Association between preoperative haemoglobin concentration and cardiopulmonary exercise variables: a multicentre study
1 Division of Surgery and Interventional Science, University College London, 21 University Street, London WC1E 6DE, UK
2 The Portex Unit, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
3 Department of Medicine, Centre of Cardiovascular Genetics, University College London, 5 University Street, London WC1E 6JF, UK
4 Integrative Physiology and Critical Illness Group, Division of Clinical and Experimental Science, Faculty of Medicine, University of Southampton, University Road, Southampton SO17 1BJ, UK
5 UCL Institute for Human Health and Performance, c/o 4th Floor, Rockefeller Building, 21 University Street, London WC1E 6DE, UK
6 Newcastle Upon Tyne NHS Foundation Trust, Freeman Hospital, Freeman Road, High Heaton, Newcastle Upon Tyne NE7 7DN, UK
7 Torbay Hospital, South Devon Healthcare NHS Foundation Trust, Torbay Hospital, Lawes Bridge, Torquay TQ2 7AA, UK
Perioperative Medicine 2013, 2:18 doi:10.1186/2047-0525-2-18Published: 13 September 2013
Preoperative anaemia and low exertional oxygen uptake are both associated with greater postoperative morbidity and mortality. This study reports the association among haemoglobin concentration ([Hb]), peak oxygen uptake ( peak) and anaerobic threshold (AT) in elective surgical patients.
Between 1999 and 2011, preoperative [Hb] and cardiopulmonary exercise tests were recorded in 1,777 preoperative patients in four hospitals. The associations between [Hb], peak and AT were analysed by linear regression and covariance.
In 436 (24.5%) patients, [Hb] was <12 g dl-1 and, in 83 of these, <10 g dl-1. Both AT and peak rose modestly with increasing [Hb] (r2 = 0.24, P <0.0001 and r2 = 0.30, P <0.0001, respectively). After covariate adjustment, an increase in [Hb] of one standard deviation was associated with a 6.7 to 9.7% increase in peak, and a rise of 4.4 to 6.0% in AT. Haemoglobin concentration accounted for 9% and 6% of the variation in peak and AT respectively.
To a modest extent, lower haemoglobin concentrations are independently associated with lower oxygen uptake during preoperative cardiopulmonary exercise testing. It is unknown whether this association is causative.