ORIGINAL RESEARCH. International Journal of Surgery

Transcription

1 International Journal of Surgery 10 (2012) 563e567 Contents lists available at SciVerse ScienceDirect International Journal of Surgery journal homepage: Original research Evaluation of rapid training in ultrasound guided tourniquet application skills U. Jaffer a, *, M. Aslam a, V. Kasivisvanathan a, R. Patni a, M. Midwinter b, N. Standfield a a Department of Vascular Surgery, Imperial College School of Medicine, Hammersmith Hospital, Du Cane Road, London W12 0HS, UK b Academic Department of Military Surgery and Trauma, Royal Centre for Defence Medicine, ICT Centre, Birmingham Research Park, Vincent Drive, Birmingham B15 2SQ, UK article info abstract Article history: Received 9 April 2012 Received in revised form 17 July 2012 Accepted 22 August 2012 Available online 5 September 2012 Keywords: Trauma Tourniquet Ultrasound Teaching Tourniquet application has been widely accepted to improve survival for major limb trauma. Colour duplex ultrasound (US) can be used as a non-invasive method of confirming cessation of arterial flow. Participants with no or limited experience of ultrasound were taught to apply the Combat Application Tourniquet with ultrasound guidance. Following this, participants were tested in effective tourniquet application: Blind and with ultrasound guidance. US guidance improved abolition of limb perfusion from 22 to 93 per cent in upper limb; from 25 to 100 per cent in lower limb (p ¼ and <0.0001). No significant difference was found in application time for the lower limb; less time was taken for application with US guidance in the upper limb 8.1 (7.1, 8.6) vs 4.5 s (4.0, 5.3; median (IQR)), p ¼ Tourniquet ultrasound skills are rapidly acquired by novice operators. Accuracy improves with ultrasound guidance, this may have a role in improving survival. Ó 2012 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved. 1. Introduction Tourniquets can be vital for haemorrhage control in a variety of trauma conditions. Vascular injury to the arms and legs is of concern in both the combat and civilian settings of blunt and penetrating trauma. 1e4 Current guidance on successful application of a limb tourniquet for haemorrhage is to tighten the tourniquet until there is cessation of external haemorrhage on visual inspection. 5 This approach may be confounded by bleeding from the distal ends of damaged vessels and medullary blood flow from bones. Ultrasound technology is relatively inexpensive and portable. The Duplex machine (Fig. 1) is a real-time scanner with built-in Doppler instrumentation to measure and visualize flow. Better and more effective tourniquet application may result using ultrasound to visualize the target artery which needs to be occluded. Confirmation of arterial occlusion can be achieved by visualizing the artery in transverse section distal to the site of tourniquet application (Fig. 2). Appropriate ultrasound-guided tourniquet adjustment will ensure that the artery is occluded without excess compression to the injured limb. The Combat Application Tourniquet (CAT; SP services, Hortonwood, UK; Fig. 3) is a small, lightweight one-handed tourniquet * Corresponding author. Tel.: þ ; fax: þ addresses: usman.jaffer@doctors.org.uk (U. Jaffer), m.aslam@ imperial.ac.uk (M. Aslam), v.kasivisivanathan@imperial.ac.uk (V. Kasivisvanathan), r.patni@imperial.ac.uk (R. Patni), MILSURG@rcdm.bham.ac.uk (M. Midwinter), n.standfield@imperial.ac.uk (N. Standfield). that can completely occlude arterial blood flow in an extremity. The CAT uses a Self-Adhering Band and a Friction Adaptor Buckle to fit a wide range of extremities combined with a one-handed windlass system. The windlass uses a free moving internal band to provide true circumferential pressure to an extremity. The windlass is then locked in place; this requires only one hand, with the Windlass Clip. The CAT also has a Hook-and-Loop Windlass Strap for further securing of the windlass during patient transport. A study evaluating eight tourniquet designs reported that tourniquets of the windlass design, placed with one hand often fail. 6 We intended to teach tourniquet application based upon obliteration of Colour Duplex Ultrasound CDU) detected flow in the superficial femoral artery of the thigh to novice users and assess competence post-teaching. This study compares ultrasound-guided versus blind tourniquet placement in a cohort of healthy volunteers. 2. Methods Medical students at Imperial College Medical School, London and junior doctors working at Imperial College Healthcare Trust, London were invited to attend optional teaching in the application of ultrasound guided tourniquet application. Local departmental ethical review was given. As the data was gathered as part of an audit of the teaching exercise, formal National Ethical approval was not applicable Teaching procedure The participants were given a short document to read regarding Colour Doppler Ultrasound and a short demonstration of the basic features and nature of ultrasound /$ e see front matter Ó 2012 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.

