Is Tourniquet Pain the Result of Increased Compartment Pressure in the Forearm?

ABSTRACT: The pneumatic tourniquet has been a mainstay in upper extremity surgery by allowing the surgeon to operate in a blood-free field. Many upper extremity surgical procedures are done under local anesthesia or minimal sedation, and the problem of tourniquet pain is a vexing one. The question is posed: Is tourniquet pain the result of increased compartment pressure in the forearm? This study measured compartment pressures of the volar forearm in 10 healthy normotensive volunteers before inflation of a pneumatic tourniquet and compared it with pressure measurements taken while the tourniquet was still inflated after 15 minutes. Compartment pressures were measured using a Stryker needle manometer; all measurements were taken in the volar forearm by the senior author (C.H.M.). There was no increase in the volar/flexor compartment pressure of the forearm after 15 minutes of tourniquet inflation. All subjects complained of pain of the forearm, characteristically what is commonly called "tourniquet pain." We therefore conclude that in the upper extremity, at least for relatively short operating times, appropriate inflation of a tourniquet does not induce the early onset of increased compartment pressure in the forearm.

Effectiveness and safety of tourniquet utilization for civilian vascular extremity trauma in the pre-hospital settings: a systematic review and meta-analysis.

BACKGROUND: Tourniquets (TQ) have been increasingly adopted in pre-hospital settings recently. This study examined the effectiveness and safety of applying TQ in the pre-hospital settings for civilian patients with traumatic vascular injuries to the extremities. MATERIALS AND METHODS: We systematically searched the Ovid Embase, PubMed, and Cochrane Central Register of Controlled Trials databases from their inception to June 2023. We compared pre-hospital TQ (PH-TQ) use to no PH-TQ, defined as a TQ applied after hospital arrival or no TQ use at all, for civilian vascular extremity trauma patients. The primary outcome was overall mortality rate, and the secondary outcomes were blood product use and hospital stay. We analyzed TQ-related complications as safety outcomes. We tried to include randomized controlled trials (RCTs) and non-randomized studies (including non-RCTs, interrupted time series, controlled before-and-after studies, cohort studies, and case-control studies), if available. Pooled odds ratios (ORs) were calculated and the certainty of evidence was assessed using Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology. RESULTS: Seven studies involving 4,095 patients were included. In the primary outcome, pre-hospital TQ (PH-TQ) use significantly decrease mortality rate in patients with extremity trauma (odds ratio [OR], 0.48, 95% confidence interval [CI] 0.27-0.86, I2 = 47%). Moreover, the use of PH-TQ showed the decreasing trend of utilization of blood products, such as packed red blood cells (mean difference [MD]: -2.1 [unit], 95% CI: -5.0 to 0.8, I2 = 99%) or fresh frozen plasma (MD: -1.0 [unit], 95% CI: -4.0 to 2.0, I2 = 98%); however, both are not statistically significant. No significant differences were observed in the lengths of hospital and intensive care unit stays. For the safety outcomes, PH-TQ use did not significantly increase risk of amputation (OR: 0.85, 95% CI: 0.43 to 1.68, I2 = 60%) or compartment syndrome (OR: 0.94, 95% CI: 0.37 to 2.35, I2 = 0%). The certainty of the evidence was very low across all outcomes. CONCLUSION: The current data suggest that, in the pre-hospital settings, PH-TQ use for civilian patients with vascular traumatic injury of the extremities decreased mortality and tended to decrease blood transfusions. This did not increase the risk of amputation or compartment syndrome significantly.

Tourniquet does not affect intraoperative kinematics during total knee arthroplasty: Results of a prospective study using a robotic assistance system.

