TY - JOUR
AU - RAMC, Paul Parker,
AB - ABSTRACT Background: Limb tourniquets have been used extensively during modern Middle Eastern conflicts. Despite its undeniable successes, the combat applied tourniquet (C-A-T) has some shortfalls, principally its inability to reliably control lower limb bleeding when applied to the mid-thigh. We tested two tourniquets which may represent an improvement to the combat applied tourniquet; the tactical mechanical tourniquet and the tactical pneumatic tourniquet. Methods: We recruited 12 healthy service personnel and applied the tactical mechanical tourniquet and tactical pneumatic tourniquet to both lower limbs in a randomly generated sequence. Tourniquets were tightened until popliteal artery occlusion. This was measured via a SonoSite portable ultrasound machine by a single consultant vascular radiologist familiar with its use. A longitudinal view of the popliteal artery was obtained, and Doppler waveform monitored. The tourniquets were tightened around volunteers' mid-thigh by a second researcher accustomed with their use. Time to complete occlusion, number of windlass revolutions, and pain scores were collected by a third researcher. Non-normally distributed data are present as median (interquartile range). Ordinal nonparametric data are analysed by Mann–Whitney U testing. Results: Participants had a median age of 32.5 (28–35). Both tourniquets demonstrated complete occlusion of the popliteal artery in all limbs (n = 24). The mechanical tourniquet achieved arterial occlusion after a median of 3.8 (3–4) turns, and 16 (12–20) seconds. No participants dropped out of the study because of intolerable pain, or any cause. Median pain scores for the mechanical tourniquets were 4.5 (3–7) (maximum pain) and 4.0 (2–7) (pain when locked). Median pain scores for the pneumatic tourniquet were 5 (2–6) (maximum pain) and 5 (2–6) (pain when fully applied). There was no statistical difference in maximum pain scores between the tactical mechanical tourniquet and the tactical pneumatic tourniquet (p = 0.75). No participant had any tourniquet applied for longer than 80 seconds. Conclusion: Both tourniquets completely occluded the popliteal artery in all participants within an acceptable pain threshold. Further testing is required before the presented tourniquets can be taken to the battlefield; particularly measures of self-application, and use on other anatomical areas. INTRODUCTION The use of a prehospital limb tourniquet has undeniably saved many lives during recent military conflicts.1,–5 The combat applied tourniquet (C-A-T) (Composite Resources South Carolina) is widely used by the British Army from point-of-wounding to definitive casualty care. Familiar to most soldiers, the C-A-T uses a windlass system with a free moving internal band to apply circumferential pressure to a limb. It can be operated with only one hand and can therefore be used by the casualty themselves at the point of wounding in austere environments. Despite the clear advantages to casualty survivorship from limb trauma, the C-A-T has been subject to certain criticisms. One pertinent criticism is its inconsistent ability to completely control lower limb bleeding when used at the mid-thigh level. This has been previously reported when using the C-A-T6,–8; with both military and civilian sources advocating the use of a second tourniquet if bleeding has not been adequately controlled with one tourniquet.9,–11 Both the U.S. Department of Defence Tactical Combat Casualty Care guidelines,12 and the British Army Battlefield Advanced Trauma Life Support manual13 mandate the usage of a second tourniquet side by side with the first in cases of uncontrolled bleeding, therefore a patient with bilateral above knee amputations is likely to require the application of four tourniquets (perhaps even five if there is the usual concomitant upper limb injury). An improvement to the currently used C-A-T would be a device that consistently controlled haemorrhage when used at the mid-thigh level without the need for a paired application. We tested two such devices that we believe can control lower limb haemorrhage when applied singly to the mid-thigh. DEVICES Tactical Mechanical