The Journal of Bone and Joint Surgery, Vol 67, Issue 2 303-314, Copyright © 1985 by Journal of Bone and Joint Surgery, Inc
Optimizing tourniquet application and release times in extremity surgery. A biochemical and ultrastructural study
AA Sapega, RB Heppenstall, B Chance, YS Park and D Sokolow
Despite numerous studies investigating the pathophysiology of tourniquet
ischemia, definitive data at the cellular level have been lacking and no
consensus regarding safe tourniquet-application times in extremity surgery
has emerged. In light of the particular vulnerability of skeletal muscle to
ischemic injury, we determined the degree of muscular metabolic derangement
and cell damage produced by seven different protocols of tourniquet
application and release, each providing three hours of total tourniquet
time. We performed thirty-six experiments on canine hind limbs, comparing
the following time-patterns of tourniquet application: I--three sequential
one-hour periods, II--two sequential one and one-half-hour periods,
III--two hours followed by one hour, and IV--a single continuous three-hour
application. Five and fifteen-minute reperfusion intervals between ischemic
periods were compared for the first three time-patterns, creating a total
of seven different tourniquet protocols. Muscular metabolic derangement and
cell injury were evaluated by monitoring changes in the cellular
bioenergetic state (high-energy phosphate profile), cell pH, post-ischemic
leakage of creatine phosphokinase, and ultrastructural cell degeneration.
At the intracellular level, the metabolic recovery of muscle during
reperfusion was much faster than previous studies focusing on extracellular
parameters have indicated. In all instances complete intracellular
bioenergetic recovery occurred within five minutes after tourniquet
release. The use of one or more five-minute reperfusion intervals
significantly reduced the degree of ischemic cell injury, as indicated by a
decrease in creatine phosphokinase leakage and myofibrillar destruction. No
additional benefit was derived by extending the reperfusion periods to
fifteen minutes. The longest period of continuous ischemia in each
tourniquet-application protocol bore the closest relationship with the
amount of cell damage produced. Within the spectrum of observed
pathological changes, time-patterns I and II produced comparatively little
muscle damage.
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