A simplified closed circuit helium dilution method for the determination of the residual volume of the lungs

Multiple breath helium dilution measurement of lung volumes in adults

“…The widely used multibreath helium equilibration method is based on equilibration of gas in the lung with a known volume of gas containing a known amount (or fraction) of helium [1,17,18]. For systems that utilize a spirometer, the spirometer capacity should be 7-10 L with 3% or better static volume accuracy over the entire range and resolution should be 25 mL or better.…”

“…Opinions and recommendations vary as to how to account for the effect of helium absorption, if at all. Based on theoretical considerations, it has been recommended that 100-110 mL be subtracted from the FRC value obtained [1,18]. Another investigator argued that the correction for helium absorption could be based only on very approximate estimates and chose to omit a correction [17].…”

“…Correction has been recommended when carbon dioxide production (V'CO 2 ) is less than oxygen consumption (V'O 2 ) (R<1) [18]. Such a difference would mean that helium would be concentrated in the lung and, at "equilibration", the concentration in the lung actually would be greater than in the spirometer.…”

Respiratory muscle strength and gas exhange in neuromuscular diseases: Comparison with chronic pulmonary emphysema and idiopathic pulmonary fibrosis.

“…FRC was obtained with the He-gas dilution method (Meneely et al 1960) using a water-sealed spirometer. TLC and RV were also obtained.…”

Small Airway Involvement in Mixed Connective Tissue Disease.

“…Slow vital capacity (VC) and forced expiratory volume in one second (FEV1) were measured with a 13.5-liter Benedict-Roth spirometer, and the ratio of FEV1 to VC (FEV1%) was calculated. Total lung capacity (TLC), functional residual capacity (FRC), and residual volume (RV) were measured by the closed-circuit inert gas dilution technique (Meneely et al 1960), and the ratio of RV to TLC (RV%) was calculated. Diffusing capacity for carbon monoxide (DL~o) and alveolar volume (VA) were measured by the single breath technique (Forster et al 1954), and the ratio of DL~o to VA (DLCO/VA) was calculated.…”