Optimising the performance of intermittent pneumatic compression devices

Objectives: this study was designed to determine whether an intermittent pn eumatic compression device (IPC) with an increased maximal inflation pressu re, a decreased time to maximal pressure and a longer duration of compressi on would improve venous return compared to a standard IPC device. Methods: thirty limbs in 15 volunteers without evidence of venous disease w ere studied using duplex scanning at rest and during the application of two different IPC devices with different compression parameters. The first dev ice IPC-1 (SCD 5325, Kendall) has a six-chambered cuff applying 45 mmHg aft er 12 s, sequentially from ankle to thigh followed by 60 s of non-compressi on. The second device IPC-2 (Vena-Assist(R), ACl Medical) has a foot, ankle and calf cuff, applies a pressure of 80 mmHg, has a pressure rise time of 0.3 s, maintains inflation for 5.5 s, and has a cycling time of 1 min. Peak venous velocity and acceleration time were measured at rest and during the IPC application. Measurements were obtained in supine position from the co mmon femoral vein 1 cm above the saphenofemoral junction to include the ent ire venous outflow from the limb. Results: peak venous velocity at rest was significantly higher in the right limb than in the left limb (26 +/- 7.2 vs. 22 +/- 5.7 cm/s, p<0.01). Peak venous velocity was significantly increased by both IPC devices (p<0.0001). IPC-2 achieved significantly higher peak venous velocity than IPC-1 (55.1 +/- 17.8 vs. 37.4 +/- 6.9 cm/s, p<0.0001). Acceleration time was also found to be significantly shorter (370 +/- 93.4 vs. 560 +/- 83.5 ms, p<0.0001) i n IPC-2 than in IPC-1, respectively. Conclusions: we have demonstrated that progressive inflation at the foot, a nkle and calf increasing maximal inflation pressure and decreasing time to maximal pressure result in increased venous return. These changes may impro ve the efficacy of IPC devices in the prevention of deep-venous thrombosis (DVT) formation.