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| Optimisation of Indices of External Pneumatic Compression for Prophylaxis against Deep Vein Thrombosis: Radionuclide Gated Imaging Studies |
| Source: Kamm R, Butcher R, Froelich J, et al. Cardiovascular Research 20(8): 588-596, 1986 |
| Summary: Healthy human subjects with radionuclide-labeled blood were examined for the effect of external pneumatic compression in order to determine the optimal parameters necessary for DVT prophylaxis. They found that the optimal cycle has some combination of gradation and sequencing. The optimal pressure differential between distal and proximal aircells is 5-10 mmHg providing gradation. Sequential aircell inflation from distal to proximal should occur within 0.5 sec of the neighboring distal aircell's inflation. Most blood ejection occurred in 2-4 s from the start of the compression cycle and 30-50 s was needed for the blood vessels to refill. They also found that the maximum proportion of venous blood ejected was directly related to the degree of collapse of the vessel, and the square of the maximum velocity is directly proportional to turbulent shear stress. Shear stress is important since it can mechanically strip seeds of thrombi off the endothelium. |