2 564 U. Jaffer et al. / International Journal of Surgery 10 (2012) 563e567 Fig. 3. Photograph of the combat application Tourniquet (CAT). image produced by a portable colour Duplex ultrasound machine. Also, participants were shown the Combat Application Tourniquet (CAT) and given basic information on the vascular anatomy of the lower limb and tourniquet application technique. It was explained to the participants that the tourniquet application may be uncomfortable and that if they wanted to stop the application to raise their hand. Following the teaching phase and answering any questions the participants had, an assessment phase was undertaken Testing procedure Fig. 1. Portable colour duplex ultrasound machine. Assessment was performed in pairs. One participant would be evaluated applying the tourniquet on their partner and then the roles would be reversed. The participant to have the tourniquet applied was asked to remove their outer clothing to their lower half and lie down on an examination couch. CATs were applied to both upper thighs and photo plethysmography (PPG) probes were attached to both great toes. A folded piece of gauze was placed beneath the windlass of the tourniquet to avoid skin pinching. The PPG output was displayed as a realtime tracing on an LCD screen. When arterial flow into the limb is abolished, the PPG trace falls to a baseline level and loses pulsatility. A separate evaluator was present to time the tourniquet application and assess success of application by observing the PPG tracing. The first leg to be used was randomly chosen by coin toss. The participant was asked to tighten the CAT blindly to this leg. The procedure was then repeated on the contralateral leg e but this time with the aid of Colour Doppler Ultrasound. The operating participant was aided to acquire a transverse section image of the superficial femoral artery in the thigh distal to the tourniquet. Once established, the ultrasound probe was held by the examiner to maintain the image of the artery. Now, with the Colour Doppler Ultrasound image as guidance the operating participant was again asked to tighten the tourniquet. The evaluators recorded the time taken and success of application of the CAT for each attempt. The participant having the CAT applied to them was asked to record the level of discomfort experienced on a visual analogue scale after each application Data analysis Descriptive statistics were used to describe baseline participant data. Significance was taken at the five per cent level. To test the differences in time taken while in blind position or ultrasound guided application, we used a non-parametric Wilcoxon matched-paired signed rank test taking account of the paired nature of the testing procedure. 3. Results 3.1. Lower limb tourniquet application There were 46 subjects in total, 35 males and 11 females. The salient characteristics of the participants are shown in Table 1. None Fig. 2. Typical ultrasound probe position (transverse) to obtain a cross sectional image of the common femoral artery e highlighted with colour Doppler imaging.

3 U. Jaffer et al. / International Journal of Surgery 10 (2012) 563e Table 1 Baseline characteristics of the upper and lower limb participants. Lower limb mean (IQR) Upper limb mean (IQR) Age (years) 23 (21e24) 25 (18e26) Weight (kg) 72.5 (66.3e81.5) (46e69.3) Height (cm) 176 (168e183) (164.5e170.5) Limb girth (cm) Right leg 44.2 (41.3e47.5) 24.2 (20.9e26.7) Left leg 44.2 (41.3e47.5) 24.1 (21.4e27.2) Heart rate (min 1 ) 74 (71e80) (72e79) Blood pressure (mm Hg) Systolic 118 (118e122) 122 (118e125) Diastolic 76 (72e80) 78 (77e80) of the subjects were smokers, had diabetes or renal failure. One patient was on roaccutane and one was on the combined oral contraceptive pill. Four subjects had previous experience of ultrasound use, the remainder had either no knowledge or a theoretical knowledge. The time taken to apply and pain score on application of the tourniquet according to technique used is shown in Fig. 4. The efficacy of application of the tourniquet according to technique used is shown in Fig Upper limb tourniquet application There were 12 subjects in total, 2 males and 10 females. The salient characteristics of the subjects are shown in Table 1. None of the subjects were smokers, had diabetes or renal failure. Three participants had theoretical knowledge only of ultrasound use, the remainder had no knowledge. The time taken to apply and pain score on application of the tourniquet according to technique used is shown in Fig. 6. The efficacy of application of the tourniquet according to technique used is shown in Fig Discussion Bleeding from limb vessels is one of the most common causes of death on the battlefield. 7 The control of catastrophic haemorrhage following injury is a priority. Indeed in the military setting a paradigm of <C> ABC has replaced ABC in the initial hierarchy of management (where <C> stands for catastrophic haemorrhage control in recognition of the lethality of this in the battlefield. 8 This has led to the introduction of the CAT for UK troops. The CAT Fig. 5. Stacked bar chart showing frequencies of successful abolition of perfusion with tourniquet technique for the lower limb.*, p < tourniquet use in UK military forms part of the pre-deployment training package and the use has been reviewed. 9 Effective tourniquet use has been associated with elimination of deaths from limb haemorrhage in a series of 550 injured patients. 10 Lack of tourniquet experience may be a critical issue as undertightening may not stem haemorrhage and over-tightening may result in unnecessary tissue and nerve damage. Success application has been associated with medical personnel application rather than fellow soldier and in upper limb versus lower limb application - 94% versus 71%. 11 The most prominent and robust findings of this study were that US guidance improved successful abolition of limb perfusion from 22 to 93 per cent in upper limb tourniquet and from 25 to 100 per cent in lower limb tourniquet application (p ¼ and < respectively). These finding are of great interest in that novice users do not apply tourniquets tightly enough and US guidance appears to have Fig. 4. Box and whisker plot of (A) time taken to apply tourniquet and (B) pain score vs. technique used for the lower limb.

