TNF and hydrops fetalis: The aims of this study were (i) to develop an innovative procedure combining MEPS with UHPLC-MS/MS for the simultaneous determination of 8-isoprostaglandin F2α and cortisol in saliva and (ii) to monitor lactate, uric acid, TNF-α, cortisol, α-amylase and 8-isoprostaglandin F2α concentrations in stimulated saliva samples collected from 44 HF patients during their hospitalisation due to acute HF.