Premium
Low‐frequency vs. High‐frequency respiratory mechanics after methacholine challenge in artificially ventilated rabbits
Author(s) -
Belaguid A.,
Marchal F.,
Mazurek H.,
Hascoet J. M.,
Peslin R.
Publication year - 1993
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.1950160505
Subject(s) - methacholine , medicine , transpulmonary pressure , respiratory system , linear regression , anesthesia , respiratory physiology , tidal volume , elastance , high frequency ventilation , lung volumes , lung , respiratory disease , mechanical ventilation , mathematics , statistics
Respiratory system resistance (R rs ) and elastance (E rs ) were estimated by two methods, before and after methacholine in six anesthetized, paralyzed, and artificially ventilated rabbits. R rs and E rs , were obtained (1) by multiple linear regression analysis of the relationship between tracheal pressure and tidal volume and flow [R rs (mlr)], E rs (mlr), and (2) by analysis of the Fourier transforms of tracheal pressure and flow resulting from 4 to 30 Hz pseudorandom pressure oscillations delivered by an Infant Star respirator [R rs (os), E rs (os)]. R rs (os) was significantly lower than R rs (mlr). For instance, R rs (os) at 20 Hz [R rs (os)20] was (mean±SD) 17.3±3.5 vs 21.4±3.6 cm H 2 O · L −1 · s ( P < 0.01) for R rs (mlr). E rs (os) was significantly higher than the respective value obtained by multiple linear regression (718.2±81.0 vs 403.7±43.0 cm H 2 O L −1 ; P < 0.01). After methacholine, the changes of respiratory mechanics were similar with both methods. R rs (mlr) and R rs (os)20 increased respectively by 131±45 and 134±76%, and E rs (mlr) and E rs (os) increased respectively by 63±7 and 54±13%. A significant correlation was observed between R rs (mlr) and R rs (os)20 ( r = 0.97) and between E rs (mlr) and E rs (os) ( r = 0.96). We conclude that positive response to methacholine may be detected by forced oscillation as well as by multiple linear regression. However, the identified physiological components of the lung response (alteration in lung viscoelastic properties, increased lung inhomogeneity or increased intrathoracic airway shunt) are likely to be different with each method. Pediatr Pulmonol. 1993; 16:297–302. © 1993 Wiley‐Liss, Inc.