Tourniquet The tactical mechanical tourniquet (Alphapointe, Kansas City, Missouri) is a design familiar to users of the current C-A-T. It uses a Velcro (Velcro Companies, Manchester, New Hampshire) strap with windlass mechanism. Important differences to the C-A-T include a buckle that can be fastened and unfastened without the need for looping the strap around a limb, and a larger plastic backplate to the windlass. It is claimed these features make the tourniquet both easier to apply and more effective at overcoming limb arterial pressure. It is also broader than the C-A-T, and has significantly more travel on the windlass mechanism (110 mm compared to 30 mm), allowing for more even pressure distribution and greater tightening capacity. The tactical mechanical tourniquet is shown in Figure 1. FIGURE 1 View largeDownload slide Tactical mechanical tourniquet. Descriptive photograph shows partially tightened application at the thigh; A plastic backplate, B wide strap, and Cunhooking buckle. FIGURE 1 View largeDownload slide Tactical mechanical tourniquet. Descriptive photograph shows partially tightened application at the thigh; A plastic backplate, B wide strap, and Cunhooking buckle. Tactical Pneumatic Tourniquet The tactical pneumatic tourniquet (Alphapointe) has more complicated components than either the C-A-T or the mechanical tourniquet abovementioned, featuring a bladder inflated by a robust hand-held bulb. There is a manual valve to release the pressure in much the same way as a sphygmomanometer. It has a circumferential Velcro strap, but no windlass mechanism. It is slightly broader and slightly longer than the tactical mechanical tourniquet, but is still easily portable. The tactical pneumatic tourniquet is shown in Figure 2. FIGURE 2 View largeDownload slide Tactical pneumatic tourniquet. Descriptive photograph showing non-inflated application at the thigh; (D) inflatable bulb and (E) circumferential Velcro strap with incorporated inflatable bladder. FIGURE 2 View largeDownload slide Tactical pneumatic tourniquet. Descriptive photograph showing non-inflated application at the thigh; (D) inflatable bulb and (E) circumferential Velcro strap with incorporated inflatable bladder. METHODS Pilot Study Three volunteers were recruited to test and refine the methodology presented below. Data from that pilot are not included in this study. Volunteer Selection Twelve healthy actively serving soldiers and sailors were recruited. All participants had passed their personal fitness tests within the last 12 months, and were free from cardiovascular disease, diabetes, diagnosed atherosclerosis, limb injury, or any other condition that could be worsened by participation in the study. Ministry of Defence Research and Ethical Committee approval was sought and granted (712/MODREC/15). Methodology The mechanical and pneumatic tourniquets were tested in both lower limbs of all volunteers. The limb and the order in which the devices were applied were randomised according to a preprepared, electronically generated, random algorithm. Tourniquets were applied by the same researcher at the mid-thigh level, (defined as the half-way point between the greater trochanter and the superior pole of the patella) onto bare skin with no interference from clothing. Tourniquets were inspected before each use, and a new tourniquet used if any evidence of wear was identified. Blinding was not possible because of the differing methods of application; however volunteers were not shown the actual tourniquets before participation to limit potential biases. Testing occurred sequentially and all participants were isolated from one another to limit any expectations of pain. Popliteal artery flow was measured via a SonoSite portable ultrasound machine (FUJIFILM SonoSite, Inc., Bothell, Washington) by a single consultant radiologist familiar with its use. The tourniquets were tightened by the same single researcher, accustomed with the application of both devices, until popliteal artery flow was completely occluded. Timings, pain, and other data were collected by a third researcher. Data Collection Demographic data on age and gender were collected. Participants were asked to rate