Tourniquet System Research Articles

Effectiveness of the American College of Surgeons Bleeding Control Basic Training Among Laypeople Applying Different Tourniquet Types

More than 500 000 laypeople in the United States have been trained in hemorrhage control, including tourniquet application, under the Stop the Bleed campaign. However, it is unclear whether after hemorrhage control training participants become proficient in a specific type of tourniquet or can also use other tourniquets effectively. To assess whether participants completing the American College of Surgeons Bleeding Control Basic (B-Con) training with Combat Application Tourniquets (CATs) can effectively apply bleeding control principles using other tourniquet types (commercial and improvised). This nonblinded, crossover, sequential randomized clinical trial with internal control assessed a volunteer sample of laypeople who attended a B-Con course at Gillette Stadium and the Longwood Medical Area in Boston, Massachusetts, for correct application of each of 5 different tourniquet types immediately after B-Con training from April 4, 2018, to October 9, 2018. The order of application varied for each participant using randomly generated permutated blocks. Full B-Con course, including cognitive and skill sessions, that taught bleeding care, wound pressure and packing, and CAT application. Correct tourniquet application (applied pressure of ≥250 mm Hg with a 2-minute time cap) in a simulated scenario for 3 commercial tourniquets (Special Operation Forces Tactical Tourniquet, Stretch-Wrap-and-Tuck Tourniquet, and Rapid Application Tourniquet System) and improvised tourniquet compared with correct CAT application as an internal control using 4 pairwise Bonferroni-corrected comparisons with the McNemar test. A total of 102 participants (50 [49.0%] male; median [interquartile range] age, 37.5 [27.0-53.0] years) were included in the study. Participants correctly applied the CAT at a significantly higher rate (92.2%) than all other commercial tourniquet types (Special Operation Forces Tactical Tourniquet, 68.6%; Stretch-Wrap-and-Tuck Tourniquet, 11.8%; Rapid Application Tourniquet System, 11.8%) and the improvised tourniquet (32.4%) (P < .001 for each pairwise comparison). When comparing tourniquets applied correctly, all tourniquet types had higher estimated blood loss, had longer application time, and applied less pressure than the CAT. The B-Con principles for correct CAT application are not fully translatable to other commercial or improvised tourniquet types. This study demonstrates a disconnect between the B-Con course and tourniquet designs available for bystander first aid, potentially stemming from the lack of consensus guidelines. These results suggest that current B-Con trainees may not be prepared to care for bleeding patients as tourniquet design evolves. ClinicalTrials.gov identifier: NCT03538379.

B.F.R. For Proximal Benefit: Blood Flow Restriction Therapy For The Shoulder?

Blood flow restriction (BFR) therapy has been observed to improve post-operative recovery in the limbs when combined with low intensity resistance exercise (LIX). Little data exists regarding use of BFR for proximal benefit of the upper limbs (shoulders). PURPOSE: (1) Determine if rotator cuff (RC) exercises combined with BFR (BFR-Rx) promote greater increases in strength, muscular endurance, and lean mass compared to exercise alone (NoBFR-Rx); (2) Determine if BFR applied to the arm during acute LIX increases activation of RC muscles. METHODS: Eighteen healthy adults (♂11, 32±5yr, 92.3±15.2kg | ♀7, 34±7yr, 81.9±6.3kg) were recruited and randomized into 2 groups (BFR-Rx, NoBFR-Rx). Each performed 8wks of LIX (2/wk) using 4 RC exercises: cable external rotation (ER), cable internal rotation (IR), dumbbell scaption, and side-lying dumbbell ER; 20%1RM; 1set/30reps followed by 3sets/15reps (30s rest between sets, 2min rest between exercises, ^1lb resistance each week all repetitions achieved). For the BFR-Rx group, BFR was applied to using an tourniquet system (Delfi®) that maintained 50% limb occlusion pressure during each exercise with pressure released between exercises. A group x time ANCOVA (co-varied on baseline) followed by a tukey’s post hoc test was used to detect absolute & relative changes in strength (pre/post training), lean mass (pre/post training; DEXA, GE®), and achieved weekly exercise volume (sets x reps x resistance). A two-tailed paired samples t-test was used to detect differences in RC muscle activation (EMG, Delsys®) recorded during acute ER and IR fatigue tests in all subjects. Type I error was set at α=0.05. CONCLUSIONS: Combined BFR-Rx using RC exercises may yield greater increases in shoulder/arm lean mass, strength, and muscular endurance compared to exercise alone. These findings may be partially due to a greater activation of shoulder musculature while using BFR. Data collection is ongoing and will be completed prior to conference.

