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The article discusses the importance of autoregulation in blood flow restriction (BFR) exercise, focusing on the responsiveness of BFR cuffs with autoregulation features. Two studies, Jacobs et al. and Rolnick et al., compared the effects of autoregulation on exercise performance and perceptual responses using different BFR cuffs. The findings suggest that the responsiveness of the autoregulation feature in BFR cuffs can impact acute physiological responses during exercise, potentially influencing long-term outcomes like muscle hypertrophy and strength. Researchers and clinicians should consider the implications of autoregulation in BFR training to optimize the effectiveness of their interventions. [Extracted from the article]

Blood flow restriction (BFR) has been identified as a potential countermeasure to mitigate physiological deconditioning during spaceflight. Guidelines recommend that tourniquet pressure be prescribed relative to limb occlusion pressure (LOP); however, it is unclear whether body tilting or reduced gravity analogues influence LOP. We examined LOP at the leg and arm during supine bedrest and bodyweight suspension (BWS) at 6° head‐down tilt (HDT), horizontal (0°), and 9.5° head‐up tilt (HUT) positions. Twenty‐seven adults (age, 26 ± 5 years; height, 1.75 ± 0.08 m; body mass, 73 ± 12 kg) completed all tilts during bedrest. A subgroup (n = 15) additionally completed the tilts during BWS. In each position, LOP was measured twice in the leg and arm using the Delfi Personalized Tourniquet System after 5 min of rest and again after a further 5 min. The LOP at the leg increased significantly from 6° HDT to 9.5° HUT in bedrest and BWS by 9–15 mmHg (Cohen's d = 0.7–1.0). Leg LOP was significantly higher during BWS at horizontal and 9.5° HUT postures relative to the same angles during bedrest by 8 mmHg (Cohen's d = 0.6). Arm LOP remained unchanged between body tilts and analogues. Intraclass correlation coefficients for LOP measurements taken after an initial and subsequent 5 min rest period in all conditions ranged between 0.91–0.95 (leg) and 0.83–0.96 (arm). It is advised that LOP be measured before the application of a vascular occlusion in the same body tilt/setting to which it is applied to minimize discrepancies between the actual and prescribed tourniquet pressure. [ABSTRACT FROM AUTHOR]

Background: This study aims to systematically compare the efficacy of two distinct approaches that is limb occlusion pressure (LOP) and systolic blood pressure (SBP) in determining the optimal tourniquet pressure for primary total knee arthroplasty. The overarching goal is to identify the method that yields superior outcomes in minimizing post-operative thigh pain while simultaneously reducing complications in our patient population. Methods: 311 patients scheduled for primary total knee replacement (TKR) were randomized in two groups. Group A (LOP) had 154 patients and group B had 157 patients. In group A, LOP was determined for all patients. After adding the safety margin, the tourniquet pressure was determined which was kept during the procedure. By adding 150 mm Hg to SBP in group B, the tourniquet inflation pressure was ascertained. Postoperatively, thigh pain was evaluated from day 1 to day 3 and at 6 weeks. Results: The average tourniquet pressure in group A patients having thigh circumference between 40 and 50 cm was 223.8 mm + − 19.8 mm Hg and in group B it was 262.1 + − 15.9 mm Hg (P <.01). Patients having thigh circumference between 51 and 60 cm had average tourniquet pressure of 240.07 + − 20.1 mm Hg in group A and 264.5 + − 17.4 mm Hg in group B (P <.01). The average tourniquet pressure for patients with thigh circumference more than 60 cm was 296 + /15.3 mm Hg in group A and 267.3 + /19.2 mm Hg in group B (P < 0.01). Conclusion: Tourniquet pressure determination based on the limb occlusion pressure (LOP) method provide less postoperative thigh pain and better range of motion. Optimizing Tourniquet Pressure in Primary Total Knee Replacement: Limb Occlusion Pressure vs Systolic blood pressure method to minimize thigh pain. [ABSTRACT FROM AUTHOR]

