Ventilation-Perfusion RatioPulmonary EmbolismKrypton RadioisotopesLaser-Doppler FlowmetryPulmonary Gas ExchangeHindlimbTechnetium Tc 99m Aggregated AlbuminAdministration, InhalationPerfusion ImagingIschemiaNoble GasesPerfusionPulmonary CirculationLungXenon RadioisotopesBlood Gas AnalysisVentilationRespiration, ArtificialPulmonary VentilationOxygenInhalation ExposureFrasier SyndromeCarbon DioxidePulmonary ArteryRespiratory Function TestsSmoke Inhalation InjuryAnoxiaBurns, InhalationHigh-Frequency VentilationInhalationTidal Volume