Efficacy of Novel Commercial Tourniquet Systems in Extremity Hemorrhage Control - An Ultrasound and Generated Force Study

Introduction:Tourniquets (TQ) save lives. Although military-approved TQ are more effective than improvised TQ in controlling exsanguinating extremity hemorrhage, their bulk may preclude every day carry (EDC) by civilian lay-providers.Aim:The purpose of the current study was to compare the efficacy of 3 novel commercial TQ to a military-approved TQ.Methods:A convenience sample of EM residents was utilized. Four different TQ were evaluated: Gen 7 Combat Application Tourniquet (CAT; control), Stretch Wrap and Tuck Tourniquet (SWAT-T), Gen 2 Rapid Application Tourniquet System (RATS), and Tourni-Key (TK). Popliteal artery occlusion was determined using a ZONARE ZS3 ultrasound. Steady-state maximal generated force was measured for 30 seconds with a thin-film force sensor (Singletract). Opinions were solicited at the conclusion of the study.Results:Nine residents participated in the study (7 male, 2 female). Success rates for complete arterial occlusion were 89% CAT, 67% SWAT-T, 89% RATS, and 78% TK (H 0.89, p = 0.83). Mean (± SD) times to achieve occlusion were 10.4 ± 1.7 sec CAT, 23.1 ± 9.0 sec SWAT-T, 11.1 ± 3.8 sec RATS, and 20.0 ± 7.1 sec TK (F 9.71, p &lt; 0.001). Steady-state maximal forces were 29.9 ± 1.2 N CAT, 23.4 ± 0.8 N SWAT-T, 33.0 ± 1.3 N RATS, and 41.9 ± 1.3 N TK. Participants felt that the CAT was easiest to apply (61%), followed by the RATS (33%). Participants were most likely to select the TK (44%) for EDC, followed by the RATS (33%).Discussion:In this small convenience sampling, all novel TQ systems were non-inferior to the military-approved CAT TQ. Mean application times were less than 30 seconds. The size and unique nature of these novel TQs may make them more conducive to lay-provider EDC, thereby improving the response to high threat events.

Blood Flow Restriction Exercise Increases the ACE2/ACE Ratio and ACE2 Shedding in CD34+ Cells in Healthy Individuals

Adult CD34+ hematopoietic stem/progenitor cells in the systemic circulation are bone marrow‐derived and have the propensity of maintaining cardiovascular health. We have previously shown that activation of the vascular protective axis of renin angiotensin system (RAS), Angiotensin Converting enzyme‐2 (ACE2)/Angiotensin‐(1–7)/Mas receptor axis stimulates vasoreparative functions of CD34+ cells in health and disease. Importantly, in vitro exposure of CD34+ cells to hypoxia enhanced the expressions of ACE2 and Mas, and stimulated ACE2 shedding, but ACE and AT1 receptors, members of the vascular detrimental axis of RAS were not affected. This study tested if acute regional hypoxia recapitulates the in vitro observations in healthy individuals. Blood flow restriction exercise (BFR) was performed in the lower body by applying 80% limb occlusion pressure (LOP). Delphi personalized tourniquet system was used to accomplish the target LOP. Exercise protocol consisted of total four sets (30/15/15/15 repetitions) of movements at 10% of maximal strength. Muscle oxygen saturation was determined by using MOXY muscle oxygen monitor. Peripheral blood was collected two weeks before (control) and 30 min after BFR. CD34+ cells were enumerated by flow cytometry, and ACE and ACE2 activities in plasma, and in cell lysates and cell‐free supernatants were determined. Plasma concentrations of SDF and VEGF were analyzed by ELISA. BFR prescribed at 80% LOP resulted in muscle oxygen levels of 14.1% compared to 50.9% in the resting condition. As predicted, circulating CD34+ cells were increased following BFR (before 356±59.1 and after 835±62.1/mL blood, P&lt;0.001, n=5), which was associated with increased plasma levels of SDF and VEGF (4‐ and 3‐fold, respectively, compared to control (P&lt;0.001, n=5)). ACE2 activity was increased in the whole cell lysates of Lineage‐negative cells resulting in the ACE2/ACE ratio of 11.7±0.5 compared to the baseline ratio of 9.1±0.9 (P&lt;0.05, n=5). Cell supernatants have 3‐fold increase in ACE2/ACE ratio following BFR compared to the baseline levels (P&lt;0.001, n=5). Collectively, these findings provide compelling evidence for the upregulation of ACE2, the vasoprotective enzyme of RAS, by acute regional hypoxia in HSPCs. BFR‐exercise regimen could be a promising approach for enhancing or restoring cardiovascular health in individuals that are poor mobilizers or those at risk for the development of cardiovascular complications.Support or Funding InformationNational Institute of General Medical Sciences (NIGMS) and National Institute of Aging (NIA) AG056881.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Smart tourniquet systems for military and civilian applications

