Esophageal pH MonitoringGastroesophageal RefluxEsophagusGastric Acidity DeterminationHydrogen-Ion ConcentrationProton Pump InhibitorsManometryCapsule EndoscopyEsophagoscopyMonitoring, PhysiologicGastric AcidMonitoring, AmbulatoryGastric JuiceAntacidsRanitidineAnti-Ulcer AgentsStomachOmeprazoleFamotidine2-PyridinylmethylsulfinylbenzimidazolesDuodenogastric RefluxHistamine H2 AntagonistsMagnesium HydroxideLansoprazoleTechnetium Tc 99m DisofeninGastrinsPneumonia, AspirationGastric MucosaCimetidineGastrointestinal ContentsCross-Over StudiesRabeprazolePreanesthetic Medication