the American Association for Respiratory Care.
TABLE 72–6. Definitions
Physiology Associated With Positive-Pressure Ventilation
Modes of Positive-Pressure Ventilation
Positive End-Expiratory Pressure Devices
Physiology Associated With Continuous Positive Airway Pressure/Positive End-Expiratory Pressure
Physiologic Alterations due to Airway-Pressure Therapy
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