Beneath the cuff: Often overlooked and under-reported blood flow restriction device features and their potential impact on practice-A review of the current state of the research

Knowledge, attitudes, and practices of orthopedic operating room personnel regarding the use of pneumatic tourniquets

INTRODUCTION

Pneumatic tourniquets (PTs) play a crucial role in hemostasis during orthopedic surgery. This study aimed to investigate the current knowledge, attitudes, and practices (KAP) of orthopedic operating room personnel concerning the use of PTs.

METHODS

This cross-sectional study was conducted from Jul. 2023 to Aug. 2023. An online questionnaire was used to collect demographic information and KAP score data of the orthopedic operating room personnel from Hangzhou Regional Hospitals.

RESULTS

A total of 336 participants included orthopedic physicians (37.8%), orthopedic nurses (31.5%), anesthesiologists (8.9%), operating room nurses (19.9%) and medical students (1.8%). The median knowledge score was 28.5 (24, 32), with a maximum score of 38; the median attitude score was 31 (28, 35), of a maximum of 35; the median practice score was 41 (36, 44), of a maximum of 45. Correlation analysis showed links between knowledge and attitude (r = 0.388, p<0.001), knowledge and practice (r = 0.401, p<0.001), and attitude and practice (r = 0.485, p<0.001). Multivariate logistic regression analysis confirmed that female gender (OR = 0.294, 95% CI: 0.167-0.520; p<0.001), working in a specialized hospital (OR = 0.420, 95% CI: 0.219-0.803; p = 0.009), and occupation as a surgical anesthesiologist (OR = 3.358, 95% CI: 1.466-7.694; p = 0.004) were associated with better knowledge scores. A higher educational degree (OR = 0.237, 95% CI: 0.093-0.608; p = 0.003) was associated with better practice scores. No previous training was associated with lower knowledge (OR = 0.312, 95% CI: 0.187-0.520; p<0.001) and practice (OR = 0.325, 95% CI: 0.203-0.521; p<0.001) scores.

CONCLUSION

Orthopedic personnel in this study had acceptable knowledge, attitude, and practice concerning the use of PTs; additional training and guidance might enhance proficiency.

Validity and reliability of a wearable blood flow restriction training device for arterial occlusion pressure assessment

Purpose

The blood flow restriction (BFR) training is an effective approach to promoting muscle strength, muscle hypertrophy, and regulating the peripheral vascular system. It is recommended to use to the percentage of individual arterial occlusion pressure (AOP) to ensure safety and effectiveness. The gold standard method for assessing arterial occlusive disease is typically measured using Doppler ultrasound. However, its high cost and limited accessibility restrict its use in clinical and practical applications. A novel wearable BFR training device (Airbands) with automatic AOP assessment provides an alternative solution. This study aims to examine the reliability and validity of the wearable BFR training device.

Methods

Ninety-two participants (46 female and 46 male) were recruited for this study. Participants were positioned in the supine position with the wearable BFR training device placed on the proximal portion of the right thigh. AOP was measured automatically by the software program and manually by gradually increasing the pressure until the pulse was no longer detected by color Doppler ultrasound, respectively. Validity, inter-rater reliability, and test-retest reliability were assessed by intraclass correlation coefficients (ICC) and Bland-Altman analysis.

Results

The wearable BFR training device demonstrated good validity (ICC = 0.85, mean difference = 4.1 ± 13.8 mmHg [95% CI: -23.0 to 31.2]), excellent inter-rater reliability (ICC = 0.97, mean difference = -1.4 ± 6.7 mmHg [95% CI: -14.4 to 11.7]), and excellent test-retest reliability (ICC = 0.94, mean difference = 0.6 ± 8.6 mmHg [95% CI: -16.3 to 17.5]) for the assessment of AOP. These results were robust in both male and female subgroups.

Conclusion

The wearable BFR training device can be used as a valid and reliable tool to assess the AOP of the lower limb in the supine position during BFR training.

Measurement of arterial occlusion pressure using straight and curved blood flow restriction cuffs

Arterial occlusion pressure (AOP) is influenced by the characteristics of the cuff used to measure AOP. Doppler ultrasound was used to measure AOP of the brachial and superficial femoral arteries using straight and curved blood flow restriction cuffs in 21 males and 21 females. Vessel diameter and blood flow were evaluated as independent predictors of AOP. Overall, there were no significant differences in AOP when using the straight and curved cuffs in the brachial (129 mmHg vs. 128 mmHg) or superficial femoral artery (202 mmHg vs. 200 mmHg), respectively. Overall, AOP was greater (p < 0.05) in males than in females in the arm (135 mmHg, 123 mmHg) and leg (211 mmHg, 191 mmHg). Brachial (0.376 mm, 0.323 mm) and superficial femoral (0.547 mm, 0.486 mm) arteries were larger (p = 0.016) in males than in females, respectively. Systolic blood pressure (SBP) and arm circumference were predictive of brachial artery AOP, whereas SBP, diastolic blood pressure, thigh circumference, and vessel diameter were predictive of superficial femoral artery AOP. Straight and curved cuffs are efficacious in the measurement of AOP in the arm and leg. Differences in vessel size may contribute to sex differences in AOP but this requires further investigation.

