Lessons Learned: “Four Hours of Tourniquet Time”

Below is an excerpt from a lessons learned compilation titled “First to Cut: Trauma Lessons Learned in the Combat Zone.” Though it is geared toward FST surgeons and forward medical providers, some of the lessons are applicable to tactical medics and mountain rescue. The larger take-away point is that the physiology occurring distally to a tourniquet applied for a long duration needs to be considered when changing or loosening, especially in environments where medical care may be limited (e.g., Third World).

    “Four Hours of Tourniquet Time”

    “26 y.o. male with foot traumatic amputation and
    multiple frag wounds to the right leg with a high thigh
    field tourniquet in place. Arrived to the CSH with SBP of
    100 HR of 120. we had no report on duration of the
    tourniquet. We took down the tourniquet and he promptly
    coded. We put the tourniquet back up, intubated him and
    gave him fluid and bicarb and he came back. We found
    out later that the tourniquet had been in place for over 4

    The use of tourniquets – while rare in civilian trauma is
    very common in combat injuries. Tourniquets are the
    number 1 instrument that a medic can employ to lower the
    KIA numbers. The use of tourniquet with application until
    the absence of a distal pulse by default causes distal
    ischemia. Release of a functioning tourniquet after several
    hours can result in the release of acidic fluid and potassium.
    The patient intubated and without a head injury can be
    briefly hyperventilated. Before taking down a long
    duration tourniquet make sure the patient is well hydrated,
    resuscitated, adding an ampule of sodium bicarbonate or
    THAM can prophylax against the release of “bad humors”,
    lactic acid, and potassium. Also release the tourniquet
    slowly – if the rare arrhythmia arises re–employ the
    tourniquet and retry after further bicarb and fluid. If the leg
    is necrotic remember “life before limb” and perform an

    Lessons Learned:
    –Prolonged tourniquet times can result in the release
    of acidotic fluid and hyperkalemia
    –Perform 4 compartment fasciotomy with all lower
    extremities with significant tourniquet times

6 replies
  1. Mike S.
    Mike S. says:

    I don’t think medics on the ground should loosen tourniquets just for the simple fact that if they don’t know where the bleeding is coming from, than they can’t properly discern whether or not it should be coming off in the first place. Plus, I don’t remember when I had sodium bicarbonate in my aid bag, which brings me to a question. Would the use of Sodium chloride, or lactated ringers have the same affects as the sodium bicarb?

  2. Cdn_Medic
    Cdn_Medic says:

    Strange how doctors need studies to tell them what we have known for years in the combat medic’s ranks.

    No shit… If you leave a Tq on for an extended period of time the affected limb will release acidi fluids and potassium. Yeah, it’s dangerous, but can be fixed some what easily and sure as hell beat try to bring back a guy with no pulse and no blood.

  3. just sayin
    just sayin says:

    Mike S. LR or NS would not replace the bicarb.Its primary use is as a buffering agent to combat acidosis(it has additional uses in certain over doses).The LR/NS might alter the pH through dilution ,but it would be minimal compared to the bicarb.

  4. Alan Frankfurt
    Alan Frankfurt says:

    Total ischemia of a limb, regardless of the reason, results in anaerobic metabolism and the accumilation of lactic acid, both within the cell and in the extracellular fluid distal to the TQ. Orthopedic literature has suggested that two hours is the upper limit for at TQ to be up before cellular changes due to lack of oxygenated blood delivery occur. It has also been suggested that up to 90% of bleeding due to clot formation (and possibly relative hypotension) will have occured in a bleeding limb after one hour of TQ application. Hence, under the right conditions, release of a TQ within the two hour time limit, even for five minutes, buys you another two hours of TQ time. This concept must be vetted through the operational/battlefield filter, where factors such as darkness, light discipline, use of blankets to prevent hypothermia and transport issues often prevent continual observation of the TQ and wound.
    Often in the OR during orthopedic procedures, that utilize a TQ, release of the TQ will be accompanied by a drop in BP on the arterial line and an increase in the ETCO2 as lactic acid is converted to CO2 in the blood. Bottom line, if a TQ is up for more than two hours, literature and experience suggest care be used prior to TQ release and probably should be done with EKG and BP monitoring. This also underscores the importance of good/great communication regarding care given to the casualty.
    NS or LR would not impact the acidosis other than to treat the vasodilation that occurs and that is partially responsible for the hypotension that occurs with TQ release after prolonged application. Vascular reactivity and cardiac contractility is pH dependent and once the pH is below 7. 2 things go to shit. Bicarb and fluids are effective along with Neosynephrine; all things not available to the medic. Hence, the importance of paying attention to TQ application time and making sure the TQ remains tight. IMHO.

  5. tems_wildmed
    tems_wildmed says:

    Something else to consider….how long does it take the normal hemostatic process to occur? For individuals without coagulopathy, most clotting takes 5-15 minutes to occur. Wilderness Medical Associates recommends that, in a prolonged care setting, tourniquets be slowly released after about an hour to assess for re-bleeding. If no re-bleeding occurs, does the TQ REALLY need to be left on and risk this reperfusion injury?

    • admin
      admin says:

      That is a great point. I think the context does matter. The reason most tactical medicine instruction favors leaving it on is the short evacuation times and the possibility of having to move the patient often. Most quality programs do teach to evaluate the wound and change to a pressure dressing when applicable, while leaving the tourniquet in place so that you can re-tighten it if needed.

      Thanks for the comments.


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