Scaling of respiratory variables in mammals

Abstract

Data were collected from the literature on respiratory variables and cor-related aginast body weight on the assumption of log-log relationships (allometry) with the use of computer regression analysis. Statistically validated power law formulas, with correlation coefficients of 0. 99-0. 90, are presented for lung weight, VC[long dash]vital capacity, TLC[long dash]total lung capacity, FRC[long dash]functional residual capacity, VT-tidal volume, VD, O2, E. f[long dash]number of breaths/min, Cl[long dash]pulmonary compliance, DLCO-Diffusing capacity of the lung for CO, DLO2-Diffusing capacity of the lung for 02, total respiratory flow resistance, work per breath, and several nonrespiratory parameters. The study deals principally with the rat-human size range, but the prediction formulas probably cover mice to steer and possibly all mammals. Predicted and observed values are compared for the rat, cat, dog, and man; good agreement is demonstrated. Size-independent dimensionless and dimensional respiratory invariants or design parameters may be obtained by forming simple and complex quotients from the individual power laws that have net residual mass exponents (dependency on body weight) approaching zero.