It's time to regulate - The importance of accurate surgical-grade tourniquet autoregulation in blood flow restriction exercise applications

OBJECTIVE

Evaluate the efficacy of five common blood flow restriction (BFR) systems to accurately maintain and autoregulate BFR pressure in the tourniquet cuff near target pressure throughout exercise.

DESIGN

Randomised crossover design.

SETTING

Laboratory.

PARTICIPANTS

15 healthy individuals.

OUTCOME MEASURES

1) Percentage of total BFR time that surgical-grade tourniquet autoregulation, defined as automatic and rapid self-regulation of cuff pressure to within ±15 mmHg of initial target pressure within 1 s in the presence of transient pressure changes associated with exercise, was provided; 2) pressure change in the BFR cuff throughout exercise, by comparing the initial target pressure to the measured pressure at completion of BFR exercise.

RESULTS

One BFR system could provide surgical-grade tourniquet autoregulation for the whole duration (100 ± 0%) of the BFR exercise in all subjects. In two of the five BFR systems evaluated, measured cuff pressure at the end of exercise was not different (p < 0.05) to the initial target pressure.

CONCLUSIONS

Surgical-grade tourniquet autoregulation is important to consistently and reliably apply a targeted BFR pressure stimulus. This may allow BFR methodology and protocols to be accurately implemented and controlled so that the results can be more meaningfully compared, leading to the potential optimization of applications.

Autoregulated and Non-Autoregulated Blood Flow Restriction on Acute Arterial Stiffness

This study aimed to investigate the acute effects of autoregulated and non-autoregulated applied pressures during blood flow restriction resistance exercise to volitional fatigue on indices of arterial stiffness using the Delfi Personalized Tourniquet System. Following a randomized autoregulated or non-autoregulated blood flow restriction familiarization session, 20 physically active adults (23±5 years; 7 females) participated in three randomized treatment-order sessions with autoregulated and non-autoregulated and no blood flow restriction training. Participants performed four sets of dumbbell wall squats to failure using 20% of one repetition maximum. Blood flow restriction was performed with 60% of supine limb occlusion pressure. Testing before and post-session included an ultrasonic scan of the carotid artery, applanation tonometry, and blood pressure acquisition.Carotid-femoral pulse wave velocity increased in the non-autoregulated and no blood flow restriction training groups following exercise while carotid-radial pulse wave velocity increased in the no blood flow restriction training group (all p<0.05). Carotid-femoral pulse wave velocity exhibited an interaction effect between autoregulated and non-autoregulated blood flow restriction in favor of autoregulated blood flow restriction (p<0.05). Autoregulated blood flow restriction training does not influence indices of arterial stiffness while non-autoregulated and no blood flow restriction training increases central stiffness.

No Differences in Exercise Performance, Perceptual Response, or Safety Were Observed Among 3 Blood Flow Restriction Devices

Purpose

To compare 3 separate blood flow restriction (BFR) systems in their capacity to reduce repetitions to failure, impact perceptual responses, and cause adverse events during a low-load free-flow exercise.

Methods

The study included healthy subjects aged 18 years or older who presented to an ambulatory-care sports medicine clinic. On day 1, participants' demographic characteristics and anthropomorphic measurements were recorded. Each participant performed dumbbell biceps curl repetitions to failure using 20% of his or her 1-repetition maximum weight with each arm. Participants were exposed to 3 different tourniquet systems for familiarization. On day 2, each participant's arm was randomized to a cuff system, and the participant performed 2 sets of biceps curl repetitions to failure with the cuff inflated. Repetitions to failure, rating of perceived effort (RPE), rating of perceived discomfort, and pulse oxygenation levels were recorded after each set. On day 3, participants completed a survey of their perceived delayed-onset muscle soreness.

Results

The final analysis was performed on 42 arms, with 14 limbs per system. The study population had a mean age of 28.7 ± 2.4 years and a mean body mass index of 24.9 ± 4.3. All 3 systems successfully reduced repetitions to failure compared with unrestricted low-load exercise from baseline to BFR set 1 and from baseline to BFR set 2. There were no significant between-group differences among BFR systems regarding the number of repetitions to failure performed at baseline versus BFR set 1 or BFR set 2. The Delfi Personalized Tourniquet System (PTS) cohort had the greatest reductions in repetitions to failure from BFR set 1 to BFR set 2 (P = .002) and reported the highest RPE after set 2 (P = .025).

Conclusions

The Delfi PTS, SmartCuffs Pro, and BStrong BFR systems were each safe and were able to significantly reduce repetitions to failure compared with a low-load free-flow condition when used in a BFR exercise protocol. The Delfi PTS system may produce a higher RPE with prolonged use in comparison to the other systems.

Level of Evidence

Level II, prospective cohort study.