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Replicating measurements of total hemoglobin mass (tHb-mass) within a single day: Precision of measurement; feasibility and safety of using oxygen to expedite carbon monoxide clearance

Plumb, J; Kumar, S; Otto, J; Schmidt, W; Richards, T; Montgomery, HE; Grocott, M; (2018) Replicating measurements of total hemoglobin mass (tHb-mass) within a single day: Precision of measurement; feasibility and safety of using oxygen to expedite carbon monoxide clearance. Physiological Reports , 6 (17) , Article e13829. 10.14814/phy2.13829. Green open access

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Abstract

Hemoglobin concentration ([Hb]) is a function of total hemoglobin mass (tHb‐mass) and plasma volume. [Hb] may fall by dilution due to plasma volume expansion and changes in the perioperative period may therefore correlate poorly with blood loss. A simple, reliable, repeatable way to measure plasma volume and tHb‐mass would have substantial clinical utility. The “optimized carbon monoxide re‐breathing method” (oCOR) meets these criteria. However, it is recommended that a minimum of 12 h (when breathing room air) is left between repeat measurements. Twenty‐four subjects underwent 3 days of testing. Two oCOR tests were performed (T1 and T2), 3 h apart, with a different CO clearance method employed between tests aiming to keep the carboxyhemoglobin level below 10%. The primary aim was to ascertain whether tHb‐mass testing could be safely repeated within 3 h if carboxyhemoglobin levels were actively reduced by breathing supplemental oxygen (PROCA). Secondary aims were to compare two other clearance methods; moderate exercise (PROCB), or a combination of the two (PROCC). Finally, the reliability of the oCOR method was assessed. Mean (SD) tHb‐mass was 807.9 ± (189.7 g) (for T1 on day 1). PROCA lowered the carboxyhemoglobin level from the end of T1 (mean 6.64%) to the start of T2 (mean 2.95%) by a mean absolute value of 3.69%. For PROCB and PROCC the mean absolute decreases in carboxyhemoglobin were 4.00% and 4.31%, respectively. The fall in carboxyhemoglobin between T1 and T2 was greatest in PROCC; this was statistically significantly lower than that of PROCA (P = 0.0039) and PROCB (P = 0.0289). The test‐retest reliability for the measurement of total hemoglobin mass was good with a mean typical error (TE) of 2.0%. The oCOR method is safe and can be repeated within 3 h when carbon monoxide is suitably cleared between tests. Using oxygen therapy alone adequately achieves this.

Type: Article
Title: Replicating measurements of total hemoglobin mass (tHb-mass) within a single day: Precision of measurement; feasibility and safety of using oxygen to expedite carbon monoxide clearance
Open access status: An open access version is available from UCL Discovery
DOI: 10.14814/phy2.13829
Publisher version: https://doi.org/10.14814/phy2.13829
Language: English
Additional information: © 2018 The Authors. This is an open access article under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Keywords: Blood volume, optimized carbon monoxide re‐breathing, plasma volume, red cell volume, total hemoglobin mass (tHb‐mass)
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Medicine
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Medicine > Internal Medicine
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Inst of Clinical Trials and Methodology
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Inst of Clinical Trials and Methodology > MRC Clinical Trials Unit at UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > UCL GOS Institute of Child Health
URI: https://discovery.ucl.ac.uk/id/eprint/10053185
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