the maximum pain experienced during tourniquet application via a 1 to 10 Numeric Pain Rating Score (1 no pain to 10 worst pain ever experienced). Participants were also asked to rate the pain experienced when the tourniquet was fully applied and in a satisfactory position. Participants were given the opportunity to drop out of the study if the pain became intolerable. After the tourniquet had been closely applied, the number of windlass turns (mechanical tourniquet) required to occlude arterial flow was measured, as were the number of bulb-pumps (pneumatic tourniquet). Qualitative data on the nature of maximum pain experienced were collected when pain scores exceeded 6/10. The time taken from beginning of tightening to complete occlusion was recorded, as well as the total length of time applied. Data Analysis Time is recorded in seconds. Non-normally distributed data are presented as median (interquartile range [IQR]). Ordinal nonparametrically distributed data are analysed via Mann–Whitney U testing. Outcomes The primary outcome was occlusion of popliteal artery flow as measured by a SonoSite portable ultrasound machine. The secondary outcome was pain assessed by the participant during application. RESULTS Twelve healthy volunteers were recruited with a median age of 32.5 (28–35), there were ten males and two females. All were active duty (serving) soldiers or sailors. Both tourniquets demonstrated complete occlusion of the popliteal artery in all limbs (n = 24). The mechanical tourniquet achieved arterial occlusion after a median of 3.8 (3–4) turns and 16 (12–20) seconds. No participants dropped out of the study because of intolerable pain, or any cause. Median pain scores for the mechanical tourniquets were 4.5 (3–7) (maximum pain) and 4.0 (2–7) (pain when locked). Four participants experienced maximum pain >6/10 when using the mechanical tourniquet, with three reporting “skin pinching,” and one reporting “pressure” as a cause. The pneumatic tourniquet achieved arterial occlusion after a median of 30.5 (25–32) pumps and 11 (7–12) seconds. Median pain scores for the pneumatic tourniquet were 5 (2–6) (maximum pain) and 5 (2–6) (pain when fully applied). Two participants experienced maximum pain >6/10 with the pneumatic tourniquet, reporting “Velcro scratching” as the main cause. There was no statistical difference in maximum pain scores between the tactical mechanical tourniquet and tactical pneumatic tourniquet (p = 0.75). No tourniquet was left in place for more than 75 seconds. Data are summarised in Table I. TABLE I Occlusion and Pain Scores Healthy Volunteers n = 12 Median (IQR)  Age  32.5 (28–35)  Male:Female  10:2  Healthy Volunteers n = 12 Median (IQR)  Age  32.5 (28–35)  Male:Female  10:2     Mechanical Limbs = 12  Pneumatic Limbs = 12  Median (IQR)  Median (IQR)  Left:Right  5:7  7:5  Turns/Pumps to Occlusion  3.8 (3–4)  30.5 (25–32)  Time to Occlusion Seconds  16.0 (12–20)  11.0 (7–12)  Maximum Pain Score 0–10 Scale  4.5 (3–7)  5.0 (2–6)  Locked Pain Score 0–10 Scale  4.0 (2–7)  5.0 (2–6)  Maximum Time Applied Seconds  26.5 (20–40)        Mechanical Limbs = 12  Pneumatic Limbs = 12  Median (IQR)  Median (IQR)  Left:Right  5:7  7:5  Turns/Pumps to Occlusion  3.8 (3–4)  30.5 (25–32)  Time to Occlusion Seconds  16.0 (12–20)  11.0 (7–12)  Maximum Pain Score 0–10 Scale  4.5 (3–7)  5.0 (2–6)  Locked Pain Score 0–10 Scale  4.0 (2–7)  5.0 (2–6)  Maximum Time Applied Seconds  26.5 (20–40)     View Large TABLE I Occlusion and Pain Scores Healthy Volunteers n = 12 Median (IQR)  Age  32.5 (28–35)  Male:Female  10:2  Healthy Volunteers n = 12 Median (IQR)  Age  32.5 (28–35)  Male:Female  10:2     Mechanical Limbs = 12  Pneumatic Limbs = 12  Median (IQR)  Median (IQR)  Left:Right  5:7  7:5  Turns/Pumps to Occlusion  3.8 (3–4)  30.5 (25–32)  Time to Occlusion Seconds  16.0 (12–20)  11.0 (7–12)  Maximum Pain Score 0–10 Scale  4.5 (3–7)  5.0 (2–6)  Locked Pain Score 0–10 Scale  4.0 (2–7)  5.0 (2–6)  Maximum Time Applied Seconds  26.5 (20–40)        Mechanical Limbs = 12  Pneumatic Limbs = 12  Median (IQR)  Median (IQR)  Left:Right  5:7  7:5  Turns/Pumps to Occlusion  3.8 (3–4)  30.5 (25–32)  Time to Occlusion Seconds  16.0 (12–20)  11.0 (7–12)  Maximum