Gaseous micro emboli: concepts and considerations.

The production of gaseous micro emboli associated with bubble oxygenators during extracorporeal perfusion has prompted considerable attention regarding product design and arterial filtration needs. There are a variety of routes by which gas bubbles are introduced into the vasculature. As invasive diagnostics and extracorporeal perfusion are used more widely, likewise, the incidence of gas embolism increases and thus the need arises for improved product design and standards. Recent studies13 have attempted to evaluate many of the commercially available devices to determine both the degree of gaseous emboli production and the extent of removal by arterial blood filters. A review of the various testing protocols and equipment used in these evaluative studies indicates an apparent lack of consistency in methodology. Before discussing these inconsistencies, however, it is desirable to review the sources and pathophysiological effects of intravascular bubbles as well as any physical characteristics inherent to a gas bubble in blood. It has been demonstrated that micro aggregates and micro gas emboli form in blood as a result of extracorporeal bypass and both have been implicated in the pathogenesis of organ dysfunction. 4 The major concern of this paper is with gaseous micro emboli production by bubble oxygenators and their removal by arterial blood filters. It is intended that standarized procedures will be recommended for evaluation of bubble oxygenators or arterial filters with regards to emboli production or removal. Accidental administration of an em-