Clot Formation in a Blood-Collection Bag Used for Acute Normovolemic Hemodilution

Abstract

Acute normovolemic hemodilution is a popular method of blood conservation in eligible patients undergoing cardiac surgery at our facility. Standard Teruflex blood-collection bags (Terumo Corporation, Tokyo, Japan) containing 63 mL of citrate-phosphate-dextrose anticoagulant are attached to the side-port of a large-bore central catheter; blood-collection bags are placed on the ground using gravity to drive the whole blood into the bag. During blood collection, in order to ensure adequate mixture of blood and anticoagulant, the anesthesiologist manually kneads the blood-collection bag. Once the blood bag is full, it is labeled and stored in the operating room at room temperature. This whole-blood product is typically transfused back to the patient after termination of cardiopulmonary bypass on completion of protamine administration. Recently, we encountered a case of inadequate admixture of blood and anticoagulant in a collected unit of whole blood. The patient was a 75-year-old man undergoing coronary artery bypass graft surgery in whom 2 U of whole blood were sequestered before surgical incision. The blood-collection process proceeded smoothly in that each unit of whole blood was collected over 5 to 10 minutes with frequent manual kneading of the bag. The surgery also proceeded uneventfully, and, after protamine administration, whole blood was reinfused via a 210-μm filter Y-type blood administration set (Arrow International, Reading, PA) and Hotline fluid warmer (Smiths-Medical, Dublin, OH). However, on completion of the reinfusion of the second unit of autologous whole blood, the blood bag was noted to contain visible clumps of blood clot (Fig. 1). This finding prompted our blood bank to examine our procedures for blood agitation and mixing during autologous blood collection. The American Association of Blood Banks' technical manual recommends that blood be collected rapidly, with a target collection time of 4 to 10 minutes per 450-mL bag, not exceeding 15 minutes; “there should be frequent, gentle mixing of the blood with the anticoagulant.”1Brecher M.E. Collection, preparation, storage, and distribution of components from whole blood donations.in: Technical Manual. ed 15. American Association of Blood Banking, Bethesda, MD2005: 175-202Google Scholar The blood bag manufacturer recommends that the bag be manually agitated every 45 seconds during the collection process. Although automated mixers or agitators obviate the need to manually attend to the blood-collection bag during mixing, they are expensive and not available in every facility. Furthermore, Follea et al2Follea G. Bigey F. Jacob D. et al.Comparative validation of manual and automated methods for mixing and volume control of total blood samples.Transfus Clin Biol. 1997; 4: 391-402Crossref PubMed Scopus (4) Google Scholar found no advantage of automated mixers over manual agitation, citing several practical difficulties associated with automated devices. De Korte et al3De Korte D. Veldman H.A. Automated blood-mixing devices still fail to mix at low bleeding rates.Vox Sang. 2001; 80: 34-39Crossref PubMed Scopus (4) Google Scholar compared manual mixing to automated mixing devices, reporting that automated devices may still fail to mix blood and anticoagulant at low blood collection rates. In addition, during blood collection, if the blood-collection bag folds on itself, a pocket of inadequate mixing may be created within the blood bag (Fig 2). This might occur if the blood bag is maintained in an upright position or if the bag inadvertently comes to rest against the wheel base of the anesthesia machine or other equipment. Subsequently, our vigilant efforts have increased, particularly in ensuring that blood flow during collection is unimpeded and that blood-collection bags are intermittently agitated during and after collection. Although the patient described earlier exhibited no untoward sequelae and recovered uneventfully from the surgery, macroscopic clot formation in a blood-collection bag could adversely affect the quality of the whole-blood product or obstruct the blood-administration set components.