Comparative respiratory system mechanics in rodents

tem mechanics in rodents. J Appl Physiol 89: 908–916, 2000.—Because of the wide utilization of rodents as animal models in respiratory research and the limited data on mea-surements of respiratory input impedance (Zrs) in small animals, we measured Zrs between 0.25 and 9.125 Hz at different levels (0–7 hPa) of positive end-expiratory pressure (PEEP) in mice, rats, guinea pigs, and rabbits using a com-puter-controlled small-animal ventilator (Schuessler TF and Bates JHT, IEEE Trans Biomed Eng 42: 860–866, 1995). Zrs was fitted with a model, including a Newtonian resistance (R) and inertance in series with a constant-phase tissue compart-ment characterized by tissue damping (Gti) and elastance (Hti) parameters. Inertance was negligible in all cases. R, Gti, and Hti were normalized to body weight, yielding nor-malized R, Gti, and Hti (NHti), respectively. Normalized