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

Abstract

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.

Keywords: activity; bioimpedance; compensation; diabetes; fluid transport; interface stress; peripheral arterial disease; prosthesis; prosthetic fit; volume accommodation.

Figures

FIGURE 1

A residual limb instrumented with electrodes for bioimpedance testing

FIGURE 2. Definitions of types of activities

REST, STAND, and WALK activities were conducted. REST includes both SIT and TRANSITION from walk-to-sit and sit-to-walk. Limb extracellular fluid volume is in arbitrary units in this figure.

FIGURE 3. Percentage TOTAL fluid volume change by WALK fluid volume change

The correlation between TOTAL fluid volume change and WALK fluid volume change was 0.63. However, WALK explained only 39.3% of TOTAL thus was not a good predictor of TOTAL. A, B, C, and D identify quadrants described in the text.

FIGURE 4. A–C. Percentage fluid volume change for different activities and subject characteristics

Subject data are ordered left-to-right from low to high TRANSITION-SIT percentage fluid volume differences for subjects who lost fluid volume during WALK and for subjects who gained fluid volume during WALK. * = subject on lifetime antibiotics.

FIGURE 5

A,B Red arrows – volume flow of transport from the arteries into the interstitium. Blue arrows – volume transport from the interstitium into the veins. A: During resting with the socket doffed. Fluid volume transport is in balance. B: During STAND. Fluid volume transport is out of balance. More fluid is entering the veins and exiting the residual limb than is moving across the arteries and entering the residual limb, resulting in overall tissue fluid volume loss and a reduction in residual limb volume.