Autotransfusion in the Austere Prehospital Setting?
Let’s start out with a scenario…
During a training mission to an extremely austere environment, one if your highly trained partner force Commandos takes a penetrating wound to the chest due to a negligent discharge by one of the new guys they are integrating into the longstanding unit. After initial treatment
and getting him back to your team house for a secondary assessment, you determine that the patient has developed difficulty breathing, decreased breathing sounds and hyporesonance to the injured side.
You glove up and insert a chest tube. Upon entrance into the pleural space, you get a gush of hemothorax blood. As it flows out onto the ground, you are able to clamp the tube. Though breathing has improved, our patient begins to show signs of compensated hemorrhagic shock. You administer TXA and start actively warming your patient. You are far from any medical support, so you do not have any cold stored blood, but you do have your walking blood bank (WBB). Due to the limited supply of lyophilized plasma being prioritized to CENTCOM, you have no FDP.
We’ll be optimistic and assume 4-5 people on your team are O low titer donors. You have 4-5 units of blood (1800-2250ml) that will take a little while to be drawn and transfused. Your evac time to his country’s nearest surgical facility is over 12 hours away by ground and you want to prepare for this long transport by ground convoy. You could possibly go back to your own pre-screened teammates for a second unit of blood (Total: 3600-4500mls), and they would happily volunteer it, but you may be burning through these units and watching them come right out of your chest tube minutes later. You can also get some blood from your partner force squad(it’s “their guy” right?), but that will take significant effort and coordination, unless you have conducted thorough screening and rehearsals previously. There is always the risk of transmissible diseases without properly screening donors.
The process is discussed, but is deemed too labor intensive with the effort and time currently required. We can also administer other substandard fluids or attempt hypotensive resuscitation and hope for a clot to form, but without the ability to ligate, shunt, or otherwise control hemorrhage in the thorax, we’re just praying at that point. A massive hemothorax can easily cost the patient 1500ml of blood initially and 200-250 ml per hour after that. For 18 hours, assuming a miracle clot does not form to save you, that is upwards of 5-6 liters. That is more than the average human total blood volume, and can easily eat through your entire walking blood bank and then some.
So, what can we do, except to try to fill a leaking bucket faster than it can empty? We can’t stop the bleed definitively. The bucket will keep leaking. We do not have a definitive solution in the austere or prolonged field care setting, but we may have something worth looking into if we are unwilling to concede our teammate’s life as expectant.
Reading the Joint Trauma System Clinical Practice Guideline (JTS CPG) on Wartime Thoracic Injury, you’ll find a small note in the middle of page 9. “Autotransfusion of shed pleural blood using a chest tube collection system and autotransfusion accessory can be considered”. It’s right at the end of the Hemothorax section and is a “blink and you’ll miss it” kind of note.
Autologous transfusion or autotransfusion is a technique in which a patient’s shed blood is collected and transfused back into the patient. The pleural space is an exceptionally clean compartment and can theoretically contain clean FWB that can be collected through a chest tube, and then transfused back into the patient. The risks of transfusion related issues are also lowered, as this is the patient’s own blood, not someone else’s. This is not a novel procedure. The first successful autotransfusion on record was conducted in 1818 by James Blundell on a patient suffering from postpartum hemorrhage. Through the end of the 1800s and into the early 1900s, surgeons utilized this technique with surprising success. Blood typing and banking improvements in the 30s and 40s made autotransfusion less popular, but advances in the washing process of blood in the late 60s brought about a resurgence. Since then, autotransfusion has been generally limited to the operating room to wash and return the patient’s blood lost during operations and to the austere setting where blood products are not readily available. The relative abundance of lab-tested blood products have undercut the interest in Western medicine for exploring autotransfusion further, but researchers have been looking into its possible role in the future of medicine.
One multi-institutional retrospective study1 looked at 272 patients (136 receiving autotransfusion, and 136 receiving traditional allogeneic transfusions) and found that “the autologous transfusion of patient’s shed blood collected through chest tubes for hemothorax was found to be safe without complications”. Furthermore, this study found no adverse effects to 24hr post admission INR and patients required fewer allogeneic RBC and platelet transfusions. When you consider the broad support in our community for prehospital administration of blood products, autotransfusion seems to be a procedure worth looking into (at least based on this particular study).