Pain Score 0–10 Scale  4.5 (3–7)  5.0 (2–6)  Locked Pain Score 0–10 Scale  4.0 (2–7)  5.0 (2–6)  Maximum Time Applied Seconds  26.5 (20–40)     View Large DISCUSSION Volunteers were usefully heterogeneous. Both tourniquets occluded popliteal artery flow in 100% of limbs tested. Pain scores were comparable between the tourniquets presented, although four participants reported pain >6/10 with the mechanical tourniquet, compared to only two with the pneumatic tourniquet. Previous studies have found pneumatic tourniquets to be less painful than mechanical devices.14,15 This is hypothesized to be the result of the more uniform way in which the pneumatic tourniquet delivers its pressure effect, causing less skin pinching than the mechanical tourniquets. The advantages of a tourniquet that can control lower limb haemorrhage at the mid-thigh level without the need for side-by-side application are intuitive, and include both time-saving during Care Under Fire (CUF), and improved resuscitation for the casualty. This study has demonstrated the efficacy of both tourniquets for complete occlusion of the popliteal artery in healthy volunteers. The need for popliteal artery occlusion is paramount, but if tourniquets are not tolerated because of excessive pain, then the efficacy of arterial occlusion could be compromised. The ideal tourniquet in the CUF setting would be easy and quick to apply, efficacious, and acceptable to the casualty. Size is an additional factor considering that CUF equipment must be man-portable. When the casualty is in an area of more definitive treatment, such as an enhanced medevac platform or medical treatment facility, point-of-wounding tourniquets may be replaced with subsequent devices that can give deliver more refined pressure regulation. The need to determine ongoing catastrophic haemorrhage may demand releasing of tourniquets in a controlled environment. Tourniquets that afford more refined control are more suitable for such inspection than crude devices that can only function in a binary manner (on/off). Now that both tourniquets have demonstrated their efficacy in controlled conditions, more rigorous real-world testing should occur to determine their acceptability for prehospital trauma practitioners. Crucially, successful self-application should be tested, as well as use at other anatomical sites, and a measure of durability in austere environments. Limitations The median age of 32.5 years among study volunteers is 4.5 years younger than the average age of United Kingdom Armed Forces officer ranks, and 3.5 years older than other ranks.16 There are no convincing biological reasons that threaten translatability amongst UK service personnel. Environment Although not the focus of this study, the authors feel that the mechanical tourniquet is best suited to point-of-wounding care, whereas the pneumatic tourniquet is more appropriate for areas of definitive care. A potential model could include mechanical tourniquet use at the point-of-wounding and replacement with the pneumatic tourniquet once an area of definitive care (or definitive care-giver) has been reached. The mechanical tourniquet is smaller than the pneumatic tourniquet, and is therefore more easily carried in the prehospital environment. The mechanical tourniquet is easier to use, and can be applied more quickly than the pneumatic tourniquet, which makes it more appropriate for use in the field. The pneumatic tourniquet could be reserved for use in definitive care (including Medical Emergency Response Teams and Light Surgical Teams), as it is potentially more difficult to apply in the austere environment. The inflatable bladder affords more finesse over pressure control, and so release is a more finely controlled process. The bladder and bulb, although hardy, need further testing under austere conditions before full confidence in their quality is achieved. CONCLUSION Both the tactical mechanical tourniquet and the tactical pneumatic tourniquet demonstrated ability to completely occlude the popliteal artery in 100% of limbs when applied at the mid-thigh level in healthy volunteers. All participants reported acceptable pain scores with both tourniquets. These devices require further investigation to assess their battlefield utility, once this is done, current tourniquet guidelines should be urgently reviewed. ACKNOWLEDGMENTS Materials (tourniquets) were supplied by Alphapointe, Kansas City, Missouri. No compensation, financial or otherwise, was received for any part of this study. The authors are in no way professionally affiliated with the manufacturers. REFERENCES 1. Kragh JFJr, Littrel ML, Jones JA, et al.   