Article Text
Abstract
Background In a care under fire situation, a first line response to haemorrhage is to apply a tourniquet and return fire. However, there is little understanding of how tourniquets and other haemorrhage control devices impact marksmanship.
Methods We compared the impact of the iTClamp and the Combat Application Tourniquet (CAT) on marksmanship. Following randomisation (iTClamp or CAT), trained marksmen fired an AR15 at a scaled silhouette target in prone unsupported position (shooting task). Subjects then attempted to complete the shooting task at 5, 10, 15, 30 and 60 min post-haemorrhage control device application.
Results All of the clamp groups (n=7) completed the 60 min shooting task. Five CAT groups (n=6) completed the 5 min shooting task and one completed the 5 and 10 min shooting task before withdrawing. Four CAT groups were stopped due to unsafe handling; two stopped due to pain. When examining hits on mass (HOM) for the entire shooting task, there was no significant difference between tourniquet and iTClamp HOM at 5 min (p=0.18). However, there was a significant difference at 10 min, p=0.003 with tourniquet having significantly fewer HOM (1.7±2.7 HOM) than the iTClamp (8.1±3.3 HOM) group. The total effective HOM for the entire 60 min shooting task showed that the iTClamp group achieved significantly (p=0.001) more HOM than the tourniquet group. Over the entire 60 min shooting exercise, the iTClamp group achieved a median 72% (52/72) of available HOM while the tourniquet group obtained 19% (14/72).
Conclusions Application of a tourniquet to the dominant arm negates effective return of fire in a care under fire setting after a brief time window. Haemorrhage control devices that preserve function may have a role in care under fire situations, as preserving effectiveness in returning fire has obvious operational merits.
- ACCIDENT & EMERGENCY MEDICINE
- PAIN MANAGEMENT
- Marksmanship
- Military Medicine
- Hemorrhage Control
- EXTREMITY INJURY
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- ACCIDENT & EMERGENCY MEDICINE
- PAIN MANAGEMENT
- Marksmanship
- Military Medicine
- Hemorrhage Control
- EXTREMITY INJURY
Key messages
The literature clearly documents that tourniquets save lives that were previously being lost from severe extremity haemorrhage.
In a limb with residual functional capacity, the effective application of a tourniquet will be rapidly (<10 min) and completely incapacitating to that limb.
Randomised comparison between a wound clamp and tourniquets revealed highly significant functional abilities for marksmen to return effective fire with the wound clamp in place.
Actual wounds and haemorrhage were not induced in this study and haemorrhage control effectiveness was not the focus of this marksmanship evaluation.
For less devastating (non-amputation) peripheral wounds, other haemorrhage control devices such as the iTClamp may have operational merit especially in care under fire situations.
Introduction
Bleeding to death continues to be the most common cause of potentially preventable post-traumatic death.1 Thus, in combat-care situations, the practical mnemonic to guide hands-on resuscitation has been C-circulation, A-airway and B-breathing, with the understanding that efforts to prevent bleeding to death will have the greatest overall benefit.2 This mnemonic has resulted in a reduced soldier mortality in the recent experiences in the Near East than in any other conflict. A re-emphasised use of tourniquets to avoid extremity exsanguination is an example of a notable success of this doctrine.3 The safety and effectiveness of tourniquet use is well documented in the literature especially when applied in the prehospital setting, before the onset of shock and even for extended periods of time.3–7 Limb exsanguination mortality dropped from 9% in the Vietnam War to 2% in the current wars due to the implementation of tourniquet use in battle, with the Israeli Defense Force reporting 0% life loss to limb exsanguination.8 A review of Tactical Combat Casualty Care at the Canadian Role III experience in Kandahar, Afghanistan also concluded that tourniquets save lives,9 a finding confirmed in Canadian civilian practice.5
However, the application of a tourniquet is not a benign intervention, as it has been associated with nerve palsies,10 limb ischaemia11 and iatrogenic amputations.12 Furthermore, the individual applying the device must be well trained in order for the tourniquet to be effective.2 ,8 Tourniquets applied in field conditions have been reported to be ineffective, with 83% of patients that had a tourniquet placed in the field still having a distal pulse and only 35% of patients presented with an effective arterial tourniquet in one report.13 The physical tourniquets themselves are also not without their reported issues as recent studies have noted that tourniquets exposed to combat environments have decreased efficacy and increased breakage.14 Finally, tourniquets remove any remaining function of the injured limb, a concern with increasing importance when the casualty is still under fire.
