1 Institute of Anesthesiology, University Hospital Zurich, Zurich, Switzerland; Institute of Physiology, University of Zurich, Zurich, Switzerland. Electronic address: martin.schlaepfer@uzh.ch.
2 Department of Anesthesiology, University of Florida College of Medicine, Gainesville, FL, USA. Electronic address: afrantz@anest.ufl.edu.
3 Department of Anesthesiology, University of Florida College of Medicine, Gainesville, FL, USA. Electronic address: bfahy@anest.ufl.edu.