Battle casualty survival with emergency tourniquet use to stop limb bleeding. J Emerg Med  2011; 41( 6): 590– 7. Google Scholar CrossRef Search ADS PubMed  2. Kragh JFJr, Murphy C, Dubick MA, et al.   New tourniquet device concepts for battlefield hemorrhage control. US Army Med Dep J  2011: 38– 48. 3. Kragh JFJr, Dubick MA, Aden JK, et al.   U.S. Military use of tourniquets from 2001 to 2010. Prehosp Emerg Care  2015; 19( 2): 184– 90. Google Scholar CrossRef Search ADS PubMed  4. Mawhinney AC, Kirk SJ A systematic review of the use of tourniquets and topical haemostatic agents in conflicts in Afghanistan and Iraq. J R Nav Med Ser  2015; 101( 2): 147– 54. 5. Kragh JFJr, Walters TJ, Baer DG, et al.   Survival with emergency tourniquet use to stop bleeding in major limb trauma. Ann Surg  2009; 249( 1): 1– 7. Google Scholar CrossRef Search ADS PubMed  6. Kragh JFJr, Walters TJ, Baer DG, et al.   Practical use of emergency tourniquets to stop bleeding in major limb trauma. J Trauma  2008; 64( 2 Suppl): S38– 49; discussion S49–50. Google Scholar CrossRef Search ADS PubMed  7. Taylor DM, Vater GM, Parker PJ An evaluation of two tourniquet systems for the control of prehospital lower limb hemorrhage. J Trauma  2011; 71( 3): 591– 5. Google Scholar CrossRef Search ADS PubMed  8. Unlu A, Petrone P, Guvenc I, et al.   Combat application tourniquet (CAT) eradicates popliteal pulses effectively by correcting the windlass turn degrees: a trial on 145 participants. Eur J Trauma Emerg Surg  2015. doi:10.1007/s00068-015-0582-0. Available at http://link.springer.com/article/10.1007/s00068-015-0582-0/fulltext.html; accessed September 3, 2016. 9. National Health Service South West Ambulance Service Major Haemorrhage Clinical effectiveness group 2013. Trust clinical guidelines . Available at http://www.swast.nhs.uk/Downloads/ClinicalGuidelinesSWASFTstaff/CG14_Major_Haemorrhage.pdf; accessed July 27, 2016. 10. National Association of Emergency Medical Technicians Prehospital Trauma Life Support , Ed 7, Sudbury, MA, Jones and Bartlett, 2010. PubMed PubMed  11. Real First Aid: Use of Tourniquets . Available at http://www.realfirstaid.co.uk/tourniquets; accessed July 27, 2016. 12. United States Department of Defense Tactical Combat Casualty Care 03 June 2015. Basic Management Plan for Tactical Field Care, para 4.a . Available at http://www.naemt.org/docs/default-source/education-documents/tccc/10-9-15-updates/tccc-guidelines-for-medical-personnel-150603.docx?sfvrsn=2; accessed July 27, 2016. 13. British Army Battlefield Advanced Trauma Life Support manual 26 February 2016 Chapter 3: Catastrophic Haemorrhage . Available at https://i-site.mod.uk/course/view; accessed July 27, 2016. 14. Kragh JFJr, O'Neill ML, Walters TJ, et al.   The military emergency tourniquet program's lessons learned with devices and designs. Mil Med  2011; 176( 10): 1144– 52. Google Scholar CrossRef Search ADS PubMed  15. King RB, Filips D, Blitz S, et al.   Evaluation of possible tourniquet systems for use in the Canadian Forces. J Trauma  2006; 60( 5): 1061– 71. Google Scholar CrossRef Search ADS PubMed  16. Ministry of Defence UK Armed Forces Annual Personnel Report 23 May 2013 . Available at https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/284564/uk-af-personnel-report-1-april-2013-revised.pdf; accessed July 27, 2016. Reprint & Copyright © Association of Military Surgeons of the U.S.
TI - Two New Effective Tourniquets for Potential Use in the Military Environment: A Serving Soldier Study
JF - Military Medicine
DO - 10.7205/MILMED-D-16-00298
DA - 2017-07-01
UR - https://www.deepdyve.com/lp/oxford-university-press/two-new-effective-tourniquets-for-potential-use-in-the-military-uXqojN4jSe
SP - e1929
EP - e1932
VL - 182
IS - 7
DP - DeepDyve
ER -