Letter to the Editors
In-Flight Risk of Venous Thromboembolism and Use of Tranexamic Acid in Trauma Patients Dear Editors: We read with interest the case series presentation by Vu et al1 describing the integration of tranexamic acid (TXA) into an out-of-hospital air medical evacuation program in the setting of major trauma with confirmed or suspected hemorrhagic shock. Over a 4-month period, a total of 13 trauma patients received TXA during their air medical evacuations. All patients received an initial dose of 1 g TXA over 10 minutes. The average time to TXA administration was 32 minutes (95% confidence interval, 25.76-39.99). No complications with the administration of TXA were reported in any patient. First, TXA has been shown to be an important part of the hospital-based provider’s armamentarium for the treatment of traumatic hemorrhage, especially when its administration was early (ideally ⬍ 1 hour from the time of injury). TXA has also been evaluated in the military field hospital setting (the Military Application of Tranexamic Acid in Trauma Emergency Resuscitation study) with good outcomes.2 We totally agree with the authors concerning the fact that there was sufficient evidence for the introduction of TXA into the prehospital arena as an adjunct in combating the effects of major blood losss before arrival to definitive care. We also agree concerning the feasibility of such a potentially lifesaving protocol and the earliest possible administration after the time of injury, which underscored the value of having this adjunct available in the prehospital setting. As part of our comprehensive effort to improve casualty care and eliminate preventable death, the French military health service approved TXA for prehospital use in the management of bleeding after major trauma in 2011. Second, the authors discussed the integration of TXA during primary and secondary air medical evacuations and explained the limitations of their case series presentation. However, nothing or little is known about the air medical evacuation time, in particular for the secondary medical evacuation, the rate of hemorrhagic shocks and massive transfusions over the study period, and the description of anatomic injuries. They could not report if the patients have had any idiosyncratic drug reaction or other complications (eg, venous thromboembolism [VTE]) during their hospital stay; therefore, this study focused only on inflight complications after the administration of TXA. However, an early outcome cannot be viewed in isolation when considering VTE in trauma patients. Indeed, trauma patients are at high risk of VTE, especially because of the trauma itself (in particular, lower-limb injuries), immobilization, surgery, and air medical evacuations. There is an estimated 1- to 9-fold increased VTE risk associated with air travel, which increased to 3- to 9fold with air travel of ⬎ 8 hours.3 VTE can occur later. 48
MacCallum et al4 confirmed the strength of the association of long-haul travel with VTE in the subsequent 4 weeks and showed that the risk associated with air travel is not confined only to single long flights but also to the cumulative flying time. The Military Application of Tranexamic Acid in Trauma Emergency Resuscitation study, a retrospective, observational study at a surgical field hospital (role 3), examined the use of TXA in combat victims who received at least 1 unit of packed red blood cells.2 TXA was administered within 24 hours of admission. The authors found that TXA improved survival, especially among massively transfused casualties. They also found an increased rate of VTE in casualties treated with TXA, although there were no fatalities attributed to these events. In the absence of more information on the time of flights, the massive transfusion, and the rate of VTE during their hospital stay, we do not totally agree with Vu et al when they specified that TXA “can safely. . . be incorporated into an air medical evacuation program.” To conclude, we believe that the harm-benefit balance of TXA is favorable in severe bleeding after major trauma and should be administered as soon as possible in the prehospital setting, ideally ⬍ 1 hour from the time of injury. However, when bleeding is not life threatening, especially when an air medical evacuation is planned, the thrombotic risk is too poorly documented to justify exposing patients to a plausible risk. Strict compliance with an established administration protocol is essential, pending further studies focused on the use of TXA during air medical evacuations and thrombosis in trauma patients.
References 1. Vu EN, Schlamp RS, Wand RT, Kleine-Deters GA, Vu MP, Tallon JM. Prehospital use of tranexamic acid for hemorrhagic shock in primary and secondary air medical evacuation. Air Med J. 2013;32:289-292. 2. Morrison JJ, Dubose JJ, Rasmussen TE, Midwinter MJ. Military Application of Tranexamic Acid in Trauma Emergency Resuscitation (MATTERs) Study. Arch Surg. 2012;147:113-119. 3. Kuipers S, Schreijer AJM, Cannegieter SC, Buller HR, Rosendaal FR, Middledorp S. Travel and venous thrombosis: a systematic review. J Intern Med. 2007;262:615-634. 4. MacCallum PK, Ashby D, Hennessy EM, et al. Cumulative flying time and risk of venous thromboembolism. Br J Haematol. 2011;155:613-619.
