ABSTRACT
Preoperative care includes a clinical examination before invasive or non-invasive interventions for anaesthesia/analgesia and is the responsibility of the anaesthesiologists. Methemoglobinemia should be considered, as well as cardiac, pulmonary, and peripheral circulatory disorders in patients with central cyanosis and low oxygen saturation despite treatment with sufficient oxygen during anaesthesia. Methemoglobinemia is a serious clinical condition, associated with increased blood methemoglobin levels characterized by clinical signs, such as cyanosis and hypoxia due to lack of oxygen-carrying capacity. Here, we present our anaesthesia management in a patient with unnoticed congenital methemoglobinemia during preoperative evaluation, in whom clinical signs of methemoglobinemia developed after local anaesthesia administration before the surgery.