Purpose: It is recommended that the pressure applied in training with blood flow restriction (BFR) be relativized based on the arterial occlusion pressure (AOP). However, several factors can affect the measurement of AOP that may require consideration. The purpose of this review was to explore variables capable of impacting AOP and provide recommendations for measurement. Methods: On August 8, 2023, PubMed® and Scopus databases were consulted to identify studies that analyzed variables capable of affecting AOP. In addition, the list of references of eligible studies, as well as Google Scholar citations, were consulted to identify additional studies. Results: Twenty-three studies (n = 1335 participants) were included in this review. Studies analyzed the effects of cuff characteristics (n = 9), cuff bladder position (n = 1), body position (n = 6), inflation protocol (n = 1), time (n = 1), sex (n = 5), and segment (n = 5) on AOP. Results demonstrated that wider cuffs promote arterial occlusion with lower external pressures. In addition to width, cuff placement also affects AOP; when the bladder is positioned above the artery, less external pressure is needed to promote arterial occlusion. Body position significantly affects AOP, with more pronounced effects in the lower limbs. The time of day AOP is measured, but not the inflation protocol, has a significant effect on AOP. For the effect of sex and segment, results were divergent. Conclusion: In conclusion, several factors may influence AOP. For standardizing the prescribed pressure in training with BFR, all these variables should be considered. [ABSTRACT FROM AUTHOR]

Our study assessed limb occlusion pressure (LOP) variability over time and between limbs. Collegiate athletes (n=42; Sample 1 = 15 soccer players, Sample 2 = 13 cross country runners, Sample 3 = 14 cross country runners) attended five visits separated by ≥48 hours (Sample 1), three visits separated by ~3 weeks each (Sample 2), or four visits separated by ~3 weeks each (Sample 3). For all samples, supine LOP was assessed in each leg (and also in each arm for Sample 3) using an automated system. Paired samples t-tests or RMANOVA were used to compare LOP between limbs and across trials, respectively. Additionally, agreement and variability across measures were assessed using intraclass correlations and mean absolute percent differences (MAPD). There were no significant differences in LOP across visits for any of the samples, with primarily moderate or good agreement (intraclass correlations r=0.29-0.88) and low variability (MAPD 4.3-9.0%). There were no significant differences in LOP between left and right limbs, with moderate to good agreement (r=0.74-0.93) and low variability (MAPD 3.2-7.2%). The demonstrated stability in LOP over time and between sides of the body suggests that LOP may not always need to be measured daily or bilaterally, adding feasibility to field-based implementation.

Context: Neuromuscular electrical stimulation (NMES) combined with blood flow restriction (BFR) has been shown to improve muscular strength and size better than NMES alone. However, previous studies used varied methodologies not recommended by previous NMES or BFR research. Objective: The present study investigated the acute effects of NMES combined with varying degrees of BFR using research-recommended procedures to enhance understanding and the clinical applicability of this combination. Design: Randomized crossover. Setting: Physiology laboratory. Participants: A total of 20 healthy adults (age 27 [4] y; height 177 [8] cm; body mass 77 [13] kg). Interventions: Six sessions separated by at least 7 days. The first 2 visits served as familiarization, with the experimental conditions performed in the final 4 sessions: NMES alone, NMES 40% BFR, NMES 60% BFR, and NMES 80% BFR. Main Outcome Measures: Maximal voluntary isometric contraction, muscle thickness, blood pressure, heart rate, rating of perceived exertion, and pain were all recorded before and after each condition. Results: The NMES 80% BFR caused greater maximal voluntary isometric contraction decline than any other condition (-38.9 [22.3] N-m, P< .01). Vastus medialis and vastus lateralis muscle thickness acutely increased after all experimental conditions (P< .05). Pain and ratings of perceived exertion were higher after NMES 80% BFR compared with all other experimental conditions (P < .05). No cardiovascular effects were observed between conditions. Conclusion: The NMES combined with 80% BFR caused greater acute force decrement than the other conditions. However, greater perceptual ratings of pain and ratings of perceived exertion were observed with NMES 80% BFR. These acute observations must be investigated during chronic interventions to corroborate any relationship to changes in muscle strength and size in clinical populations. [ABSTRACT FROM AUTHOR]