So, why aren’t we doing this already? Several reasons; spent blood, through hemothorax, has a bit of a coagulopathy problem. When bleeding starts in the thorax, the clotting cascade is activated as the body tries to form a clot. The spent blood’s supply of clotting factors gets expended relatively quickly. It has been shown to have decreased fibrinogen, hematocrit and platelet content, as well as elevated fibrin degradation products (FDP). One study2 found that hemothorax blood has longer activated partial thromboplastin times (aPTT), indicating decreased clotting capability. When this blood was mixed with the patient’s plasma samples, interestingly, the study found the mixture to be hypercoagulable. The authors of this study concluded that autotransfusion “should not be used in place of other blood products to resuscitate a trauma patient”. Though, in closing, they did concede that “autotransfusion of [hemothorax] may, however be of use in a resource limited environment where other blood products are not available.” Another study3 found that shed pleural blood from hemothorax contained elevated levels of pro-inflammatory cytokines (IL-6, IL-8, TNFα, and GM-CSF). This study recommended further randomized trials to better assess the safety of autotransfusion.
There is also the possibility of contamination of the blood with various substances. Fat emboli may be present in the collected blood, if long bones have been compromised, which are difficult to detect and are not easily filtered out. Also, if there is diaphragmatic and gastric compromise the blood may be unsafe to administer, due to contaminants. Gastric compromise is likely to be detectable, either by visual inspection of collected blood, or by physical examination of the patient, but remains a potential complication.
All this might be a moot point though. Many of these instances utilized blood-cleaning devices, which remove fat emboli, clots and other debris from blood that could potentially cause harm to our patients. No medic in his or her right mind has the space in an aid bag for a bulky piece of very expensive equipment that has only one use. How feasible would this be outside of a hospital environment?
A retrospective study4 out of India looked at 100 cases in which hemothorax and hemoperitoneum patients were autotransfused without the use of blood cleaning products. The study authors stated that “all patients had safe and unremarkable transfusions”. They used a ROMO- Abdominal Drain Kit (an Indian version of an Atrium collection bag, which is essentially a sterile bag with no anti-coagulants). They heparinized the blood collected (though stating that citrate could serve as an acceptable substitute). The autotransfusion was administered through a 40 µm micro-filter as “protection against potentially harmful micro-aggregates and non-blood component particulate matter”. They also discarded the last 100 MLs of blood as a further precaution against emboli. This study was borne out of necessity, as these facilities commonly lacked adequate allogeneic blood supply to treat these patients. This particular study lacked detail on the patient morbidity and mortality, but opens the door to the feasibility of autotransfusion in an austere setting. Theoretically, with the addition of collection bags, we could replicate this technique in an austere or prehospital environment with our existing WBB supplies.
A military case report5 detailed the treatment of an Afghan soldier by US providers at a Role I Medical Treatment Facility in Afghanistan. They diagnosed severe hemothorax and autotransfused 1400mls of the patients spent pleural blood before evacuating to a Role III facility where he received emergency surgery. He was transferred to Afghan care after 5 days, but no long term details were discussed. In this case they utilized a Pleur-evac ATS system to collect and autotransfuse. Looking at this particular device, essentially, it consists of a water seal and a collection bag. This system could be streamlined for packing in an aid bag or, at the very least, set up in an aid station. SOF Medics are proficient in chest tubes and blood administration. The only skill needed to perform this procedure, that we do not already currently have, is transferring the blood from the collection system to the transfusion bag, which does not seem like a significant hurdle.
The International Committee of the Red Cross (ICRC) recommends the use of autotransfusion for patients who have lost roughly 1000mls of blood or more when supply of alternate blood products is limited. In the ICRC War Surgery Volume 2 (Chapter 34), they outline very clearly the potential risks and complications, but also state that, “autotransfusion has proven safe and effective. It causes only transient haematological abnormalities that disappear within 72 hours post-operatively. Furthermore, autotransfusion is not associated with increased mortality, or haematological, cardiopulmonary, and renal complications above what is considered normal for these severely injured patients”.
There is a solid precedent for the use of autotransfusion in the austere and resource limited environment. The ability to conjure up several units of blood for a hemodynamically unstable patient seems to be a capability that is too good to overlook dismissively. There are some definite drawbacks to autotransfusion. Coagulopathy can be an issue with shed pleural blood from hemothorax and various pro-inflammatory cytokines can definitely complicate a critical patient in an austere environment. These complications seem to be transient in nature, and have not been shown to have an adverse effect on patient outcomes. The possibility of contamination remains an ever-present risk in battlefield medicine, and this procedure would require strict aseptic execution. With a 200-year track record and the amount of study done so far, autotransfusion seems like a viable resuscitative strategy, but as with anything in medicine, more research can always be done to improve practice.
As medical practitioners in the austere and prolonged field care setting, we should be asking ourselves some questions:
-Are we, as medics, capable of performing this skill, not only aseptically, but also responsibly in the PFC or austere setting?
-Is the addition of oxygen carrying capacity through salvaged blood worth the potential drawbacks of coagulopathy?
