Effects of compression on leg pulsatile blood flow

Leg external compression is an effective treatment for venous ulcers yet its impact on arterial hemodynamics is poorly understood. Herein the effect of foot-to-knee, 4-layer bandage compression on leg arterial pulsatile blood flow (Q, ml/min/100cc) was assessed by magnetic resonance flowmetry in 14 healthy supine subjects. Bilateral measurements at 5 below-knee sites without compression, and after compressing one leg revealed a potentially important new phenomena. Q in compressed legs increased as compared with baseline in all subjects whereas in control legs Q either decreased or remained unchanged. There was no group difference in paired leg Q prior to compression (1.69+/-0.11 vs. 1.64+/-0.11) but Q in the bandaged leg increased to 2.11 +/-0.08, p<0.01, whereas the control leg Q decreased to 1.55 +/-0.08, p<0.05. Baseline flow ratios (compressed leg/control leg) increased from 0.97+/-0.02 to 1.35+/-0.04, p=0.001. Flow increases were associated with increases in pulse width which showed a width ratio increase from 0.97+/-0.05 to 1.34+/-0.10, p=0.01. The responsible mechanisms are unknown but may be due to increased arterial compliance via decreased transmural pressure and increased venous resistance due to compression. Possible changes in pulse wave reflections may also play a role. Independent of the mechanism, the finding of a compression associated pulsatile flow increase may in part explain the documented beneficial therapeutic aspects.