Clinical question: What are the frequency of laboratory testing, the average total blood volume drawn per patient, and the resulting transfusion utilization in patients undergoing cardiac surgery?
Background: Healthcare providers seldom recognize the amount of phlebotomy, and, therefore, its consequences and possible solutions have not been fully evaluated.
Study design: Retrospective, cohort study.
Setting: Major U.S. academic medical center.
Synopsis: The authors examined 1,894 patients undergoing cardiac surgery over a six-month period. They determined the number and type of lab tests drawn on each patient during hospitalization, as well as the estimated total blood volume drawn on each patient.
Patients averaged 115 lab tests during their hospitalization and had cumulative median phlebotomy volume of 454 ml (equivalent to one to two units of red blood cells). They also found that increasing total phlebotomy volume correlated with increased blood product use and that increasing length of stay correlated with higher levels of both.
During an average patient day in the ICU, of the average 116 ml of blood drawn, 80 ml was discarded at the bedside.
Limitations include the broad applicability of this study, which focused on cardiac surgery patients, all of whom stayed in an ICU and had central lines as the source of the majority of their blood draws. Appropriateness of lab testing and transfusions were not examined in this study.
Bottom line: Blood volumes equivalent to one to two units of red blood cells are drawn for lab tests on patients undergoing cardiac surgery, with a large portion of that blood being wasted at the bedside. Initiatives to reduce blood draw volume may help to reduce resource utilization related to such high rates of blood loss from phlebotomy.
Citation: Koch CG, Reinecks EZ, Tang AS, et al. Contemporary bloodletting in cardiac surgical care. Ann Thorac Surg. 2015;99(3):779-784.
