Arterial Carboxyhemoglobin Levels In Covid-19 Critically Ill Patients

Abstract

Background : Oxidative stress conditions may be responsible for an up-regulation of the expression of heme oxygenase, the enzyme synthesizing carbon monoxide (CO) in cells. Elevated levels of arterial carboxyhemoglogin (CO-Hb) have been found in critically ill patients, including those suffering from acute lung injury. We aimed to investigate the changes of arterial CO-Hb levels in COVID-19 critically ill patients.Methods : A retrospective cohort study was conducted on the medical charts of 63 patients admitted in the ICU for severe COVID-19 infection over the period March 1 – May 31, 2020.Results : The overall ICU mortality rate was 39%. Non-survivors had a significantly higher profile of arterial CO-Hb levels than survivors (p<0.001), but arterial CO-Hb increased significantly from admission to day 30 in both groups (p<0.001). Mortality could not be predicted by the changes in arterial CO-Hb, but there was a correlation between the maximal arterial CO-Hb value and SOFA score on admission. No correlation could be demonstrated between arterial CO-Hb and serum C-reactive protein (CRP) as a marker of the inflammatory response.Conclusions : A greater increase of arterial CO-Hb levels over time may represent another marker of severity of COVID-19 infection in ICU patients.

The Role of Methemoglobin and Carboxyhemoglobin in COVID-19: A Review

“…The study selection process is shown in Figure 1a. For the case of COHb and COVID-19, 73 articles were retrieved from PubMed (n = 1) and Google Scholar (n = 72), one duplicate was removed and 68 articles were excluded after abstract review, leading to three articles that were finally included in the present study [20,24,25]. The study selection process is shown in Figure 1b…”

“…For the case of the three studies concerning COHb and COVID-19, two were cross sectional studies [ 24 , 25 ] and one a case report [ 20 ]. Two of the studies were published in journals [ 20 , 25 ] and one on the preprint server Research Square (researchsquare.com) [ 24 ].…”

“…Paccaudi et al [ 24 ] analyzed the data of 63 patients admitted in the hospital for severe COVID-19 and found that, while COHb was not different for survivors in comparison to non-survivors (1.10 ± 0.50% vs. 0.95 ± 0.24%) ( Figure 2 b), COHb increased to statistically significantly higher values during the course of the hospital stay in non-survivors compared to survivors (see Figure 3 c), leading the authors to conclude that a greater increase in COHb over time seems to represent a relevant marker of COVID-19 severity and seems to play a role in the determination of the survival probability of a COVID-19 infection.…”

“…In the case report of Faisal et al [ 20 ], COHb was 3.2% during the disease course. According to the study of Paccaud et al [ 24 ], COHb rose above the reference range on about the 10th day after hospitalization. Interestingly, this study also clearly demonstrated that at admission, COHb was in the normal range for the COVID-19 patients, while COHb was statistically significantly more elevated on the 31st day of the hospital stay in COVID-19 patients compared to patients suffering from other illnesses.…”

“…Regarding COHb, 67% (2/3) studies reported an increase, and one found no elevated COHb. As highlighted by the observations of Palmer et al [ 22 ] and Paccaud et al [ 24 ], the time of MetHb and COHb measurement during the course of the disease is critical, since MetHb and COHb seem to generally increase in hospitalized COVID-19 patients. The type of medical treatment is also of importance since some drugs currently used to treat COVID-19 have a high oxidizing potential provoking methemoglobinemia and carboxyhemoglobinemia.…”