Smart tourniquet systems for military and civilian applications

Silicone ring tourniquet versus pneumatic cuff tourniquet in total knee arthroplasty surgery: A randomised comparative study

IntroductionThe aim of the present study was to compare a silicone ring tourniquet (SRT) and a classic pneumatic cuff tourniquet (PT) in patients undergoing total knee replacement. We have compared the impact on the glycolytic activity caused by the ischaemia applied to the limb during the surgery. Material and methods140 patients that underwent total knee arthroplasty (TKA) were randomised in two groups. Serum lactate determination was made by reactive strips of enzymatic-amperometric detection, 5 min before tourniquet application and 5 min after tourniquet removal. ResultsThe mean tourniquet time was similar for both groups (p 0.13). Postoperative serum lactate levels were higher with statistical significance than the preoperative levels and with a positive Pearson´s correlation in the overall cases. The postoperative serum lactate levels where higher in the PT group (4.097 ± 2.248 mmol/L) than the SRT group (3.499 ± 1.566 mmol/L). There was no significant difference (p 0.07) to be able to affirm that there was a difference of the anaerobic metabolism according to the tourniquet system used. DiscussionIschaemia applied to the lower extremity during knee replacement surgery can produce tissue injury. Serum lactate determination allows comparison of the ischaemic changes during TKA surgery caused by two different tourniquet systems. ConclusionsSRT may be not disadvantageous compared to the classic PT from the impact on the glycolytic activity caused by the ischaemia.Level of evidence II.

Influence and reliability of lower-limb arterial occlusion pressure at different body positions.

BackgroundTotal arterial occlusive pressure (AOP) is used to prescribe pressures for surgery, blood flow restriction exercise (BFRE) and ischemic preconditioning (IPC). AOP is often measured in a supine position; however, the influence of body position on AOP measurement is unknown and may influence level of occlusion in different positions during BFR and IPC. The aim of this study was therefore to investigate the influence of body position on AOP.MethodsFifty healthy individuals (age = 29 ± 6 y) underwent AOP measurements on the dominant lower-limb in supine, seated and standing positions in a randomised order. AOP was measured automatically using the Delfi Personalised Tourniquet System device, with each measurement separated by 5 min of rest.ResultsArterial occlusive pressure was significantly lower in the supine position compared to the seated position (187.00 ± 32.5 vs 204.00 ± 28.5 mmHg, p < 0.001) and standing position (187.00 ± 32.5 vs 241.50 ± 49.3 mmHg, p < 0.001). AOP was significantly higher in the standing position compared to the seated position (241.50 ± 49.3 vs 204.00 ± 28.5 mmHg, p < 0.001).DiscussionArterial occlusive pressure measurement is body position dependent, thus for accurate prescription of occlusion pressure during surgery, BFR and IPC, AOP should be measured in the position intended for subsequent application of occlusion.

Does Pain Have a Role When It Comes to Tourniquet Training?

