Gaseous / Thrombotic Emboli

[miketsp]

I have been reading some articles on gas bubble detection using noninvasive procedures - specifically ultrasound and several of the articles refer to the need to be able to separate gaseous from thrombotic emboli.
Having an engineering background and not a medical one the term thrombotic threw me.
Searching the web I found several definitions which would appear to define it as some sort of blood clot but this would not seem to be a problem within the context of the articles which generally use the nonlinear resonant properties of bubbles pumped with two frequencies to generate a return with sidebands at the sum and difference of the stimuli.

Can somebody clarify for me in layman's terms what "thrombotic" emboli are? Are they always solid?

 

[Dr Deco]

Hello miketsp:

Emboli

Emboli come in different forms, classified according to their composition. Most are composed of red blood cells and are blood clots. Some come from ruptured adipose cells (or bone marrow) and are fat emboli. Still others come from tears in blood vessels and are filled with air.

In some cases, gaseous emboli can be produced by the action of mechanical heart valves. These are cavitation nuclei. Since they are formed by heart valves, they are in a position to be carried to the brain. When monitoring for clots is being performed on the patient (e.g., with a transcranial Doppler device), the signals appear and are referred to often at “HITS” (high intensity transient signals). This means that it cannot be said with certainty whether these are solid or gaseous entities.

Certainly the difference in acoustic impedance would give easy identification of a solid versus a gaseous object if they were of the same physical size. Since size is rarely known in a clinical setting, some other method is needed. Resonance techniques have been suggested as well as two-frequency approaches.

For patients with artificial heart valves and strange ultrasound signals, it is of clinical interest to know whether these are gaseous or solid since the treatment is different (anticlotting agents for solid emboli and nothing yet for gaseous ones).

Dr Deco :doctor:

Readers, please note the next class in Decompression Physiology :umnik:
http://wrigley.usc.edu/hyperbaric/advdeco.htm

 

[miketsp]

Thanks for the fast & complete answer.
Michael