“…This may become evident in situations of (1) metabolic stress and high energy demand (a ''priming factor'' [14], such as critical illness with central nervous system activation and endogenous production of catecholamines, glucocorticoids, Fig. 2 Propofol and phenylephrine infusion doses and creatinine kinase levels of the third patient with PRIS and cytokines), (2) low availability of alternative sources of energy, such as carbohydrates (in children more than adults, because of higher dependence of the former on fatty-acid oxidation, due to lower glycogen storage capability [6,13,16]), and (3) high availability of lipids (due to the high-lipid content in the propofol emulsion and the additional catecholamine-mediated lipolysis [13,21,22]), which are inefficiently oxidized because of propofol. Risk factors for developing the syndrome include younger age, severe neuro-critical illness, inborn errors of mitochondrial fatty-acid metabolism (such as very long chain acyl-coenzyme A dehydrogenase deficiency), acquired carnitine deficiency (with administration of valproic acid, malabsorption syndrome, cirrhosis, or chronic renal failure [18]), ketogenic diet or low carbohydrate intake [13,14], exogenous catecholamine or steroid administration [13,14,[22][23][24], and high-dose, prolonged infusions of 2% propofol (>5 mg/kg/hour for more than 48 h [8,11]).…”