One of the greatest conundrums with tourniquet (TQ) education is the use of an appropriate surrogate of hemorrhage in the training setting to determine whether a TQ has been successfully used. At our facility, we currently use loss of audible Doppler signal or loss of palpable pulse to represent adequate occlusion of vasculature and thus successful TQ application. We set out to determine whether pain can be used to indicate successful TQ application in the training setting. Three tourniquet systems (a pneumatic tourniquet, Combat Application Tourniquet® [C-A-T], and Stretch Wrap and Tuck Tourniquet™ [SWAT-T]) were used to occlude the arterial vasculature of the left upper arm (LUA), right upper arm (RUA), left forearm (LFA), right forearm (RFA), right thigh (RTH), and right calf (RCA) of 41 volunteers. A 4MHz, handheld Doppler ultrasound was used to confirm loss of Doppler signal (LOS) at the radial or posterior tibial artery to denote successful TQ application. Once successful placement of the TQ was noted, subjects rated their pain from 0 to 10 on the visual analog scale. In addition, the circumference of each limb, the pressure with the pneumatic TQ, number of twists with the C-A-T, and length of TQ used for the SWAT-T to obtain LOS was recorded. All 41 subjects had measurements at all anatomic sites with the pneumatic TQ, except one participant who was unable to complete the LUA. In total, pain was rated as 1 or less by 61% of subjects for LUA, 50% for LFA, 57.5% for RUA, 52.5% RFA, 15% for RTH, and 25% for RCA. Pain was rated 3 or 4 by 45% of subjects for RTH. For the C-A-T, data were collected from 40 participants. In total, pain was rated as 1 or less by 57.5% for the LUA, 70% for the LFA, 62.5% for the RUA, 75% for the RFA, 15% for the RTH, and 40% for the RCA. Pain was rated 3 or 4 by 42.5%. The SWAT-T group consisted of 37 participants for all anatomic locations. In total, pain was rated as 1 or less by 27% for LUA, 40.5% for the LFA, 27.0% for the RUA, 43.2 for the RFA, 18.9% for the RTH, and 16.2% for the RCA. Pain was rated 5 by 21.6% for RTH application, and 3 or 4 by 35%. The unexpected low pain values recorded when loss of signal was reached make the use of pain too sensitive as an indicator to confirm adequate occlusion of vasculature and, thus, successful TQ application.

The Combat Application Tourniquet Versus the Tactical Mechanical Tourniquet.

Exsanguination from limb injury is an important battlefield consideration that is mitigated with the use of emergency tourniquets. The Combat Application Tourniquet (C-A-T®) is the current British military standard tourniquet. We tested the self-application of a newer tourniquet system, the Tactical Mechanical Tourniquet (TMT), against self-application of the C-A-T. A total of 24 healthy British military volunteers self-applied the C-A-T and the TMT to their mid thigh in a randomized, sequential manner. Popliteal artery flow was monitored with a portable ultrasound machine, and time until arterial occlusion was measured. Pain scores were also recorded. Results The volunteers allowed testing on their lower limbs (n = 48 legs). The C-A-T was applied successfully to 22 volunteers (92%), and the TMT was successfully applied to 17 (71%). Median time to reach complete arterial occlusion was 37.5 (interquartile range [IQR], 27-52) seconds with the C-A-T, and 35 (IQR, 29-42) seconds with the TMT. The 2.5-second difference in median times was not significant (ρ = .589). The 1-in-10 difference in median pain score was also not significant (ρ = .656). The success or failure of self-application between the two tourniquet models as assessed by contingency table was not significant (p= .137). The TMT is effective when self-applied at the mid thigh. It does not offer an efficacy advantage over the C-A-T.

Efficacy and safety of a new elastic tourniquet cuff in total knee arthroplasty: a prospective randomized controlled study

BackgroundThe effects of cuff shape, timing of tourniquet application, and automated systems using limb occlusion pressure (LOP) have been reported to minimize the appropriate tourniquet pressure. However, studies on the raw material of the cuff itself to reduce the complications related to the tourniquet have been very rarely reported. The purpose of this study is to report the efficacy and safety of a tourniquet system with a new elastic cuff in which pressure is set with LOP in total knee arthroplasty (TKA).MethodsA total of 63 patients who underwent primary TKA for osteoarthritis were enrolled from July to December 2015. Thirty-one patients were allocated to the new elastic cuff group and 32 in the conventional cuff group. Bloodless surgical field, pain visual analog scale (VAS) on the thigh, thigh circumference, range of motion, incidence of deep vein thrombosis, and muscle enzyme level after surgery were checked and compared between the 2 groups.ResultsOnly 1 of the 31 patients in the elastic cuff group required more pressure for obtaining a bloodless surgical field, whereas 4 of the 32 patients in the conventional cuff group required more pressure to complete surgery without being disturbed by sustained bleeding. Two patients in the conventional cuff group needed treatment for blisters and bullae at the tourniquet application site. There was no difference in pain VAS score, thigh circumference, range of motion, incidence of deep vein thrombosis, and level of muscle enzyme.ConclusionsA new elastic tourniquet cuff provided a more proper bloodless surgical field with less adjustment of tourniquet pressure despite a similar level of tourniquet pressure compared to the conventional cuff and had a low incidence of skin complications on the site of tourniquet application in TKA. These benefits make it an effective and safe medical device for orthopedic surgery requiring a tourniquet, such as TKA.

