Haemoglobin oxygen affinity in patients with severe COVID‐19 infection: Still unclear

Harutyunyan, Gurgen; Harutyunyan, Garnik; Mkhoyan, G.; Harutyunyan, Varsenik; Soghomonyan, Suren

doi:10.1111/bjh.17051

Cited by 13 publications

(19 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In vivo effects of altered bicarbonate and lactate (La − ) concentrations in the erythrocytes are largely abolished, as these molecules easily cross the red cell membrane and will “disappear” in the buffer solution. A similar criticism has been published by Harutyunyan et al ( 41 ) and was accepted by the authors ( 42 ). We have therefore modified this method in our laboratory many years ago in that we used a plasma-like bicarbonate buffer and added CO 2 to the equilibration gas [e.g., Böning and Enciso ( 43 )].…”

Section: The Oxygen Dissociation Curve In Covid-19supporting

confidence: 68%

The oxygen dissociation curve of blood in COVID-19

Böning

Kuebler

Bloch

2021

American Journal of Physiology-Lung Cellular and Molecular Phys

View full text Add to dashboard Cite

COVID-19 hinders oxygen transport to the consuming tissues by at least 2 mechanisms: In the injured lung saturation of hemoglobin is compromised, in the tissues an associated anemia reduces the volume of delivered oxygen. For the first problem increased hemoglobin oxygen affinity (left shift of the oxygen dissociation curve ODC) is of advantage, for the 2nd, however, the contrary is the case. Indeed a right shift of the ODC has been found in former studies for anemia caused by reduced cell production or hemolysis. This resulted from increased 2,3-biphosphglycerate (2,3-BPG) concentration. In 3 investigations in COVID-19, however, no change of hemoglobin affinity was detected in spite of probably high [2,3-BPG]. The most plausible cause for this finding is formation of methemoglobin, which increases the oxygen affinity and thus apparently compensates for the 2,3-BPG effect. But this "useful effect" is cancelled by the concomitant reduction of functional hemoglobin. In the largest study on COVID-19 even a clear left shift of the ODC was detected when calculated from measurements in fresh blood rather than after equilibration with gases outside the body. This additional „in vivo" left shift possibly results from various factors (e. g. concentration changes of Cl-, 2,3-BPG, ATP, lactate, nitrocompounds, glutathione, glutamate, because of time delay between blood sampling and end of equilibration, or enlarged distribution space including interstitial fluid and is useful for O2 uptake in the lungs. Under discussion for therapy are the affinity-increasing 5-hydroxymethyl-2-furfural (5-HMF), erythropoiesis stimulating substances like erythropoietin, and methylene blue against MetHb formation.

show abstract

Section: The Oxygen Dissociation Curve In Covid-19supporting

confidence: 68%

The oxygen dissociation curve of blood in COVID-19

Böning

Kuebler

Bloch

2021

American Journal of Physiology-Lung Cellular and Molecular Phys

View full text Add to dashboard Cite

show abstract

“…The SpO 2 equal or less than 92%, despite maximum oxygen supplementation with a rebreathing mask, is usually defined as the indication of mechanical ventilation [ 8 – 11 ]‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬.‬ However, during the emerging pandemic, preliminary empirical experience showed that patients with SpO 2 lower than 92% presented with a good tolerance to the silent hypoxemia. For this reason, the SpO 2 threshold of 85% was arbitrarily determined by our group as definition of silent hypoxemia, which is in accord with the findings of Sohrabi C et al [ 6 ] and Harutyunyan et al [ 7 ].‬‬‬‬‬‬‬‬…”

Section: Introductionsupporting

confidence: 65%

“…Patients affected by SARS-CoV-2 interstitial pneumonia often present with tachypnea and desaturation without dyspnea or respiratory distress, defined as “silent hypoxemia” [ 6 , 7 ]. The SpO 2 equal or less than 92%, despite maximum oxygen supplementation with a rebreathing mask, is usually defined as the indication of mechanical ventilation [ 8 – 11 ]‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬.‬ However, during the emerging pandemic, preliminary empirical experience showed that patients with SpO 2 lower than 92% presented with a good tolerance to the silent hypoxemia.…”

Section: Introductionmentioning

confidence: 99%

Admission criteria in critically ill COVID-19 patients: A physiology-based approach

et al. 2021

View full text Add to dashboard Cite

Introduction The COVID-19 pandemic required careful management of intensive care unit (ICU) admissions, to reduce ICU overload while facing limitations in resources. We implemented a standardized, physiology-based, ICU admission criteria and analyzed the mortality rate of patients refused from the ICU. Materials and methods In this retrospective observational study, COVID-19 patients proposed for ICU admission were consecutively analyzed; Do-Not-Resuscitate patients were excluded. Patients presenting an oxygen peripheral saturation (SpO2) lower than 85% and/or dyspnea and/or mental confusion resulted eligible for ICU admission; patients not presenting these criteria remained in the ward with an intensive monitoring protocol. Primary outcome was both groups’ survival rate. Secondary outcome was a sub analysis correlating SpO2 cutoff with ICU admission. Results From March 2020 to January 2021, 1623 patients were admitted to our Center; 208 DNR patients were excluded; 97 patients were evaluated. The ICU-admitted group (n = 63) mortality rate resulted 15.9% at 28 days and 27% at 40 days; the ICU-refused group (n = 34) mortality rate resulted 0% at both intervals (p < 0.001). With a SpO2 cut-off of 85%, a significant correlation was found (p = 0.009), but with a 92% a cut-off there was no correlation with ICU admission (p = 0.26). A similar correlation was also found with dyspnea (p = 0.0002). Conclusion In COVID-19 patients, standardized ICU admission criteria appeared to safely reduce ICU overload. In the absence of dyspnea and/or confusion, a SpO2 cutoff up to 85% for ICU admission was not burdened by negative outcomes. In a pandemic context, the SpO2 cutoff of 92%, as a threshold for ICU admission, needs critical re-evaluation.

show abstract

“…Although they used a different methodology based on the calculation of P 50 , their results are consistent with ours. However, the real situation regarding oxygen affinity for hemoglobin in these patients is still under discussion 18 , 19 . Our results also remind us of the enormous gap between in silico or in vitro estimates and real-world practice.…”

Section: Discussionmentioning

confidence: 99%