Objective. In physiological conditions, arterial blood lactate concentration is equal to or lower than central venous blood lactate concentration. A reversal in this rate (i.e., higher lactate concentration in central venous blood), which could reflect a derangement in the mitochondrial metabolism of lung cells induced by inflammation, has been previously reported in patients with ARDS but has been never explored in COVID-19 patients. The aim of this study was to explore if the COVID-19-induced lung cell damage was mirrored by an arterial lactatemia higher than the central venous one; then if the administration of anti-inflammatory therapy (i.e., canakinumab 300 mg subcutaneous) could normalize such abnormal lactate a-cv difference. Methods. A prospective cohort study was conducted, started on March 25, 2020, for a duration of 10 days, enrolling 21 patients affected by severe COVID-19 pneumonia undergoing mechanical ventilation consecutively admitted to the ICU of the Rimini Hospital, Italy. Arterial and central venous blood samples were contemporarily collected to calculate the difference between arterial and central venous lactate (Delta a-cv lactate) concentrations within 24 h from tracheal intubation (T0) and 24 hours after canakinumab administration (T1). Results. At T0, 19 of 21 (90.5%) patients showed a pathologic Delta a-cv lactate (median 0.15 mmol/L; IQR 0.07–0.25). In the 13 patients undergoing canakinumab administration, at T1, Delta a-cv lactate decreased in 92.3% of cases, the decrease being statistically significant (T0: median 0.24, IQR 0.09–0.31 mmol/L; T1: median −0.01, IQR −0.08–0.04 mmol/L; p=0.002). Conclusion. A reversed Delta a-cv lactate might be interpreted as one of the effects of COVID-19-related cytokine storm, which could reflect a derangement in the mitochondrial metabolism of lung cells induced by severe inflammation or other uncoupling mediators. In addition, Delta a-cv lactate decrease might also reflect the anti-inflammatory activity of canakinumab. Our preliminary findings need to be confirmed by larger outcome studies.

Objective. In physiological conditions arterial blood lactate concentration is equal or lower than central venous. The aim of this study was to explore if the COVID-19 induced lung cells damage was mirrored by an arterial lactatemia higher than the central venous one; then if the administration of immunosuppressant drugs (i.e. canakinumab) could normalize such abnormal lactate a-cv difference.Methods. Prospective cohort study started on March 25 th 2020 for a duration of 10 days, enrolling 21 patients affected by severe COVID-19 pneumonia undergoing mechanical ventilation consecutively admitted to the ICU of the Rimini Hospital, Italy.Arterial and central venous blood samples were contemporary collected to calculate the difference between arterial and central venous lactate (Delta a-cv lactate) concentration within 24 h from tracheal intubation (T 0 ), and 24 hours after canakinumab administration (T 1 ). Results.At the T 0 19/21 (90.5%) patients showed a pathologic Delta a-cv lactate (median 0.22 mmol/L; IQR 0.07-0.36), suggesting severe inflammation. In the 13 patients undergoing canakinumab administration, at the T 1 Delta a-cv lactate decreased in 92.3% of cases, being the decrease statistically significant (T 0 : median 0.15, IQR 0.07-0.25 mmol/L; T 1 : median -0.01, IQR -0.09-0.04 mmol/L; p=0.002). Conclusion.A reversed Delta a-cv lactate is likely to be one of the effects of COVID-19 related cytokine storm, that could reflect a derangement in the lung cells mitochondrial metabolism induced by inflammation or other uncoupling mediators. Delta a-cv lactate decrease may reflect the antiinflammatory activity of canakinumab. Our preliminary findings need to be confirmed by larger outcome studies.