PURPOSE: Tourniquet use during total knee arthroplasty (TKA) remains controversial. There are limited data demonstrating the effect of tourniquet use on flexion and extension gaps. The use of a tourniquet can theoretically affect the kinematics of the knee joint, specifically the extension and flexion gaps and the laxity, by mechanically compressing the soft tissues including the muscles above the knee joint. Therefore, this study was designed to prospectively evaluate changes in flexion and extension gaps with and without the use of a tourniquet. METHODS: The following prospective study included 50 consecutive patients who underwent TKA using a surgical robot. The inclusion criteria were advanced osteoarthritis (OA) and varus-alignment or valgus-alignment <3° (hip-knee-ankle angle, standing long-leg X-ray), and the exclusion criteria were BMI >35 kg/m2 and mechanical axis in >3° valgus. A CR-TKA was performed, and the medial and lateral gaps (in mm) throughout the full range of motion in 10° increments were recorded. The procedure was conducted both with and without an applied tourniquet (350 mmHg). RESULTS: No significant differences were observed in the medial joint space. By contrast, the lateral gap showed significant differences in 10-20° of flexion (with a tourniquet 1.9 mm vs. without a tourniquet 2.1 mm, p = 0.018), 20-30° (1.6 vs. 1.8 mm, p = 0.02), 100-110° (0.9 vs. 1.1 mm, p = 0.021), and 110-120° (0.8 vs. 1 mm, p = 0.038). Thus, at the above degrees of flexion on the lateral side, there was a decrease in the mean of 0.2 mm with the use of a tourniquet. CONCLUSION: Although the use of a tourniquet showed a detectable change in the lateral gap in four 10° segments of flexion, clinical relevance with an average difference of 0.2 mm is not achieved. Thus, the use of a tourniquet in TKA can still be advocated based on the presented data. LEVEL OF EVIDENCE: Level I.

Prospective Analysis of Simulated Pneumatic Tourniquet Use and Oedema Following Axillary Lymph Node Dissection.

Background: Tourniquet use during upper extremity surgery in patients with a history of axillary lymph node dissection (ALND) remains controversial due to the perceived but unproven risk of lymphoedema. We prospectively evaluated upper extremity swelling in patients with a history of unilateral ALND using a standardised tourniquet model. Methods: A tourniquet was applied to the upper arm bilaterally, with the unaffected side serving as an internal control. Each arm was subsequently held in an elevated position to reduce swelling. Hand volume was measured using an aqueous volumeter. Results: The patients' ALND arms experienced slightly greater increases in volume following tourniquet application compared to their healthy control arms. However, this amount of oedema was temporary and reversible, as both arms experienced spontaneous resolution of swelling with no significant difference in residual hand volume at the conclusion of the study. Conclusions: Tourniquet use may be safe in patients with a history of ALND. Further investigation is needed to verify this in a surgical setting. Level of Evidence: Level II (Therapeutic).

Aquatic Feasibility of Limbs Application of Tourniquets (AFLAT) during a Lifeguard Water Rescue: A Simulation Pilot Study.

INTRODUCTION: Control of massive hemorrhage (MH) is a life-saving intervention. The use of tourniquets has been studied in prehospital and battlefield settings but not in aquatic environments. OBJECTIVE: The aim of this research is to assess the control of MH in an aquatic environment by analyzing the usability of two tourniquet models with different adjustment mechanisms: windlass rod versus ratchet. METHODOLOGY: A pilot simulation study was conducted using a randomized crossover design to assess the control of MH resulting from an upper extremity arterial perforation in an aquatic setting. A sample of 24 trained lifeguards performed two randomized tests: one using a windlass-based Combat Application Tourniquet 7 Gen (T-CAT) and the other using a ratchet-based OMNA Marine Tourniquet (T-OMNA) specifically designed for aquatic use on a training arm for hemorrhage control. The tests were conducted after swimming an approximate distance of 100 meters and the tourniquets were applied while in the water. The following parameters were recorded: time of rescue (rescue phases and tourniquet application), perceived fatigue, and technical actions related to tourniquet skills. RESULTS: With the T-OMNA, 46% of the lifeguards successfully stopped the MH compared to 21% with the T-CAT (P = .015). The approach swim time was 135 seconds with the T-OMNA and 131 seconds with the T-CAT (P = .42). The total time (swim time plus tourniquet placement) was 174 seconds with the T-OMNA and 177 seconds with the T-CAT (P = .55). The adjustment time (from securing the Velcro to completing the manipulation of the windlass or ratchet) for the T-OMNA was faster than with the T-CAT (six seconds versus 19 seconds; P < .001; effect size [ES] = 0.83). The perceived fatigue was high, with a score of seven out of ten in both tests (P = .46). CONCLUSIONS: Lifeguards in this study demonstrated the ability to use both tourniquets during aquatic rescues under conditions of fatigue. The tourniquet with the ratcheting-fixation system controlled hemorrhage in less time than the windlass rod-based tourniquet, although achieving complete bleeding control had a low success rate.

