Table 4.

Parameter	Abbr.	Description
lung resistance	RL	quantitatively assesses the level of obstruction in the lungs and comprises the resistance of the conducting airways (Raw) and tissue (Rti)
lung conductance	GL	reciprocal of lung resistance (1/RL)
dynamic compliance	Cdyn	primarily reflects the elasticity of the lung parenchyma, but is also affected by surface tension, smooth muscle constriction, and peripheral airway inhomogeneities. In contrast, static compliance is measured at true equilibrium, when resistances and compliances are not uniform throughout the lung, e.g. in the absence of any motion.
methacholine	MCh	non-specific cholinergic bronchoconstrictor used to assess airway responsiveness
elastance	E	captures the elastic rigidity of the lungs.
reactance	X	reflects respiratory compliance (1/elastance) and characterizes the lung parenchyma
input impedance	Z	expresses the combined effects of resistance, compliance and inertance as a function of frequency.
inertance	I	represents the inertive properties of the gases in the airways. The majority of I resides in the central airways bypassed by the tracheal cannula. Inertance can be ignored in the mouse below 20 Hz.
tissue damping	G	is closely related to tissue resistance and reflects the dissipative properties of the lung tissues.
tissue elastance	H	reflects the elastic properties of the lung tissues.
enhanced pause	Penh	is a unitless, empirical measurement derived from box pressure signals during inspiration and expiration and the timing comparison of early and late expiration and is used as a non-invasive measure of bronchoconstriction.
tidal midexpiratory flow	EF50	is defined as the tidal flow at the midpoint of expiratory tidal volume and is used as a non-invasive measure of airway constriction.
positive end-expiratory pressure	PEEP	is the amount of pressure above atmospheric pressure present in the airway at the end of the expiratory cycle. PEEP improves gas exchange by preventing alveolar collapse, recruiting more lung units, and increasing functional residual capacity.