Abstract Background In minor hand surgery, tourniquet is typically inflated to 250 mmHg. The pressure may be too high and cause unnecessary adverse effects. Limb occlusion pressure plus safety margin or recommended tourniquet pressure (RTP), has been reported as optimal pressure to provide bloodless field in limb surgeries. This study aimed to compare the RTP with the standard tourniquet pressure of 250 mmHg in minor hand surgery. Methods A double-blinded randomized control trial was conducted from July to December 2019 and June 2020 to May 2021. Patients were randomly assigned into two groups: RTP and 250 mmHg with 3:1 ratio allocation. The outcomes were measurement of cuff pressure reduction, time to develop of tourniquet pain and discomfort, pain score, discomfort score, motionless and bloodless of operative field determined by the surgeon’s satisfaction. Results A total of 112 patients were included, 84 were in RTP and 28 were in 250 mmHg group. Mean of tourniquet pressure was significantly lower in the RTP group (228.3 ± 17.2 mmHg) (P

Blood flow restriction (BFR) may become ineffective or potentially dangerous without sufficient standardization. The purpose of this investigation was therefore to (1) assess the viability of multiple sizes of a novel BFR cuff to determine arterial occlusion pressure (AOP) and (2) compare resting arterial, venous and calf muscle pump (cMP)-mediated blood flow between the aforementioned conditions and a commonly employed wide-rigid, tourniquet-style cuff. In randomized, counter-balanced, and crossover fashion, 20 apparently healthy males (18–40 years) donned a widely employed wide-rigid (WR) cuff, along with the largest (NE) and manufacturer-recommended sizes (NER) of a novel narrow-elastic cuff. Participants subsequently assessed AOP, as well as (at 80%AOP) arterial, venous, and venous cMP flow relative to baseline values via ultrasound. All analyses were performed at a significance level of p < 0.05. Analyses revealed a significant condition effect for AOP (p < 0.001; ηp2 = 0.907) whereby WR was significantly lower than both NE and NER; in addition, the latter two did not differ. Compared with baseline, there were no statistically significant differences between cuffs for either arterial or cMP-mediated blood flow. Unsurprisingly, no participants demonstrated venous blood flow at 80% AOP. These findings support the viability of a novel narrow-elastic BFR product, evidenced by consistent AOP acquisition and equivocal blood flow parameters.

Ischemic preconditioning (IPC) has been shown to improve exercise performance, but many factors related to IPC administration are unresolved. This study evaluated the effect of IPC performed with different pressures for exercise performance. Fifteen collegiate male soccer players completed five separate sessions in randomized order. For each session, blood pressure cuffs were placed on the thigh bilaterally, and IPC was administered in 2x5 minute cycles at cuff pressures of 0%, 25%, 50%, 75%, or 100% of each participant’s limb occlusion pressure (LOP), the pressure needed to occlude arterial flow of blood to the leg. Participants then completed vertical jump, soccer passing accuracy, and 1,600 meter run tests. Repeated-measures analysis of variance was used to assess differences in outcomes across the five trials. There were no significant differences in vertical jump or passing accuracy across the five trials. However, 1,600 meter run times were significantly faster for the 50-75% trials than the 0-25% trials (mean difference 7.1-8.4 seconds). In summary, IPC pressures below LOP improved running times while not negatively influencing jumping or passing accuracy in collegiate soccer players. Improved comfort and reduced risk from using cuff pressures below LOP may facilitate more effective IPC use in field-based settings.

Background: In minor hand surgery, tourniquet is typically inflated to 250 mmHg. The pressure may be too high and cause unnecessary adverse effects. Limb occlusion pressure plus safety margin or recommended tourniquet pressure (RTP), has been reported as optimal pressure to provide bloodless field in limb surgeries. This study aimed to compare the RTP with the standard tourniquet pressure of 250 mmHg in minor hand surgery. Methods: A double-blinded randomized control trial was conducted from July to December 2019 and June 2020 to May 2021. Patients were randomly assigned into two groups: RTP and 250 mmHg with 3:1 ratio allocation. The outcomes were measurement of cuff pressure reduction, time to develop of tourniquet pain and discomfort, pain score, discomfort score, motionless and bloodless of operative field determined by the surgeon's satisfaction. Results: A total of 112 patients were included, 84 were in RTP and 28 were in 250 mmHg group. Mean of tourniquet pressure was significantly lower in the RTP group (228.3 ± 17.2 mmHg) (P < 0.001). Even though, time to develop pain was not significantly different, the RTP group reported significantly less pain and discomfort, according to the pain score (P = 0.02) and discomfort score (P = 0.017). The RTP group provided better motionless field, while both groups equally created a bloodless field. Conclusion: The RTP significantly reduced tourniquet related pain and discomfort during minor hand surgeries. It provided better motionless operative field and adequate bloodless field. Therefore, the RTP should be considered as optimal tourniquet pressure for minor hand surgeries. Trial registration: TCTR20210519001 (retrospectively registered). Level of evidence: I. [ABSTRACT FROM AUTHOR]