Tactical Medicine (TM) describes the provision of healthcare in unconventional settings and adverse environments, such as the ‘pointy end’ of combat, peacekeeping, law enforcement and hostage-rescue missions. TM is typically embedded within the fabric of such operations, which require a strict focus on task completion.15 In many, if not most, of these activities, there can be no separation of medicine from the mission, meaning no evacuations, minimal if no distraction from the mission and little if any care can be provided by others to a casualty. Realistically, if a small unit is outgunned, all members will eventually be killed and any medical care provided previously to any member becomes irrelevant. Current doctrine for penetrating extremity wounds thus emphasises tourniquet application, often with the casualty self-administration.2 ,3 ,16 ,17 However, while effective if properly applied, tourniquets completely immobilise the limb to which it is applied, and are painful. Tourniquet application presumably drastically degrades a potential combatant's ability to participate in further effective combat operations. These findings suggest that outside of traumatic amputation (which mandates tourniquet application) other lifesaving options should be examined.
Such an alternative extremity haemorrhage control device may be the iTClamp (Innovative Trauma Care, Edmonton, Alberta, Canada) which is designed to rapidly seal the skin overlying a bleeding wound, thus creating an internal haematoma and haemostatic clot formation.18 Preclinical studies have demonstrated the safety and effectiveness of the iTClamp to control bleeding.19 Surprisingly, however, the impact of care under fire medical aid such as tourniquet application has yet to be examined. As there has been no formal study of the retained marksmanship capabilities after haemorrhage control device application, we sought to carry out a randomised controlled study of this critical capability between shooters randomised to application of either device.
Methods
Study design
The study was ethically approved by the Chesapeake IRB (Pro00011305). The study design was a non-blinded randomised controlled trial of the application of either an iTClamp (Innovative Trauma Care, San Antonio, Texas, USA) or a Combat Application Tourniquet (CAT) (Composite Resources, Rock Hill, South Carolina, USA), on marksmanship and ability to complete a standardised shooting assignment. The study was unblinded to the participants, but analysed by a data analyst blinded to the group allocation. Trained marksmen were defined as an individual that had previous police or military training in marksmanship and had prior experience with an AR15 rifle. These trained marksmen were randomised to shoot with either the iTClamp or CAT applied to their dominant arm. The CAT was placed as high up on the arm as it could go and was tightened until the distal radial pulse was no longer palpable. The iTClamp was placed 6 inches (15 cm) below the shoulder on the outside of the arm—the distal pulse remains intact with the iTClamp (Figures 1 and 2). Block randomisation was used to ensure that a similar number of marksmen would end up in both groups. The study coordinator enrolled the participants after a health screening questionnaire and used a random number generator to assign the group (http://www.random.org). Marksmen with any vascular concerns would have been excluded from the study, but no exclusions were necessary.
A total of 12 (0.556×55 g) rounds were fired, during each shooting task, using an AR15 in the prone unsupported position. During the shooting task, each marksman fired four rounds in serial at a 50, 100 and 150 m scaled silhouette target in 2 min. Subsequent to a control shoot (no device on), subjects then attempted to complete the shooting task at 5, 10, 15, 30 and 60 min posthaemorrhage control device application. All range activities were under complete control of a Range Safety Officer (RSO). Subject participation in the study ended if the RSO felt that the participant was no longer handling their weapon safely, if the subject reported a pain level ≥8 on the Likert scale or if the subject withdrew themselves. This study was completed at the certified gun range in Alberta, Canada.
