1 Skills Centre, University of Leipzig, Leipzig, Germany.
2 Department of Anaesthesiology and Intensive Care, Heart Center Leipzig, Leipzig, Germany; Department of Anaesthesiology, University of the Free State, Bloemfontein, South Africa.
3 Department of Anaesthesiology and Intensive Care, Heart Center Leipzig, Leipzig, Germany.
4 Department of Anaesthesiology and Intensive Care, University of Leipzig Medical Center, Leipzig, Germany.