A study of the blood flow restriction pressure of a tourniquet system to facilitate development of a system that can prevent musculoskeletal complications.

After an emergency or disaster, subsequent trauma can cause severe bleeding and this can often prove fatal, so promptly stopping that bleeding is crucial to preventing avoidable trauma deaths. A tourniquet is often used to restrict blood flow to an extremity. In operation and hospital, the tourniquet systems currently in use are pneumatically actuated by an air compressor, so they must have a steady power supply. These devices have several drawbacks: they vibrate and are noisy since they are pneumatically actuated and they are far from portable since they are large and heavy. Presumably, the drawbacks of pneumatic tourniquets could be overcome by developing a small, lightweight, vibration-free, quiet, and battery-powered tourniquet system. The current study built a small, vibration-free electrohydrodynamic (EHD) pump and then used that pump to restrict blood flow to the leg of rats in an experiment. This study explored the optimal conditions for effective restriction of blood flow by assessing biochemical and musculoskeletal complications following the restriction of blood flow, and this study also examined whether or not an EHD pump could be used to actuate a tourniquet system. A tourniquet cuff (width 12 mm × length 150 mm, material: polyolefin) was placed on the thigh of Wistar rats and pressure was applied for 2 hours by a device that uses EHD phenomena to generate pressure (an EHD pump). Animals were divided into four groups based on how much compressive pressure was applied with a tourniquet: 40 kPa (300 mm Hg, n = 13), 30 kPa (225 mm Hg, n = 12), 20 kPa (150 mm Hg, n = 15), or 0 kPa (controls, n = 25). Tissue oxygen saturation (regional oxygen saturation, denoted here as rSO2) was measured to assess the restriction of blood flow. To assess behavior once blood flow resumed, animal activity was monitored for third day and the amount of movement was counted with digital counters. Body weight was measured before and after the behavioral experiment, and changes in body weight were determined. Blood was sampled after a behavioral experiment and biochemically assessed and creatine kinase (CK) levels were measured. Tissue oxygen saturation decreased significantly in each group. When a tourniquet was applied at a pressure of 30 kPa or more, tissue oxygen saturation decreased significantly. The amount of movement (the count) over third day decreased more when a tourniquet was applied at a higher pressure. The control group resumed the same amount of movement per day second after blood flow resumed. Animals to which a tourniquet was applied at a pressure of 20 or 30 kPa resumed the same amount of movement third day after blood flow resumed. In contrast, animals to which a tourniquet was applied at a pressure of 40 kPa did not resume the same amount of movement third day after blood flow resumed. After the behavioral experiment, animals to which a tourniquet was applied at a pressure of 40 kPa had a significantly lower body weight in comparison to the control group. After the behavioral experiment, animals to which a tourniquet was applied at a pressure of 40 kPa had significantly elevated CK levels in comparison to the control group. A relationship between blood flow restriction pressure and tissue oxygen saturation was noted. rSO2 measurement can be used to assess the restriction of blood flow during surgery. On the basis of the decrease in rSO2, blood flow was effectively restricted at a pressure of 30 kPa or more. When, however, blood flow was restricted at a pressure of 40 kPa, weight loss and decreased movement were noted and CK levels increased after the behavioral experiment. Thus, complications had presumably developed due to damage to muscle tissue. These findings indicate that blood flow was effectively restricted in this experiment and they also indicate the existence of an optimal blood flow restriction pressure that does not cause musculoskeletal complications. The pressure in question was around 30 kPa. The tourniquet system that was developed here is actuated with an EHD pump that is still in the trial stages. That said, its pressure can readily be controlled and this pump could be used in a tourniquet system since it is quiet, vibration-free, and small. The pressure of this pump can be finely adjusted to prevent musculoskeletal complications.

Technique for Measuring Limb Occlusion Pressure that Facilitates Personalized Tourniquet Systems: A Randomized Trial.

