Beyond hypoxia: Systemic acidemia and respiratory insufficiency in Lance-Adams syndrome

Abstract Although cardiac arrests are common, most survivors do not develop post-hypoxic myoclonus (Lance-Adams syndrome, LAS), suggesting that hypoxia alone may be insufficient. We retrospectively identified LAS cases from electronic records and video archives (2000–2025) and reviewed the literature. Among 17 patients, 12 had peri-event blood gases, all showing severe acidemia (mean pH, 7.08), with respiratory acidosis in seven and metabolic acidosis in five; the remaining five had respiratory failure. In published reports, respiratory events commonly preceded LAS. Systemic acidemia associated with respiratory insufficiency frequently accompanies hypoxic injury in LAS and may explain its rarity after isolated cardiac arrest.