Blood Vessel Occlusion by the Layperson Audiovisual Assist Tourniquet (LAVA TQ) Compared to the Combat Application Tourniquet: Randomized Controlled Trial.

INTRODUCTION: While windlass-rod style tourniquets stop bleeding in limbs when used by skilled responders, they are less successful in the hands of the untrained or not recently trained public. To improve usability, an academic-industry partnership developed the Layperson Audiovisual Assist Tourniquet (LAVA TQ). The LAVA TQ is novel in design and technology and addresses known challenges in public tourniquet application. A previously published multisite, randomized controlled trial of 147 participants showed that the LAVA TQ is much easier for the lay public to use compared to the Combat Application Tourniquet (CAT). This study evaluates the LAVA TQ's ability to occlude blood flow in humans compared to the CAT. METHODS: This study was a prospective, blinded, randomized controlled trial to demonstrate the non-inferiority of the LAVA TQ to occlude blood flow when applied by expert users compared to the CAT. The study team enrolled participants in Bethesda, Maryland, in 2022. The primary outcome was the proportion of blood flow occlusion by each tourniquet. The secondary outcome was surface application pressure for each device. RESULTS: The LAVA TQ and CAT occluded blood flow in all limbs (21 LAVA TQ, 100%; 21 CAT, 100%). The LAVA TQ was applied at a mean pressure of 366 millimeters of mercury (mm Hg) (SD 20 mm Hg), and the CAT at a mean pressure of 386 mm Hg (SD 63 mm Hg) (P = 0.14). CONCLUSION: The novel LAVA TQ is non-inferior to the traditional windlass-rod CAT in occluding blood flow in human legs. The application pressure of LAVA TQ is similar to that used in the CAT. The findings of this study, coupled with LAVA TQ's demonstrated superior usability, make the LAVA TQ an acceptable alternative limb tourniquet.

The Untrained Public's Ability to Apply the Layperson Audiovisual Assist Tourniquet vs a Combat Application Tourniquet: A Randomized Controlled Trial.

BACKGROUND: Although the Stop the Bleed campaign's impact is encouraging, gaps remain. These gaps include rapid skill decay, a lack of easy-to-use tourniquets for the untrained public, and training barriers that prevent scalability. A team of academic and industry partners developed the Layperson Audiovisual Assist Tourniquet (LAVA TQ)-the first audiovisual-enabled tourniquet for public use. LAVA TQ addresses known tourniquet application challenges and is novel in its design and technology. STUDY DESIGN: This study is a prospective, randomized, superiority trial comparing the ability of the untrained public to apply LAVA TQ to a simulated leg vs their ability to apply a Combat Application Tourniquet (CAT). The study team enrolled participants in Boston, MA; Frederick, MD; and Linköping, Sweden in 2022. The primary outcome was the proportion of successful applications of each tourniquet. Secondary outcomes included: mean time to application, placement position, reasons for failed application, and comfort with the devices. RESULTS: Participants applied the novel LAVA TQ successfully 93% (n = 66 of 71) of the time compared with 22% (n = 16 of 73) success applying CAT (relative risk 4.24 [95% CI 2.74 to 6.57]; p < 0.001). Participants applied LAVA TQ faster (74.1 seconds) than CAT (126 seconds ; p < 0.001) and experienced a greater gain in comfort using LAVA TQ than CAT. CONCLUSIONS: The untrained public is 4 times more likely to apply LAVA TQ correctly than CAT. The public also applies LAVA TQ faster than CAT and has more favorable opinions about its usability. LAVA TQ's highly intuitive design and built-in audiovisual guidance solve known problems of layperson education and skill retention and could improve public bleeding control.

ThoraSite: A device to improve accuracy of lateral decompression needle and chest tube placement.

BACKGROUND: Multiple reports have detailed an unacceptably high error rate in the siting of decompression needles and tubes and describe associated iatrogenic injuries. The objective of the current study was to measure the accuracy of the novel ThoraSite template for identifying an acceptable intercostal space (ICS) for lateral needle or tube thoracostomy. METHODS: Two trained operators used the ThoraSite to place radiopaque needles in the left and right lateral chests of 12 cadavers. An independent radiologist reviewed fluoroscopy images to determine the primary outcome: the ICS in which each needle was placed. Secondary outcomes were ICS's palpable through ThoraSite's Safe Zone; needle placement relative to the anterior axillary line (AAL) and midaxillary line (MAL); and percent correct placement (defined as the third, fourth, or fifth ICS from 1 cm anterior to the AAL to 1 cm posterior to the MAL). RESULTS: The six female and six male cadavers spanned 4 ft and 11 inches (150 cm) to 6 ft and 7 inches (201 cm), 80 lb (36 kg) to 350 lb (159 kg), and 16 kg/m to 42 kg/m body mass index. All 24 needles were placed in either the third (4 [17%] of 24 needles), fourth (10 [42%] of 24 needles), or fifth ICS (10 [42%] of 24 needles). In 10 (42%) of 24 assessments, two ICSs were palpable in ThoraSite's Safe Zone. All palpable ICSs were either the third (8 [24%] of 34), fourth (15 [44%] of 34); or fifth ICS (11 [32%] of 34). Twenty-three (96%) of 24 needles were inserted from 1 cm anterior to the AAL to 1 cm posterior to the MAL. Twenty-three (96%) of 24 needle placements were correct. CONCLUSION: ThoraSite use was associated with needle placement in the third, fourth, or fifth ICS in an area roughly spanning the AAL to MAL in anatomically diverse cadavers. By facilitating appropriate needle/tube placement, ThoraSite use may decrease iatrogenic injuries. Future study involving representative users may be useful to further evaluate ThoraSite accuracy. LEVEL OF EVIDENCE: Therapeutic and care management, level IV.

Effect of bladder wall thickness on miniature pneumatic artificial muscle performance.

Pneumatic artificial muscles (PAMs) are actuators known for their high power to weight ratio, natural compliance and light weight. Due to these advantages, PAMs have been used for orthotic devices and robotic limbs. Small scale PAMs have the same advantages, as well as requiring greatly reduced volumes with potential application to prostheses and small scale robotics. The bladder of a PAM affects common actuator performance metrics, specifically: blocked force, free contraction, hysteresis, and dead-band pressure. This paper investigates the effect that bladder thickness has on static actuation performance of small scale PAMs. Miniature PAMs were fabricated with a range of bladder thicknesses to quantify the change in common actuator performance metrics specifically: blocked force, free contraction, and dead-band pressure. These PAMs were then experimentally characterized in quasi-static conditions, where results showed that increasing bladder wall thickness decreases blocked force and free contraction, while dead-band pressure increases. A nonlinear model was then applied to determine the structure of the stress-strain relationship that enables accurate modeling and the minimum number of terms. Two nonlinear models are compared and the identified parameters are analyzed to study the effect of the bladder thickness on the model.