Reduction of blood flow to the limb using cuffs before or during exercise has become increasingly popular for training and rehabilitation. Our study tested the effects of cuff brand/width on pressures required to reach limb occlusion pressure (LOP) and developed, cross-validated, and compared accuracy of two LOP prediction equations to previously created methods. Supine LOP was determined in the distal popliteal artery using four different cuff brands/widths in 23 adult participants. Participants then had demographic and resting variables assessed, and two LOP prediction equations were developed from these variables and were compared to five previously developed models and a method using posterior tibial artery palpation for LOP assessment in an independent sample (n = 14 adult runners). For cuff comparison, the widest two cuffs had significantly lower LOP (mean ~149 mmHg) than the narrowest cuffs (mean ~176 mmHg), with the narrowest cuff unable to reach LOP. The eight methods used to predict LOP ranged in accuracy (mean absolute percent errors 3.9–23.0%), with highest accuracy in equations using mean arterial pressure (MAP) and BMI. Practitioners using blood flow reduction methods should be consistent with cuff use due to demonstrated differences across brands/widths. Equations using MAP and BMI appear best for prediction of leg LOP. [ABSTRACT FROM AUTHOR]

The purpose of this investigation was to determine the effect of different relative pressures of blood flow restriction (BFR) on muscle oxygen saturation (SmO2) while walking at 3.0 mph (4.83 kph). Fifteen physically active healthy adults performed seven 5-minute stages of walking at 3.0 mph with a blood flow restriction cuff applied to the proximal portion of the left or right leg while bilateral SmO2 changes were measured using near infra-red spectroscopy (NIRS) on the medial head of the gastrocnemius (GM) and vastus lateralis (VL) muscles. Other measurements including heart rate (HR), blood pressure (BP), rating of perceived exertion (RPE), and ground contact time balance (GCTB) were also collected. SmO2 measurements were analyzed using two-way repeated measures (RM) ANOVA while other measurements were analyzed using one-way RM ANOVA. We observed a significant main effect of LOP% (limb occlusion pressure) on the difference in total area of desaturation that occurred during each occlusion stage (ADS), p < 0.0001 η² = .336, early ΔSmO2, p < 0.0001 in both the GAS η² = .132 and VL η² = .335. The results suggest that there are significant differences in SmO2 desaturation between 40%, 80%, and 100% LOP. Our findings suggest that incremental increases in LOP will bring about greater SmO2 desaturation during walking and may therefore induce a larger adaptive response on the muscles. However, increased LOP% may intensify perception of effort. [ABSTRACT FROM AUTHOR]

The use of blood flow restriction is becoming more common and requires the use of individualized pressures in order to remain a safe and effective rehabilitation modality. Measuring limb occlusion pressure (LOP) allows the practitioner to set the restriction pressure so that full occlusion does not occur. Objective: Compare a research-grade clinical vascular doppler and a consumer-grade vascular doppler in the measurement of LOP. Design: A randomized crossover design measuring LOP in the upper and lower body. Methods: 20 participants (men=10) visited the laboratory on one occasion. Limb circumference in the arm and thigh was measured. Following 10 min of supine rest, LOP was measured either in the arm, using a 5 cm wide inelastic cuff, or in the leg, using a 10 cm wide inelastic cuff. Measurements were repeated at 5 min intervals until LOP had been measured in both limbs with both dopplers. Results: Bland-Altman analysis showed agreement between the two dopplers in both the upper body (mean bias: 0.6 (-1.3 - 2.4) mmHg) and lower body (mean bias: -1.5 (-4.4 - 1.4) mmHg). Two one-sided tests of equivalence determined that both dopplers measured a statistically equivalent LOP in the upper body (p = .547) and lower body (p = .288). Conclusions: In a healthy, young population, the consumer-grade vascular doppler measured LOP equally as well as the research-grade clinical doppler. [ABSTRACT FROM AUTHOR]

