Most ventilatormodessetpositiveend-expiratorypressure(PEEP)asabaselinepre-
ssureandsecondarilyincreaseairwaypressureabovethebaselinetoreachaplateau
pressure,subsequentlydevelopingtidalventilationbypushinggasintothelung.Conversely,
APRVintegrateswithinthePHigh:(1)theplateaupressure(baselinepressure),(2)tidal
gas ventilation,and(3)theabilitytoretainaportionofthePHighaspositiveend-
releasepressuresimilartoPEEP(refertoFig1of “AdjunctstoVentilatorySupportPart1:
Nitricoxide,surfactants,prostacyclin,steroids,sedation,andneuromuscularblockade”). The
P HighinAPRVequatestoaplateaupressureandasPHighisreleasedtowardPLow,
expiratorygas flow generatestidalventilation.Tidalventilationduringthereleasephaseof
APRVisaidedbythenaturalrecoiloftherespiratorysystemtoreachalower-restingelastic
equilibrium