“Auto-Peep” (Occult-Peep), is an unexpected-Peep which is generated, when a premature or early- breath is delivered before expiration is actually completed to result as air-trapping in lungs, in pt who is on mechanical ventilator. Later, such progressively Auto-peep causes for hyperinflation of alveoli to rupture and results into barotrauma, hypotension, reduced PaO2.