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Title: The importance of haemoglobin to physical function
Author: Otto, J. M.
ISNI:       0000 0004 8498 857X
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2017
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Haemoglobin (Hb) within erythrocytes establishes a fundamental link between oxygen (O2) in ambient air and aerobic metabolism by transporting O2 in the blood from lung to tissue. Historically, blood O2 carriage has been quantified using the concentration of Hb in whole blood ([Hb]). Anaemia, defined as a fall in [Hb] below 130 g.l-1 in males and 120 g.l-1 in females may cause fatigue and impaired fitness. [Hb] is dependent on both plasma volume (PV) and total haemoglobin mass (tHb-mass). Thus, anaemia may result when tHb-mass falls but also when PV is expanded. Therefore, reliance on [Hb] may be misleading. tHb-mass may represent a better guide to O2 carrying capacity and of aerobic fitness than [Hb]. The relationship between tHb-mass and [Hb] has, however, been studied little across disease states, nor has the relationship between tHb-mass and preoperative cardiopulmonary exercise testing (CPET) variables. I used the optimised carbon monoxide rebreathing (oCOR) method to determine tHb-mass, first seeking its test-retest reliability in healthy volunteers (HV). Typical error of repeat tHb-mass measurements was low in my hands, in keeping with other studies. Subsequently, the relationship between tHb-mass and [Hb] in HV and in different diseases was studied; inflammatory bowel disease (IBD), chronic liver disease (CLD), heart failure (HF) and those awaiting surgery. I found the relationship between tHb-mass and [Hb] varied considerably across disease states, with PV a key confounding variable affecting both [Hb] and the diagnosis of anaemia. Subsequently, in a separate cohort of surgical patients I determined the relationship between tHb-mass, [Hb] and physical fitness quantified by CPET. Unlike [Hb], I found tHb-mass to be an important variable associated with preoperative fitness. The oCOR method is feasible and well tolerated by patients and provides a more comprehensive assessment of haematological and volume status compared to relying on [Hb] and its future use is advocated.
Supervisor: Richards, T. ; Montgomery, H. ; Grocott, M. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available