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of tourniquet-related injuries. The ability to determine LOP and use that as
the basis for tourniquet pressure rather than using an estimate, will help
reduce the likelihood of injuries.
5. Intraoperative LOP. While personalized tourniquets help deter-
mine LOP before surgery, what they can't take into account are the changes
to LOP that occur throughout a procedure. What happens is at the start of a
surgery, a patient is anesthetized, then during the surgery the blood pres-
sure varies. There are also different physiological parameters that vary due
to the anesthetic and pain incurred when the surgeon is working on a limb.
As a result, the LOP will vary in the sense that, in some instances, if
blood pressure is higher, more blood will be trying to pump through the
tourniquet, while in other instances, if the blood pressure is lower, there
will be less blood trying to pump through the tourniquet. In short: The min-
imum pressure required to occlude the blood flow changes throughout the
surgery.
To address this change, we're investigating an algorithm that looks at all
of the measures that affect the LOP, including blood pressure and heart
rate, and trying to develop technology that will use that algorithm to deter-
mine an updated estimate of LOP throughout the surgery, then adjust the
tourniquet pressure accordingly.
The LOP helped us get lower tourniquet pressures than what a surgeon
would normally use. The next step to improve it further would be to do what
we're doing with LOP at the beginning of the surgery, but be able to carry
this throughout the surgery by continuously knowing exactly how much
pressure is needed to occlude blood flow and develop technology that auto-
matically adjusts the tourniquet pressure.
6. Sensor-adjusted LOP. We're also investigating the development
of a system that incorporates sensors at the tourniquet cuff to measure
T O U R N I Q U E T S
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