Single Breath Nitrogen Test in an Epidemiologic Survey in North Italy: Reliability, Reference Values and Relationships with Symptoms

doi:10.1378/chest.93.6.1213

Chest

Volume 93, Issue 6, June 1988, Pages 1213-1220

https://doi.org/10.1378/chest.93.6.1213 Get rights and content

The usefulness of single breath nitrogen test (SBN₂) was evaluated in a cross-sectional epidemiologic survey on a general population sample (n = 3,289) of North Italy. Each subject was submitted to CNR standardized questionnaire and to lung function testing using automated equipment (Hewlett-Packard 47804S). Acceptable closing volume (CV) and slope of alveolar plateau (DN₂%/L) tracings were performed by only 1,370 and 1,982 subjects respectively, in comparison with the 2,638 diffusing capacity and the 3,079 forced vital capacity acceptable maneuvers. Prediction equations were computed on normal subjects for CV indices, with the exception of DN₂%/L: they were similar to those found in other studies. Significant differences among smoking categories were found for all the SBN₂ parameters in males, but only for DN₂%/L in females. The latter was also able to distinguish either subjects with airway obstruction from those without it or symptomatic from asymptomatic individuals, but DN₂%/L did not give more information than $\dot{V} \max 75$ , a sensitive index of flow volume curve. Our results suggest that the place of SBN₂ in large scale epidemiologic testing has not been justified.

Section snippets

MATERIAL AND METHODS

A multistage, stratified cluster sample (n = 3,289) of the general population (about 110,000) living in the rural area of the Po river delta (about 40 km southwest of Venice) was enrolled in the first cross-sectional study of a longitudinal epidemiologic survey. Only one small city and various small towns are present, and there are no large industries in the area. The study was performed in 1980 through 1982, before the start of operation of a large oil-burning thermoelectric power plant when

RESULTS

Only 1,370 subjects (42 percent of the overall sample) were able to perform an acceptable CV maneuver and 1982 (60 percent) an acceptable DN₂%/L tracing, whereas the corresponding figures for the other tests were 3,079 (94 percent) for FVC indices and 2,638 (80 percent) for Dco_sb (Table 1). Men provided a larger number of acceptable tracings than women: the difference was statistically significant for CV and DN₂%/L. There were also statistically significant differences by age: subjects >45

DISCUSSION

Few subjects of our sample were able to perform an acceptable SBN₂ test compared to those who performed acceptable spirometry, flow-volume curve and CO diffusing capacity tests. Our results are in agreement with those of two epidemiologic studies on children;17, 28 however, they are in contrast with the findings of other authors, especially those of Northern Europe.11, 14, 18, 19 Though it is a common finding that subjects unable to perform lung function tests are in worse condition (older,

ACKNOWLEDGMENT

The authors thank Dr. T. Sapigni (University of Ferrara, Italy) and the Scientific Committee of the Porto Tolle Power Plant who made it possible to plan and implement the study; Mr. G. Paggioro and Mr. O. Zagatti for the administrative and lodging support during the field survey; Drs. R. Polato, M. Saetta, R. Zambon, (University of Padova) P Fazzi (University of Pisa) and the nurses of USL n. 31 and n. 33 for data collection. The writers thank also the hundreds of residents of the delta del Po

REFERENCES (30)

DS McCarthy et al.
Measurement of “closing volume” as a simple and sensitive test for early detection of small airway disease.
Am J Med
(1972)
AS Buist
Current status of small airways disease.
Chest
(1984)
JA Dosman et al.
Sensitivity and specificity of early diagnostic tests of lung function in smokers.
Chest
(1981)
R Detels et al.
The UCLA population studies of chronic obstructive respiratory disease. 5. Agreement and Disagreement of tests in identifying abnormal lung function.
Chest
(1982)
G Pistelli et al.
Comparison of algorithms for determining the end-point of the forced vital capacity maneuver.
Chest
(1987)
AS Buist et al.
Predicted values for closing volumes using a modified single breath nitrogen test.
Am Rev Respir Dis
(1973)
AS Buist et al.
A comparison of conventional spirometric tests and the test of closing volume in an emphysema screening center.
Am Rev Respir Dis
(1973)
RR Martin et al.
Measurement of “closing volume,”: Application and limitations.
Bull Eur Physiopathol Respir
(1973)
M Cosio et al.
The relations between structural changes in small airways and pulmonary-function tests.
N Engl J Med
(1978)
AS Buist et al.
Quantitative analysis of the alveolar plateau in the diagnosis of early airways obstruction.
Am Rev Respir Dis
(1973)

AS Buist et al.

