 Nirav R. Bhakta

Nirav R. Bhakta is first author of the 2023 European Respiratory Society/American Thoracic Society technical statement standardizing measurement of lung volumes. The report defines lung-volume subdivisions and distinguishes body plethysmography from gas-dilution measurements.^[ref] This is a contribution to making physiological measurements comparable across acquisition systems and laboratories.

The relationships among functional residual capacity, inspiratory capacity, expiratory reserve volume, total lung capacity and residual lung volume are also a useful test of data reduction. For an original accounting example, writeSubtracting gives vital capacity $\mathrm{VC}=\mathrm{IC}+\mathrm{ERV}$. At stipulated FRC 3 L, IC 2 L and ERV 1 L, the derived values are TLC 5 L, RV 2 L and VC 3 L. These are illustrative inventories, not clinical reference values.

The same recorded FRC enters TLC and RV with the same coefficient. If independent FRC, IC and ERV estimates each have standard uncertainty 0.10 L, the derived TLC and RV each have variance $0.02{\mathrm{L}}^2$, but their covariance is $0.01{\mathrm{L}}^2$. HenceThe standard uncertainty is about 0.141 L, matching direct propagation through IC + ERV. Incorrectly treating the two derived capacities as independent gives 0.20 L instead.

Bhakta's technical work helps make the definitions and acquisition conditions behind such comparisons explicit. The algebra does not establish that a gas-dilution estimate and a plethysmographic estimate sample exactly the same accessible gas in every circumstance. A consistent volume identity and an appropriate measurement mechanism are separate requirements.