Any unexpected peri-procedural neurological event should prompt urgent consideration of gas embolism.
The ideal treatment is to offer Hyperbaric Oxygen therapy (HBOT) immediately. At the moment, the aim is to offer treatment within 6 hours. However it is important to realise that many cases still benefit several hours beyond this golden window.
This can only improve if clinicians have a clear action plan to deal with this potentially fatal disaster.
The incidence in most health care systems is unknown. Hyperbaric units may have the most accurate estimation of the incidence(1), since most clinicians accept Hyperbaric Therapy (HBO) as the only useful treatment.
We are particularly interested to learn more about retrograde cerebral venous gas embolism (CVGE). All cases with air in the cerebral venous sinuses and tracts will be of great interest to us. The natural course and also response to hyperbaric treatment is still unknown. These may represent a large part of cases of CGE responding to a hyperbaric oxygen despite significant delays.
Virtually any medical procedure, including peripheral intravenous cannulation, could potentially allow air or gas to enter the circulation.
Any unexpected neurological event happening in healthcare or particularly a peri-procedural ‘stroke’ should elicit a careful consideration of gas embolism as a cause.
Injection of air/gas directly into the arterial system.
Paradoxically, from the venous system through an intracardiac right-to-left shunt, or where intracardiac shunt is excluded, AV malformations in the lungs or overwhelming of the pulmonary capillary filter mechanism.
Retrograde Cerebral Venous Gas Embolism (RCVGE) (First described by Ploner(2) and Schlimp(3)).
Schlimp et al(3) and later Fracasso et al(7) designed a laboratory model, explaining the flow dynamics that allow retrograde cerebral venous gas embolism. This may not answer all the questions, but potentially explain a very import issue. We aim to get a better understanding of CVGE with the help of interested clinicians reporting their cases.
The first case report of RCVGE treated with HBO was published in 2012(8). A review of textbooks, Review Articles and Editorials of cerebral gas embolism indicates a lack of recognition of this variant of CGE(9).
Gorman, Helps, et al, have done some excellent animal research. Their work is worth a read.