Table 1. Summary of tissue nitrogen correction equations.

Study (citation)	n	Age range	Equation used
Lundin, 1953 [9]	7	16–42	Rate of excretion (in mL/min) at time t: $\frac{\mathrm{d}{V}_{N2}}{dt}={37.3e}^{-0.45t}+{13.9e}^{-0.056t}+{4.82e}^{=0.0054t}$ Integrating to derive VN2 at time t: $V_{N2}={\displaystyle \int }37.3e^{-0.45t}+13.9e^{-0.056t}+4.82e^{-0.0054t}dt$ $V_{N2}=\left(\frac{37.3}{0.45}\right)\left(1-e^{-0.45t}\right)+\left(\frac{13.9}{0.056}\right)\left(1-e^{-0.056t}\right)+\left(\frac{4.82}{0.0054}\right)\left(1-e^{-0.0054t}\right)$ Where t = time in minutes
Cournand, 1941 [6]	30	9–44	$V_{N2}=\frac{t}{420}\times \left[\right(96.5\times BSA)+35]$ Where t = time in seconds
ATS/ERS [16]	NA	NA	VN2 = (96.5 × BSA) + 35

$BSA=BodySurface\left[m^2\right]=\frac{{Weight\left[kg\right]}^{0.425}\times {Height\left[cm\right]}^{0.725}\times 71.84}{10000}$

VN₂ = excreted volume of nitrogen (mL)

NA = Not applicable