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Thoughts and Progress
Author(s) -
Solen Kenneth A.,
Mohammad Syed F.,
Pijl Aarnout J.,
Swier Patrick,
Monson Ryan D.,
Olsen Don B.
Publication year - 1990
Publication title -
artificial organs
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.684
H-Index - 76
eISSN - 1525-1594
pISSN - 0160-564X
DOI - 10.1111/j.1525-1594.1990.tb03005.x
Subject(s) - engineering ethics , engineering
The constant‐pressure filtration (CPF) method has been developed to assess blood microemboli (BME) in terms of their ability to occlude microvascular flow. Previous reports suggest that the method is sensitive to the effects of platelet stimulation and to blood‐pumping conditions. BME production and heparin activity were studied in bovine and human blood pumped by a Pelle‐thane ventricle with Pellethane molded valves connected via smooth quick‐connects to a Pellethane horseshoe‐shaped reservoir. In each experiment, blood was collected into heparin by cardiac puncture from a stunned animal or by venepuncture from a human donor. The blood from each donor was filled into three ventricle‐reservoir systems (50 cc ventricle and 1,500 cc reservoir for the bovine blood, and 20 cc ventricle and 150 cc reservoir for the human blood). One of the systems received aspirin (ASA; 25 mg/dl) shortly after the onset of pumping, whereas the other two served as pumping and non‐pumping controls. The blood was pumped in a full‐fill/full‐eject mode for up to 10 h. BME concentration was measured by the CPF method in which the blood was filtered through 20‐μm pore filters at 20 mm Hg for 10 s, and the flowrate curves were evaluated from an occlusion model. Heparin activity was measured by the activated partial thromboplastin time (APTT) test. In the early period after the onset of pumping, the BME concentration increased, whereas the APTT decreased from an initial value of<250 s, with the relative rate of change for both the BME and the APTT being the following: pumping control < pumping ASA blood < quiescent control. When the APTT fell below a critical value (an average oi 36 s for the bovine blood and 126 s for the human blood), the BME increased very rapidly, presumably because oi microdot formation. The CPF method appears to be sufficiently sensitive to detect BME when anticoagulation is adequate and to detect microdot formation when anticoagulation is inadequate. The method also indicated that the effects of ASA on BME formation were similar to ASA effects on heparin neutralization. Finally, the results indicated species differences in the rate of heparin neutralization and in the heparin activity corresponding tc the onset of microdot formation.