We developed a technique for measuring patient limb occlusion pressure (LOP) through a tourniquet cuff that overcomes many limitations of existing LOP measurement techniques. The purpose of the study is to determine whether the LOP measured by the proposed technique is statistically or clinically different from that measured by the gold standard Doppler ultrasound technique. The study used randomized crossover multicenter trials. 143 pre- and post-surgical patients with a mean age of 54 years (range 17–86 years) were enrolled in the study. Pneumatic cuffs were applied to the non-operative upper and lower limbs and LOP was measured using the proposed technique and the Doppler ultrasound technique. From a total of 252 usable measurements for each technique (134 for upper limbs and 118 for lower limbs), the mean difference in LOP between the two techniques was 1 ± 8 mmHg for the upper limbs, 0 ± 15 mmHg for the lower limbs, and 1 ± 12 mmHg overall. The differences between the proposed technique and the Doppler technique were neither statistically nor clinically significant. The simplicity, effectiveness, and accuracy of the proposed technique should lead to broader clinical usage and acceptance of LOP measurement, thus leading to safer, personalized pressures in surgical tourniquet applications.

New Technique for Measuring Limb Occlusion Pressure Facilitates Personalized Tourniquet Systems

Category: Basic Sciences/Biologics Introduction/Purpose: Optimal tourniquet safety depends on accurately determining the minimum pressure necessary to achieve a bloodless surgical field, known as a patient’s limb occlusion pressure (LOP). However, LOP is not yet routinely measured in all patients due to limitations of current techniques. We have evaluated a novel technique for measuring the LOP through the tourniquet cuff that overcomes many limitations of current LOP measurement techniques. Methods: The new technique of measuring LOP involves the use of unique dual-purpose disposable tourniquet cuffs along with a tourniquet instrument containing LOP calculation sensors and software. A randomized crossover multicenter trial with 143 pre-surgical or post-surgical patients enrolled in the study. Pneumatic cuffs were applied to the non-operative upper and lower limbs and LOP was measured using the new technique and the Doppler ultrasound technique. For each patient a set of four LOP measurements was taken, using the new technique (experimental) and the Doppler technique (control) on one upper and one lower limb. Blinding was achieved during LOP measurement by using two experimenters and blinding the experimenter who measured the LOP using Doppler ultrasound from the LOP reading using the new automatic technique. Participants were blinded from all LOP measurement results by keeping the displays of measurement equipment out of their view. Results: The differences between the new technique and Doppler technique were neither statistically nor clinically significant and the new technique is as robust as the Doppler technique. The results of this study can be used to develop personalized tourniquet systems consisting of unique dual-purpose cuffs connected to instruments suitable for measuring tourniquet LOP with the new measurement technique. The simplicity, effectiveness, and accuracy of this technique should lead to broader clinical usage and acceptance of LOP measurement, thus leading to safer, personalized pressures in surgical tourniquet applications. Conclusion: The new technique is equally robust as the Doppler technique. Both techniques worked successfully in the 252 limbs from which usable data was collected. Of the 34 limbs for which there were data collection errors or exclusion, only two measurements were excluded because of an instrument error using the automatic technique compared to one measurement excluded because of a Doppler technique measurement error.

Pure laparoscopic right hemihepatectomy by the caudodorsal side approach

Aims: We have performed pure laparoscopic right hemihepatectomy for 14 patients. We present our standardized procedure using the caudodorsal side approach. Methods: A trocar as a scope was placed at the umbilicus and 4 trocars for the instruments were placed beneath the costal arch. A tourniquet system for Pringle's maneuver was prepared and its use was initiated when the field could not be kept dry. Parenchymal dissection proceeded utilizing a unique laparoscopic view from the caudal side. The caudate lobe was dissected from the right-ventral side of the vena cava and hanging tape was placed between the right and middle hepatic vein. The right Glissonean pedicle was taped after opening Calot's area. The caudate lobe was cut first from the back side by using CUSA. Then, the parenchyma just above the hilar plate was divided along the major hepatic fissure and the inferior aspect of the middle hepatic vein (MHV) was exposed near the hilum. After this, parenchymal dissection was advanced between the demarcation line on the liver surface and the MHV, exposing the MHV on the cutting plane of the liver remnant. After sufficient opening of the major hepatic fissure on the cranial side of the hepatic hilum, the anterior and posterior Glissonean pedicles were divided separately. Then, division proceeded toward the hanging tape, pulling the cranial side liver to the caudal side. After accomplishing parenchymal dissection, the right hepatic vein was divided and finally the right lobe was dissected from the diaphragm. Results: The mean operation time was 452 min. The mean blood loss was 331 g. The only major postoperative complication was bile leakage in one patient. The postoperative courses of the other patients were uneventful. Conclusions: Our standardized procedure utilizing the unique view from the caudal side in the laparoscopic approach is feasible and safe.

