Oxygen Not in Hyperventilation — MFDS Part 1 MCQ
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Correct answer: B — Anxiety-related hyperventilation with SpO2 98% after organic illness has been excluded
Explanation lettering: E = shown as A · A = shown as B · B = shown as E
A is correct. Pure anxiety-related hyperventilation causes hypocapnia rather than hypoxaemia. When organic illness has been excluded and SpO2 is normal, stop dental treatment, reassure the patient and encourage slow, controlled diaphragmatic breathing. Supplemental oxygen does not correct the hypocapnia and is unnecessary; paper-bag rebreathing should also be avoided. Anaphylaxis and severe asthma require oxygen alongside condition-specific treatment while emergency help is awaited. Oxygen is not routine for a normoxic myocardial infarction, but it is indicated here because SpO2 is 89%. UK dental emergency guidance also recommends high-concentration oxygen during a generalised epileptic seizure, particularly when cyanosis is present.
Reference: Birmingham and Solihull Mental Health NHS Foundation Trust. Oxygen in Adults: Prescribing and Administration, version 5, sections 3.7 and Appendix 3, 2022. https://www.bsmhft.nhs.uk/wp-content/uploads/2023/09/Oxygen-Policy-Final-2.pdf