Functional Residual Capacity and Airway Resistance of the Rat Measured with a Heat- and Temperature-Adjusted Body Plethysmograph

Fourteen healthy normal volunteers were randomly exposed to air and 0.5 ppm of ozone (O3) in a controlled exposure chamber for a 2-h period during which 15 min of treadmill exercise sufficient to produce a ventilation of approximately 40 l/min was alternated with 15-min rest periods. Before testing an esophageal balloon was inserted, and lung volumes, flow rates, maximal inspiratory (at residual volume and functional residual capacity) and expiratory (at total lung capacity and functional residual capacity) mouth pressures, and pulmonary mechanics (static and dynamic compliance and airway resistance) were measured before and immediately after the exposure period. After the postexposure measurements had been completed, the subjects inhaled an aerosol of 20% lidocaine until response to citric acid aerosol inhalation was abolished. All of the measurements were immediately repeated. We found that the O3 exposure 1) induced a significant mean decrement of 17.8% in vital capacity (this change was the result of a marked fall in inspiratory capacity without significant increase in residual volume), 2) significantly increased mean airway resistance and specific airway resistance but did not change dynamic or static pulmonary compliance or viscous or elastic work, 3) significantly reduced maximal transpulmonary pressure (by 19%) but produced no changes in inspiratory or expiratory maximal mouth pressures, and 4) significantly increased respiratory rate (in 5 subjects by more than 6 breaths/min) and decreased tidal volume.(ABSTRACT TRUNCATED AT 250 WORDS)

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A reevaluation of the validity of unrestrained plethysmography in mice

Journal of Applied Physiology ◽

10.1152/japplphysiol.00080.2002 ◽

2002 ◽

Vol 93 (4) ◽

pp. 1198-1207 ◽

Cited By ~ 166

Author(s):

Lennart K. A. Lundblad ◽

Charles G. Irvin ◽

Andy Adler ◽

Jason H. T. Bates

Keyword(s):

Tidal Volume ◽

Functional Residual Capacity ◽

Airway Resistance ◽

Ambient Conditions ◽

Closed Chamber ◽

Time Integral ◽

Gas Compression ◽

Compression And Expansion ◽

Residual Capacity ◽

Gas Conditioning

Presently, unrestrained plethysmography is widely used to assess bronchial responsiveness in mice. An empirical quantity known as enhanced pause is derived from the plethysmographic box pressure [Pb( t), where t is time] and assumed to be an index of bronchoconstriction. We show that Pb( t) is determined largely by gas conditioning when normal mice breathe spontaneously inside a closed chamber in which the air is at ambient conditions. When the air in the chamber is heated and humidified to body conditions, the changes in Pb( t) are reduced by about two-thirds. The remaining changes are thus due to gas compression and expansion within the lung and are amplified when the animals breathe through increased resistances. We show that the time integral of Pb( t) over inspiration is accurately predicted by a term containing airway resistance, functional residual capacity, and tidal volume. We conclude that unrestrained plethysmography can be used to accurately characterize changes in airway resistance only if functional residual capacity and tidal volume are measured independently and the chamber gas is preconditioned to body temperature and humidity.

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Restrained whole body plethysmography for measure of strain-specific and allergen-induced airway responsiveness in conscious mice

Journal of Applied Physiology ◽

10.1152/japplphysiol.00464.2006 ◽

2006 ◽

Vol 101 (5) ◽

pp. 1495-1505 ◽

Cited By ~ 21

Author(s):

Jennifer L. S. Lofgren ◽

Melissa R. Mazan ◽

Edward P. Ingenito ◽

Kara Lascola ◽

Molly Seavey ◽

...

Keyword(s):

Functional Residual Capacity ◽

Airway Resistance ◽

Allergen Challenge ◽

Airway Disease ◽

Airway Responsiveness ◽

Whole Body ◽

Forced Oscillation Technique ◽

Body Plethysmography ◽

Residual Capacity ◽

Whole Body Plethysmography

The mouse is the most extensively studied animal species in respiratory research, yet the technologies available to assess airway function in conscious mice are not universally accepted. We hypothesized that whole body plethysmography employing noninvasive restraint (RWBP) could be used to quantify specific airway resistance (sRaw-RWBP) and airway responsiveness in conscious mice. Methacholine responses were compared using sRaw-RWBP vs. airway resistance by the forced oscillation technique (Raw-FOT) in groups of C57, A/J, and BALB/c mice. sRaw-RWBP was also compared with sRaw derived from double chamber plethysmography (sRaw-DCP) in BALB/c. Finally, airway responsiveness following allergen challenge in BALB/c was measured using RWBP. sRaw-RWBP in C57, A/J, and BALB/c mice was 0.51 ± 0.03, 0.68 ± 0.03, and 0.63 ± 0.05 cm/s, respectively. sRaw derived from Raw-FOT and functional residual capacity (Raw*functional residual capacity) was 0.095 cm/s, approximately one-fifth of sRaw-RWBP in C57 mice. The intra- and interanimal coefficients of variations were similar between sRaw-RWBP (6.8 and 20.1%) and Raw-FOT (3.4 and 20.1%, respectively). The order of airway responsiveness employing sRaw-RWBP was AJ > BALBc > C57 and for Raw-FOT was AJ > BALB/c = C57. There was no difference between the airway responsiveness assessed by RWBP vs. DCP; however, baseline sRaw-RWBP was significantly lower than sRaw-DCP. Allergen challenge caused a progressive decrease in the provocative concentration of methacholine that increased sRaw to 175% postsaline values based on sRaw-RWBP. In conclusion, the technique of RWBP was rapid, reproducible, and easy to perform. Airway responsiveness measured using RWBP, DCP, and FOT was equivalent. Allergen responses could be followed longitudinally, which may provide greater insight into the pathogenesis of chronic airway disease.

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