Preliminary Comparison of New and Established Tactical Tourniquets in a Manikin Hemorrhage Model

Emergency tourniquet use has been associated with hemorrhage control and improved survival during the wars since 2001. The purpose of the present study is to compare the differential performance of two new tactical tourniquets with the standard-issue tourniquet to provide preliminary evidence to guide decisions on device development.A laboratory experiment was designed to test the effectiveness of tourniquets on a manikin thigh. Three models of tourniquets were assessed. The Rapid Application Tourniquet System (RATS) and the Tactical Mechanical Tourniquet (TMT) were compared with the standard-issue Combat Application Tourniquet(®) (C-A-T). Two users conducted 30 tests each.Percentages for effectiveness (hemorrhage control, yes/no) and distal pulse cessation did not differ significantly by model. When compared with the RATS, the C-A-T performed better (ρ < .001) for time to hemorrhage control and fluid loss. The C-A-T and TMT had comparable responses for most measures, but the C-A-T applied more pressure (ρ = .04) than did the TMT for hemorrhage control.All three tactical tourniquets showed substantial capacity for hemorrhage control. However, the two new tourniquet models (RATS and TMT) did not offer any improvement over the C-A-T, which is currently issued to military services. Indeed, one of the new models, the RATS, was inferior to the C-A-T in terms of speed of application and simulated loss of blood. Opportunities were detected for refinements in design of the two new tourniquets that may offer future improvements in their performance.

Low Spring Index NiTi Coil Actuators for Use in Active Compression Garments

This paper describes the modeling, development, and testing of low spring index nickel titanium (NiTi) coil actuators designed for use in wearable compression garments, and presents a prototype tourniquet system using these actuators. NiTi coil actuators produce both large forces (>1 N) and large recoverable displacements (>100% length) that are well suited for compression garment design. Thermomechanical coil models are presented that describe temperature and force as a function of nondimensionalized coil geometry, extensional strain, and applied voltage. These models suggest that low spring index coils maximize activation force, and an analytical model is presented to predict garment counter-pressure based on actuator architecture. Several low spring index ( C $=$ 3.08) coils were manufactured, annealed, and tested to assess their detwinning and activation characteristics. Results suggest both annealing and applied stress affect activation thresholds. Actuator force increases both with extensional strain and applied voltage up to 7.24 N. A first-generation compression tourniquet system using integrated actuators with direct voltage control of applied pressure is presented, demonstrating >70% increase in applied pressure during activation. This approach enables new, dynamic garments with controllable activation and low effort donning and doffing, with applications ranging from healthcare solutions to advanced space suit design.

Pneumatic Tourniquet for Surgical Procedures of Hemodialysis Vascular Access

Pneumatic tourniquet has been frequently utilized in various surgical specialties to facilitate surgical procedures on the extremities. However, its use for surgical procedures of hemodialysis access has been limited to some surgeons in the United States and often confined to the hospital settings under general anesthesia or regional nerve block. We have successfully employed a pneumatic tourniquet system for surgical procedures of hemodialysis access under conscious sedation and local anesthesia in an outpatient setting. Because prolonged tourniquet inflation is associated with ischemic pain and other potential complications, we have limited the continuous inflation time to <30minutes. Our recent data from 550 surgical procedures of hemodialysis access have emphasized that pneumatic tourniquet use is well tolerated under conscious sedation and not associated with significant adverse events. These and other reported data suggest that pneumatic tourniquet can reduce procedure time, minimize required dissection, reduce vascular trauma by eliminating vascular clamps and potentially improve the outcomes of surgical procedures of hemodialysis access. These advantages may be translated into cost savings for hemodialysis access care. This review discusses practical issues of pneumatic tourniquet use and its applications in surgical procedures of hemodialysis access.

