Tourniquets and Scientific Studies

A tourniquet is a piece of  live saving equipment.  With that in mind, it is troubling to know that officers are either carrying tourniquets, or contemplating the purchasing of tourniquets, that are questionable with regard to effectiveness. What is more, they are making these decisions based on a questionable scientific study, most of which they did not completely read ( TQReport). It is not being hyperbolic to state that what it is arguing is a matter of life or death. If you question that, then please revisit the last blog entry.

One not wanting to read the entire study is understandable. It is 90 pages of dry, scientific writing. At first glance, the study is methodologically sound. It is constructed to test the effectiveness of tourniquets in an environment that simulates combat conditions. However, after one reads the study completely, there is one glaring deficiency. The study did not test which tourniquets achieved 100% occlusion. I Repeat: IT DID NOT TEST IF TOURNIQUETS ACHIEVED 100% OCCLUSION.  That should be the FIRST criterion a tourniquet must meet to continue a study.  While the ISR study (see below) tested tourniquets that could achieve 100% occlusion, the Navy study did not, so all other criteria are irrelevant.  Instead, it tested how easy it was to apply an ineffective tourniquet. As the study states:

Applications to arms were performed one-handed, but use of both hands was allowed for applications to thighs. A maximum of 5 minutes was allowed to apply the tourniquet, after which time the trial was terminated as an “application failure.” Application of the tourniquet was successful if the subject vocally declared, “Tourniquet on” — indicating that he had reached a point just before continued tightening would produce unbearable pain and had secured the device — within 5 minutes of being handed the test tourniquet. Upon such a declaration, a double event mark was recorded to mark the end of the application time period. The subject was asked to remain still throughout the remainder of the procedure.

Although the above may not seem like an issue, it is. First, applying a tourniquet until one thinks he/she has achieved hemorrhage control is not how it works. One applies a tourniquet to stop bleeding. One must continue to apply pressure until the bleeding stops. It is as simple at that. Second, using pain as indicator to cease applying pressure is not a good indicator. Doing so requires one to extrapolate the findings of a conscious, non-traumatic subject and apply them to an injured patient that has experienced enough trauma to require catastrophic-hemorrhage control.

Savvy distributors and manufacturers of different tourniquets have begun using this study to tout the effectiveness of their product. Beware. They are doing so based on the age-old assumption that consumers will not take the time to read all 90 pages. For example, they are giving potential consumers a chart that gives you a snapshot of the test that enumerates the tourniquets from best to worst. Please read the studies for yourself and make an educated decision. There are two tourniquets approved for use by the Army’s Institute for Surgical Research (ISR) (ISR Tourniquet Study). Do not let the desire to carry a tourniquet that is small–and possibly ineffective–outweigh the need to achieve hemorrhage control. Furthermore, short transport times DO NOT compensate for an ineffective tourniquet that can INCREASE bleeding. Finally, rid yourself of the disturbingly-common attitude that you will not actually need one . If that is the case, save yourself both money and weight and just don’t carry one. However, read the below post before doing so.

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