Relationship between the single-breath N2 test and age, sex, and smoking habit in three North America cities.

Am Rev Respir Dis

(1979)

H Oxhoj et al.

Ability of spirometry, flow-volume curves and the nitrogen closing volume test to detect smokers.

A population study. Scand J Respir Dis

(1977)

PJ Sterk et al.

The single breath nitrogen test in epidemiological surveys: an appraisal.

Bull Eur Physiopathol Respir

(1981)

HA Menkes et al.

Nitrogen washout and mortality.

Am Rev Respir Dis

(1985)

RJ Knudson et al.

The closing volume test: evaluation of nitrogen and bolus methods in a random population.

Am Rev Respir Dis

(1977)

Cited by (16)

Single breath nitrogen test as predictor of lung function decline and COPD over an 8-year follow-up
2022, Pulmonology
Citation Excerpt :
We observed that baseline N2-slope was associated with higher risks of lung function decline and airways obstruction incidence in a relatively young population; this result reinforces the importance of SAD in the natural history of COPD, as even higher risks may be expected in an older population possibly exposed to smoking for a longer period. N2-slope has been repeatedly found to be the most sensitive SBN2 index in separating smokers from non-smokers,3,22,37 as we previously found.23 In the present longitudinal study, an association between N2-slope and decline in FEV1 was found adjusting for smoking habit, while current or former smoking were not significant determinants for incident airway obstruction.
The single breath nitrogen (SBN₂) test was proposed for early detection of “small airways disease” in the seventies. Few longitudinal studies have subsequently evaluated the relationships between SBN₂ test measurements and lung function decline or COPD incidence.
This study evaluates whether SBN₂ test abnormalities may be significant predictors of lung function decline and COPD incidence over an 8-year follow-up.
In this longitudinal study, 907 adults (20+ years old; 56% males) from the prospective Po River Delta epidemiological study underwent SBN₂ test at baseline and spirometry testing at both baseline and follow-up 8-year apart. Multinomial and multiple regression models were used to assess associations of SBN₂ indexes and rates of FEV₁ decline or risk of COPD incidence over time, after adjusting for sex, height and baseline age, FEV₁ and smoking status. COPD was defined according to either GOLD or ATS-ERS criteria.
Among SBN₂ indexes, only the slope of alveolar plateau (N₂-slope) was significantly associated with rates of FEV₁ decline (7.93 mL/year for a one-unit change in N₂-slope, p<0.0001), and with an increased risk of developing COPD as defined by GOLD (RR 1.81, 95%CI 1.29-2.52, mild; RR 2.78, 95%CI 1.70-4.53, moderate or severe obstruction) and ATS-ERS criteria (RR 1.62, 95%CI 1.14-2.29, mild; RR 3.40, 95%CI 1.72-6.73, moderate or severe obstruction).
In this population-based study, N₂-slope from SBN₂ test is a significant predictor of lung function decline and COPD incidence over an 8-year follow-up, confirming the role of the “small airways disease” in the natural history of COPD.
The single-breath nitrogen test in coal miners: Factors associated with failure to perform
1997, Respiratory Medicine
The single-breath nitrogen washout (SBN₂) test was used, along with spirometry, in the baseline examination of a longitudinal study in a cohort of active coal miners from North-eastern France. The procedure was computerized, allowing the technician to coach and encourage the subject, and excluding computation errors. While all miners performed satisfactory spirometry, a significant number were unable to meet the National Heart and Lung Institute recommendation concerning a 10% agreement of vital capacities. When the limits were set at ± 12%, 57 miners (24·2%) were still classified as failing to perform. When compared to those who succeeded, those failing proved to be significantly older, had more cumulated dust exposure, a higher prevalence of chronic cough and sputum, and a trend for more micronodulation on the chest radiographs. The ventilatory function did not differ between the two groups.
These results confirm previous data on spirometric test failure concerning older age and respiratory symptoms, extending them to the SBN₂ test. The present study further indicates that dust exposure and roentgenologic pneumoconiosis nodulation are associated with failure to perform the SBN₂ test.
An 8-year follow-up of carbon monoxide diffusing capacity in a general population sample of northern italy
2001, Chest
Citation Excerpt :
The Po River Delta Epidemiologic Study is a follow-up study on the natural history of COPD in a large population sample living in North Italy, near Venice. Population characteristics, sampling methodology, and main findings of the first cross-sectional investigation, including questionnaire and lung function, were previously reported.8,17,18,19,20,21,22,23 In particular, a detailed description of the method used to measure Dlco is reported in the articles describing the reference equations8 and the relationships of Dlco with respiratory symptoms.19
Diffusing capacity of the lung forcarbon monoxide (Dlco) is frequently assessed as part of athorough pulmonary function assessment in patients with pulmonary orcardiopulmonary diseases. However, little information regarding thelongitudinal trends of Dlco is available. In this study, weexamined the temporal trends in Dlco to determine theeffects of smoking and changes in smoking habits.
A longitudinal study was recently conducted in the Po River Delta area of northern Italy, in which Dlcomeasurements were taken approximately 8 years apart in the samesubjects; this offered the unique opportunity to assess the temporalchanges in Dlco. The longitudinal Dlco datawere analyzed independently in two age groups (20 to 40 years, and≥40 years) using a repeated-measures analysis.
Included were 928 subjects > 20 years old whohad Dlco assessments both at baseline and follow-up. Malesubjects had higher mean levels of Dlco than femalesubjects in the older age group (≥ 40 years). Continuous smokers hadsignificantly lower Dlco levels than “never-smokers,”but their changes in Dlco during follow-up were the same. This suggests that the lung damage due to smoking had occurred prior to Dlco testing. We also found that the annual decline in Dlco accelerated with age in adults ≥ 40 years old.
We conclude that in adults ≥ 40 years of agefrom the general population, Dlco accelerates downwardsregardless of gender, smoking, and initial FEV₁level.
Defining COPD in the 21st century
2024, ERS Monograph
Utility of single versus multiple breath washout in adult asthma
2018, Clinical Physiology and Functional Imaging
Respiratory symptoms and peripheral airways disease in a cross-sectional study on a random population sample
2012, BMJ Open

