As I do trauma, I’m intrigued by the fact that, I autotransfuse shed blood collected from a chest tube but not from other sources of bleeding. That brings up some interesting questions. For example (there are probably more):
- How did autotransfuison of shed chest tube blood come about?
- Why doesn’t shed chest tube blood clot?
- Is autotransfusion of shed chest tube blood equivalent to giving fresh whole blood?
- How long is shed blood good for?
- Should we be concerned about autotransfusing microclots that might contribute to TRALI (transufsion related acute lung injury)?
- Why don’t we autotransfuse shed abdominal blood from liver or splenic lacerations if there is no intestinal injury?
- What are the recommendations for autotransfusing shed blood?
This article provides some insight into the historical aspects of autotransfusing shed chest tube blood.
Autotransfusion dates back to 1818 when Blundell used it to treat postpartum hemorrhage. The autotransfusion of hemothorax blood was first used during WWI in life threatening traumatic hemothorax injuries. The cardinal features of the system are that it is “simple, safe, and easy” to employ. As recently as 1988, Barriot, et al, described a pre-hospital collection device that includes a 750 collection bag, a 120 um micropore filter that filters the shed blood before it enters the bag, and a 50 um micropore filter that filters the blood again before it leaves the bag. This is similar to currently available collection devices.
This more recent article answers many of the remaining questions.
The shed blood probably does not clot because ﬁbrin is formed and either lysed in the process of drainage or lysed in vivo before drainage. It is important to understand that this defibrination takes time. If the shedding of blood is very rapid then an anticoagulant may need to be added to prevent the blood from clotting (see Atrium® chart below).
Shed pleural blood is not the same as fresh whole blood:
Additionally, pleural blood is extremely deficient in coagulation factors and contains the products of fibrinogen degradation. Hemothorax blood may be useful for acute resuscitation but requires concomitant factor replacement.
The electrolyte profile of shed pleural blood vs. venous blood is shown here.
The authors of the above study conclude that hemothorax blood cannot substitute for whole blood, cryoprecipitate, or fresh frozen plasma. There is, in some cases, residual factor VIII; however, the aPTT and INR show that other remaining coagulation factors are either markedly reduced or inhibited in their current form. Although platelets are present in the hemothorax blood, their numbers are not sufficient for restoration of the platelet count, and the function of these platelets is not known. In no way can hemothorax be considered a resource for coagulation factors sufficient to resuscitate the patient.
However, 726 mL of hemothorax provides the equivalent of 1 U of RBC. While this will decrease and minimize the risks of autologous blood transfusions, it underscores that a large volume of hemothorax blood is needed to provide only a single unit of RBC.
This is a chart from the Atrium® Auto Transfusion System guide book that shows the difference between banked and autotranfusion blood…
This chart suggests that the clotting factors of shed blood are near normal, which unfortunately is probably not the case. It is probably reasonable to predict that there is nothing in shed blood that is likely to cause the equivalent of the “storage lesion” found in banked blood. Thus the higher 2-3 DPG levels, the presence of some platelets, and the pH of 7.4 of shed blood should be beneficial.
Shed hemothorax blood is only good for 6 hours.
Transfusion of microemboli and clots are a concern with shed blood autotransfusion.
For the Atrium® ATS, the manufacturer says, “For any procedure requiring reinfusion of unwashed shed blood, a microemboli blood filter suitable for autotransfusion must be used. A standard 40 micron blood filter traps clumped cells, debris, and coagulated protein. A new microemboli filter must be used for each new ATS bag.”
The writer is unaware of any system for autotransfusion of abdominal shed blood. However, there is no logical reason why this couldn’t be done. In fact the first reported autotransfusion was that of postpartum hemorrhage blood. The principles should be the same.
The most unfortunate aspect of autotransfusion is the loss of clotting factors and platelets.
Regarding recommendations and guidelines, The Society for Thoracic Surgery and Society for Cardiothoracic Anesthesiology’s (2007) practice guidelines concluded that “Because of the risks associated with autotransfusion of shed blood and the lack of clear cut benefit, direct reinfusion of shed blood cannot be recommended for routine blood conservation (in cardiac surgery).” The full text of the section on shed blood reinfusion says,
Direct reinfusion of shed mediastinal blood from postoperative chest tube drainage is not recommended as a means of blood conservation and may cause harm.
(Level of evidence B)
Studies using postoperative reinfusion of shed mediastinal blood to limit blood transfusion ﬁrst appeared in the early 1970s. Since then, 17 reports provided conﬂicting results about the beneﬁt of this intervention . Nine of these 17 studies suggest that postoperative shed blood reinfusion limits blood transfusion and the rest do not. These studies are heterogeneous as some compared washed (cell saved) versus nonwashed (cardiotomy reservoir) postoperative shed mediastinal blood reinfusion while others compared either of these techniques to simply discarding shed mediastinal blood. In addition, mediastinal blood contains ﬁbrinolytics, inﬂammatory cytokines, complement, endotoxin, tissue factor, and free hemoglobin. Infusion of shed mediastinal blood results in activation of the extrinsic coagulation pathway, although washing of mediastinal blood may reduce these abnormalities. Furthermore, mediastinal blood contains lipid particles and thromboemboli that are incompletely removed by existing blood ﬁlters, and these impurities are postulated to contribute to neurologic dysfunction after cardiac surgery. Use of a cell-saving device to wash shed mediastinal blood results in a signiﬁcant decrease in lipid emboli and in inﬂammatory cytokines in the reinfused blood compared with blood obtained directly using a cardiotomy reservoir. Importantly, two studies suggest that postoperative unwashed shed blood reinfusion is associated with increased sternal or systemic infections. Because of the risks associated with this technique and the lack of clear cut beneﬁt, direct reinfusion of shed blood can not be recommended for routine blood conservation; whereas, postoperative reinfusion of washed shed mediastinal blood may be helpful as part of a multimodality blood conservation program.
There are apparently no guidelines on the use of shed hemothorax blood in life threatening trauma.