Evaluating time until ligation in a novel tourniquet - A crossover randomized-controlled trial.

INTRODUCTION AND AIM: Severe external hemorrhage is a significant reason for morbidity and mortality in adults; thus, the swift and correct application of a tourniquet by laypersons can be lifesaving. We conducted this randomized-controlled cross-over study to investigate the use of a novel tourniquet. METHODS: Participants were recruited at the Heidelberg University Hospital. Eligible participants were ≥ 18 years old with a medical background but without prior experience in applying a tourniquet. Participants were 1:1 randomized to the intervention group (PAX tourniquet) or the control group (SAM or CAT tourniquet). In the control group, participants underwent another randomization to either the SAM or CAT tourniquet without a predefined allocation ratio. Hyperspectral measurements were undertaken (i) before ligation, (ii) 30 s after ligation, and (iii) 30 s after the reopening of the tourniquet. The primary outcome was time until ligation before crossover between the respective groups. The analysis of secondary endpoints included all attempts to assess a possible learning effect, intraoperator variability, and hyperspectral measurements. Participants were crossed to the other study group after a brief wash-out phase. RESULTS: In total, 50 participants were recruited, resulting in 100 attempts. A success rate of 98% was observed across the study population. Time until ligation was 49 s and 56 s (p = 0.572) in the intervention and control group, respectively. However, there was a significant difference between the PAX and SAM (54 vs 75 s; p = 0.037) and the SAM and CAT tourniquet (75 vs. 47 s; p = 0.015). Further, we observed a significant learning effect in participants allocated to the control group first, with a median reduction of 9 s in the time until ligation. Hyperspectral measurements showed a significant decrease in perfusion and tissue oxygenation after ligation. Further, a significant increase in perfusion and tissue oxygenation was found after reopening the tourniquet compared to the baseline measurement. CONCLUSION: The novel PAX tourniquet can be applied quickly and effectively by medical personnel without prior experience in applying a tourniquet.

Results of combat medic junctional tourniquet training: a prospective, single-blind, randomized, cross-over study.

BACKGROUND: Bleeding remains the leading cause of potentially preventable deaths both in military and civilian pre-hospital trauma settings. Conventional extremity tourniquets do not control bleeding if an iliac artery or a common femoral artery is injured. Stopping junctional bleeding is particularly challenging and requires the use of specifically designed junctional tourniquets. SAM® Junctional Tourniquet (SJT®, United States of America) and Tactical Abdominal Junctional Tourniquet (T-AJT®, Fora Group Türkiye) have been actively used by Turkish security forces. This study questioned the effect of training on combat medics' successful junctional tourniquet applications and application times (AT). METHODS: Our research on two different junctional tourniquet models was designed as a prospective randomized, crossover, single-blinded study. All 40 participants in the study were attendees of a 12-week combat medic training course with updated medical approvals, which were used as an eligibility criterion. Randomization was performed by drawing T-AJT®-SJT cards. The study consisted of pretraining and after-training tourniquet application phases. In each study phase, all participants' AT and the presence or absence of arterial flow were recorded for each group. Finally, the combat medics were presented with a 6-question survey. RESULTS: Although training increased successful T-AJT® application rates, training was not statistically significantly associated with successful applications for any tourniquet types (p>0.05). The pretraining phase ATs for SJT® and T-AJT® were 55±11.8 and 93.8±2.9 seconds, respectively, and the difference was statistically significantly different (p<0.001). Likewise, after-training phase ATs for SJT® and T-AJT® were 49±22.6 and 79.2±17.5 seconds, respectively, and participants' SJT® ATs were significantly shorter (p<0.001). Overall, when participants' applied any of the tourniquet unsuccessfully, the odds of participants' lower Visual Analogue Scale scores were 0.2 (95% CI [0.08, 0.49]. p<0.001). CONCLUSION: Our study basically investigates the effects of training on effective tourniquet application. Unfortunately, our after-training success rates remained unsatisfactory when compared to other studies. This is also the first study on T-AJT® tourniquet application, and further studies on its efficacy are also required.

