Interleukin-6 in Critical Coronavirus Disease 2019, a Driver of Lung Inflammation of Systemic Origin?

Crit Care Explor. 2021 Sep 28;3(10):e0542. doi: 10.1097/CCE.0000000000000542. eCollection 2021 Oct.


To examine whether interleukin-6 in critical coronavirus disease 2019 is higher in arterial than in central venous blood, as a sign of predominantly local pulmonal rather than systemic interleukin-6 production.

Design: Prospective cohort pilot study with repeated weekly measurements of interleukin-6 in arterial and central venous blood. Respiratory function, assessed with Pao2/Fio2 ratio, was measured at the time of blood sampling.

Setting: ICU at a university hospital.

Subjects: Nine adult patients with critical coronavirus disease 2019, actively treated and receiving mechanical ventilation.

Measurements and main results: No difference between arterial and central venous interleukin-6 was found. There was a significant negative relationship between interleukin-6 concentration and P/F ratio in both arterial (p = 0.04) and central venous (p = 0.03) blood.

Conclusions: The absence of an arteriovenous interleukin-6 difference implies that interleukin-6 in critical coronavirus disease 2019 is mainly produced outside the lungs as part of a systemic inflammatory response syndrome and act as a driver of local inflammation and damage in the lungs.

Keywords: coronavirus disease 2019; interleukin-6; interleukin-6/analysis; interleukin-6/antagonists and inhibitors; respiratory distress syndrome; systemic inflammatory response syndrome.