Measurements
After the completion of each shooting task pain, grip strength, hits on mass (HOM), accuracy and precision were all recorded. Pain was recorded on a 0–10 Likert scale: 0 being no pain and 10 the worst pain they ever experienced. Grip strength was recorded to one decimal place in kilograms for the dominant and non-dominant hand. Three measurements were taken on each hand using a Camry Electronic Hand Dynamometer (Model EH101, Zhongshan Camry Electronics Co., Zhongshan, Guangdong, China), and the mean measurement for each hand was used in calculations. Accuracy was taken as the mean of three measurements of the shot group size for each of the 50, 100 and 150 m targets. A Mastercraft series digital calliper (Model 58-6800-4, Mastercraft Tools, Sunninghill Johannesburg, Africa) was used to record shot group size by measuring the distance between the two furthest shots (mm), for each shot group, on each target (50, 100 and 150 m). The measurement was taken from the outside edge of each of the two furthest bullet holes minus the diameter of the 0.556 round. Precision was taken as the mean of three measurements from the centre of the shot group to the centre of the bull’s-eye for each of the 50, 100 and 150 m targets. To find the centre of the shot group, the Mastercraft digital calliper was used. For each shot group, a vertical line was drawn through the centre of the leftmost bullet hole and a horizontal line was drawn through the centre of the lowest bullet hole. The distance from the outer edge of each bullet hole to the horizontal line was measured three times, and half the diameter of the 0.556 round was subtracted from each measurement. Using the digital calliper, the average of all the horizontal measurements was marked on the vertical axis measuring from the intersection point of the horizontal and vertical axis. A horizontal line was drawn through this measurement (centre shot line). The distance from the outer edge of each bullet hole to the vertical line was measured three times, with half the diameter of the 0.556 round subtracted from each measurement. Using the digital calliper, the average of all the vertical measurements was marked on the centre shot line, from the vertical line, representing the shot group centre. The distance between the shot group centre and the centre of the bull’s-eye was collected as the precision measure. HOM was recorded as the number of bullets that hit the silhouette portion of the target at each of the distances. For instance, if there were only three bullet holes on the silhouette, HOM was recorded as three, not four for that target and if there were no holes on the target, HOM was recorded as zero; if participants were unable to continue in the study, HOM was recorded as zero for the targets not fired on. In some cases, it was evident that there were two bullets in the same hole, those were recorded as two HOM. Hits for total shooting task were the number of HOM for the 50, 100 and 150 m combined. Figure 3 demonstrates a HOM calculation.
Statistical analyses
t-Tests were used to compare pain, grip strength, precision, accuracy and HOM between groups. The Mann-Whitney U-test was used as the non-parametric equivalent. Paired sample t-tests were used to compare within group measures, while Wilcoxon signed-rank test or sign test was used as the non-parametric test where required. One-way repeated measures analysis of variance (ANOVA) or Friedman's two-way ANOVA by ranks was used to examine change over several time periods. Because of the nature of the study, a convenience sample was used as we needed local marksmen that were available during the study phase.
Results
In total, 13 participants were enrolled in the study in one day in April 2015. The tourniquet group had six male participants with a mean age of 42.3±11.9 and 24.3±13.8 years of experience as a marksman. The iTClamp group consisted of seven male participants with a mean age of 47.3±11.9 and 25.5±16.7 years of marksmanship experience. There was no statistical difference between the two groups in age, level of experience or on any of the marksmanship control measures (Table 1).
Shooting
All of the participants in the iTClamp group were able to complete the 60 min shooting task, while five (83.3%) of the tourniquet group participants completed only the 5 min shooting task before withdrawing or being excluded from the study, and only one (16.7%) tourniquet marksman was able to complete both the 5 and 10 min shooting task before withdrawing or being excluded from the study. Ultimately, four (67%) of the tourniquet group participants were stopped by the RSO due to unsafe handling or inability to fire their weapon, and two (33%) withdrew due to intolerable pain. Comparatively, none of the iTClamp group was stopped by the RSO or withdrew due to pain.
There was no significant difference in precision or accuracy measures from control to 10 min shoot within groups or between groups. Accuracy and precision could not be compared after 10 min as all participants in the tourniquet group withdrew. The total effective HOM for the entire 60 min shooting task showed that the iTClamp group achieved significantly (p=0.001) more HOM than the tourniquet group. When examining HOM for the entire shooting task, there was no significant difference between tourniquet (5.8±1.7 HOM) and iTClamp (7.7±2.8 HOM) at 5 min (p=0.18). However, there was a significant difference at 10 min (6.5 (95% CI 2.8 to 10.2), p=0.003) with tourniquet having significantly fewer HOM (1.7±2.7 HOM) than the iTClamp (8.1±3.3 HOM) group. Figure 4 demonstrates the total HOM for each shooting phase delineated by group. Over the entire 60 min shooting exercise, the iTClamp group achieved a median 72% (52/72) of available HOM while the tourniquet group obtained 19% (14/72). Furthermore, effective fire ceased after 10 min in the tourniquet group. Figure 3 illustrates how HOM was calculated. Each of the circled bullet holes was counted as a single HOM. A HOM that was partly on the target was counted as a HOM. When examining HOM at the three distances 50, 100 and 150 m, there was no significant difference between the tourniquet and iTClamp groups at 5 min on either the 50 m (p=0.86) or 100 m (p=0.41) targets; there was significant difference at the 150 m distance 0.5 (95% CI 0.2 to 2.5), p=0.03. At the 10 min shooting task, the tourniquet group performed significantly worse than the iTClamp group at the 50 m (0.6 (95% CI 1.3 to 3.9), p=0.001), 100 m (0.5 (95% CI 0.8 to 3.1), p=0.003) and 150 m (0.7 (95% CI 0.2 to 3.6), p=0.031) distances. Table 2 further details characteristics of the shooting tasks listed.
