Esophageal pH MonitoringGastroesophageal RefluxEsophagusGastric Acidity DeterminationHydrogen-Ion ConcentrationProton Pump InhibitorsManometryCapsule EndoscopyEsophagoscopyGastric AcidMonitoring, PhysiologicMonitoring, AmbulatoryGastric JuiceAntacidsRanitidineAnti-Ulcer AgentsStomachOmeprazoleFamotidine2-PyridinylmethylsulfinylbenzimidazolesDuodenogastric RefluxHistamine H2 AntagonistsMagnesium HydroxideLansoprazoleTechnetium Tc 99m DisofeninGastrinsGastric MucosaPneumonia, AspirationCimetidineGastrointestinal ContentsCross-Over StudiesRabeprazolePreanesthetic MedicationImino Acids