Krehl, L-M;
Plumb, JOM;
Wachsmuth, NB;
Haupt, S;
Kumar, SB;
Otto, JM;
Schierbauer, J;
... Schmidt, WFJ; + view all
(2020)
A carbon monoxide ‘single breath’ method to measure total haemoglobin mass: a feasibility study.
Experimental Physiology
10.1113/EP089076.
(In press).
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Abstract
NEW FINDINGS: What is the central question of this study? Is it possible to modify the CO-rebreathing method to acquire reliable measurements of haemoglobin mass in ventilated patients? What is the main finding and its importance? A 'single breath' of carbon monoxide with a subsequent 30 sec breath hold provides almost as exact a measure of haemoglobin mass as the established optimized CO-rebreathing method when applied to healthy subjects. The modified method has now to be checked in ventilated patients before it can be used to quantify the contributions of blood loss and of dilution to the severity of anaemia. ABSTRACT: Anaemia is defined by the concentration of haemoglobin ([Hb]). However, this value is dependent upon both the total circulating haemoglobin mass (tHb-mass) and the plasma volume (PV) - neither of which are routinely measured. Carbon monoxide- (CO) rebreathing methods have been successfully used to determine both PV and tHb-mass in various populations. However, these methods are not yet suitable for ventilated patients. This study aimed to modify the CO-rebreathing procedure such that a single inhalation of a CO bolus would enable its use in ventilated patients. Eleven healthy volunteers performed four CO-rebreathing tests in a randomized order, inhaling an identical CO-volume. In two tests, CO was rebreathed for 2min (oCOR), and in the other two tests, a single inhalation of a CO bolus was conducted with a subsequent breath hold of 15sec (Procnew 15sec) or 30sec (Procnew 30sec). Subsequently, the CO volume in the exhaled air was continuously determined for 20 min. The amount of CO exhaled after 7min (after 20min) for oCOR was 3.1 ±0.3ml (5.9 ±1.1ml); for Procnew 15sec, 8.7 ±3.6ml (12.0 ±4.4ml); and for Procnew 30sec, 5.1 ±2.0ml (8.4 ±2.6ml)). tHb-mass determined by oCOR was 843 ±293g, from Procnew 15sec 821 ±288g (difference: p <0.05), and from Procnew 30sec 849 ±311g. Bland-Altman plots demonstrated slightly lower tHb-mass values for Procnew 15sec compared with oCOR (-21.8 ±15.3g) and similar values for Procnew 30sec. In healthy volunteers, a single inhalation of a CO bolus, preferably followed by a 30 sec breath hold, can be used to determine tHb-mass. These results must now be validated for ventilated patients. This article is protected by copyright. All rights reserved.
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