Luiking YC, et al. - In a long-term randomised double-blind placebo-controlled parallel-group study, experts aspired to explore whether prolonged (72-h) intravenous L-arginine administration in sepsis patients improves microcirculation, as well as analyzing the impacts on arginine and protein metabolism and organ function. Participants in the study were critically ill patients with a diagnosis of septic shock. For this investigation, they continuously infused L-arginine-HCl (1.2 μmol.kg-1.min-1; n = 9) or L-alanine (isocaloric control: 2.4 μmol.kg-1.min-1; n = 9). In spite of a rise in WB NO synthesis, prolonged intravenous L-arginine administration does not improve local perfusion and organ function. Regarding global hemodynamics, the administration is safe, but the observed rise in P_r-aCO₂ and intra-abdominal pressure warrants cautious implementation of L-arginine infusion and further study, particularly in the early stage of septic shock.