Clément Hoffmann, MD, Elisabeth Falzone, MD, Alexis Donat, MD, Thomas Leclerc, MD, and Nicolas Donat, MD, Percy Military Teaching Hospital, Clamart, France, Jean-Pierre Tourtier, MD, PhD, Emergency Department, Fire Brigade of Paris 1067-991X/$36.00 Copyright 2014 by Air Medical Journal Associates http://dx.doi.org/:10.1016/j.amj.2013.11.004 Air Medical Journal 33:2
In-Flight Risk of Venous Thromboembolism and Use of Tranexamic Acid in Trauma Patients Dear Editors: We read with interest the case series presentation by Vu et al1 describing the integration of tranexamic acid (TXA) into an out-of-hospital air medical evacuation program in the setting of major trauma with confirmed or suspected hemorrhagic shock. Over a 4-month period, a total of 13 trauma patients received TXA during their air medical evacuations. All patients received an initial dose of 1 g TXA over 10 minutes. The average time to TXA administration was 32 minutes (95% confidence interval, 25.76-39.99). No complications with the administration of TXA were reported in any patient. First, TXA has been shown to be an important part of the hospital-based provider’s armamentarium for the treatment of traumatic hemorrhage, especially when its administration was early (ideally ⬍ 1 hour from the time of injury). TXA has also been evaluated in the military field hospital setting (the Military Application of Tranexamic Acid in Trauma Emergency Resuscitation study) with good outcomes.2 We totally agree with the authors concerning the fact that there was sufficient evidence for the introduction of TXA into the prehospital arena as an adjunct in combating the effects of major blood losss before arrival to definitive care. We also agree concerning the feasibility of such a potentially lifesaving protocol and the earliest possible administration after the time of injury, which underscored the value of having this adjunct available in the prehospital setting. As part of our comprehensive effort to improve casualty care and eliminate preventable death, the French military health service approved TXA for prehospital use in the management of bleeding after major trauma in 2011. Second, the authors discussed the integration of TXA during primary and secondary air medical evacuations and explained the limitations of their case series presentation. However, nothing or little is known about the air medical evacuation time, in particular for the secondary medical evacuation, the rate of hemorrhagic shocks and massive transfusions over the study period, and the description of anatomic injuries. They could not report if the patients have had any idiosyncratic drug reaction or other complications (eg, venous thromboembolism [VTE]) during their hospital stay; therefore, this study focused only on inflight complications after the administration of TXA. However, an early outcome cannot be viewed in isolation when considering VTE in trauma patients. Indeed, trauma patients are at high risk of VTE, especially because of the trauma itself (in particular, lower-limb injuries), immobilization, surgery, and air medical evacuations. There is an estimated 1- to 9-fold increased VTE risk associated with air travel, which increased to 3- to 9fold with air travel of ⬎ 8 hours.3 VTE can occur later. 48
MacCallum et al4 confirmed the strength of the association of long-haul travel with VTE in the subsequent 4 weeks and showed that the risk associated with air travel is not confined only to single long flights but also to the cumulative flying time. The Military Application of Tranexamic Acid in Trauma Emergency Resuscitation study, a retrospective, observational study at a surgical field hospital (role 3), examined the use of TXA in combat victims who received at least 1 unit of packed red blood cells.2 TXA was administered within 24 hours of admission. The authors found that TXA improved survival, especially among massively transfused casualties. They also found an increased rate of VTE in casualties treated with TXA, although there were no fatalities attributed to these events. In the absence of more information on the time of flights, the massive transfusion, and the rate of VTE during their hospital stay, we do not totally agree with Vu et al when they specified that TXA “can safely. . . be incorporated into an air medical evacuation program.” To conclude, we believe that the harm-benefit balance of TXA is favorable in severe bleeding after major trauma and should be administered as soon as possible in the prehospital setting, ideally ⬍ 1 hour from the time of injury. However, when bleeding is not life threatening, especially when an air medical evacuation is planned, the thrombotic risk is too poorly documented to justify exposing patients to a plausible risk. Strict compliance with an established administration protocol is essential, pending further studies focused on the use of TXA during air medical evacuations and thrombosis in trauma patients.
References 1. Vu EN, Schlamp RS, Wand RT, Kleine-Deters GA, Vu MP, Tallon JM. Prehospital use of tranexamic acid for hemorrhagic shock in primary and secondary air medical evacuation. Air Med J. 2013;32:289-292. 2. Morrison JJ, Dubose JJ, Rasmussen TE, Midwinter MJ. Military Application of Tranexamic Acid in Trauma Emergency Resuscitation (MATTERs) Study. Arch Surg. 2012;147:113-119. 3. Kuipers S, Schreijer AJM, Cannegieter SC, Buller HR, Rosendaal FR, Middledorp S. Travel and venous thrombosis: a systematic review. J Intern Med. 2007;262:615-634. 4. MacCallum PK, Ashby D, Hennessy EM, et al. Cumulative flying time and risk of venous thromboembolism. Br J Haematol. 2011;155:613-619.
Clément Hoffmann, MD, Elisabeth Falzone, MD, Alexis Donat, MD, Thomas Leclerc, MD, and Nicolas Donat, MD, Percy Military Teaching Hospital, Clamart, France, Jean-Pierre Tourtier, MD, PhD, Emergency Department, Fire Brigade of Paris 1067-991X/$36.00 Copyright 2014 by Air Medical Journal Associates http://dx.doi.org/:10.1016/j.amj.2013.11.004 Air Medical Journal 33:2
