Abstract
Introduction
Haemorrhage is the main cause of preventable death on the modern battlefield. As Improvised Explosive Devices (IED) in Afghanistan become increasingly powerful, more proximal limb injuries are occurring. Significant concerns now exist about the ability of the windlass Combat Application Tourniquet to control distal haemorrhage following mid-thigh application.
Aim
To evaluate the efficacy of the CAT windlass tourniquet in comparison to the newer pneumatic Emergency Military Tourniquet (EMT).
Method
Serving soldiers were recruited from a military orthopaedic outpatient clinic. Participants' age, Body Mass Index and blood pressure were recorded and a short medical history obtained to exclude any arteriopathic conditions. Doppler ultrasound was used to identify the popliteal pulses bilaterally. The CAT was randomly self-applied by the participant at mid-thigh level and the presence or absence of the popliteal pulse on Doppler was recorded. This process was repeated on the contra lateral leg with the CAT now applied by a trained researcher. Finally, the EMT tourniquet was applied to the first leg and the presence of a popliteal pulse on Doppler recorded again.
Results
50 consecutive patients were invited to participate in the study. 15 declined to participate. 1 was excluded via pre-determined exclusion criteria. A total of 24 participants were recruited. The self applied CAT occluded popliteal flow in only 4 subjects (16.6%). The CAT applied by a researcher occluded popliteal flow in 2 subjects (8.3%). The EMT prevented popliteal flow in 18 subjects (75%). Statistical analysis demonstrated significance in the performance difference between the two tourniquets (p=0.001), but no significant difference between the two applications of the CAT (p=0.25). The BMI and systolic BP were significantly higher in those patients in whom the EMT failed (p=0.01 & p=0.04 respectively).
Conclusion
This study demonstrates that the CAT tourniquet is ineffective in controlling arterial blood flow when applied at mid-thigh level. The EMT was successful in a significantly larger number of participants, and its failures may be related to increased BMI and systolic pressure.