Pain
Pain scores between the two groups did not differ significantly when the devices were initially applied (p=0.09). At 5 min, the tourniquet (6.6±1.5) was significantly more painful than the application of the iTClamp ((1.0±0.58), −5.6 (95% CI −7.0 to −4.3), p<0.001). Similarly, at 10 min, the tourniquet (8.5±0.6) was again significantly more painful ((1.0±0.6), −7.5 (95% CI −8.3 to −6.7), p<0.001). After the 10 min shooting task, the pain levels could no longer be compared between groups as all of the participants in the tourniquet group had withdrawn from the study.
There was a significant decrease in pain from the initial application of the iTClamp to 60 min, χ2(5)=24.03, p<0.0005. Comparing iTClamp initial application pain (3.0±1.0) with iTClamp 5 min pain (1.0±0.6) and 10 min pain (1.0±0.6) demonstrated a significant decrease in pain at both time points from initial application (2.0 (95% CI 1.3 to 2.8), p=0.001). All seven iTClamp participants reported a statistically significant median decrease in pain (2 Likert scores) from initial application of the iTClamp to the final pain score recorded at the 60 min shooting task, p=0.02. There was no significant difference between tourniquet application pain scores from initial application of the tourniquet and 5 min (p=0.13) or from 5 to 10 min (p=0.07); however, pain scores increased significantly from the initial application of the tourniquet (4.8±2.2) to the 10 min (final) shooting task ((8.5±0.6), 4.1 (95% CI 0.3 to 7.9), p=0.04).
Strength
Grip strength was also measured from both the dominant and non-dominant hand after each shooting task in kilograms. There was no significant difference in the grip strength of the dominant hand (p=0.74) or non-dominant hand (p=0.40) between the two groups when the devices were originally applied, or between the groups of the non-dominant hand after the 5 min (p=0.47) or 10 min (p=0.38) shooting tasks. Following the 5 min shooting task, grip strength for the dominant hand in the iTClamp group (49.1±11.7 kg) was significantly stronger than the grip strength in the dominant hand of the tourniquet group ((26.4±9.2 kg), 22.7 (95% CI 9.7 to 35.7), p=0.003). After the 10 min shooting task, the iTClamp group (48.8±11.8 kg) continued to be significantly stronger than the tourniquet group ((10.6±9.5 kg), 38.2 (95% CI 20.3 to 56.2), p=0.001). Following the 10 min shooting task, grip strength could no longer be compared between groups as all of the participants in the tourniquet group had withdrawn from the study. Both the tourniquet (F(2,10)=4.09, p=0.05) group and the iTClamp group (F(6,36)=3.8, p=0.005) saw a significant decrease in dominant hand grip strength over time. The tourniquet group saw a 60% decrease in grip strength from control (60.3±7.2 kg) to post 5 min shooting task (10.6±9.5 kg). The iTClamp group saw a 6% decrease in grip strength from the control measure (52.6±9.9 kg) taken prior to device application to post 60 min shooting task (49.4±10.5 kg). The iTClamp did not significantly impact the non-dominant hand grip strength over time (F(6,36)=.503, p=0.08). The tourniquet did significantly affect the grip strength in the non-dominant hand (F(2,10)=4.01, p=0.05) dropping the grip from 59.3±12.3 kg (control) to 54.3±12.5 kg post 5 min shooting task.
Discussion
This study suggests that from an operational standpoint, while potentially life-saving, committing to tourniquet application on a dominant arm quickly and completely negates the marksmanship potential of that operator. After 5 min, the effective fire was cut to one-fifth of ability, and thereafter silenced. Furthermore, those with tourniquets applied had significantly increased and distracting pain with marked weakness leading to incapacitated limbs. Thus, the iTClamp was markedly superior in all measures examined in preserving marksmanship.
