Usability and Performance Evaluation of an Automated Tourniquet (AutoTQ) by Laypersons

Abstract

1. Introduction

Blood loss is the number one cause of preventable death in trauma, annually claiming over 1.5 million lives [1,2]. Extremity vascular injuries are the most common injuries in civilian public mass shooting incidents, followed by abdomen and chest injuries [3]. Depending on the location of the bleed and severity of the injury, hemorrhage can become life-threatening in seconds. A tourniquet is a compression device placed above a site of bleeding on an extremity that applies a high amount of pressure to a limb, therefore compressing arteries and veins to stop blood loss. Rapid access to tourniquets is critical to stop extremity bleeding and prevent morbidity and mortality. Windlass tourniquets are the standard for prehospital care, however they are conducive to neither speed nor accuracy, which are critical to save a life in emergency scenarios.

A study involving 198 participants revealed that over 84% of lay people failed to correctly apply a windlass tourniquet immediately after training [4]. Similarly, another study with 305 lay people reported an 80.33% failure rate in tourniquet application immediately post-training [5]. These findings are echoed in numerous other studies. The authors concluded that significant factors contributing to the failure of windlass tourniquets in controlling bleeding include slow response time, improper placement, and inadequate tightness. AutoTQ is a new tourniquet that seeks to reduce failure rates in prehospital tourniquet application.

2. Methodology

2.1 Study Design and Setting

A prospective, observational usability evaluation was conducted during a professional safety conference. The protocol was designed to simulate a first-encounter scenario for a layperson bystander in a controlled, non-emergency environment.

2.2 Participant Cohort

Participants were volunteers from the conference attendee population. Inclusion criteria required that participants confirm no prior hands-on experience with or exposure to the AutoTQ device. One individual was excluded for prior exposure. The final cohort consisted of 18 qualifying participants (N=18). All participation was voluntary and anonymous.

2.3 Intervention Protocol

Each participant received a standardized, sub-30-second verbal just-in-time (JIT) demonstration of the AutoTQ's operation. Following the demonstration, participants were timed as they applied the device to a live human volunteer from the GHM team. The scenario was designed to assess performance based on this minimal instruction set.

2.4 Outcome Measures

Four primary performance metrics were recorded by trained observers:

• Application Time: Total time elapsed from task initiation to successful device activation.
• Placement Accuracy: Correct positioning of the device on the limb proximal to a simulated wound.
• Activation Success: Successful inflation of the device via the user interface.
• Required Assistance: Any instance of verbal guidance required to complete the application protocol.

3. Results

The study yielded a 100% success rate across all primary endpoints for the entire cohort (N=18). All participants correctly placed and successfully activated the AutoTQ device.

3.1 Quantitative Analysis

3.2 Qualitative Observations

• 15 participants (83%) completed the task autonomously without any additional guidance.
• 3 participants (16%) required brief verbal cues to complete the task.

4. Discussion

The central finding of this evaluation is the 100% success rate in device application by novice users. This result is unprecedented when compared to the existing body of literature on layperson tourniquet application, where failure rates are consistently high. The study by Tsur et al. (2019), for example, found an 80% failure rate even after training, primarily due to incorrect placement and insufficient pressure application. The AutoTQ's performance suggests its design may mitigate these common failure modes.

The minor user errors observed are notable, as they underscore the importance of formal training. While it is significant that all users still achieved a successful outcome with minimal verbal correction—highlighting the device's operational resilience—the mandatory training provided with every AutoTQ kit is designed to eliminate these minor deviations and ensure optimal performance.

This evaluation was a performance observation, not a formal clinical trial, and was conducted in a non-stress environment. Future research should evaluate performance under simulated stress with a larger sample size and compare the AutoTQ directly against other commercial tourniquets in a randomized controlled setting.

5. Conclusion

The AutoTQ automated tourniquet demonstrated an exceptionally high degree of usability and application success in a cohort of non-medical first-time users. The ability of every participant to correctly and effectively apply the device with less than 30 seconds of instruction suggests that its intuitive design successfully bridges the gap between professional-grade medical technology and layperson accessibility. These findings indicate a strong potential for the AutoTQ to improve outcomes in civilian-led hemorrhage control scenarios.