Introduction
Life-threatening abdominal aortic, iliac, and femoral vascular injuries occur in both military and civilian settings.Reference Markov, DuBose and Scott 1 Trauma to the thoraco-axillary and, more commonly, the abdominal-pelvic region is often referred to as junctional trauma, which has been reported in American,Reference Eastridge, Mabry and Seguin 2 Canadian,Reference Pannell, Brisebois and Talbot 3 British,Reference Parker 4 and Israeli military personnel.Reference Katzenell, Ash and Tapia 5 Junctional trauma is a leading cause of potentially survivable battlefield death.Reference Eastridge, Mabry and Seguin 2 Deep vascular structures can be damaged by improvised explosive devices, gunshots, and vehicle collisions, and lethal exsanguination can occur within minutes. Therefore, there have been calls for more research, and for novel clinical interventions.Reference Eastridge, Mabry and Seguin 2 , Reference Kragh, Murphy and Dubick 6 , Reference Kelly, Ritenour and McLaughlin 7
Direct pressure and hemostatic dressings have saved many lives following extremity hemorrhage.Reference Kragh, Littrel and Jones 8 However, they typically cannot be used for injury above the inguinal ligament.Reference Walker, Eardley, Bonner and Clasper 9 Therefore, proprietary devices have been developed for junctional trauma.Reference Kragh, Murphy and Dubick 6 These include a novel abdominal aortic tourniquet that has been shown to reduce femoral artery flow substantially in humans.Reference Lyon, Shiver and Greenfield 10 , Reference Taylor, Coleman and Parker 11 Unfortunately, these devices are not widely available, and require time and training to apply. As such, using the rescuer's hands to temporize life-threatening hemorrhage seems intuitive.
Military medics have been instructed to press both hands above the umbilicus in order to extinguish flow below the abdominal aorta. Blavais et al also suggested compression with a single knee.Reference Blaivas, Shiver and Lyon 12 However, there is minimal evidence regarding whether this is feasible or sustainable for most rescuers. Blaivas did conduct a small (n = 9) study by placing weights on the abdomen of military volunteers, and determining when Doppler flow was extinguished. They concluded that 120 lbs of pressure was required to guarantee occlusion of internal iliac artery flow, and 140 lbs for distal abdominal aortic flow.Reference Blaivas, Shiver and Lyon 12 It is unclear whether civilian clinician rescuers (or most soldiers) can achieve this level of compression.
Manual external aortic compression (MEAC) (Figure 1) has been deployed successfully following postpartum hemorrhageReference Soltan and Sadek 13 and ruptured abdominal aortic aneurysm.Reference Kin, Hayashida and Chang 14 It also has been applied successfully to restore consciousness to a roadside victim of multiple abdominal and pelvic gunshots.Reference Acheson, Kheirabadi and Deguzman 15 However, when handed off to a smaller rescuer, this victim again started to bleed, and again became unconscious. Following successful resumption of aortic compression by the first compressor, a paramedic weighing over 200 lbs took over. This third rescuer did stop bleeding on the roadside, but could not maintain it during a ten minute ambulance transfer. Ultimately, the patient died. This report showed that while MEAC can be successful, it may not be widely achievable or maintainable. This study was undertaken to build upon Blaivas et al and to examine a possible relationship between rescuer body weight and successful abdominal compression.
Figure 1 Manual External Aortic Compressions
Methods
This participant-blinded, simulation study of deep vessel compression enrolled clinician volunteers from a large urban trauma center emergency department (ED) and a large academic university hospital intensive care unit (ICU), in Edmonton, Alberta, Canada (population 1 million). The ED has an annual census of 75,000 and the ICU has 26 beds and > 90% occupancy. Written informed consent was obtained from all participants and approval obtained from the University of Alberta's Institutional Review Board.
The simulation model consisted of a folded hospital blanket over a 250 ml bag of saline. This was placed atop a high-capacity medical scale (Seca Scales Model 874, Hamburg, Germany) and on a cement floor. Participants compressed the simulation model with their fist covered by their second hand (Figure 1), and then with their knee. They were read a script of instructions to compress the model with a force they thought they could maintain for a 20 minute transport (ie, a maintainable effort). They also were instructed to apply a maximum effort that they could exert for two minutes (ie, a maximum effort). Maneuvers were performed in alternating order, controlling for fatigue and skill acquisition. Participant weight was then determined by having them stand on the same medical scale with the simulation model removed. All participants were blinded to all results, which were recorded in the researcher's notebook. Data was entered into a Microsoft Excel spreadsheet Version 7.0.25 (Microsoft Corporation, Redmond, Washington USA) and descriptive statistical analysis was performed. These results represent preliminary findings from a larger, ongoing investigation into what variables affect manual hemorrhage control.