Impact of tourniquet use on severity of snakebite envenoming in Chongqing, China: a single-center retrospective study.

OBJECTIVE: To identify risk factors associated with snakebite severity and determine whether tourniquet use can affect the severity and outcome of snakebites. METHODS: The clinical data of patients who sustained limb snakebites from 1 March 2021 to 31 October 2022 were reviewed. The patients were divided into three groups according to snakebite severity: mild (517 cases), moderate (112 cases), and severe (8 cases). We compared the clinical data of mild versus moderate to severe snakebites. Multivariate logistic regression was used to determine the independent risk factors for moderate to severe snakebites. RESULTS: The study involved 637 patients. There were statistically significant differences in age, tourniquet use, onset time, white blood cell increase, platelet decrease, creatine kinase (CK) increase, activated partial thromboplastin time shortening, and length of stay between patients with mild snakebites and those with moderate to severe snakebites. Multivariate logistic regression analysis showed that age, tourniquet use, and CK increase were independent risk factors for moderate to severe snakebites. CONCLUSION: The overall severity of snakebites in Chongqing is mild, and the prognosis is good. Age, tourniquet use, and CK increase are independent risk factors for the severity of snakebites. We do not recommend tourniquet use after snakebites in Chongqing.

Tourniquet use in ankle arthroscopy: A systematic review.

BACKGROUND: Ankle arthroscopy is commonly performed using a thigh tourniquet and is thought to improve visibility and reduce operative time. However, the current evidence is unclear as to whether the use of a tourniquet provides these benefits. The aim of this study was to investigate whether there is any clinical benefit of using a tourniquet in ankle arthroscopy. METHODS: A systematic review following PRISMA guidelines was undertaken. All clinical studies published in Medline, Embase, PubMed and the Cochrane Library Database from inception until January 2023 reporting on the use of a tourniquet in ankle arthroscopy were included. RESULTS: 180 studies were identified of which 3 (164 patients) met the inclusion criteria. All studies showed no statistically significant difference in mean surgical time and complication rate between the tourniquet and non-tourniquet groups. Overall, the quality of the evidence was moderate to poor without data in favour or against the routine use of tourniquets in ankle arthroscopy. CONCLUSION: The current literature suggests that there are no significant differences in mean surgical time and complication rate between the tourniquet and non-tourniquet groups.

Tourniquet-free minimally invasive total knee arthroplasty is associated with early aseptic loosening.

BACKGROUND: While tourniquet-free (T-) total knee arthroplasty (TKA) has gained popularity, tourniquet-use during minimally-invasive (MIS)-TKA has not been adequately studied. Traditional techniques employ knee hyper-flexion, compressing vasculature and reducing impact of bleeding, while MIS-TKA embraces the semi-extended knee position, which does not restrict the effects of bleeding on cementation and visualization. We compared the risk of aseptic loosening between patients undergoing T- MIS-TKA compared to T + MIS-TKA. METHODS: This single-surgeon cohort study included 329 consecutive MIS-TKA (226 T+,103 T-) patients with minimum 3-year follow-up. Aseptic loosening, radiolucent lines (RLL), health related quality of life scores, and complications were recorded. T-test and chi-square test were used to compare continuous and categorical variables, and logistic regression included BMI, age, ASA, patellar-resurfacing, and tourniquet-use. RESULTS: There were no differences in baseline demographics. One (0.4 %) aseptic loosening occurred with T+, versus 7 (6.8 %) with T- (p = 0.002). No T + and 3 T- patients (2.9 %, p = 0.01) had revision for aseptic loosening. The incidence of RLLs was 16.8 % in T + and 30.1 % in T- (p = 0.008). Logistic regression revealed T + was significantly associated with decreased aseptic loosening and risk of RLL (odds ratio = 16.4, odds ratio = 2.8). CONCLUSION: In this consecutive series, T- MIS-TKA was associated with increased rates of revision for aseptic loosening as compared to the T + MIS-TKA, even controlling for BMI, age, ASA level, and patellar resurfacing. Radiolucent lines were increased with T- MIS-TKA compared to T + MIS-TKA. Complications, all-cause revision, ROM, and HRQoL scores were similar between tourniquet-use and tourniquet-free cohorts.

