Liu K, Chen LE, Seaber AV, Urbaniak JR.
Influences of inflation rate and duration on vasodilatory effect by intermittent
pneumatic compression in distant skeletal muscle.
J Orthop Res 1999 May;17(3):415-20

Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710, USA.

Previous study has demonstrated that application of intermittent pneumatic
compression on legs can cause vasodilation in distant skeletal muscle at the
microcirculation level. This study evaluated the influence of inflation rate and
peak-pressure duration on the vasodilatory effects of intermittent pneumatic
compression. The cremaster muscles of 50 male rats were exposed and divided into
five groups of 10 each. A specially designed intermittent pneumatic-compression
device was applied in a medial-lateral fashion to both legs of all rats for 60
minutes, with an inflation rate and peak-pressure duration of 0.5 and 5 seconds,
respectively, in group A, 5 and 0 seconds in group B, 5 and 5 seconds in group C,
10 and 0 seconds in group D, and 10 and 5 seconds in group E. Diameters of
arterial segments were measured in vessels of three size categories (10-20,
21-40, and 41-70 microm) for 120 minutes. The results showed that the greatest
increase in diameter was produced by intermittent pneumatic compression with the
shortest inflation rate (0.5 seconds). A moderate increase resulted from
compression with an inflation rate of 5 seconds, and no effective vasodilation
occurred during compression with the longest inflation rate (10 seconds). When
the groups with different inflation rates but the same peak-pressure duration
were compared, there was a significant difference between any two groups among
groups A, C, and E and between groups B and D. When the groups with different
peak-pressure durations but the same inflation rate were compared, compression
with a peak-pressure duration of 5 seconds caused a generally similar degree of
diameter change as did compression without inflation at peak pressure. The
findings suggest that inflation rate plays an important role in the modulation of
distant microcirculation induced by intermittent pneumatic compression whereas
peak-pressure duration does not significantly influence the vasodilatory effects
of the compression. This may be due to the fact that rapid inflation produces a
significant increase in shear stress on the vascular wall, which stimulates
vascular endothelium to release nitric oxide, causing systemic vasodilation.