Better late than never: correcting the error in the Exhalyzer nitrogen washout system

To determine pulmonary function abnormalities in patients with neonatal bronchopulmonary dysplasia (BPD), we measured distribution of ventilation by nitrogen washout, minute and tidal volume, and arterial and alveolar gases in three groups of ten preterm infants with similar birth weights (mean = 1,340 g) and gestational ages (mean = 30.3 weeks). Infants in group A were never artificially ventilated, those in group B were ventilated but had no subsequent BPD, and those in group C were ventilated and developed BPD. Infants with BPD had severe maldistribution of ventilation (pulmonary clearance delay 223% versus 47% and 60% for groups A and B). They had decreased tidal volumes (5.3 ml versus 7.0 and 6.2 ml) and higher respiratory rates (60/min versus 47 and 48) but similar minute volumes. They also had increased Paco2 (53.6 torr versus 41.9 and 43.4 torr) and increased arterial-alveolar carbon dioxide gradients (6.8 torr versus 3.1 and 1.8 torr). There was no statistically significant difference between groups B and C for the time spent in fractional inspired oxygen > 0.40 and > 0.60, or the time ventilated or intubated, or the incidence of patent ductus arteriosus. Early pulmonary interstitial emphysema was much more common in the infants who subsequently developed BPD (eight of ten versus two of ten, P < .01).

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Inflection point on transpulmonary pressure-volume curves and closing volume

Journal of Applied Physiology ◽

10.1152/jappl.1975.38.2.228 ◽

1975 ◽

Vol 38 (2) ◽

pp. 228-235 ◽

Cited By ~ 23

Author(s):

M. Demedts ◽

J. Clement ◽

D. C. Stanescu ◽

K. P. van de Woestijne

Keyword(s):

Inflection Point ◽

Vital Capacity ◽

Transpulmonary Pressure ◽

Bronchial Obstruction ◽

Closing Volume ◽

Lung Volumes ◽

Nitrogen Washout ◽

Single Breath ◽

Space Effect ◽

Washout Curves

In 20 healthy subjects and 18 patients with bronchial obstruction, closing volume (CV) on single-breath nitrogen washout curves and inflection point (IP) on transpulmonary pressure-volume curves were recorded simultaneously during slow expiratory vital capacity maneuvers. IP and CV did not occur at identical lung volumes, IP being systematically larger than CV for small CV values. This discrepancy could not be attributed to an esophageal or mediastinal artifact. It is suggested that, though CV and IP both express “airway closure,” their sensitivity to closure may differ: CV underestimates closure because of a dead space effect; the latter may vary individually. On the other hand, IP may not reflect the true beginning of closure, particularly when it occurs at higher lung volumes.

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Volume Correction For Diffusion Capacity: Use Of Total Lung Capacity By Either Nitrogen Washout Or Body Plethymography Instead Of Alveolar Volume By Single Breath Methane Dilution

10.1164/ajrccm-conference.2010.181.1_meetingabstracts.a2115 ◽

2010 ◽

Author(s):

Anthony O. Uvieghara ◽

Jesus Lanza ◽

Viswanath P. Vasudevan ◽

Farhand Arjomand

Keyword(s):

Total Lung Capacity ◽

Alveolar Volume ◽

Diffusion Capacity ◽

Volume Correction ◽

Lung Capacity ◽

Nitrogen Washout ◽

Single Breath ◽

Breath Methane

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The Effect of Alveolar Dead Space on the Measurement of End-Expiratory Lung Volume by Modified Nitrogen Washout/Washin in Lavage-Induced Lung Injury

Respiratory Care ◽

10.4187/respcare.01800 ◽

2012 ◽

Author(s):

Rui Tang ◽

Yingzi Huang ◽

Qiuhua Chen ◽

Xia Hui ◽

Yang Li ◽

...