Abstract Background Development of automatic, pneumatic tourniquet technology and use of personalised tourniquet pressures has improved the safety and accuracy of surgical tourniquet systems. Personalisation of tourniquet pressure requires accurate measurement of limb occlusion pressure (LOP), which can be measured automatically through two different methods. The ‘embedded LOP’ method measures LOP using a dual-purpose tourniquet cuff acting as both patient sensor and pneumatic effector. The ‘distal LOP’ method measures LOP using a distal sensor applied to the patient’s finger or toe of the operating limb, using photoplethysmography to detect volumetric changes in peripheral blood circulation. The distal LOP method has been used clinically for many years; the embedded LOP method was developed recently with several advantages over the distal LOP method. While both methods have clinically acceptable accuracy in comparison to LOP measured using the manual Doppler ultrasound method, these two automatic methods have not been directly compared. The purpose of this study is to investigate if the embedded and distal methods of LOP measurement have clinically acceptable agreement. The differences in pairs of LOP measurement in the upper and lower limbs of 81 healthy individuals were compared using modified Bland and Altman analysis. In surgery, it is common for cuff pressure to deviate from the pressure setpoint due to limb manipulation. Surgical tourniquet systems utilise a ± 15 mmHg pressure alarm window, whereby if the cuff pressure deviates from the pressure setpoint by > 15 mmHg, an audiovisual alarm is triggered. Therefore, if the difference (bias) ± SE, 95% CI of the bias and SD of differences ± SE in LOP measurement between the embedded and distal methods were all within ±15 mmHg, this would demonstrate that the two methods have clinically acceptable agreement. Results LOP measurement using the embedded LOP method was − 0.81 ± 0.75 mmHg (bias ± standard error) lower than the distal LOP method. The 95% confidence interval of the bias was − 2.29 to 0.66 mmHg. The standard deviation of the differences ± standard error was 10.35 ± 0.49 mmHg. These results show that the embedded and distal methods of LOP measurement demonstrate clinically acceptable agreement. Conclusions The findings of this study demonstrate clinically acceptable agreement between the embedded and distal methods of LOP measurement. The findings support the use of the embedded LOP method of automatic LOP measurement using dual-purpose tourniquet cuffs to enable accurate, effective and simple prescription of personalised tourniquet cuff pressures in a clinical setting.

Background: The limb occlusion pressure (LOP) is determined to calculate the relative LOP. The different levels of relative LOP (percentage of LOP) influence the treatment effect and perceived discomfort during low-load blood flow restriction (BFR) strength training. Thus, determining the LOP is of the utmost importance when using BFR in clinical practice. Purpose: The objective of this study was to investigate the concurrent validity and intra-rater (test-retest), intra-day reliability of an inexpensive, portable, easy-to-use handheld (HH) oximeter compared to a high-resolution Doppler ultrasound scanner in detecting LOP in the lower extremity. Study design: Cross-sectional validity and reliability study Methods: Two raters who were blinded from each other simultaneously assessed 50 healthy participants (mean age of 25.8 years). A 20 cm-wide thigh cuff with an attached sphygmomanometer was inflated until the raters independently registered the LOP with the HH oximeter and the Doppler ultrasound scanner. The test session was repeated once after a five-minute time interval. Results: The HH oximeter recorded a non-significantly higher LOP than the Doppler ultrasound scanner, with a mean difference of 6.3 mmHg in the test session (95% limits of agreement (LoA): -16.2 to 28.8, p = 0.13) and 5.4 mmHg in the retest session (95% LoA: -13.3 to 24.0, p = 0.10). The intra-rater reliability for both devices was moderate (ICC = 0.72-0.79). The measured LOP was significantly lower (p < 0.005) in the retest session than in the test session for both the HH oximeter (mean difference: -5.7 mmHg) and the Doppler ultrasound scanner (mean difference: -4.8 mmHg). Conclusions: The HH oximeter is a valid and reliable measuring device for determining the LOP in the lower extremity in healthy adults. The authors recommend performing at least two LOP measurements with a one-minute rest interval. [ABSTRACT FROM AUTHOR]

