Continuous monitoring in the intensive care setting has transformed our capacity to rapidly respond with interventions for patients in extremis. Non-invasive monitoring has generally been limited to transdermal or intravascular systems coupled to transducers including oxygen saturation or pressure. We hypothesized that gastric fluid (GF) and gases, accessible through nasogastric (NG) tubes, commonly found in intensive care settings, could provide continuous access to a broad range of biomarkers. We conducted a broad characterization of swine GF coupled to time-matched serum and observed a broad range of biomarkers in GF. We established the relationship and kinetics of GF-derived analyte level dynamics by correlating these to serum levels in an acute renal failure and an inducible stress model performed in swine. Non-invasive access to the dynamic profile of a broad range of biomarkers introduces the possibility to observe changes in real time facilitating rapid responses in evolving clinical settings.