Physical effects of heliox versus oxygen on measurements of functional residual capacity by the nitrogen washout technique in small lung volumes: A model study

2001 ◽  
Vol 31 (3) ◽  
pp. 255-260 ◽  
Author(s):  
Roland Hentschel ◽  
Andreas Suska ◽  
Andreas Volbracht ◽  
Erik Harms ◽  
Hellmut Haberland ◽  
...  
Keyword(s):  
Functional Residual Capacity ◽  
Lung Volumes ◽  
Nitrogen Washout ◽  
Model Study ◽  
Residual Capacity ◽  
Physical Effects

Measurement of high lung volumes by nitrogen washout method

1994 ◽  
Vol 77 (3) ◽  
pp. 1562-1564 ◽  
Author(s):  
Y. Sivan ◽  
J. Hammer ◽  
C. J. Newth
Keyword(s):  
Lung Volume ◽  
Human Infants ◽  
Lung Volumes ◽  
Nitrogen Washout ◽  
Thoracic Gas Volume ◽  
Residual Capacity ◽  
The Difference ◽  
Gas Dilution ◽  
Spontaneously Breathing ◽  
Gas Volume

Studies on human infants suggested that thoracic gas volume (TGV) measured at end exhalation may not depict the true TGV and may differ from TGV measured from a series of higher lung volumes and corrected for the volume added. This was explained by gas trapping. If true, we should expect the discrepancy to be more pronounced when functional residual capacity (FRC) and higher lung volumes are measured by gas dilution techniques. We studied lung volumes above FRC by the nitrogen washout technique in 12 spontaneously breathing rhesus monkeys (5.0–11.3 kg wt; 42 compared measurements). Lung volumes directly measured were compared with preset lung volumes achieved by artificial inflation of the lungs above FRC with known volumes of air (100–260 ml). Measured lung volume strongly correlated with and was not significantly different from present lung volume (P = 0.05; r = 0.996). The difference between measured and preset lung volume was 0–5% in 41 of 42 cases [1 +/- 0.4% (SE)]. The direction of the difference was unpredictable; in 22 of 42 cases the measured volume was larger than the preset volume, but in 17 of 42 cases it was smaller. The difference was not affected by the volume of gas artificially inflated into the lungs. We conclude that, overall, lung volumes above FRC can be reliably measured by the nitrogen washout technique and that FRC measurements by this method reasonably reflect true FRC.

Automated nitrogen-washout methods for infants: evaluated using cats and a mechanical lung

1982 ◽  
Vol 52 (5) ◽  
pp. 1378-1382 ◽  
Author(s):  
R. Richardson ◽  
M. Anderson
Keyword(s):  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Correlation Coefficient ◽  
Distress Syndrome ◽  
Lung Model ◽  
Lung Volumes ◽  
Nitrogen Washout ◽  
Mechanical Lung ◽  
Residual Capacity ◽  
Computerized System

Infants with respiratory distress syndrome are treated with constant distending pressures to counter atelectasis and increase the functional residual capacity (FRC). However, FRCs are not monitored in these severely ill infants because present methods are impractical. We computerized N2-washout techniques for estimating the lung volume in these infants. The system has been evaluated using 1) a mechanical lung model and 2) small cats with normal and edematous lungs. Comparing the results of measured lung volumes with the fixed mechanical lung volumes yielded a correlation coefficient 0.996 (n=50). Decreasing the N2 gradient between initial N2 concentration and the washout medium from 0.79 to 0.10 did not affect the accuracy or reproducibility of measurements in the mechanical lung. For normal cats, comparing the results of N2-washout measurements of FRC with He-dilution values yielded a correlation coefficient of 0.921 (n=128); results from cats with pulmonary edema yielded a correlation coefficient 0.989 (n=80). We conclude that this computerized system is accurate, reproducible, and clinically acceptable for monitoring infants.

Problems in measurement of thoracic gas volume in infancy

1982 ◽  
Vol 52 (4) ◽  
pp. 995-999 ◽  
Author(s):  
C. S. Beardsmore ◽  
J. Stocks ◽  
M. Silverman
Keyword(s):  
Functional Residual Capacity ◽  
Clinical Status ◽  
Pleural Pressure ◽  
Whole Body ◽  
Airway Closure ◽  
Lung Volumes ◽  
Airway Occlusion ◽  
Thoracic Gas Volume ◽  
Residual Capacity ◽  
Gas Volume

Thoracic gas volume (TGV) was measured with a whole-body plethysmograph in 20 infants at functional residual capacity (FRC) and at a series of higher lung volumes achieved by artificial inflation of the lungs with known volumes of air after airway occlusion. There was a discrepancy between the corrected values of TGV measured at high and low lung volumes in nine infants; in six cases TGV measured at high lung volumes exceeded that measured at FRC, and in three cases it was reduced when compared with the measurement made at FRC. These changes were not related to age, size, or clinical status and could be explained by airway closure at FRC, combined with an uneven distribution of pleural pressure.

scholarly journals In vitro and in vivo functional residual capacity comparisons between multiple-breath nitrogen washout devices

2017 ◽  
Vol 3 (4) ◽  
pp. 00011-2017 ◽  
Author(s):  
Katrina O. Tonga ◽  
Paul D. Robinson ◽  
Claude S. Farah ◽  
Greg G. King ◽  
Cindy Thamrin
Keyword(s):  
Functional Residual Capacity ◽  
Measurement Accuracy ◽  
Lung Model ◽  
Nitrogen Washout ◽  
Device Validation ◽  
Residual Capacity

Functional residual capacity (FRC) accuracy is essential for deriving multiple-breath nitrogen washout (MBNW) indices, and is the basis for device validation. Few studies have compared existing MBNW devices. We evaluated in vitro and in vivo FRC using two commercial MBNW devices, the Exhalyzer D (EM) and the EasyOne Pro LAB (ndd), and an in-house device (Woolcock in-house device, WIMR).FRC measurements were performed using a novel syringe-based lung model and in adults (20 healthy and nine with asthma), followed by plethysmography (FRCpleth). The data were analysed using device-specific software. Following the results seen with ndd, we also compared its standard clinical software (ndd v.2.00) with a recent upgrade (ndd v.2.01).WIMR and EM fulfilled formal in vitro FRC validation recommendations (>95% of FRC within 5% of known volume). Ndd v.2.00 underestimated in vitro FRC by >20%. Reanalysis using ndd v.2.01 reduced this to 11%, with 36% of measurements ≤5%. In vivo differences from FRCpleth (mean±sd) were 4.4±13.1%, 3.3±11.8%, −20.6±11% (p<0.0001) and −10.5±10.9% (p=0.005) using WIMR, EM, ndd v.2.00 and ndd v.2.01, respectively.Direct device comparison highlighted important differences in measurement accuracy. FRC discrepancies between devices were larger in vivo, compared to in vitro results; however, the pattern of difference was similar. These results represent progress in ongoing standardisation efforts.

Validation of a nitrogen washout system to measure functional residual capacity in premature infants with hyaline membrane disease

1995 ◽  
Vol 20 (6) ◽  
pp. 403-409 ◽  
Author(s):  
Jason Miller ◽  
Amy B. Law ◽  
Robert A. Parker ◽  
Håkan W. Sundell ◽  
Daniel P. Lindstrom ◽  
...  
Keyword(s):  
Premature Infants ◽  
Functional Residual Capacity ◽  
Hyaline Membrane Disease ◽  
Nitrogen Washout ◽  
Hyaline Membrane ◽  
Residual Capacity
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