Ventilation-Perfusion RatioPulmonary EmbolismLungKrypton RadioisotopesPulmonary VentilationPulmonary Gas ExchangeLaser-Doppler FlowmetryHindlimbRespiration, ArtificialTechnetium Tc 99m Aggregated AlbuminPerfusion ImagingXenon RadioisotopesIschemiaNoble GasesPulmonary CirculationPerfusionRespirationOxygenCarbon DioxideBlood Gas AnalysisTidal VolumeVentilationOne-Lung VentilationPositive-Pressure RespirationPartial PressureRespiratory MechanicsThoracic Surgical ProceduresPulmonary ArteryIntubation, IntratrachealAlligators and CrocodilesAdministration, InhalationLung Volume MeasurementsHypoventilationRespiratory Function TestsHeliumAirway ObstructionTechnetium Tc 99m PentetateXenonTurtlesHypergravityAirway ResistanceRana catesbeianaTomographyAnoxiaAirway RemodelingHigh-Frequency VentilationLung DiseasesMetamorphosis, BiologicalTomography, X-Ray Computed