“Patent became unwell on mobilisation with cardiorespiratory compromise and reduced level of consciousness. Noted one lumen on the right internal jugular central catheter was leaking following return of patient to supine position in bed. Subsequent transoesphageal echocardiography has demonstrated gas present in both right and left sides of the heart with a patent foreman ovale.”

Air entrainment seems to be the likely cause of harm here.

Air embolism can occur when there is a route for air into the circulation, and the circulatory pressure is lower than atmospheric pressure at the point of entry. Arterial air emboli are usually associated with endovascular procedures where air inadvertently gets into an arterial line. Venous air emboli most commonly seen with head and neck surgery, neurosurgery, endovascular procedures and with central lines in the internal jugular vein. Air embolism can occur at the point of line insertion or removal, or if there is a problem with the connections that allows air to be entrained. Air embolism can lead to rapid cardiac arrest, which can be difficult to treat.

The lessons from this report remind us to check central line connections regularly, and particularly when mobilising a patient (where the central venous pressure will drop). If a venous embolism is recognised or suspected, the priority is to stop further entrainment of air by raising the venous pressure and covering the site of entry. In surgical cases this can be achieved by flooding the area with sterile saline. Standard resuscitation measures should commence, and the patient can also be placed in the Trendelenburg (head
down) position. Durant’s manoeuvre involves additionally placing the patient on their left side to encourage any ‘airlock’ in the right ventricle to migrate to the right atrium. If the patient has a central line in situ, attempted aspiration may help to remove air from the right side of the heart.

Removal of central lines is another high-risk period and should be undertaken with the patient supine or head down to ensure that the venous pressure at the neck is relatively high.

This phenomenon (not this case) has been the subject of a coroner’s Report to Prevent Future Deaths.[1] The
Association’s Quick Reference Handbook has a specific page devoted to treating circulatory embolus (including air) during anaesthesia [2] and McCarthy and colleagues have written a useful open access review of the topic.[3]

1. Prevention of Future Deaths Report: Richard Kew, Coroner’s Court, 49, Feb 2023
2. Quick Reference Handbook, Association of Anaesthetists, 2022
3. McCarthy,CJ; Behravesh, S; et al. Air Embolism: Practical Tips for Prevention and Treatment. J Clin Med. 2016 5(11), 93. (NB: paywall)