View all citing articles on Scopus

This work was supported in part by the Italian National Research Council, Special Project on preventive and rehabilitation medicine (chronic lung disease-contract n. 86.01818.56), the Health Departments of the Veneto and Emilia Romagna regions, and by a grant from the Italian Electric Power Authority.

Manuscript received August 3; revision accepted December 17.

View full text

Chest

Single Breath Nitrogen Test in an Epidemiologic Survey in North Italy: Reliability, Reference Values and Relationships with Symptoms

Section snippets

MATERIAL AND METHODS

RESULTS

DISCUSSION

ACKNOWLEDGMENT

Am J Med

Chest

Chest

Chest

Chest

Predicted values for closing volumes using a modified single breath nitrogen test.

Am Rev Respir Dis

A comparison of conventional spirometric tests and the test of closing volume in an emphysema screening center.

Am Rev Respir Dis

Measurement of “closing volume,”: Application and limitations.

Bull Eur Physiopathol Respir

The relations between structural changes in small airways and pulmonary-function tests.

N Engl J Med

Quantitative analysis of the alveolar plateau in the diagnosis of early airways obstruction.

Am Rev Respir Dis

Relationship between the single-breath N2 test and age, sex, and smoking habit in three North America cities.

Am Rev Respir Dis

Ability of spirometry, flow-volume curves and the nitrogen closing volume test to detect smokers.

A population study. Scand J Respir Dis

The single breath nitrogen test in epidemiological surveys: an appraisal.

Bull Eur Physiopathol Respir

Nitrogen washout and mortality.

Am Rev Respir Dis

The closing volume test: evaluation of nitrogen and bolus methods in a random population.

Am Rev Respir Dis