Comparison of Hematologic Effects of Coronary Artery Bypass Grafting Surgery Performed with and without Use of Cardiopulmonary Bypass

摘要

Coronary artery graft surgery (CABG) using a cardiopulmonary bypass (CPB) pump to allow for stopping the heart, commonly designated as "on pump CABG" or ONCAB, requires complete anticoagulation and is associated with significant postoperative anemia. In addition, a reduction in postoperative platelet counts is relatively common in large part due to heightened activation of hemostatic pathways and platelet consumption secondary to blood passing through the CPB circuit. It has been demonstrated that both anemia and nadir platelet counts after ONCAB are associated with the incidence and severity of postoperative acute kidney injury (AKI). Over the past several years, techniques have been refined for performing CABG without CPB, commonly designated as "off pump CABG" or simply OPCAB. This approach removes the need for anticoagulation thus potentially reducing postoperative bleeding and anemia, and negates the effect of CPB on platelet consumption. Whether OPCAB surgery mitigates the severity of postoperative anemia and thrombocytopenia relative to ONCAB, however, remains unclear. Furthermore, it remains unknown if the association between nadir platelet counts and AKI evident in ONCAB patients is present following OPCAB. The present study was designed to test the hypotheses that: a) nadir platelet counts and hemoglobin values, as well as bleeding and transfusion requirements differ between ONCAB and OPCAB surgeries; b) the postoperative recovery of platelet counts and hemoglobin values is more protracted in ONCAB vs. OPCAB; and c) that hemostatic derangements are more closely associated with postoperative AKI in ONCAB as compared to OPCAB surgeries.;Methods: With IRB approval, a retrospective study from a single institution was conducted involving 634 adult patients undergoing elective OPCAB (n=255) or ONCAB (n=379). Data were captured for demographics, medical history, surgical characteristics, postoperative blood loss (defined as chest tube output in the first 48 hours), hemoglobin levels and platelet counts, and blood product transfusions. Between groups, daily median, postoperative nadir, and discharge values for hemoglobin and platelets were compared with nadir counts defined as the median lowest in-hospital value measured over the first 5 postoperative days and at discharge. In addition, the incidence of frank thrombocytopenia, defined as platelet values of < 74 x 10 9/dL, was compared along with the administration of packed red blood cells (RBC), fresh frozen plasma (FFP) and platelet suspensions. AKI was defined according to KDIGO criteria, whereby postoperative serum creatinine rise >50% or 0.3 mg/dL was indicative of injury. The incidence of AKI was then determined for the OPCAB and ONCAB groups, both as a whole and when subdivided into the segment of each group that was thrombocytopenic.;Results: The ONCAB and OPCAB cohorts were similar in regard to age (67 +/- 10 vs 67 + 10), and male/female distribution (80/20 vs 72/28). For both groups, the median nadir platelet values were observed on the second postoperative day and were not different (145K vs 142K, p =0.44). Similarly, the incidence of thrombocytopenia was the same following both OPCAB and ONCAB (5.88% vs. 5.54%) surgeries. Median nadir postoperative hemoglobin concentration in OPCAB patients was 10.10 mg/dl and occurred on postoperative day 2. In ONCAB patients, the median nadir postoperative hemoglobin concentration was not different (9.90 mg/dl, p = 0.95) but occurred on postoperative 4. There was no difference in postoperative bleeding measured by chest tube output between ONCAB vs. OPCAB (892 +/- 421 mL vs. 850 +/- 441 mL, p = 0.24). The incidence of red blood cell (RBC) transfusion was comparable between groups. In contrast, both rates of FFP (ONCAB 20% vs. OPCAB 8%; p<0.001) as well as platelet transfusion (ONCAB 35% vs. OPCAB 10%; p<0.001) were different. Overall the pattern of postoperative platelet recovery was comparable, with both cohorts recovering beyond baseline values by postoperative day 5. The overall incidence of postoperative AKI was comparable between ONCAB vs. OPCAB [33.3% (n=126) and 34.5% (n = 88)]. Patients (combined ONCAB and OPCAB) who developed severe thrombocytopenia (n=36) had a higher rate of AKI as compared to those with normal platelet counts (55.6% vs. 32.4%; p=0.004). Further, intragroup analysis (ONCAB only) demonstrated a higher incidence of AKI in those with severe postoperative thrombocytopenia as compared to patients with "normal" platelet counts [62% (n=13) vs. 32% (n = 113); p =<0.004]. However, the same analysis of OPCAB patients showed no difference in the incidence of AKI [47% (n =7) vs. 34% (n=81); p = 0.31] for severe thrombocytopenia vs. normal platelet counts. (Abstract shortened by ProQuest.).