Red Cell Deformability Changes as a Prognostic Indicator of Postoperative Morbidity in Cardiac Surgery Using Cariopulmonary Bypass

Abstract

Preoperative and intraoperative red cell deformability assessed by a standard microfiltration technique was used to study the gross rheologic changes of red cells due to disease and mechanical trauma in relation to postoperative compli cations following the use of cardiopulmonary bypass (CPB) for elective heart surgery in 142 patients in NYHA (New York Heart Association) class III. The red cell filtration rate (RCFR) in μL/s was determined before surgery and grouped rheologically into four functional classes (GTCA = Gothenborg Cardio-Thoracic Association). Compared with their laboratory's normal reference for 200 healthy individuals (mainly blood donors) (61 ± 9 μL/s ± 2 SD), the RCFR was signifi cantly reduced by 21% (p < 0.05) to GCTA class I (1-25% reduction) in 18 pa tients, by 34% (p<0.01) to class II (26-50% reduction) in 99, and by 54% (p<0.001) to class III (51-75% reduction) in 25. Significant RCFR reductions during CPB were seen in all the groups, where the mean reduction was lowest in class I (15% p<0.001) and highest in class III (76% p<0.001) as compared with normal subjects. The analyses of complications showed that significantly higher frequencies of bleeding, blood transfusion, respirator usage, and arrhythmia were found in class III than in class I (1.5 vs 0.8 L, p<0.05; 3 vs 1.5 units, p < 0.05; 14 vs 6 hours, p<0.05 respectively). The authors conclude that preoperative red blood cell deformability testing and grading of the patients' microrheologic status of red blood cells can be a complement to the NYHA function classification and can also be useful for study ing the morbid effects of surgical trauma associated with CPB.