Arterial gas embolism (AGE)
Overview
Arterial gas embolism (AGE) is an immediately life‑threatening form of decompression illness in which gas bubbles enter the arterial circulation and occlude end arteries, producing focal and global tissue ischaemia. AGE classically occurs in divers during or immediately after ascent and is a medical emergency that requires rapid recognition, high‑concentration oxygen and urgent discussion with a hyperbaric centre for recompression therapy.
Mechanisms
Bubbles cause mechanical vascular occlusion, endothelial injury and a secondary inflammatory response that produces tissue ischaemia, oedema and sometimes haemorrhage. In diving‑related AGE the common mechanisms are:
- Pulmonary barotrauma: expanding gas during ascent causes alveolar rupture (eg from breath‑holding, airway obstruction or pre‑existing bullous disease). Gas may enter the pulmonary veins and thence the systemic arterial circulation.
- Right‑to‑left shunt: venous bubbles bypass the pulmonary capillary filter through a patent foramen ovale (PFO) or pulmonary arteriovenous malformation.
- Overwhelming the pulmonary filter: a large venous bubble load (eg deep/long dives, rapid ascent, exertion after surfacing) may allow bubbles to pass through the pulmonary circulation unfiltered.
Emboli may lodge in any arterial bed. Cerebral arterial gas embolism (CAGE) causes rapid neurological deterioration and is the most serious presentation. Coronary embolism causes arrhythmia and myocardial ischaemia. Spinal and peripheral emboli cause focal pain and deficits.
Clinical features
Onset is often abrupt (during ascent, immediately on surfacing, or...