Abstract
Anaemia commonly complicates surgery and critical illness. This thesis comprised four
studies ofthis important clinical problem. Thefirst study was a retrospective study based in a
major teaching hospital Intensive Care Unit (ICU). Three existing datasets were merged to
provide a study dataset that described the demographics and severity of illness for a cohort of
critically ill patients (n = 489). The epidemiology of anaemia during ICU admission to death
or discharge home from hospital was described. 81.5% of patients were discharged anaemic
to the community after surviving critical illness. 35.5% had a haemoglobin concentration
<100g/L. 82% of patients had normocytic normochromic blood indices at hospital discharge.
The second study was a prospective observational study that further investigated blood
transfusion practice in a cohort of patients (n = 185) after ICU discharge. 72.2 % of these
patients were discharged home anaemic; 83% had normocytic normochromic blood indices at
hospital discharge. These data confirmed the retrospective analysis. Hospital physicians used
restrictive transfusion practice after ICU discharge; the median pre-transfusion Hb was 74 g/L
(interquartile range: 68-76 g/L). The third study measured red blood cell 2,3-
diphosphoglycerate (2,3-DPG) levels and P50, which both reflect the ability of red cells to
deliver oxygen to tissues, in a prospective cohort of 111 patients admitted to the ICU. Factors
that were associated with 2,3-DPG and P50 were investigated. The data showed that critically
ill patients have lower levels of 2,3-DPG compared with normal healthy controls. Red cell
2,3-DPG during critical illness had a strong association with patients' acid base status.
Acidemia was strongly associated with low DPG concentrations, which was counterintuitive.
2,3-DPG concentration had the strongest association with P50 raising the possibility that
oxygen unloading could be impaired in critically ill patients. The fourth study merged several
large existing databases to document the incidence, patterns, and likely aetiology of anaemia
and the incidence of red cell transfusion in patients presenting for elective major orthopaedic
surgery. The dataset comprised approximately 3500 patients presenting over one year to a
single orthopaedic hospital. The relation between pre-operative haemoglobin status, other factors, and peri-operative transfusion was investigated. 17 % of patients with known pre¬
admission Hb levels were anaemic. Most ofthese patients (64%) had normocytic
normochromic anaemia. 303 patients received a total of 838 red cell units. Low per-admission
Hb levels were common among those who were transfused during hospital admission.