Results
Forty-four Doctor of Medicine and Registered Nurse participants were enrolled, and all completed the study. Twenty-seven were females (61%) with a mean weight of 143 lbs (range, 95-189 lbs). Seventeen were males (39%) with a mean weight of 174 lbs (range, 120-240 lbs). Mean weight of all participants was 156 lbs (range, 95-240 lbs).
Compression was proportional to rescuer body weight in a linear fashion and with a Pearson's correlation of 0.9311. This relationship held, regardless of whether effort was maintained or maximum. At maintainable effort (Table 1), participants compressed a mean of 86 lbs (range, 37-132 lbs). Seven of 44 (16%) compressed over 120 lbs, but none compressed over 140 lbs. At maintainable effort, the mean weight compressed by women was 77 lbs (range, 37-102 lbs) and men 101 lbs (range, 59-132 lbs). Expressed as proportion of body weight, women maintained 53% and men 57% of their body weight.
Table 1 Weight in Pounds Compressed by Participants
At maximum effort (Table 2), participants compressed a mean of 109 lbs (range, 55-157 lbs). Fifteen of 44 (34%) compressed greater than 120 lbs. Five of 44 (11%) compressed greater than 140 lbs; all five of these participants weighed over 200 lbs. At maximum effort, the mean weight compressed by women was 100 lbs, and for men it was 122 lbs. As a proportion of body weight, women compressed a mean of 68% and men a mean of 72% at maximum effort. All reported subjective fatigue within two minutes.
Table 2 Percentage of Body Weight Compressed
Participants compressed the largest percentage of body weight when they used a single knee. With this method, they compressed a mean of 80% of body weight. There was no difference between knee compressive force when asked to compress with either maintainable effort or maximum effort. When using a single knee, no participants had subjective or objective fatigue within two minutes.
Discussion
Lethal exsanguination can occur from the common femoral artery in less than two minutes. 16 As a result, temporizing measures need to be deployed immediately. A technique such as bimanual compression, which requires no equipment and minimal instruction, would minimize logistics, cost, and delays. However, this study suggests that while bimanual compression is feasible, it is difficult for the majority of rescuers to achieve, and even harder to maintain.
This research builds upon the work of Blauvais et al.Reference Blaivas, Shiver and Lyon 12 For clinician rescuers to achieve 140 lbs of compression, and maintain this for only two minutes, participants needed to weigh an average of 203 lbs. If the goal was to maintain compressive effort (eg, during transport, while awaiting device application, or while awaiting surgical rescue), then single rescuers needed to weigh an average of 255 lbs. Of note, even this may be an underestimate given that compression was performed against a hard surface. In contrast, patients often are injured on soft ground, and transported on a soft mattress (with or without a backboard).
The data suggests that compression with a single knee may be preferable to use of both hands. Using a knee, clinicians weighing only 150 lbs could compress 120 lbs, and clinicians weighing 175 lbs could compress 140 lbs. This was also the least-fatiguing method. Therefore, while external compression is intended only to temporize prior to expeditious surgical rescue (or device application), knee compression may be the optimal equipment-free technique. This may be especially true for smaller rescuers, single rescuers, and during protracted rescues.
In 2009, the Combat Casualty Care Research Program of the United States Army promoted the use of junctional, truncal, and abdominal tourniquets. They also estimated that from October 2001 through May 2010, almost 300 of their casualties could have benefitted from iliac artery or abdominal aortic compression.Reference Kragh, Murphy and Dubick 6 Regardless of the technique used, the immediate goal is to tamponade the bleeding vessel against the posterior vertebrae, and at its most distal point.Reference Pannell, Brisebois and Talbot 3 The ultimate goal is to temporize major hemorrhage, expedite operative rescue, and prevent avoidable death. Manual external aortic and/or iliac artery compression is not part of any published guidelines for penetrating or nonpenetrating trauma.Reference Campbell 17 , 18 Clearly, more research and innovation is required.
Limitations
This study has several limitations. Participants may have overestimated their maintainable effort and their maximal effort is likely minimized without clinical urgency. In addition, this model has not been validated for trauma. The research presented is translational in nature and may not apply to actual clinical settings.
Conclusion
Manual compression of deep abdominal vessels, such as the iliac arteries and abdominal aorta, is feasible. However, it requires considerable effort and rescuers of large body weight (>200 lbs). Manual external aortic and/or iliac artery compression is not part of any published guidelines for penetrating or nonpenetrating trauma. However, it can be easily taught, immediately applied, and requires no extra equipment. This study shows that this technique has limitations and may not be achievable by a majority of rescuers. In contrast, using a knee may be superior, especially for lower-weight rescuers, and during protracted rescues.