The history of tourniquet use in limb surgery.

PURPOSE: As tourniquets have been present in medicine since almost its conception, understanding and following their development through time is not only an exercise in history but also an insight into the evolution of medical devices over more than two millennia. From simple leather bands wrapped around patients' limbs to the modernised digital devices used widely in surgical theatres globally, tourniquets have undergone tectonic change both in their design and application, moving from battlefields to hospitals. Hence, the aim of this article is to outline the historical development of these devices alongside their present and modern use. METHODS: The historical development of emergency and surgical tourniquets is chronologically outlined, with particular emphasis on the impact of warfare on their widespread adoption in trauma and emergency medicine and elective surgery. Novel surgical trends and their impact on the future of tourniquet use are evaluated. RESULTS: The development of tourniquets across two millennia has closely reflected both the scientific understanding of human physiology and anatomy as well as technological discoveries and advancements that have reshaped their design and application. Prominent figures in the field of surgery, such as Sushruta, Fabricius Hildanus, John Louis Petit, Joseph Lister, Harvey Cushing and James McEwen, all fundamentally influenced their evolution and helped popularise and modernise them. The views on their use have been controversial and drastically changed across different eras, with data collected from modern warfare serving to embed their use in clinical practice. CONCLUSION: The historical development of tourniquets since pre-historic times represents an excellent outline of the adaptive nature of medicine, led, firstly, by scientific rigour and discipline and, secondly, by pioneers who serve as catalysts for change and improvement. The modern inflatable cuff tourniquets that are omnipresent in theatres globally will undoubtedly remain the standard of care for the foreseeable future. Tourniquets that can dynamically monitor blood pressure and consequently adjust inflation pressures, as well as ones with inbuilt axonal excitability monitoring, will further improve their safety profile, reduce associated complication rates and represent the next step in the evolution of these devices. Notably, there might be a shift away from tourniquet use altogether, reflected by the wide use of the wide-awake local anaesthesia no-tourniquet technique that has become the new norm in hand surgery.

Tourniquet Use in Extremity-Based Microsurgery.

BACKGROUND: The use of tourniquets and their role in extremity-based microsurgery has not been thoroughly investigated. The purpose of this study was to investigate tourniquet use and its associated outcomes and complications. The authors hypothesize that tourniquets enhance visualization, bloodless approaches to vessel harvest, flap elevation, and anastomosis without added complications. METHODS: A retrospective chart review was completed for patients who had undergone extremity-based microsurgery with the use of a tourniquet between January 2018 and February 2022 at two large academic institutions. Demographic characteristics, initial reasons for surgery, complications, and outcomes were recorded. Patients were separated into groups based on tourniquet use during three operative segments: (1) flap elevation, (2) vessel harvest, and (3) microvascular anastomosis. An internal comparison of complication rate was performed between cases for which a tourniquet was used for one operative segment to all cases in which it was not used for the same operative segment. Univariate and multivariate statistical analyses were performed to identify statistically significant results. RESULTS: A total of 99 patients (106 surgeries) were included in this study across sites. The mean age was 41.2 years and 67.7% of the patients were male. The most common reason for microsurgical reconstruction was trauma (50.5%). The need for an additional unplanned surgery was the most common surgical complication (16%). A total of 70, 61, and 32% of procedures used a tourniquet for flap elevation, vessel harvest, and for anastomosis, respectively. Statistical analyses identified no difference in complication rates for procedures for which a tourniquet was or was not used for interventions. CONCLUSION: Based on these results, the authors state that tourniquets can be utilized for extremity-based microsurgery to enable bloodless dissection without the concern of increased complication rates.