4 566 U. Jaffer et al. / International Journal of Surgery 10 (2012) 563e567 Fig. 6. Box and whisker plot of (A) time taken to apply tourniquet and (B) pain score vs. technique used for the upper limb.*, p < facilitated the novice in becoming highly effective in successfully abolishing limb perfusion. This has important implications both in the combat scenario and also the pre-hospital civilian setting as experience with tourniquet application can be limited or nonexistent but absolute efficacy is required. In the military setting the use of ultrasound in the care under fire 9 phase may not be pragmatic as this is either self or buddy applied while active combat is occurring (although potential future smart tourniquets to detect when arterial flow is occluded is a possibility). However, use of a small portable Doppler with appropriate training at first opportunity in the tactical field care phase to ascertain correct application may be useful. It may be that the use of Colour Doppler ultrasound could be incorporated into pre-deployment CAT training schedules. We found no significant difference in terms of time taken to apply tourniquets between techniques for the lower limb whereas there was a reduction in the time taken for application with US guidance in the upper limb 8.1 (7.1, 8.6) vs 4.5 (4.0, 5.3; median (IQR)), p ¼ The issue of simple versus mechanical advantage in tourniquet design (windlass, block and tackle or pneumatic systems) has been investigated in efficacy of tourniquet application. 12 Effectiveness of the tourniquet application in this study was judged by abolition of Doppler signal over the popliteal artery. In real world application, tourniquets are often applied where superficially located distal vessels are not accessible or traumatised due to crush or blast injuries. The dramatic increase in effective application of tourniquets in both lower and upper limbs seen using ultrasound guidance may not be easily achieved with other devices. We believe that the use of flow detection devices without vessel imaging are sub-optimal as lack of signal detection may be due to cessation of flow or due to failure of localisation of the artery. Our data (summarised in Table 2) suggests a trend towards increased pain associated with US guided application of tourniquets. However, again, tightening of the tourniquet insufficiently to cause occlusion of distal arterial flow may exacerbate haemorrhage by occluding venous outflow from the injured part thus worsening exsanguination. Walters et al., have suggested that increasing the width of the tourniquet strap may be an important consideration in being able to occlude flow with lower pressure. The authors cite data from surgical pneumatic tourniquets. 12 However, as width increases, the amount of tissue to be compressed increases, also the tourniquet strap bows reducing its functional width. 11 Transient nerve palsy rates of 1.7% have been reported in a large military series of 232 patients with 428 tourniquets applied. 13 Although a smaller previous series from the same authors reports no association between duration of tourniquet application and presence of nerve palsy, the increased pressure applied by tourniquets with ultrasound guidance may result in a greater rate of nerve palsy. 14 Table 2 Summary table of outcome measures for upper and lower limb testing. Limb Variable Blind median (IQR) Upper Lower Ultrasound guided median (IQR) p-value a Time taken to apply Tourniquet (seconds) 8.1 (7.1, 8.6) 4.5 (4.0, 5.3) Pain score 3.8 (1.3, 6.1) 4.6 (2.1, 6.6) Successful abolition (Yes) # (%) 3 (25%) 12 (100) b Time taken to apply Tourniquet (seconds) 34.3 (20.0, 44.0) 30.9 (24.0, 35.8) Pain score 3.1 (1.7, 5.5) 4.4 (2.7, 6.4) Successful abolition (Yes) # (%) 10 (22%) 43 (93%) < b Fig. 7. Stacked bar chart showing frequencies of successful abolition of perfusion with tourniquet technique for the upper limb.*, p < a Wilcoxon matched pairs signed-rank test was used. b McNemar s test for matched pairs.