-How many units of shed blood could potentially be autotransfused without adversely affecting coagulability?
-Could we figure out a ratio of shed blood to allogeneic blood that would enhance resuscitative efforts, while mitigating coagulopathic complications?
-Can the addition of this capability to our existing blood protocols save lives by increasing the medic’s organic blood supply and extending the time a medic can support a critical casualty before MEDEVAC arrives?
-Does autotransfusion deserve further consideration for a place in our Prolonged Field Care capabilities?
References
- Rhee P, Inaba K, Pandit V, et al. Early autologous fresh whole blood transfusion leads to less allogeneic transfusions and is safe. J Trauma Acute Care Surg. 2015;78(4):729-734. doi:10.1097/TA.0000000000000599 https://pubmed.ncbi.nlm.nih.gov/25807402/
- Harrison HB, Smith WZ, Salhanick MA, et al. An experimental model of hemothorax autotransfusion: impact on coagulation. Am J Surg. 2014;208(6):1078-1082. doi:10.1016/j.amjsurg.2014.09.012 https://pubmed.ncbi.nlm.nih.gov/25440491/
- Salhanick MA, Sams VG, Pidcoke HF, et al. Shed Pleural Blood from Traumatic Hemothorax Contains Elevated Levels of Pro-Inflammatory Cytokines. Shock. 2016;46(2):144-148. doi:10.1097/SHK.0000000000000609 https://pubmed.ncbi.nlm.nih.gov/26974427/
- Kothari R, Pandey N, Sharma D. A simple device for whole blood autotransfusion in cases of hemoperitoneum and hemothorax. Asian J Surg. 2019;42(4):586-587. doi:10.1016/j.asjsur.2019.01.018 https://pubmed.ncbi.nlm.nih.gov/30803766/
- Hulsebos H, Bernard J. Consider Autotransfusion in the Field. Mil Med. 2016;181(8):e945-e947. doi:10.7205/MILMED-D-15-00046 https://pubmed.ncbi.nlm.nih.gov/27483539/
- C. Giannou, M. Baldan, A. Molde. Chapter 34 Autotransfusion. War Surgery: Working with Limited Resources in Armed Conflict and other Situations of Violence Volume 2. Geneva, Switzerland, International Committee of the Red Cross. 11 JUNE 2020. https://www.icrc.org/en/doc/assets/files/publications/icrc-002-4105.pdf
If I drain the pleural blood from the chest tube into a blood collection bag, wouldn’t the citrate help dissipate some of the clotted blood? I’ve seen blood clot leaving a collection bag; that’s why we use filtered tubing. I know citrate will not unclothed clotted blood, but I wonder if it helps a little.
A lot of what I read said that spent blood in the thorax doesn’t clot much on its own, as much of the clotting cascade is spent, but most of the time they added heparin or citrate to prevent clotting in the collection or transfusion bag and delivered it through filtered line, just to be safe.
Are we, as medics, capable of performing this skill, not only aseptically, but also responsibly in the PFC or austere setting?
Absolutely. 18Ds, as you stated, are already trained in transfusion and chest tubes. The additional skill of transferring blood from collection to transfusion is minor in comparison. Also, learning to use whatever collection kit is ordered is also minor. We are talking about a potential life-saving intervention that will save us time and precious blood that will only require, what, a block of training on the equipment at home station?
68Ws, on the other hand, don’t have the standardized training. Some know how to perform transfusions and some know how to perform chest tubes, though most do not. However, that is not to say that they CANT learn. The massive push for conventional Army to learn PFC skills is well underway. They will eventually all learn transfusions and cheat tubes. What is one additional skill? Essentially, if you are capable of performing a tlcheay tube Nd a transfusion, you can learn this.
-Is the addition of oxygen carrying capacity through salvaged blood worth the potential drawbacks of coagulopathy?
This is a little more complicated and takes into account not METT-TC, but also available CL VIII, medic knowledge and skill set, and allowed scope of practice. It should, at a minimum, be available as an option for one to consider. Much like in the scenario that you started off with, it should be an available option that each critical thinking and autonomous medic is able to consider.
-How many units of shed blood could potentially be autotransfused without adversely affecting coagulability?
I’m not going to pretend that I’m smart enough to answer this. I’m sure this will have to undergo much further study and possibly have this inclusion in a future CPG. Until then, it is safe to say that each unit level provider can determine this level once they approve/allow their medics to practice this skill. This will also be determined by thenavailabke monitoring equipment on hand, which varies greatly by unit.
-Does autotransfusion deserve further consideration for a place in our Prolonged Field Care capabilities?
Absolutely. However, much more studying and testing is needed. It’s a simple enough procedure, with a 200 year history, that requires very little additional equipment.