PurposeNo current guidelines or recommendations exist informing the selection of restriction pressure during blood flow restriction exercise (BFRE). Moreover, the effects of specific relative restriction pressures on the acute muscle, metabolic and cardiopulmonary responses to BFRE are unclear. The purpose of this study was to characterize these acute responses at different levels of restriction pressure.MethodsParticipants (n = 10) completed rhythmic isometric knee extension exercise across five experimental trials in a balanced randomized order. Three were BFRE trials {B-40 [restriction pressure set to 40% LOP (total limb occlusion pressure)]; B-60 (60% LOP); and B-80 (80% LOP)} with a workload equivalent to 20% maximal voluntary force (MVC), one was non-BFRE at 20% MVC (LL) and one was non-BFRE at 80% MVC (HL). Measurements recorded were torque, muscle activity via electromyography (EMG), tissue oxygenation via near infrared spectroscopy, whole body oxygen consumption, blood lactate and heart rate.ResultsFor the LL and B-40 trials, most measures remained constant. However, for the B-60 and B-80 trials, significant fatigue was demonstrated by a reduction in MVC torque across the trial (p < 0.05). Blood lactate increased from baseline in HL, B-60, and B-80 (p < 0.05). Submaximal EMG was greater in B-60 and B-80 than LL, but lower compared with HL (p < 0.05). Tissue oxygenation decreased in HL, B-40, B-60, and B-80 (p < 0.05), which was lower in the B-80 trial compared to all other trials (p < 0.01). Whole body oxygen consumption was not different between the BFRE trials (p > 0.05).ConclusionWe demonstrate graded/progressive acute responses with increasing applied pressure during BFRE, from which we speculate that an effective minimum “threshold” around 60% LOP may be necessary for BFRE to be effective with training. While these data provide some insight on the possible mechanisms by which BFRE develops skeletal muscle size and strength when undertaken chronically across a training program, the outcomes of chronic training programs using different levels of applied restriction pressures remain to be tested. Overall, the present study recommends 60–80% LOP as a suitable “minimum” BFRE pressure.

Purpose: No current guidelines or recommendations exist informing the selection of restriction pressure during blood flow restriction exercise (BFRE). Moreover, the effects of specific relative restriction pressures on the acute muscle, metabolic and cardiopulmonary responses to BFRE are unclear. The purpose of this study was to characterize these acute responses at different levels of restriction pressure. Methods: Participants (n = 10) completed rhythmic isometric knee extension exercise across five experimental trials in a balanced randomized order. Three were BFRE trials {B-40 [restriction pressure set to 40% LOP (total limb occlusion pressure)]; B-60 (60% LOP); and B-80 (80% LOP)} with a workload equivalent to 20% maximal voluntary force (MVC), one was non-BFRE at 20% MVC (LL) and one was non-BFRE at 80% MVC (HL). Measurements recorded were torque, muscle activity via electromyography (EMG), tissue oxygenation via near infrared spectroscopy, whole body oxygen consumption, blood lactate and heart rate. Results: For the LL and B-40 trials, most measures remained constant. However, for the B-60 and B-80 trials, significant fatigue was demonstrated by a reduction in MVC torque across the trial (p < 0.05). Blood lactate increased from baseline in HL, B-60, and B-80 (p < 0.05). Submaximal EMG was greater in B-60 and B-80 than LL, but lower compared with HL (p < 0.05). Tissue oxygenation decreased in HL, B-40, B-60, and B-80 (p < 0.05), which was lower in the B-80 trial compared to all other trials (p < 0.01). Whole body oxygen consumption was not different between the BFRE trials (p > 0.05). Conclusion: We demonstrate graded/progressive acute responses with increasing applied pressure during BFRE, from which we speculate that an effective minimum "threshold" around 60% LOP may be necessary for BFRE to be effective with training. While these data provide some insight on the possible mechanisms by which BFRE develops skeletal muscle size and strength when undertaken chronically across a training program, the outcomes of chronic training programs using different levels of applied restriction pressures remain to be tested. Overall, the present study recommends 60–80% LOP as a suitable "minimum" BFRE pressure. [ABSTRACT FROM AUTHOR]

