How do walking, standing, and resting influence transtibial amputee residual limb fluid volume?

The purpose of this research was to determine how fluid volume changes in the residual limbs of people with transtibial amputation were affected by activity during test sessions with equal durations of resting, standing, and walking. Residual limb extracellular fluid volume was measured using biompedance analysis in 24 participants. Results showed that all subjects lost fluid volume during standing with equal weight-bearing, averaging a loss rate of -0.4%/min and a mean loss over the 25 min test session of 2.6% (standard deviation [SD] 1.1). Sixteen subjects gained limb fluid volume during walking (mean gain of 1.0% [SD 2.5]), and fifteen gained fluid volume during rest (mean gain of 1.0% [SD 2.2]). Walking explained only 39.3% of the total session fluid volume change. There was a strong correlation between walk and rest fluid volume changes (-0.81). Subjects with peripheral arterial disease experienced relatively high fluid volume gains during sitting but minimal changes or losses during sit-to-stand and stand-to-sit transitioning. Healthy female subjects experienced high fluid volume changes during transitioning from sit-to-stand and stand-to-sit. The differences in fluid volume response among subjects suggest that volume accommodation technologies should be matched to the activity-dependent fluid transport characteristics of the individual prosthesis user.