Keyword(s):

Lung Injury ◽

Lung Volume ◽

Dead Space ◽

Alveolar Dead Space ◽

Nitrogen Washout

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Bronchial thermoplasty reduces ventilation heterogeneity measured by multiple breath nitrogen washout

Respiratory Research ◽

10.1186/s12931-020-01575-x ◽

2020 ◽

Vol 21 (1) ◽

Author(s):

David Langton ◽

Kim Bennetts ◽

Francis Thien ◽

Virginia Plummer ◽

Peter B. Noble

Keyword(s):

Clinical Benefit ◽

Left Lung ◽

Ct Scanning ◽

Beta Agonist ◽

Oral Steroid ◽

Asthma Control Questionnaire ◽

Nitrogen Washout ◽

Lung Physiology ◽

Bronchial Thermoplasty ◽

Ct Evaluation

Abstract Background Despite demonstrated symptomatic benefit from bronchial thermoplasty (BT), the underlying pathophysiological benefits have been uncertain. The purpose of the present study was to relate clinical benefit after BT to changes in lung physiology, focusing on ventilation homogeneity assessed using multiple breath nitrogen washout (MBNW), and how this may be affected by changes in airway volume and resistance. Methods Consecutive patients (n = 21) with severe asthma scheduled for BT, were evaluated at baseline, 6 weeks and 6 months after completion of treatment. Assessments included the Asthma Control Questionnaire (ACQ), medication usage, exacerbation frequency, spirometry, plethysmography and MBNW. Eighteen of these patients underwent detailed CT evaluation for the estimation of airway volume at baseline and then after the left lung had received BT treatment but prior to right lung treatment. Data are mean ± STDEV. Results Patients responded to BT with an improvement in ACQ from 3.4 ± 0.8 at baseline to 2.0 ± 1.1 at 6 months (p < 0.001). Steroid requiring exacerbations fell from 3.1 ± 2.9 in the 6 months prior to BT to 1.4 ± 1.7 following BT (p < 0.001). Significant reductions in maintenance oral steroid dosing and short acting beta agonist use were observed. Airway volume measured by CT scanning significantly increased after treatment. The FEV1 improved from 1.34 ± 0.65 l to 1.52 ± 0.76 l (p = 0.024). The Residual Volume fell from 2.87 ± 0.89 l to 2.71 ± 0.93 l (p = 0.008) and Total Airway Resistance (Raw) from 10.58 ± 6.56 to 7.64 ± 3.74 cmH2O.s.l−1 (p = 0.020). The Lung Clearance Index (LCI) was 187 ± 63% predicted at baseline and improved after treatment from 12.7 ± 3.3 to 11.8 ± 2.4 (p = 0.049). The improvement in LCI correlated with the improvement in Raw (r = 0.463, p = 0.035). Conclusion Clinical benefit after BT is accompanied by improvements in lung physiology, including normalisation of lung homogeneity that seems to be driven by airway dilation and reduced resistance.

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Mode shift of an inhaled aerosol bolus is correlated with flow sequencing in the human lung

Journal of Applied Physiology ◽

10.1152/japplphysiol.00655.2001 ◽

2002 ◽

Vol 92 (3) ◽

pp. 1232-1238 ◽

Cited By ~ 5

Author(s):

Christopher N. Mills ◽

Chantal Darquenne ◽

G. Kim Prisk

Keyword(s):

Vital Capacity ◽

Normal Subjects ◽

Phase Iii ◽

Mode Shift ◽

Nitrogen Washout ◽

Single Breath ◽

Posture Change ◽

Supine Posture ◽

Residual Capacity ◽

Phase Iii Slope

We studied the effects on aerosol bolus inhalations of small changes in convective inhomogeneity induced by posture change from upright to supine in nine normal subjects. Vital capacity single-breath nitrogen washout tests were used to determine ventilatory inhomogeneity change between postures. Relative to upright, supine phase III slope was increased 33 ± 11% (mean ± SE, P < 0.05) and phase IV height increased 25 ± 11% ( P < 0.05), consistent with an increase in convective inhomogeneity likely due to increases in flow sequencing. Subjects also performed 0.5-μm-particle bolus inhalations to penetration volumes (Vp) between 150 and 1,200 ml during a standardized inhalation from residual volume to 1 liter above upright functional residual capacity. Mode shift (MS) in supine posture was more mouthward than upright at all Vp, changing by 11.6 ml at Vp = 150 ml ( P < 0.05) and 38.4 ml at Vp = 1,200 ml ( P < 0.05). MS and phase III slope changes correlated positively at deeper Vp. Deposition did not change at any Vp, suggesting that deposition did not cause the MS change. We propose that the MS change results from increased sequencing in supine vs. upright posture.

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