OBEJCTIVE: To investigate the clinical efficiency and complications of individualized tourniquet pressure in patients undergoing primary total knee arthroplasty. METHODS: One hundred patients with primary unilateral total knee arthroplasty were enrolled and randomly divided into trial and control groups, 50 in each group. The limb occlusion pressure was determined as tourniquet pressure by Doppler ultrasound in the trial group, while 70 kPa pressure was chosen as tourniquet pressure in the control group. All patients signed the informed consents and the study was approved by the ethics committee of the hospital. The intraoperative blood loss, postoperative drainage volume, hidden blood loss, total blood loss and the incidence of deep venous thrombosis were recorded. The Visual Analogue Scale score, range of motion of knee joint and lower extremity swelling at 1, 3 and 5 days after surgery, and the Hospital for Special Surgery score at 1 month after surgery were compared. RESULTS AND CONCLUSION: (1) The Visual Analogue Scale scores at rest and in activity at 1 and 3 days after surgery and in activity at 5 days after surgery in the trial group were significantly lower than those in the control group (P < 0.05). There was no significant difference in the Visual Analogue Scale scores at rest at 5 days after surgery between two groups (P > 0.05). (2) The lower extremity swelling at 1 and 3 days after surgery in the trial group was significantly lighter than that in the control group (P < 0.05), and there was no significant difference at 5 days after surgery between two groups (P > 0.05). (3) There was no significant difference in the range of motion of knee joint at 1, 3, and 5 days after surgery between two groups (P > 0.05). (4) There was no significant difference in the Hospital for Special Surgery score, intraoperative blood loss, postoperative drainage volume, hidden blood loss and total blood loss at 1 month after surgery between two groups (P > 0.05). (5) These results indicate that the individualized tourniquet pressure assisted by Doppler ultrasound contributes to relieving early pain and lower extremity swelling after primary total knee arthroplasty, and can accelerate the functional recovery. [ABSTRACT FROM AUTHOR]

Background: Total 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. Methods: Fifty 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. Results: Arterial 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). Discussion: Arterial 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. [ABSTRACT FROM AUTHOR]

Background Total 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. Methods Fifty 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. Results Arterial 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). Discussion Arterial 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.

Background: Total 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. Methods: Fifty 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. Results: Arterial 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). Discussion: Arterial 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. [ABSTRACT FROM AUTHOR]

Introduction This study aimed to evaluate the knowledge of tourniquet use among orthopedic surgeons in Saudi Arabia and assess the practical aspects of their use of tourniquets and the complications they have experienced in their practices. Materials and methods This cross-sectional study was conducted from December 2022 to February 2023. An online questionnaire was distributed among orthopedic surgeons and trainees in Saudi Arabia, and the surgeons' knowledge of tourniquet use was assessed using 17 questions. To investigate tourniquet usage, the participants were divided into three groups: orthopedic residents, specialists, and consultants. An upper limb cuff pressure (CP) of 200 mmHg and a lower limb CP of 250 mmHg were chosen as the cut-off values, and the doctors' choices were compared against literature recommendations using these measures. Result A total of 205 participants filled out the questionnaires; 130 residents, 15 consultants, and 60 specialists, with more males (175/205) than females responding. One hundred and twenty-one surgeons placed the cuff on patients by themselves, while 50 (24.3%) surgeons asked nurses for aid; 135 (65.6%) of them work in teaching hospitals, while 50 (24.3%) work in community hospitals. The incidence of post-tourniquet syndrome was unrelated to expertise (p=0.12). Conclusion When applied properly, tourniquets prevent excessive bleeding and keep the operative field clean during limb surgeries. This study aims to inspire the orthopedic community to reconsider long-held practices, especially regarding tourniquet pressure. The addition of ligature safety education to orthopedics training and outlining the settings and procedures for applying pressure should also be considered. The orthopedic community should set CP and process criteria to avoid complications. This study showed the importance of modifying the training of orthopedic residents to raise awareness and prevent unpleasant events from occurring., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Albaker et al.)

