Moment ratio analysis of multiple breath nitrogen washout in infants with lung disease

A. Schibler; M. Schneider; U. Frey; R. Kraemer

doi:10.1034/j.1399-3003.2000.01518.x

Moment ratio analysis of multiple breath nitrogen washout in infants with lung disease

European Respiratory Journal ◽

10.1034/j.1399-3003.2000.01518.x ◽

2000 ◽

Vol 15 (6) ◽

pp. 1094 ◽

Cited By ~ 44

Author(s):

A. Schibler ◽

M. Schneider ◽

U. Frey ◽

R. Kraemer

Keyword(s):

Lung Disease ◽

Ratio Analysis ◽

Nitrogen Washout ◽

Moment Ratio

Download Full-text

Fast real-time moment-ratio analysis of multibreath nitrogen washout in children

Journal of Applied Physiology ◽

10.1152/jappl.1985.59.4.1137 ◽

1985 ◽

Vol 59 (4) ◽

pp. 1137-1144 ◽

Cited By ~ 27

Author(s):

R. Kraemer ◽

B. Meister

Keyword(s):

Real Time ◽

Time Moment ◽

Digital Processing ◽

Ratio Analysis ◽

Delay Compensation ◽

Ventilation Inhomogeneity ◽

Moment Ratio ◽

Residual Capacity ◽

The Moment ◽

Washout Curves

To apply real-time moment-ratio analysis to multibreath N2-washout curves (MBNW) from children, a new processor-controlled device was constructed. Flow and fractional N2 concentration (FN2) were each sampled by 200 Hz. An electromagnetic triple-valve system, with an instrumental dead space of 36 ml and a valve resistance of 0.3 cmH2O . l-1 . s, was connected in series with a pneumotachograph and an N2 analyzer (Ohio 720) placed next to the mouthpiece. A FORTRAN/MACRO program on a PDP 11/23 computer enabled measurement of inspiratory and expiratory flow and FN2 sampling by a 12-bit analog-to-digital converter. The fast real-time digital processing of the N2 and flow signals incorporated filtering, delay compensation, and corrections for the effects of changes in gas composition and temperature. MBNW dynamics of the lungs were studied in 17 healthy and 28 asthmatic children and in 16 patients with cystic fibrosis, evaluating the moment ratios of the washout curves as indices of the ventilation characteristics. Intrasubject variability of the moment ratios (m1/m0, m2/m0) and determination of functional residual capacity (FRC) varied between 6.3 and 14.7% (depending on which parameter is considered) and was comparatively lower than other indices previously investigated in adults. In addition, the sensitivity of the moment ratios for discriminating different stages of ventilation inhomogeneity was superior to other indices. m2/m0 is closely related to the simultaneously measured airway resistance, and the ratio between cumulative expired volume and FRC is correlated with the ratio between residual volume and total lung capacity.

Download Full-text