Even with the many recent advances in resuscitation and surgery, isolated lower extremity trauma with vascular injury has a nearly 10% rate of mortality or limb loss.20 Many of these deaths may be unnecessary as haemorrhage control should theoretically be obtainable in almost all situations. Unfortunately reviews especially those in military conflicts have suggested that many soldiers exsanguinated from such extremity wounds,21 wounds for which even non-physician personal should have been able to temporise. A review of civilian patients who suffered cardiac arrest after penetrating extremity injury suggested that 57% were possibly preventable deaths if tourniquets had been applied early. However, there is still a requisite level of skill required to apply a tourniquet and time to deploy and administer it. A review from the Israeli Defense Force of tourniquet utilisation in the prehospital setting revealed that tourniquets were applied in <15 min in 88% of the cases with almost no complications.22
Unfortunately, these excellent results are unlikely to apply in operational settings in which an operator may need to frequently self-apply a tourniquet. Current doctrine in most coalition forces is for injured causalities without medical support to self-apply tourniquets, but detailed comparative studies of different tourniquets have revealed that overall tourniquets were less effective and the time to application was less consistent when patients had to self-apply them.3 The percentage of effectively applied tourniquets was significantly lower in the self-application scenario.3 Thus, there appears to be a requirement for other topical haemorrhage control devices that can quickly arrest exsanguinating haemorrhage and also potentially be self-applied.
Such a device may be the new iTClamp, a temporary wound closure device which controls external haemorrhage from open wounds within compressible zones. A recent comparative animal laboratory study of a complex vascular groin injury revealed that all (100%) animals treated with the iTClamp lived through the end of the experiment, compared with 60% in standard gauze treated and 0% of untreated control animals (early and late iTClamp vs control and standard gauze, Fisher's exact, p=0.003).18 In a lethal swine bleeding model (femoral artery injury), the iTClamp was 100% effective at controlling bleeding,18 packing+iTClamp reported a 100% survival rate and the iTClamp improved survival and decreased haemorrhage in both packed and unpacked wounds.19 Another preclinical reperfused cadaver study demonstrated that the iTClamp was effective at controlling blood loss from multiple compressible zones including the scalp, neck, groin and extremities.23
While controlling haemorrhage on the battlefield is a top priority, focus during a care under fire incident is actually to return effective fire with the expectation that the casualty will remain engaged as a combatant2 and not the recipient of medical treatment. Compared with being wounded, other comparatively minor factors can impact marksmanship such as loading/exercise, high altitude, caffeine consumption, visual acuity and environmental factors. Thus, in the critical setting of care under fire, we suggest that the iTClamp may have specific merit in extremity trauma involving the dominant upper extremity of the operator who has sustained a penetrating injury. If the haemorrhage can be controlled with the iTClamp, then the extremity is not rendered ischaemic and immobilised and there was no impairment in marksmanship for the entire 60 min duration of the study. Massively destructive injuries however that render the limb primarily non-functional cannot benefit in a functional way from iTClamp application, but these devices can still be applied quicker. As with all care guided by the TCCC guidelines, the later application of a tourniquet or other devices or bandages is not precluded in later phases of care once the threat to the operator/unit has decreased or been eliminated.
Substantial limitations
Realistic limitations of this study were that exsanguinating wounds were and could not be inflicted on the participants, and thus efficacy of the device was implied but not proven. The haemorrhage control devices were applied assuming that such wounds were present. An inherent assumption of the study was that application of either the iTClamp50 or a tourniquet would be haemostatic. Thus, this study did not inherently address any issues related to the theoretical or practical haemostatic results with the iTClamp, or with long-term trauma outcomes. Thus, the participants were not in pain, nor had experienced shock and tissue destruction prior to treatment allocation. While the marksmen were all military/police personalities, it is possible that actual tissue destruction/haemorrhagic shock might motivate such personalities to exceed their physiological/psychological limits and thus improve their marksmanship, but we believe that this is improbable, as by 10 min complete incapacitation in the tourniquet group seemed apparent negating any influence of will or motivation. An additional limitation is that we were unable to enrol any female marksmen in the study and are therefore unable to ascertain is there is a difference with gender.
Conclusion
For extremity haemorrhage that can be effectively controlled with an iTClamp, its use rather than tourniquet is much more effective in allowing effective use of the pertinent extremity to continue to provide effective fire with the device in place.
References
Footnotes
Funding This research was funded by the Innovative Trauma Care Corporation, San Antonio, Texas.
Competing interests AWK has received consulting fees from the Innovative Trauma Care Corporation, and reimbursement for travel and lodging to research laboratories and scientific meetings. JLM is the Clinical Director of Research for Innovative Trauma Care, San Antonio, Texas. IM is married to JLM, who is the Clinical Director of Innovative Trauma Care.
Provenance and peer review Not commissioned; externally peer reviewed.