Tourniquets are compressive devices that occlude venous and arterial blood flow to limbs and are commonly used in upper limb surgery. With the potential risk of complications, there is some debate as to whether tourniquets should continue to be routinely used. In this review, we first look at the different designs, principles, and practical considerations associated with the use of tourniquets in the upper limb. The modern pneumatic tourniquet has many design features that enhance its safety profile. Current literature suggests that the risk of tourniquet-related complications can be significantly reduced by selecting cuff inflation pressures based on the limb occlusion pressure, and by a better understanding of the actual level of pressure within the soft tissue, and the effects of cuff width and contour. The evidence behind tourniquet time, placement, and limb exsanguination is also discussed as well as special considerations in patients with diabetes mellitus, hypertension, vascular calcification, sickle cell disease and obesity. We also provide an evidence-based review of the variety of local and systemic complications that may arise from the use of upper limb tourniquets including pain, leakage, and nerve, muscle, and skin injuries. The evidence in the literature suggests that upper limb tourniquets are beneficial in promoting optimum surgical conditions and modern tourniquet use is associated with a low rate of adverse events. With the improvement in knowledge and technology, the incidence of adverse events should continue to decrease. We recommend the use of tourniquets in upper limb surgery where no contraindications exist. [ABSTRACT FROM AUTHOR]

Introduction: Pneumatic tourniquets are used extensively in orthopedic hand/wrist surgery. Complications, while rare, are associated with elevated pressure and duration of tourniquet use. Limb occlusion pressure (LOP) is the minimum tourniquet pressure at which arterial blood flow is restricted. Therefore, we performed a cross-sectional double-blinded randomized control trial to assess if there is a difference in post-operative pain at the surgical and tourniquet site between LOP and standard tourniquet pressure and if there is a difference in post-operative opioid usage., Methods: A total of 44 patients (Age 60±13, 30 female, 14 male) were randomized into two groups (LOP, 191±14 mmHg | STP, 250 mmHg) of 22 patients controlling for gender (15 female, seven male). The primary outcome was a visual analog scale (VAS) for pain at the tourniquet and surgical sites, recorded for the first two weeks post-operative. Daily pain medication usage was recorded and quantified using oral morphine milligram equivalents (MME). A group-by-time generalized mixed-model ANOVA was used to detect within-group and between group (LOP vs STP) differences in VAS at the surgical and tourniquet sites as well as medication use.  Results: LOP significantly decreased post-operative pain medication usage across the first week (-50%; p<0.05). Both groups had similar VAS pain at the surgery site, but the LOP group had 80% reduced pain at the tourniquet site when averaged across the first post-operative week (p<0.05).  Conclusions: The use of LOP compared to STP elicits reduced post-operative pain at the tourniquet site and reduces post-operative pain medication use in the first post-operative week., Competing Interests: The authors have declared financial relationships, which are detailed in the next section., (Copyright © 2021, Morehouse et al.)

Objectives: This study compared the efficacy and safety of minimal tourniquet pressure using either determined limb occlusion pressure (LOP) or estimated arterial occlusion pressure (AOP) for elective upper limb surgeries., Methods: Forty patients undergone elective upper limb surgery under general hypotensive anesthesia were randomized into groups A and B, where tourniquet pressure was calculated using AOP estimation for group A and LOP determination for group B. AOP, LOP, the time needed to estimate the AOP and determine the LOP and set the tourniquet inflation pressure, tourniquet inflation pressure, initial and maximal systolic blood pressure, heart rate, intraoperative fentanyl requirement, arm circumference, and tourniquet time were recorded. Tourniquet performance was assessed, and signs of tourniquet-related complications were noticed., Results: Systolic arterial blood pressure was comparable between the groups. Less time was recorded for measuring AOP or LOP and set the minimal inflation pressure (in second) in group A than in group B (62 ± 2 for group A vs. 120 ± 3 for group B; P < 0.001). The estimated AOP in group A was significantly higher than the determined LOP in group B (118 ± 2 vs. 91 ± 2; P < 0.001). Tourniquet inflation pressures were not significantly different between the groups. Tourniquet performance was excellent or good in all patients in both groups., Conclusions: Arterial occlusion pressure estimation or LOP determination methods to set the tourniquet inflation pressure with hypotensive anesthesia can provide effective minimal inflation pressure and satisfactory surgical field for upper extremity surgeries without tourniquet-related complications., Competing Interests: Conflict of Interests: The authors declare that they have no competing interests., (Copyright © 2020, Author(s).)