1. Visiting Assistant Professor, Department of Anesthesia, University of Iowa Hospitals, Iowa City, Iowa 52242. Present address: Department of Anaesthesia, Helsinki University Central Hospital, Haartmaninkatu 4, SF-00290 Helsinki 29, FINLAND.
2. Professor of Anesthesia, Department of Anesthesia, University of Iowa Hospitals, Iowa City, Iowa 52242.
3. Assistant Professor of Biomedical Engineering, College of Engineering, University of Iowa, Iowa City, Iowa 52242.