Effect of immersion on residual volume of able-bodied and spinal cord injured males

This study compared residual lung volumes (RV) (oxygen dilution technique) of able-bodied (AB) and spinal cord injured (SCI) males on dry land in air (RVA) and immersed to the neck in water (RVW). The effects of significant differences in RV on calculations of body density (D_b) and percent body fat (%BF) were also assessed. The subjects were eight AB, eight paraplegic (PARA), and eight quadriplegic (QUAD) males, ranging in age from 18 to 51 yr. There was a 0.99 correlation (P<0.001) between RVA and RVW for AB subjects but no significant correlations between RVA and RVW for the PARA or QUAD groups. RVA in the QUAD group was significantly higher than in the PARA or AB group (P<0.003). There were no differences in RVW among the three groups. In the QUAD group, RVA was significantly larger than RVW (P<0.001), but there were no significant differences between RVA and RVW for the PARA or AB subjects. D_b and %BF did not differ significantly among the PARA or AB groups when calculated at RVA and RVW. However, for QUAD, both D_b and %BF differed significantly (P<0.001) when calculated at RVA and RVW. It was concluded that, for the purpose of hydrostatic weighing, residual lung volume of quadriplegic persons should be measured with the subject immersed in water.