[1] KUOPIO UNIV,CENT HOSP,DEPT ANAESTHESIOL,KUOPIO,FINLAND
[2] TAMPERE UNIV,CENT HOSP,DEPT ANAESTHESIOL,TAMPERE,FINLAND
[3] UNIV HELSINKI,CENT HOSP,DEPT ANAESTHESIOL,SF-00100 HELSINKI 10,FINLAND
[4] UNIV TURKU,CENT HOSP,DEPT ANAESTHESIOL,SF-20500 TURKU 50,FINLAND