Expiratory hold, or end-expiratory pause, is a maneuver transiently performed at the end of exhalation. It is accomplished by first allowing the patient to exhale completely. The ICU ventilator then pauses before delivering the next machine breath. During this time, both the expiratory and inspiratory valves are closed. Delivery of the next inspiration is briefly delayed. The purpose of this maneuver is to measure pressure associated with air trapped in the lung s at the end of expiration.
An accurate reading of end-exhalation pressure is impossible to obtain if a patient is breathing spontaneously. However, measurement of the exact amount of auto-PEEP present isn't always necessary; simply detecting its presence may sufficient. Auto-PEEP can be detected in the flow curve on a ventilator. Auto PEEP is present if flow does not return to zero when a new mandatory ventilator breath begins.