5 U. Jaffer et al. / International Journal of Surgery 10 (2012) 563e Improvement in survival and limb salvage rates as well as any potential increase in morbidity associated with ultrasound guided tourniquet application will need to be assessed in the form of a trial. As it is impractical to take the ultrasound machine into the battlefield itself, we are currently planning to perform a trial of ultrasound adjustment of tourniquets applied in the field. This adjustment will take place, using ultrasound, in the evacuating helicopter following initial application on the battlefield. Ethical approval Not applicable. Funding None. Author contribution UJ: study design, analysis and writing up. MA, study design and editing of manuscript. VK and RP, data collection and contribution to writing up. MM and NS, study design and editorial input. Conflicts of interest None. Acknowledgements We gratefully acknowledge Patrick Musonda, Medical Statistician at the University of East Anglia for statistical analysis, Paul Watts of DP Medical for supply of the CAT, Faisal Majid for data collection and Mindray Corporation for supply of portable ultrasound equipment. References 1. Humphrey PW, Nichols WK, Silver D. Rural vascular trauma: a twenty-year review. Ann Vasc Surg 1994;8(2):179e85. Epub 1994/03/ Mabry RL, Holcomb JB, Baker AM, Cloonan CC, Uhorchak JM, Perkins DE, et al. United States Army Rangers in Somalia: an analysis of combat casualties on an urban battlefield. J Trauma 2000;49(3):515e28. discussion Epub2000/09/ Moniz MP, Ombrellaro MP, Stevens SL, Freeman MB, Diamond DL, Goldman MH. Concomitant orthopedic and vascular injuries as predictors for limb loss in blunt lower extremity trauma. Am Surg 1997;63(1):24e8. Epub 1997/01/ Patel TH, Wenner KA, Price SA, Weber MA, Leveridge A, McAtee SJ. A U.S. Army forward surgical team s experience in operation Iraqi freedom. J Trauma 2004;57(2):201e7. Epub 2004/09/ Lee C, Porter KM, Hodgetts TJ. Tourniquet use in the civilian prehospital setting. Emerg Med J 2007;24(8):584e7. Epub 2007/07/ Calkins D, Snow C, Costello M, Bentley TB. Evaluation of possible battlefield tourniquet systems for the far-forward setting. Mil Med 2000;165(5):379e84. Epub 2000/05/ Bellamy RF. The causes of death in conventional land warfare: implications for combat casualty care research. Mil Med 1984;149(2):55e62. Epub 1984/02/ Hodgetts TJ, Mahoney PF, Russell MQ, Byers M. ABC to <C> ABC: redefining the military trauma paradigm. Emerg Med J 2006;23(10):745e6. Epub 2006/09/ Battlefield advanced trauma life support (BATLS). J R Army Med Corps 2004;150(1):32e40. Epub 2004/05/ Lakstein D, Blumenfeld A, Sokolov T, Lin G, Bssorai R, Lynn M, et al. Tourniquets for hemorrhage control on the battlefield: a 4-year accumulated experience. J Trauma 2003;54(5 Suppl):S221e5. Epub 2003/05/ Walters TJ, Mabry RL. Issues related to the use of tourniquets on the battlefield. Mil Med 2005;170(9):770e5. Epub 2005/11/ Walters TJ, Wenke JC, Kauvar DS, McManus JG, Holcomb JB, Baer DG. Effectiveness of self-applied tourniquets in human volunteers. Prehosp Emerg Care 2005;9(4):416e22. Epub 2005/11/ Kragh Jr JF, Walters TJ, Baer DG, Fox CJ, Wade CE, Salinas J, et al. Survival with emergency tourniquet use to stop bleeding in major limb trauma. Ann Surg 2009;249(1):1e7. Epub 2008/12/ Kragh Jr JF, Walters TJ, Baer DG, Fox CJ, Wade CE, Salinas J, et al. Practical use of emergency tourniquets to stop bleeding in major limb trauma. J Trauma 2008;64(2 Suppl):S38e49. discussion S-50. Epub 2008/04/11.