Applying the Optimized CO Rebreathing Method for Measuring Blood Volumes and Hemoglobin Mass in Heart Failure Patients

Ahlgrim, Christoph; Birkner, Philipp; Seiler, Florian; Grundmann, Sebastian; Baumstark, Manfred W.; Bode, Christoph; Pottgießer, Torben

doi:10.3389/fphys.2018.01603

Cited by 16 publications

(26 citation statements)

References 27 publications

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“…In our study population, the median levels of CO reached 7.8% (7.0–8.8%) with no adverse events. The CO rebreathing test has been used in heart failure patients with reduced ejection fraction (<30%) with no observed cardiac adverse effects . The CO rebreathing test as performed in this study requires the patient to hold a mouthpiece for 6 minutes, which for some patients may be difficult to complete.…”

Section: Discussionmentioning

confidence: 99%

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Intravascular volumes evaluated by a carbon monoxide rebreathing method in patients undergoing chronic hemodialysis

Bomholt

Larsson

Rix

et al. 2020

Hemodialysis International

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Introduction: Treatment of fluid overload and anemia remains a challenge in patients undergoing hemodialysis. Hypervolemia can be evaluated using a carbon monoxide (CO) rebreathing method by which blood volume (BV), plasma volume (PV), and red blood cell volumes (RBCV) can be determined. We hypothesized that recurrent hypervolemia would cause hemoglobin (Hb) levels to be in the anemic range without a concurrent reduction in RBCV in patients undergoing hemodialysis.Methods: BV, PV, and RBCV were determined by a CO rebreathing test in 19 patients with type 2 diabetes undergoing chronic hemodialysis. The tests were performed 20 minutes before initiating dialysis, and the measured intravascular volumes were compared with predicted normal intravascular volumes according to Nadler's equation. Before initiating dialysis, Hb and blood pressure were measured, and edema severity was graded.Findings: Measured BV was higher in 17 out of the 19 patients with a median of 71.1 (62.4--76.9) mL/kg and higher than the predicted BV of 58.3 (53.5-59.9) mL/kg (P < 0.001). The measured PV was found to be higher in all patients. RBCV was measured as 25.2 (23.4-28.2) mL/kg with a predicted volume of 25.9 (22.4-26.7) mL/kg (P = 0.56). Eighteen patients were anemic as determined by Hb concentrations (defined as Hb < 13 g/dL for men and <12 g/dL for women), and nine were anemic according to RBCV. Discussion:The CO rebreathing test is a new approach to measuring intravascular volumes in hemodialysis patients. Compared with predicted intravascular volumes, the predialysis BV was expanded in the majority with elevated PV as the main cause. No overall difference in RBCV was found between the measured and predicted volumes. According to predialysis Hb levels, all but one patient was anemic, but according to the measured RBCV, only nine were in the anemic range, indicating dilution of Hb.

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Section: Discussionmentioning

confidence: 99%

“…Prolonging the time before measuring the post‐CO rebreathing blood sample for %HbCO could improve the accuracy of the CO rebreathing test but the improvement beyond 10 minutes is very modest . A study of heart failure patients has found that reduced CO mixing resulted in a systematic underestimation the Hb mass below 1% …”

Section: Discussionmentioning

confidence: 99%

Intravascular volumes evaluated by a carbon monoxide rebreathing method in patients undergoing chronic hemodialysis

Bomholt

Larsson

Rix

et al. 2020

Hemodialysis International

View full text Add to dashboard Cite

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“…These data suggest that any changes in COHb circulatory mixing kinetics in CLD do not necessitate adjustment of standard sample timings (Schmidt & Prommer, 2005), perhaps in contrast to the situation in heart failure (left ventricular ejection fraction < 30%) patients (Ahlgrim et al, 2018) and polycythemia (Wachsmuth et al, 2019).…”

Section: Discussionmentioning

confidence: 94%

“…As such, measurement of COHb% at 6 and 8 min (averaged to yield the “7 min” value) is commended (Schmidt & Prommer, 2005), and was used in our study. However, mixing is delayed in disease states such as cardiac failure (Ahlgrim et al, 2018) and polycythemia (Wachsmuth, Soria, Jimenez, & Schmidt, 2019). Admixture might be slowed down in CLD due to changes in regional (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Here, binding of a known volume of CO to Hb, and measurement of carboxyhemoglobin concentration (COHb) allows tHb‐mass to be measured and, using this and knowing hematocrit, PV to be derived. Predominantly applied to monitor athletes’ responses to altitude training (Gore et al, 2013), it has more recently been used in clinical medicine (Ahlgrim et al, 2018; Diaz‐Canestro, Haider, Lundby, & Montero, 2019; Koponen et al, 2013; Otto, Plumb, Clissold, et al, 2017; Otto, Plumb, Wakeham, et al, 2017; Wrobel, Pottgiesser, Birkner, Deibert, & Ahlgrim, 2016). Data regarding oCOR application to CLD patients were limited (Wrobel et al, 2016), but we demonstrated a poor relationship between [Hb] and tHb‐mass in CLD ( r = .410, p = .11) with PV explaining much of the variance in [Hb] (Otto, Plumb, Clissold, et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Application of the optimized carbon monoxide rebreathing method for the measurement of total haemoglobin mass in chronic liver disease