Vascular imaging immediately after tourniquet removal does not increase vasospasm risk.

BACKGROUND: Prehospital tourniquet use is now standard in trauma patients with diagnosed or suspected extremity vascular injuries. Tourniquet-related vasospasm is an understudied phenomenon that may confound management by causing erroneous arterial pressure indices (APIs) and abnormalities on computed tomography angiography (CTA) that do not reflect true arterial injuries. We hypothesized that shorter intervals between tourniquet removal and CTA imaging and longer total tourniquet times would be correlated with a higher likelihood of false positive CTA. MATERIALS AND METHODS: We performed a single-institution retrospective cohort study of patients presenting to a busy, urban Level 1 Trauma Center with prehospital tourniquets from 2019 to 2021. Patients who presented with a tourniquet disengaged upon arrival or who died prior to admission to the Trauma Unit were excluded. Tourniquet duration, time between tourniquet removal and CTA imaging (CTA interval), CTA findings, and management of extremity arterial injuries were extracted. The proportion of false positive injuries on CTA was assessed for correlation with increasing time interval from tourniquet removal to CTA imaging and correlation with increasing total tourniquet time using multivariable logistic regression. RESULTS: 251 patients were identified with prehospital tourniquets. 127 underwent CTA of the affected extremity, 96 patients had an abnormal CTA finding, and 57 (45% of total CTA patients) had false positive arterial injuries on imaging. Using multivariable logistic regression, neither the CTA interval nor the tourniquet duration was associated with false positive CTA injuries. Female sex was associated with false positive injuries on CTA (OR 2.91, 95% CI: 1.01 - 8.39). Vasospasm was cited as a possible explanation by radiologists in 40% of false positive CTA reports. CONCLUSIONS: Arterial vasospasm is a frequent finding on CTA after tourniquet use for extremity trauma, but concerns regarding tourniquet-related vasospasm should not alter trauma patient management. Neither the duration of tourniquet application nor the time interval since removal is associated with decreased CTA accuracy, and any delay in imaging does not appear to reduce the likelihood of vasospasm. These findings are important for supporting expedited care of trauma patients with severe extremity injuries.

The effect of tourniquet use on postoperative opioid consumption after ankle fracture surgery - a retrospective cohort study.

OBJECTIVES: A pneumatic tourniquet is often used during ankle fracture surgery to reduce bleeding and enhance the visibility of the surgical field. Tourniquet use causes both mechanical and ischemic pain. The main purpose of this study was to evaluate the effect of tourniquet time on postoperative opioid consumption after ankle fracture surgery. METHODS: We retrospectively reviewed the files of 586 adult patients with surgically treated ankle fractures during the years 2014-2016. We evaluated post hoc the effect of tourniquet time on postoperative opioid consumption during the first 24 h after surgery. The patients were divided into quartiles by the tourniquet time (4-43 min; 44-58 min; 59-82 min; and ≥83 min). Multivariable linear regression analysis was used to evaluate the results. RESULTS: Tourniquets were used in 486 patients. The use of a tourniquet was associated with an increase in the total postoperative opioid consumption by 5.1 mg (95 % CI 1.6-8.5; p=0.004) during the first 24 postoperative hours. The tourniquet time over 83 min was associated with an increase in the mean postoperative oxycodone consumption by 5.4 mg (95 % CI 1.2 to 9.7; p=0.012) compared to patients with tourniquet time of 4-43 min. CONCLUSIONS: The use of a tourniquet and prolonged tourniquet time were associated with higher postoperative opioid consumption during the 24 h postoperative follow-up after surgical ankle fracture fixation. The need for ethical approval and informed consent was waived by the Institutional Review Board of Northern Ostrobothnia Health District because of the retrospective nature of the study.

