Department of Anesthesiology, Division of Cardiothoracic Anesthesiology, Virginia Commonwealth University, Richmond, Virginia.
Department of Anesthesiology, Division of Cardiothoracic Anesthesiology, Virginia Commonwealth University, Richmond, Virginia.
Ann Thorac Surg. 2018 Apr;105(4):1176-1181. doi: 10.1016/j.athoracsur.2017.11.023. Epub 2018 Mar 3.
Cardiac surgery is associated with a significant decrease in hematocrit. It is unclear whether that occurs from hemodilution, loss of red cells, or both. Hematocrit is a major determinant of transfusion decisions although transfusion is associated with increased morbidity and mortality. Physicians must determine whether this anemia is the result of hemodilution or red blood cell loss as the former would be treated with packed red blood cell transfusions and the latter by diuresis. We hypothesize that the decrease in hematocrit observed in cardiac surgery is due to hemodilution.
Blood volume (BV), plasma volume (PV), and red blood cell volume (RBCV) were measured in 54 patients undergoing coronary artery bypass graft surgery, valve surgery, or coronary artery bypass graft/valve surgery. Measurements were made preoperatively, immediately postoperatively, and 2 hours after surgery utilizing a dilution tracer method and hematocrit measurements.
Preoperative average BV was 6,094 mL (SD 1,904 mL), RBCV was 2,024 mL (SD 720 mL), and PV was 4,070 mL (SD 1,339 mL). Postoperative average BV was 4,834 mL (SD 1,432 mL), RBCV 1,226 mL (SD 527 mL), and PV 3,607 mL (SD 993 mL). Blood volume decreased 18% (p < 0.0001), RBCV decreased 38% (p < 0.001), and PV decreased 8% (p < 0.012). There were no significant changes between postoperative values and those 2 hours later in the cardiac surgery intensive care unit.
Decreases in hematocrit observed in cardiac surgery patients are due to significant red blood cell losses and not to hemodilution. Red blood cell losses averaged 38%. Plasma volume also decreased.
心脏手术会导致血细胞比容显著下降。目前尚不清楚这是由于血液稀释、红细胞丢失还是两者共同作用的结果。血细胞比容是决定输血决策的主要因素，尽管输血会增加发病率和死亡率。医生必须确定这种贫血是血液稀释还是红细胞丢失的结果，因为前者需要用浓缩红细胞输血治疗，后者需要用利尿剂治疗。我们假设心脏手术中观察到的血细胞比容下降是由于血液稀释。
对 54 例行冠状动脉旁路移植术、瓣膜手术或冠状动脉旁路移植/瓣膜手术的患者进行了血容量 (BV)、血浆容量 (PV) 和红细胞容量 (RBCV) 的测量。使用稀释示踪剂法和血细胞比容测量值，分别在术前、术后即刻和术后 2 小时进行测量。
术前平均 BV 为 6094ml(SD 1904ml)，RBCV 为 2024ml(SD 720ml)，PV 为 4070ml(SD 1339ml)。术后平均 BV 为 4834ml(SD 1432ml)，RBCV 为 1226ml(SD 527ml)，PV 为 3607ml(SD 993ml)。血容量下降 18%(p<0.0001)，RBCV 下降 38%(p<0.001)，PV 下降 8%(p<0.012)。在心脏外科重症监护病房，术后值与 2 小时后的值之间没有显著差异。
心脏手术患者血细胞比容的下降是由于红细胞大量丢失而不是血液稀释所致。红细胞丢失平均为 38%。血浆容量也减少了。