et al. 2020

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Background Anemia is common in liver cirrhosis. This generally infers a fall in total hemoglobin mass (tHb‐mass). However, hemoglobin concentration ([Hb]) may fall due to an expansion in plasma volume (PV). The “optimized carbon monoxide rebreathing method” (oCOR) measures tHb‐mass directly and PV (indirectly using hematocrit). It relies upon carboxyhemoglobin (COHb) distribution throughout the entire circulation. In healthy subjects, such distribution is complete within 6–8 min. Given the altered circulatory dynamics in cirrhosis, we sought in this pilot study, to assess whether this was true in cirrhosis. The primary aim was to ascertain if the standard timings for the oCOR were applicable to patients with chronic liver disease and cirrhosis. The secondary aim was to explore the applicability of standard CO dosing methodologies to this patient population. Methods Sixteen patients with chronic liver parenchymal disease were studied. However, tHb‐mass was determined using the standard oCOR technique before elective paracentesis. Three subjects had an inadequate COHb% rise. In the remaining 13 (11 male), mean ± standard deviation (SD) age was 52 ± 13.8 years, body mass 79.1 ± 11.4 kg, height 175 ± 6.8 cm. To these, mean ± SD dose of carbon monoxide (CO) gas administered was 0.73 ± 0.13 ml/kg COHb values at baseline, 6 and 8 min (and “7‐min value”) were compared to those at 10, 12, 15 and 20 min after CO rebreathing. Results The “7‐min value” for median COHb% (IQR) of 6.30% (6.21%–7.47%) did not differ significantly from those at subsequent time points (8 min: 6.30% (6.21%–7.47%), 10 min: 6.33% (6.00%–7.50%), 12 min: 6.33% (5.90%–7.40%), 15 min: 6.37% (5.80%–7.33%), 20 min: 6.27% (5.70%–7.20%)). Mean difference in calculated tHb‐mass between minute 7 and minute 20 was only 4.1 g, or 0.6%, p = .68. No subjects reported any adverse effects. Conclusions The oCOR method can be safely used to measure tHb‐mass in patients with chronic liver disease and ascites, without adjustment of blood sample timings. Further work might refine and validate appropriate dosing regimens.

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Increased blood reactive oxygen species and hepcidin in obstructive sleep apnea precludes expected erythrocytosis

et al. 2023

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Obstructive sleep apnea (OSA) causes intermittent hypoxia during sleep. Hypoxia predictably initiates an increase in the blood hemoglobin concentration (Hb); yet in our analysis of 527 patients with OSA, >98% did not have an elevated Hb. To understand why patients with OSA do not develop secondary erythrocytosis due to intermittent hypoxia, we first hypothesized that erythrocytosis occurs in these patients, but is masked by a concomitant increase in plasma volume. However, we excluded that explanation by finding that the red cell mass was normal (measured by radionuclide labeling of erythrocytes and carbon monoxide inhalation). We next studied 45 patients with OSA before and after applying continuous positive airway pressure (CPAP). We found accelerated erythropoiesis in these patients (increased erythropoietin and reticulocytosis), but it was offset by neocytolysis (lysis of erythrocytes newly generated in hypoxia upon return to normoxia). Parameters of neocytolysis included increased reactive oxygen species from expanded reticulocytes' mitochondria. The antioxidant catalase was also downregulated in these cells from hypoxia‐stimulated microRNA‐21. In addition, inflammation‐induced hepcidin limited iron availability for erythropoiesis. After CPAP, some of these intermediaries diminished but Hb did not change. We conclude that in OSA, the absence of significant increase in red cell mass is integral to the pathogenesis, and results from hemolysis via neocytolysis combined with inflammation‐mediated suppression of erythropoiesis.

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Applying the Optimized CO Rebreathing Method for Measuring Blood Volumes and Hemoglobin Mass in Heart Failure Patients

Cited by 16 publications

References 27 publications

Intravascular volumes evaluated by a carbon monoxide rebreathing method in patients undergoing chronic hemodialysis

Intravascular volumes evaluated by a carbon monoxide rebreathing method in patients undergoing chronic hemodialysis

Application of the optimized carbon monoxide rebreathing method for the measurement of total haemoglobin mass in chronic liver disease

Increased blood reactive oxygen species and hepcidin in obstructive sleep apnea precludes expected erythrocytosis

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