Impact of tourniquet use in total knee arthroplasty on functional recovery and postoperative pain: a prospective study.

BACKGROUND: Tourniquet use during total knee arthroplasty (TKA) remains controversial. The purpose of this study is to determine the impact of tourniquet use only during cementation compared with its use throughout the entire surgery concerning early outcomes in functional recovery, pain, quadriceps function, and rehabilitation. METHODS: Between November 2019 and March 2020, 118 patients were enrolled in this study, with 59 patients undergoing TKA with a tourniquet during the entire surgery (group 1) and 59 patients with a tourniquet only during cementation (group 2). Twenty-eight patients were unable to complete follow-up leaving fifty in group 1 and forty in group 2. Primary endpoints were surgical time, postoperative knee and thigh pain, and functional recovery. Secondary endpoints were 6-month clinical scores and blood loss. RESULTS: Patients in group 1 had statistically significantly increased knee pain on postoperative day 3 (p = 0.004), and thigh pain on postoperative day 1 (p < 0.001), 2 (p < 0.001), and 3 (p = 0.027), and longer time intervals to achieve straight leg raise maneuver (p = 0.006) compared to group 2. However, it did not affect overall narcotic consumption, knee pain (day 1-2), functional recovery, ROM, ability to do the first walk, Oxford knee score, length of stay, and complication rate. There was no statistically significant difference in terms of 6-month postoperative knee score, surgical time, and blood loss between the two groups. CONCLUSION: Tourniquet use diminishes quadriceps function and increases postoperative thigh pain and, to a lesser extent, knee pain. We, therefore, recommend the use of a tourniquet only during cementing. LEVEL OF EVIDENCE: 1; prospective randomized study.

Effect of intravenous low-dose norepinephrine on blood loss in non-tourniquet total knee arthroplasty under general anesthesia: a randomized, double-blind, controlled, single-center trial.

OBJECTIVE: This prospective trial aimed to evaluate the effects of low-dose intravenous norepinephrine (NE) on intraoperative blood loss and bleeding from osteotomy sites during non-tourniquet total knee arthroplasty (TKA) under general anesthesia. METHODS: A total of 120 patients who underwent TKA between December 2020 and May 2022 were enrolled and randomly assigned to the intravenous low-dose NE Group (NE Group) or the control group (C Group). During surgery, NE Group received 0.05-0.1 µg/(kg min) of NE intravenously to raise and maintain the patient's mean arterial pressure (MAP). C Group received the same dose of saline as placebo. Intraoperative blood loss, bleeding score at osteotomy sites, Δlactate levels (Lac), postoperative complications, and transfusion rate during hospitalization were compared between groups. RESULTS: Intraoperative and osteotomy blood loss was significantly lower in the NE Group than in the C Group (P < 0.001). No significant difference was observed in ΔLac between groups (P > 0.05). There was no significant difference in complications between the groups 3 days after surgery (P > 0.05). In addition, there was no significant difference in blood transfusion rates between the two groups during hospitalization (P > 0.05). CONCLUSION: In non-tourniquet TKA under general anesthesia, low-dose intravenous NE safely and effectively reduced intraoperative blood loss and provided a satisfactory osteotomy site while maintaining a higher MAP.

Effects of Tourniquet Features on Application Processes.

