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Br J Anaesth. 2017 May 1;118(5):747-754. doi: 10.1093/bja/aew445.

Total haemoglobin mass, but not haemoglobin concentration, is associated with preoperative cardiopulmonary exercise testing-derived oxygen-consumption variables.

Author information

1
Division of Surgery and Interventional Science, University College London, London, UK.
2
Anaesthesia and Critical Care Research Unit, University Hospital Southampton NHS Foundation Trust, Southampton, UK.
3
Integrative Physiology and Critical Illness Group, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, University Road, Southampton, UK.
4
Critical Care Research Area, Southampton NIHR Respiratory Biomedical Research Unit, Southampton, UK.
5
Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, UK.
6
Centre for Human Health and Performance/Institute for Sport, Exercise and Health, University College London, UK.
7
Department of Sports Medicine/Sports Physiology, University of Bayreuth, Bayreuth, Germany.
8
NIHR University College London Hospitals Biomedical Research Centre, London, UK.

Abstract

Background:

Cardiopulmonary exercise testing (CPET) measures peak exertional oxygen consumption ( V˙O2peak ) and that at the anaerobic threshold ( V˙O2 at AT, i.e. the point at which anaerobic metabolism contributes substantially to overall metabolism). Lower values are associated with excess postoperative morbidity and mortality. A reduced haemoglobin concentration ([Hb]) results from a reduction in total haemoglobin mass (tHb-mass) or an increase in plasma volume. Thus, tHb-mass might be a more useful measure of oxygen-carrying capacity and might correlate better with CPET-derived fitness measures in preoperative patients than does circulating [Hb].

Methods:

Before major elective surgery, CPET was performed, and both tHb-mass (optimized carbon monoxide rebreathing method) and circulating [Hb] were determined.

Results:

In 42 patients (83% male), [Hb] was unrelated to V˙O2 at AT and V˙O2peak ( r =0.02, P =0.89 and r =0.04, P =0.80, respectively) and explained none of the variance in either measure. In contrast, tHb-mass was related to both ( r =0.661, P <0.0001 and r =0.483, P =0.001 for V˙O2 at AT and V˙O2peak , respectively). The tHb-mass explained 44% of variance in V˙O2 at AT ( P <0.0001) and 23% in V˙O2peak ( P =0.001).

Conclusions:

In contrast to [Hb], tHb-mass is an important determinant of physical fitness before major elective surgery. Further studies should determine whether low tHb-mass is predictive of poor outcome and whether targeted increases in tHb-mass might thus improve outcome.

KEYWORDS:

anaemia; anaerobic threshold; cardiopulmonary exercise test; oxygen consumption; physical fitness; surgery

PMID:
28510737
DOI:
10.1093/bja/aew445
[Indexed for MEDLINE]
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