Technique

Tourniquet time: the numbers residents get asked about

The orthobro · 2026-08-26 · 6 min read

Tourniquet time is one of the few numbers a junior gets asked in the OR where the expected answer is a specific figure. Which makes it worth knowing properly, including why the figure is softer than it sounds.

One thing up front: this is background reading, not a protocol. Your institution has a tourniquet policy and your attending has a practice, and both of those beat a web page. What follows is the reasoning behind the numbers so that you understand what you are being told.

The 90-minute figure

The commonly cited standard is no more than 90 minutes of continuous tourniquet time, followed by a rest interval before reapplying if the case needs more.

There is general agreement that for a reasonably healthy adult, 90 minutes should not be exceeded without releasing the tourniquet for a period.

You will also hear 2 hours quoted, from animal work and experience surveys describing that as the limit of safe use. Both numbers are in circulation, which is why two attendings can give you different answers and both be repeating something real.

The way to hold this: 90 minutes is the working standard you should be tracking against, and 2 hours is roughly where the literature stops offering reassurance at all. The space between them is judgment, not rule.

The reperfusion interval

When the limit is reached and the case is not finished, the cuff comes down to let the limb reperfuse before going back up.

The intervals described are at least 10 and preferably 15 minutes for the first deflation, and 15–20 minutes for subsequent ones. The interval gets longer each time, which is the part people forget — the second rest is not the same as the first.

Practically, this is worth planning rather than discovering. A case that is obviously going to run long is a case where the deflation should be anticipated, not sprung on the room at minute 91 in the middle of a critical step.

Pressure: the part that actually changed

For a long time, tourniquet pressure was set by a fixed rule — a standard number for the arm, a higher standard number for the leg, applied to everyone.

The evidence moved. Fixed pressure recommendations are often excessive, and prolonged tourniquet times at high pressures — pressures not based on limb occlusion pressure — are associated with increased pain, more opioid use, and prolonged PACU stay. Fixed pressures have also been associated with a higher rate of nerve injuries.

Limb occlusion pressure (LOP) is the alternative: measure the pressure at which arterial flow actually stops in this limb, then add a defined safety margin. It is patient-specific, and it is usually lower than the fixed number would have been.

If your unit's machine can measure LOP and it is not being used, that is a reasonable and non-annoying question to ask.

What changes the safe duration

The tolerance is not the same for every patient. Safe inflation time depends on the patient's anatomy, age, physical status, and the vascular supply to the extremity.

Which means the categories where you should be more cautious are predictable:

• Known peripheral arterial disease.
• Diabetes with vascular or neuropathic involvement.
• Prior nerve injury in that limb.
• Sickle cell disease.
• Very large or very small limbs — cuff width and fit matter, and a poorly fitting cuff needs more pressure to do the same job.

Contraindications and cautions are institution-specific and this is not the list to make a decision from. It is the list that should make you ask.

Your actual job as the junior

Three things, none of which require you to make a decision.

1. Know the time. Know when it went up. Not roughly — the actual time. If nobody has said it out loud, say it.

2. Call it at intervals. Sixty minutes, then ninety. Out loud, to the room. This is not you being officious; it is the single most useful thing a junior does with a tourniquet, and it is the reason nobody in that room ends up surprised.

3. Record it. Inflation time, pressure, deflation time, and total. It goes in the operative record, and it is the field most often missing.

That third one has an obvious application to your own notes as well. If you are keeping technique notes on a surgeon and a procedure, tourniquet pressure and typical time is exactly the kind of detail that is useless to memorise and extremely useful to have written down before your second case with the same person.

The exam-style summary

• Continuous inflation: not more than 90 minutes as the working standard; 2 hours is where the literature stops reassuring.
• Reperfusion: 10–15 minutes the first time, 15–20 minutes subsequently.
• Pressure: set from limb occlusion pressure, not a fixed number. Fixed pressures tend to be too high and are associated with more pain and more nerve injury.
• Risk is modified by vascular disease, diabetes, prior nerve injury, and limb size.
• The complications people ask about: nerve injury, skin injury under the cuff, post-tourniquet pain, and the reperfusion response on deflation.

And the honest caveat again: your institution's policy governs. Learn it, and learn what your attending does, because those are the two answers that actually apply to the case in front of you.