1. Department of AnesthesiaOtaru General Hospital Otaru Japan
2. Department of Public HealthSapporo Medical University School of Medicine Sapporo Japan
3. Department of Intensive Care MedicineSapporo Medical University School of Medicine Sapporo Japan
4. Department of Health ScienceHokkaido Chitose College of Rehabilitation Chitose Japan
5. Department of NeurosurgeryOtaru General Hospital Otaru Japan
6. Department of AnesthesiologySapporo Medical University School of Medicine Sapporo Japan