Obituary: John F. Butterworth IV, M.D. († 9th June 2023).

aDepartment of Anaesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Goethe University, Frankfurt, Germany bDepartment of Anaesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Münster, Germany Correspondence to Kai Zacharowski, Department of Anaesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Goethe University, Frankfurt, Germany. E-mail: [email protected]