Bruce D Butler | PubMed Health

PubMed2004

Bubbles and bypass: an update.

Bubbles in the bloodstream are not a normal condition--yet they remain a fact of cardiopulmonary bypass (CPB), having been extensively studied and documented since its inception some 50 years ago. While detectable levels of gaseous microemboli (GME) have decreased significantly in recent years and gross air embolism has been nearly eliminated due to increased awareness of etiologies and technological advances, methods of use of current perfusion systems continue to elicit concerns over how best to totally eliminate GME during open-heart procedures. A few studies have correlated adverse neurocognitive manifestations associated with excessive quantities of GME. Newer techniques currently in vogue, such as vacuum-assisted venous drainage, low-prime perfusion circuits, and carbon dioxide flooding of the operative field, have, in some instances, exacerbated the problem of gas embolism or engendered secondary complications in the safe conduct of CPB. Doppler monitoring (circuit or transcranial) primarily remains a research tool to detect GME emanating from the circuit or passing into the patients' cerebral vasculature. Newer developments not yet widely available, such as multiple-frequency harmonics, may finally provide a tool to distinguish particulate microemboli from GME and further delineate the clinical significance of GME.

Carbon Dioxide↗

PubMed2003

Patent foramen ovale and paradoxical systemic embolism: a bibliographic review.

A patent foramen ovale (PFO) has been reported to be an important risk factor for cardioembolic cerebrovascular accidents through paradoxical systemic embolization, and it provides one potential mechanism for the paradoxical systemic embolization of venous gas bubbles produced after altitude or hyperbaric decompressions. Here, we present in a single document a summary of the original findings and views from authors in this field. It is a comprehensive review of 145 peer-reviewed journal articles related to PFO that is intended to encourage reflection on PFO detection methods and on the possible association between PFO and stroke. There is a heightened debate on whether aviators, astronauts, and scuba divers should go through screening for PFO. Because it is a source of an important controversy, we prefer to present the findings in the format of a neutral bibliographic review independent of our own opinions. Each cited peer-reviewed article includes a short summary in which we attempt to present potential parallels with the pathophysiology of decompression bubbles. Two types of articles are summarized, as follows. First, we report the original clinical and physiological findings which focus on PFO. The consistent reporting sequence begins by describing the method of detection of PFO and goal of the study, followed by bulleted results, and finally the discussion and conclusion. Second, we summarize from review papers the issues related only to PFO. At the end of each section, an abstract with concluding remarks based on the cited articles provides guidelines.

Astronauts↗