The detection and quantification of gaseous microbubbles in the arterial line of the extracorporeal circuit (ECC) are very important aims for quality assurance of perfusion. A system that allows a continuous measurement of microbubble distribution in the range of 10 and 120 mm was tested. The two-channel ultrasonic bubble counter (UBC) was based on a 2-MHz ultrasound Doppler system with propriety ultrasound probes. The bubble size was determined using the backscattered Doppler signal and was corrected by means of a reference signal based on measurement conditions. Our studies have shown that the quality of this signal can be negatively affected in the clinical environment. Different influences are involved, such as electrocoagulation or electromagnetic disturbances. Various algorithms were tested and new ones were developed in order to minimize the effect of such interferenceson the accuracy of the bubble detection. The on-line data were recorded during the entire surgical time to allow an off-line evaluation with different algorithms. This allowed us to obtain more exact results. Two clinical studies with 91 patients were performed with microbubbles measured in the arterial line during coronary artery bypass grafting (CABG) and valve replacement. The results confirmed the expected occurrence of microbubbles during various phases of surgery. The measurement itself proved to be resistant to different external disturbances.
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References
1.
Roach GW , Kanchuger M , Mangano CMet al.Adverse cerebral outcome after coronary bypass surgery . N Engl J Med1996; 25: 1857-1863 .
2.
Walzer T , Herrmann M , Wallesch CW.Neuropsychological disorders after coronary bypass surgery . J Neurol Neurosurg Psychiatry1997; 62: 644-648 .
3.
Clark RE , Brillman J , Davis DA , Lovell MR , Price TR , Magovern GJ.Microemboli during coronary artery bypass grafting . J Thorac Cardiovasc Surg1995; 109: 249-258 .
4.
Pugsley W , Klinger L , Paschalis C , Treasure T , Harrison M , Newman S.The impact of microemboli during cardiopulmonary bypass on neuropsychological functioning . Stroke1994; 25: 1393-1399 .
5.
Kurusz M , Butler B , Katz J , Conti VR.Air embolism during cardiopulmonary bypass . Perfusion1995; 10: 361-391 .
6.
Gallagher EG , Pearson DT.Ultrasonic identification of sources of gaseous microemboli during open heart surgery . Thorax1973; 28: 295-305 .
7.
Lubbers J , Van der Berg JW.An ultrasonic detector for microgasemboli in bloodflow line . Ultrasound Med Biol1976; 2: 301-310 .
8.
Nishi RY.Ultrasonic detection of bubbles with Doppler flow transducers . Ultrasonics1972; 10: 173-179 .
9.
De Jong N , Cornet R , Lanceé CT.Higher harmonics of vibrating gas-filled micro spheres. Part 1. Simulations . Ultrasonics1994; 32: 447-453 .
10.
Jenderka KV , Dietrich G , Cobet U , Kopsch B , Klemenz A , Urbanek P.Detection and estimation of micro-bubble size distribution in blood . Proc 16th Int Congr Acoust1998; 3: 1845-1846 .
11.
Urbanek P , Erhardt G , Taborski U , Schönburg M , Tiedtke HJ , Klövekorn WP.Dynamische Luftfalle - Methode zur Beseitigung von Luftmikrobläschen aus arteriellem Blut während extrakorporaler Zirkulation . Kardiotechnik1999; 8: 100-102 .
12.
Schönburg M , Urbanek P , Erhardt G , Taborski U , Plechinger H , Klövekorn WP.A dynamic bubble trap reduces microbubbles during cardiopulmonary bypass: a case study . J Extra Corpor Technol2000; 32: 3165-3169 .
13.
Schönburg M , Urbanek P , Erhardt Get al.Significant reduction of air microbubbles with the dynamic bubble trap during cardiopulmonary bypass . Perfusion2001; 16: 19-25 .
