Small-Volume Blood Collection Tubes to Reduce Anemia and Transfusion in Intensive Care Unit Patients

Abstract

Blood sampling causes significant blood loss in intensive care unit (ICU) patients (up to 41 mL per day). Only 10% of the blood collected is used for testing suggesting that volumes can be reduced without compromising patient care or laboratory processes. Blood loss contributes to anemia which is highly prevalent in the ICU (>90% after 3 days) and is associated with major adverse cardiovascular outcomes and death. Diagnostic blood loss increases the likelihood of red blood cell (RBC) transfusion which is administered to about 40% of ICU patients (half are given in absence of hemorrhage) and has significant health risks. Small-volume blood collection tubes, which collect about 50% less blood, are available, but rarely used in adults. They have the same cost as standard-volume tubes and are compatible with laboratory equipment. The rationale for the continued use of standard-volume tubes is a theoretical concern about inadequate volume for testing, and the absence of data showing the benefit of small-volume tube use on an important clinical outcome. A study is needed to show that small-volume tubes reduce blood loss, anemia and RBC transfusion without harms or negative consequences on patient care and hospital procedures compared to standard-volume tubes. If this could be shown, it may lead to practice change regarding blood collection for laboratory testing. A stepped-wedge cluster randomized trial is the ideal study design for this low-risk intervention. By incorporating the small-volume tubes into routine clinical practice and using administrative and hospital electronic medical record data, this study would be a pragmatic, cost-effective way to evaluate effectiveness and implementation. However, prior to conducting a full-scale trial powered on clinical outcomes, a pilot study is needed to determine whether a larger study will be feasible. The goals of this thesis are to (i) summarize the existing evidence regarding small-volume tubes; (ii) discuss cluster randomized trial methodology;(iii) discuss the use of health care administrative data for research; (iv) discuss the role of pilot studies; and (v) present the design of a pilot stepped wedge randomized trial of small-volume versus standard-volume blood collection tubes to evaluate the feasibility of a full-scale trial.