TiMON: a real-time integrated monitor for improving the placement and wear of emergency tourniquets

Background: The use of emergency tourniquets among military personnel has helped to dramatically reduce battlefield deaths and has recently gained popularity in the civilian sector. Yet, even well-trained individuals can find it difficult to assess proper tourniquet application. Emergency tourniquets are typically deemed sufficiently tightened through cursory visual confirmation or pulse assessment. These indicators are not always accurate and are difficult to assess during chaotic events where fast and effective tourniquet application by both trained and untrained personnel can contribute significantly to saving lives. Towards addressing these issues, we have developed the Tourniquet Integrated Monitor (TiMON) as an easy-to-use real-time pressure sensing device designed to seamlessly integrate with pre-existing emergency tourniquets. Here, we present the results of two studies in which the TiMON was tested among a group of soldiers participating in the Army Expeditionary Warrior Experiments (AEWE) as well as in a group of untrained civilians from Massachusetts General Hospital.

Methods: In the first study, 30 soldiers with prior tourniqueting experience were asked to apply a TiMON equipped CAT tourniquet onto a leg mannequin with (unblinded) and without (blinded) assistance from the TiMON's output. In the second study, 30 lay volunteers from Massachusetts General Hospital with no prior tourniquet training were recruited and taught how to apply a tourniquet under normal conditions prior to being asked to perform the same exercises as the soldiers. In both studies, data collected for statistical analysis consisted of the real-time applied pressure along with the elapsed time for each subject to finish applying the emergency tourniquet.

Results: Subjects in both groups utilizing the TiMON had greater success in applying emergency tourniquets at the civilian clinically recommended occlusion range of 180 to 300 mmHg (soldiers: 86.67% assisted vs 33.33% unassisted; untrained volunteers: 93.33% assisted vs 40.00% unassisted). In terms of applied pressure, no significant mean differences were observed in either group (soldiers p-value = 0.13; untrained volunteers p-value = 0.26), however the unblinded subjects were found to exhibit significantly lower variances in applied pressure compared to those who were blinded (soldiers p-value < 0.0001; untrained volunteers p-value < 0.0001). In terms of application speeds, no significant differences in means and variances were observed in the soldiers (p-values = 0.85 and 0.61, respectively), while mildly significant increases in application times were observed in the untrained volunteers (p-value = 0.036).

Conclusion: Trained soldiers and lay volunteers using the TiMON were able to consistently apply tourniquets at clinically recommended occlusion pressures between 180 and 300 mmHg with significantly less under and over tightening while minimizing any negative effects to their application speeds. Despite it being their first time using the TiMON, both groups were able to quickly apply emergency tourniquets at significantly improved and consistent success rates regardless of prior training and experience.