Effect of sustained regional compression on lower extremity skin microcirculation

Laser-Doppler blood perfusion was measured on foot dorsum (lateral and medial) and medial lower calf before (10 minutes), during (40 minutes) and after (10 minutes) of lower leg regional external compression at 40 mm Hg using a blood pressure cuff in 15 healthy supine subjects. Dorsum transcutaneous oxygen tension (TcPO2) was measured simultaneously. The purpose was to determine the effect of controlled and sustained regional compression on skin microcirculation at and distal to the compression site using a pressure level routinely employed for treatment of venous ulcers. Significant (p < 0.01) reductions in laser-Doppler blood perfusion under the cuff and at both distal noncompressed sites occurred with compression and lasted the full 40 minutes. Under-cuff minimums (percent of pre-compression baseline) occurred during the first 5 minutes (55.3 percent +/- 5.7) and distally at the end of compression (60.7 percent +/- 3.9 and 63.9 percent +/- 5.2) for medial and lateral dorsum respectively. No perfusion trends during compression were noted. Dorsum TcPO2 gradually declined with a minimum (89.6 percent +/- 2.2) after 30 minutes of compression. After pressure relief, perfusion increased but no significant hyperemic response was noted in the dorsum (102.6 percent +/- 6.1) whereas below-cuff perfusion increased in the immediate 5 minute post-compression interval (122.2 percent +/- 19.3). All values were insignificantly different than baseline during the final five minutes. The sustained and significant blood perfusion decreases found in healthy subjects are directly applicable to the regional compression employed but are believed to represent an upper bound on that to be expected with full leg compression bandaging. The findings reinforce the need for caution regarding therapeutic compression levels in patients with reduced vascular function. Because the effects are manifested distally, appropriate and timely perfusion monitoring at distal un-compressed sites may be efficacious to assess patient-by-patient compression effects and help guide the choice of appropriate compression levels.