Development of adaptive pneumatic tourniquet systems based on minimal inflation pressure for upper limb surgeries

BackgroundPneumatic tourniquets are medical devices that occlude blood flow to distal part of extremities and are commonly used in upper limb surgeries to provide a dry, clean and bloodless field. To decrease pressure-related injuries and potential risk of complications subjected to the high inflation pressure of pneumatic tourniquet, minimal inflation pressures are recommended.MethodsA new occlusion pressure mathematical model for the upper limb was established based on the correlation analysis between several possible influencing parameters and the minimal pneumatic tourniquet pressure at which the peripheral pulse disappeared was recorded using a digital plethysmograph. A prototype of an adaptive pneumatic tourniquet which automatically varies the pressure in the tourniquet cuff according to the above prediction model was developed for the upper limb which used the lowest possible inflation pressure to achieve occlusion. The prototype comprises a blood pressure monitoring module, an inflatable tourniquet cuff, and a pressure relief mechanism to maintain an optimal cuff inflation pressure. Simulation experiments were conducted to verify the function and stability of the designed adaptive pneumatic tourniquet and clinical experiments using volunteers were undertaken to evaluate the performance of the prototype design in achieving adequate haemostasis in the upper limb.ResultsResults demonstrated that the mean arterial occlusion pressure was 152.3 ± 16.7 mmHg, obviously below the 250 to 300 mmHg previously recommended (J Bone Joint Surg Br 68:625-628, 1986 and Arthroscopy 11:307–311, 1995).ConclusionsIn conclusion, this adaptive method and apparatus which can provide minimal inflation pressure may be a clinically practical alternative for upper limb surgery performed with pneumatic tourniquets.

Useful and convenient procedure for intermittent vascular occlusion in laparoscopic hepatectomy

While the amount of blood loss during laparoscopic hepatectomy tends to be smaller than that during open hepatectomy, intermittent vascular occlusion to control hepatic inflow can diminish blood loss during laparoscopic hepatectomy. Described herein is a useful and convenient method for intermittent vascular occlusion, which was standardized for laparoscopic hepatectomy. A tourniquet system consisting of cloth tape and a 20-cm catheter was used for intermittent vascular occlusion. This was placed through a hole in the abdominal wall from which a 5-mm trocar had been extracted. By operating this tourniquet system outside the patient's body, we were easily able to repeat intermittent vascular occlusion. Twenty-three patients underwent laparoscopic hepatectomy using this system. The mean time of operation and vascular occlusion were 311.6 and 83.6 min, respectively. The mean blood loss was 215.0 mL. There were no intraoperative blood transfusions or critical postoperative complications. The average length of postoperative hospital stay was 6.5 days. The mean time to place this system was 354 s, and there were no complications caused by this system. During totally laparoscopic hepatectomy, surgeons can perform intermittent vascular occlusion safely by using this method.

Safety and efficacy of a new tourniquet system

BackgroundIn upper limb surgery, the pneumatic tourniquet is an essential tool to provide a clean, bloodless surgical field, improving visualization of anatomical structures and preventing iatrogenic failure. Optimal inflation pressure to accomplish these objects without injuring normal tissue and inducing complications is not yet established. Use of the minimum tourniquet pressure necessary to produce a bloodless surgical field is preferable in order to prevent injury to normal tissue. Various methods have been implemented in an effort to lower effective cuff pressure. The purpose of this study is to report clinical experience with a new tourniquet system in which pressure is synchronized with systolic blood pressure (SBP) using a vital information monitor.MethodsWe routinely used the tourniquet system in 120 consecutive upper limb surgeries performed under general anaesthesia in our operating room instead of our clinic. Cuff pressure was automatically regulated to additional 100 mmHg based on the SBP and was renewed every 2.5 minutes intervals.ResultsAn excellent bloodless field was obtained in 119 cases, with the exception of one case of a 44-year-old woman who underwent internal screw fixation of metacarpal fracture. No complications, such as compartment syndrome, deep vein disorder, skin disorder, paresis, or nerve damage, occurred during or after surgery.ConclusionsThis new tourniquet system, synchronized with SBP, can be varied to correspond with sharp rises or drops in SBP to supply adequate pressure. The system reduces labor needed to deflate and re-inflate to achieve different pressures. It also seemed to contribute to the safety in upper limb surgery, in spite of rare unexpected oozing mid-surgery, by reducing tissue pressure.