BACKGROUND: We investigated emergency-use limb tourniquet design features effects on application processes (this paper) and times to complete those processes (companion paper). METHODS: Sixty-four appliers watched training videos and then each applied all eight tourniquets: Combat Application Tourniquet Generation 7 (CAT7), SOF™ Tactical Tourniquet-Wide Generation 3 (SOFTTW3), SOF™ Tactical Tourniquet-Wide Generation 5 (SOFTTW5), Tactical Mechanical Tourniquet (TMT), OMNA Marine Tourniquet (OMT), X8T tourniquet (X8T), Tactical Ratcheting Medical Tourniquet (Tac RMT), and RapidStop™ Tourniquet (RST). Application processes were scored from videos. RESULTS: Thirty-three appliers had no prior tourniquet experience. All 512 applications were placed proximal to the recipient's simulated distal thigh injury. Thirty-one appliers (13 with no experience) had 66 problem-free applications (18 by no experience appliers). Tightening-system mechanical problems were more frequent with windlass rod systems (26 losing hold of the rod, 27 redoing rod turns, and 58 struggling to secure the rod) versus ratchet systems (3 tooth skips and 16 advance failures). Thirty-five appliers (21 with no experience) had 68 applications (45 by no experience appliers) with an audible Doppler pulse when stating "Done"; causes involved premature stopping (53), inadequate strap pull (1 SOFTTW3, 1 RST), strap/redirect understanding problem (1 SOFTTW5, 1 X8T, 4 Tac RMT, 1 RST), tightening-system understanding problem (2 CAT7, 1 SOFTTW3, 1 TMT, 1 RST), and physical inability to secure (1 SOFTTW3). Fifty-three appliers (32 no experience) had 109 applications (64 by no experience appliers) not correctly secured. Six involved strap/redirect understanding problems: 4 Tac RMT, 1 X8T, 1 SOFTTW5; 103 involved improper securing of non-self-securing design features: 47 CAT7 (8 strap, 45 rod), 31 TMT (17 strap, 19 rod), 22 OMT (strap), and 3 SOFTTW3 (rod). CONCLUSION: Self-securing systems have process advantages. Because most emergent tourniquet recipients require transport, we believe tourniquet security is a critical design aspect. Decisions regarding tourniquet choices may become very different when both occlusion and tourniquet security are considered.

Effects of Tourniquet Features on Application Processes Times.

BACKGROUND: We investigated emergency-use limb tourniquet design features effects on application processes (companion paper) and times to complete those processes (this paper). METHODS: Sixty-four appliers watched training videos then each applied all eight tourniquets: Combat Application Tour- niquet Generation 7 (CAT7), SOF™ Tactical Tourniquet-Wide Generation 3 (SOFTTW3), SOF™ Tactical Tourniquet-Wide Generation 5 (SOFTTW5), Tactical Mechanical Tourniquet (TMT), OMNA Marine Tourniquet (OMT), X8T-Tourniquet (X8T), Tactical Ratcheting Medical Tourniquet (Tac RMT), and RapidStop Tourniquet (RST). Application processes times were captured from videos. RESULTS: From "Go" to "touch tightening system" was fastest with clips and self-securing redirect buckles and without strap/redirect application process problems (n, median seconds: CAT7 n=23, 26.89; SOFTTW3 n=11, 20.95; SOFTTW5 n=16, 20.53; TMT n=5, 26.61; OMT n=12, 25.94; X8T n=3, 18.44; Tac RMT n=15, 30.59; RST n=7, 22.80). From "touch tightening system" to "last occlusion" was fastest with windlass rod systems when there were no tightening system understanding or mechanical problems (seconds: CAT7 n=48, 4.21; SOFTTW3 n=47, 5.99; SOFTTW5 n=44, 4.65; TMT n=38, 6.21; OMT n=51, 6.22; X8T n=48, 7.59; Tac RMT n=52, 8.44; RST n=40, 8.02). For occluded, tightening system secure applications, from "touch tightening system" to "Done" was fastest with self-securing tightening systems tightening from a tight strap (occluded, secure time in seconds from a tight strap: CAT7 n=17, 14.47; SOFTTW3 n=22, 10.91; SOFTTW5 n=38, 9.19; TMT n=14, 11.42; OMT n=44, 7.01; X8T n=12 9.82; Tac RMT n=20, 6.45; RST n=23, 8.64). CONCLUSIONS: Suboptimal processes in- crease application times. Optimal design features for fast, occlusive, secure tourniquet applications are self-securing strap/ redirect systems with an easily identified and easily used clip and self-securing tightening systems.