Criterion for initiating hemodialysis based on serum caffeine concentration in treating severe caffeine poisoning

[...]we conducted a multicenter prospective study to determine a criterion for initiating HD based on serum caffeine concentration for the treatment of severe caffeine poisoning.2 Materials and methods Participants were patients transported by ambulance between October 2017 and December 2018 to 10 emergency departments of hospitals that participated in this study after consuming large or massive amounts of supplements or energy drinks containing caffeine as a main ingredient (caffeine dose ≥1.0 g). The questionnaire included close-ended questions requesting information on the following: patient age and gender, commercial names and consumed amounts of caffeinated products, caffeine dose, vital signs and laboratory data on emergency department arrival, clinical signs and symptoms, physical complications during the clinical course, treatments including ventilator, HD, direct hemoperfusion (DHP), and veno-arterial extracorporeal membranous oxygenation (VA-ECMO), and outcomes. Tachypnea was defined as respiratory rate (RR) ≥20 breaths/min; tachycardia as heart rate (HR) ≥100 beats/min; depressed consciousness as a Glasgow Coma Scale (GCS) of 3 to 14; and hyperthermia as body temperature (BT) ≥37.5 °C. Hypercreatinekinasemia was defined as serum creatine kinase (CK) ≥200 IU/L; hyperglycemia as serum glucose ≥180 mg/dL; hypokalemia as serum K+ ≤ 3.4 mmol/L; hypophosphatemia as serum inorganic phosphate (IP) ≤2.4 mg/dL; and hyperlactatemia as serum lactate ≥2.0 mmol/L.2.1 Materials and reagents Standard caffeine, ethanol, acetonitrile, and phosphate-buffered saline (PBS, pH 7.2–7.4) were purchased from Wako Pure Chemical Industries (Osaka, Japan). [...]the U test was used as a non-parametric test.