Effect of Respiration on the Static Rear Stability of Wheelchairs

Kirby RL, Heimrath O, Stewart A, Smith C, MacLeod DA. Effect of respiration on the static rear stability of wheelchairs.

Objective

To test the hypothesis that the static rear stability of an occupied wheelchair is greater during full inspiration than expiration.

Design

Within-subject comparisons.

Setting

Rehabilitation center.

Participants

Able-bodied participants (N=10).

Intervention

None.

Main Outcome Measures

We measured the static rear stability (brakes unlocked) of an occupied wheelchair on a test platform according to International Organization for Standardization standards. We also used the Exhalation Threshold Test. The Exhalation Threshold Test was positive if, having been positioned at the maximum degree of platform tilt needed to maintain stability during full inspiration, the wheelchair tipped backward when the participant exhaled.

Results

The mean static rear stability values at full inspiration and expiration ± SD were 16.5°±2.3° and 16.1°±2.4°, with a mean difference of .46°±.24° (3%; P=.002). The Exhalation Threshold Test was positive in 19 (95%) of 20 trials.

Conclusions

Respiration has a slight but statistically significant effect on the rear stability of occupied wheelchairs, with greater stability at full inspiration. This has potential clinical implications for stability testing and the training of wheelchair skills, but further study is needed.