Methemoglobinemia induced by a topical anesthetic spray (cetacaine).

In two seriously ill patients, cyanosis developed shortly after a topical anesthetic spray (Cetacaine) was used. In both cases the presence of methemoglobinemia was suggested by a discrepancy between the arterial oxygen tension and the oxygen saturation of hemoglobin, as measured spectrophotometrically. The characteristic responses of the spectrophotometric oximeter to blood containing different concentrations of methemoglobin are described. Physicians administering this topical anesthetic spray (Cetacaine) should be aware of the possible development of methemoglobinemia.