The effect of various breathing maneuvers on measurement of lung volumes for hydrostatic weighing

Graduation date: 1990This study was to determine if an increase of PaC0₂, after breath-holding prior to full inspiration, could enable a person to reach the same FVC measured on land while submerged. Another purpose of this study was to explore the difference in Db and %BF between HW at RV, TLC and TLCwet with breath-holding. The FVC was measured under the conditions of on land and in water, both with breath-holding and without breath-holding. Secondly, subjects were hydrostatically weighed at RV, TLCwet, and TLCwet with breath-holding to determine the differences in estimation of Db and %BF. The RV was estimated via empirical formula. The TLC was determined by summing FVC and RV. Fifteen male (18 - 25 years old) and 15 female (19 -28 years old) students volunteered for this study. A two-way ANOVA with repeated measures and Scheffe's post hoc test were used for statistical analysis of data. The a level was set at .05 for statistical significance. There was no indication of increase in FVC with breath-holding. The FVC both with and without breath-holding was significantly reduced in water (5.4% - 5.5 % in females, 3.4% - 3.9 % in males). The mean Db calculated from RV was the lowest in both genders and was significantly lower than Db from TLCwet, TLCdry, and TLCwet with breath-holding. The Db at TLCwet was lower than at TLCdry with no statistical significance in males (average 0.002 gm/cc difference) and in females (mean difference was 0.005 gm/cc). The mean %BF difference between TLCwet and TLCdry was 0.75% in males and 2.01 % in females (p̲>.05). It is unlikely that a possible increase of PaC0₂ attained after breath-holding could facilitate inspiratory motion via stimulus to the chemoreceptors to overcome hydrostatic pressure. The empirical estimate of RV may not be suitable for young adults who have larger lungs. Using TLCdry in HW could be an alternative instead of using RV for males; for females it should be used with greater caution