Figure 2.
Input impedance (Zin) spectra of the respiratory system across various species. A: neonate mouse (data courtesy of Dr. R. Morty). B: neonate rabbit (data courtesy of Dr. J. Vanoirbeek and Dr. A. Gie). C: adult mouse. D: hamster (data courtesy of Dr. W. Mitzner). E: rat. F: adult rabbit. G: cynomolgus monkey. H: dog. I: children and adults. Impedance spectra from anesthetized, mechanically ventilated and paralyzed patients undergoing cardiac surgery extracted from Refs. 83, 85. J: adult healthy human subject, conscious and spontaneously breathing. K and L: comparison across species for resistance (K) and elastance (L). Elastance was calculated from the reactance part of the impedance. The calculation was done at every frequency up to the resonant frequency since after that point, the inertance effect dominates. The vertical dash line indicates the lowest frequency (5 Hz) used in a typical human oscillometry measurement in conscious, spontaneously breathing subjects. Zin, input impedance, expressed in the same units across species (cmH2O·s/L); R, resistance; E, elastance. Data were generated internally unless otherwise specified. Animal data were obtained with a flexiVent system and human data with a tremoflo C-100.