Haemoglobin Oxygen Affinity in Patients with Severe COVID‐19 Infection

During critical care, at least until the late stage of the disease, severely ill COVID‐19 patients may have relatively well preserved lung compliance but remain severely hypoxaemic. A recent theoretical study suggested a direct interaction between COVID‐19 viral proteins and haemoglobin (Hb) that could lead to a loss of oxygen carrying capacity. As national guidelines strongly support a restrictive transfusion strategy in the critically ill, any right‐shift in the Hb O₂ affinity curve could contribute to the hypoxaemia and be potentially harmful. We have measured Hb O₂ affinity curves from severely ill COVID‐19 patients and, in comparison to age‐ and sex‐matched controls, find no evidence for a shift in O₂ affinity that would support any change in clinical management.