Asymptomatic benzocaine spray-induced methaemoglobinaemia in preoperative sedation for oesophagogastroduodenoscopy

• Published in: BMJ case reports Vol. 15; no. 6; p. e249097
• Main Authors: Jarrah, Abdullah, Al Sbihi, Ali, Manasrah, Nouraldeen, Alqasem, Sarah
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group LTD 27.06.2022; BMJ Publishing Group
• Subjects: Anaphylaxis; Anesthesia; Anesthesia, Local; Anesthetics, Local - adverse effects; Asymptomatic; Benzocaine - adverse effects; Cardiac arrhythmia; Case reports; Case Reports: Unusual association of diseases/symptoms; Cyanosis; Dyspnea; Edema; Endoscopy, Digestive System - adverse effects; Heart rate; Hemoglobin; Humans; Hypoxia; Metabolism; Metabolites; Methemoglobinemia - chemically induced; Methemoglobinemia - diagnosis; Methemoglobinemia - drug therapy; Oxygen saturation; Patients; Pneumothorax; Ulcers; Vital signs; Unwanted effects / adverse reactions; Adult intensive care; Endoscopy; Haematology (incl blood transfusion)
• ISSN: 1757-790X; 1757-790X
• DOI: 10.1136/bcr-2022-249097

Methaemoglobinaemia is defined as elevated methaemoglobin in the blood which is characterised by conversion of some of the reduced ferrous iron elements [Fe2+] to the oxidised ferric [Fe3+] form which does not have capacity to bind and transport oxygen resulting in functional anaemia. Causes can be genetic mutations or acquired by medications such as dapsone, nitrates or benzocaine. Benzocaine is currently being used as a topical anaesthetic agent before certain procedures. We report a case of benzocaine spray-induced methaemoglobinaemia in a patient who underwent oesophagogastroduodenoscopy for evaluation of upper gastrointestinal bleeding.