Haemoglobin levels of different patient populations. (a) Haemoglobin levels of different groups of haemodilutional anaemia during the study period. red line: 25% hct group, orange line: 20% hct group. (b) Haemoglobin levels of patients with and without prolonged intensive care unit (ICU) treatment. blue line: patients with 48 hours or more ICU treatment, green line: patients with less than 48 hours ICU treatment. CPB = cardiopulmonary bypass.