Issues for surgery
Risk of anaemia related post-operative complications if discontinued for a prolonged period pre-operatively.
Risk of demyelination and neurological symptoms, which could be exacerbated by use of nitrous oxide anaesthesia, if vitamin B12 deficiency not diagnosed and treated – see Further information.
Advice in the perioperative period
Elective and emergency surgery
For intramuscular preparations confirm frequency and date of next dose with patient.
Pre-operative initiation
Screen for anaemia pre-operatively as early as possible in the patient’s pathway if surgery is anticipated to result in more than 500ml blood loss. Follow diagnostic algorithm in Centre of Perioperative Care Guidelines to determine type of anaemia. It is recommended that diagnosis is confirmed before treatment is commenced to avoid masking a folate deficiency.
Post-operative advice
For oral preparations
Restart post-operatively when enteral intake resumes.
For intramuscular preparations
Restart post-operatively when next dose due.
Interactions with common anaesthetic agents
None.
Interactions with other common medicines used in the perioperative period
None.
Further information
Nitrous oxide
Nitrous oxide irreversibly chelates cobalamin (vitamin B12) preventing it acting as a coenzyme in the production of components needed for myelin formation. There have been several reports of myelopathy developing 2 to 6 weeks after nitrous oxide anaesthesia in patients with an underlying, untreated vitamin B12 deficiency. The Medicines and Healthcare products Regulatory Agency advise assessing vitamin B12 levels before nitrous oxide anaesthesia in patients with risk factors for deficiency, e.g., elderly, poor or vegetarian diet and history of anaemia.
Recreational use of nitrous oxide is increasingly common; chronic abuse of nitrous oxide has also been linked to vitamin B12 deficiency and associated neurological sequalae.
References
Safari A, Emadi F, Jamali E et al. Clinical and MRI manifestations of nitrous oxide induced vitamin B12 deficiency: A case report. Iranian Journal of Neurology 2013; 12(3): 111-113
Centre for Perioperative Care. Guideline for the Management of Anaemia in the Perioperative Pathway (September 2022). Available at: https://cpoc.org.uk/guidelines-resources/guidelines [Accessed on 7th September 2022]
Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 27th August 2022]
Summary of Product Characteristics – Cyanocobalamin 50 mcg Tablets. ADVANZ Pharma. Accessed via www.medicines.org.uk 27/08/2022 [date of revision of the text May 2019]
Baxter K, Preston CL (eds), Stockley’s Drug Interactions (online) London: Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 27th August 2022]
Medicines and Healthcare products Regulatory Agency. Drug Safety Update. Nitrous oxide: neurological and haematological toxic effects. Published 11th December 2014. Available at www.gov.uk [Accessed 27th August 2022]
Shoults K. Case report: Neurological complications of nitrous oxide abuse. BC Medical Journal 2016; 58(4): 192-194