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ORIGINAL ARTICLE
Year : 2021  |  Volume : 35  |  Issue : 1  |  Page : 8-11

The study of fractional exhaled nitric oxide in newly diagnosed cases of bronchial asthma and chronic obstructive pulmonary disease


Department of Pulmonary Medicine, Grant Medical College and Sir J.J. Group of Hospitals, Mumbai, Maharashtra, India

Date of Submission08-Aug-2020
Date of Acceptance01-Sep-2021
Date of Web Publication07-Dec-2021

Correspondence Address:
Dr. V Lakshmi
House No. 23, Chikkathimmasandra, Muthanalluru Post, Anekal Taluk, Bengaluru - 560 099, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijaai.ijaai_48_20

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  Abstract 


INTRODUCTION: Fractional exhaled nitric oxide (FENO) is a measurement of fractional nitric oxide (NO) concentration in exhaled breath. It is a quantitative, noninvasive, simple, and safe method to measure airway inflammation for the assessment of airways diseases.
OBJECTIVE: The study was conducted at the tertiary care hospital to study the FENO levels in newly diagnosed patients of bronchial asthma and chronic obstructive pulmonary disease (COPD).
MATERIALS AND METHODS: A total number of 105 patients were included in the study, diagnosed based on pulmonary function test and symptomatology. FENO levels were measured using Medisoft FENO machine, and the results were analyzed.
RESULTS AND CONCLUSIONS: We found that both COPD and bronchial asthma are more prevalent among males. FENO levels were higher in bronchial asthma patients as compared to COPD patients. In bronchial asthma, FENO levels were higher in patients with very severe obstruction, and in COPD, patients with mild obstruction had slightly higher FENO values.

Keywords: Bronchial Asthma, chronic obstructive pulmonary disease, fractional exhaled nitric oxide, forced expiratory volume in 1 s


How to cite this article:
Lakshmi V, Meshram P, Kumar U, Pujari V, Sagar P. The study of fractional exhaled nitric oxide in newly diagnosed cases of bronchial asthma and chronic obstructive pulmonary disease. Indian J Allergy Asthma Immunol 2021;35:8-11

How to cite this URL:
Lakshmi V, Meshram P, Kumar U, Pujari V, Sagar P. The study of fractional exhaled nitric oxide in newly diagnosed cases of bronchial asthma and chronic obstructive pulmonary disease. Indian J Allergy Asthma Immunol [serial online] 2021 [cited 2022 May 25];35:8-11. Available from: https://www.ijaai.in/text.asp?2021/35/1/8/331804




  Introduction Top


Nitric oxide (NO) is present in virtually all mammalian organ systems and is produced by the lungs. It is recognized to play key roles in virtually all the aspects of lung biology and has been implicated in the pathophysiology of lung diseases including bronchial asthma. Fractional exhaled NO (FENO) measurements have been considered a surrogate for eosinophilic airway inflammation, especially in bronchial asthma.[1]

Chronic obstructive pulmonary disease (COPD) is considered to be a noneosinophilic airway inflammation. Since FENO is a surrogate marker for eosinophilic airway inflammation, it tends to be decreased or equivocal in stable COPD patients. Current smokers and severe COPD patients have low FENO values,[2] whereas COPD patients with exacerbation have been found to have high FENO values.[3]


  Materials and Methods Top


Study design

This was a prospective, cross-sectional study conducted in the department of pulmonary medicine at a tertiary care hospital. The participants were adults of 18 years and above. Patients who were newly diagnosed bronchial asthma and COPD were included in our study. Approval of the Ethical Committee of the Medical College for Research on human participants was obtained before the start of the study.

Selection of the patients

Hundred and five patients of either gender who attended outpatient department of pulmonary medicine were included in the study. All these patients were newly diagnosed cases of either bronchial asthma or COPD based on symptoms and spirometry.

The following were the inclusion and exclusion criteria.

Inclusion criteria

  1. Newly diagnosed cases of bronchial asthma and COPD
  2. Either sex
  3. Age more than 18 years.


Exclusion criteria

  1. Patients with other respiratory comorbidities
  2. Patients who have not consented for the study
  3. Patients with other systemic comorbidities such as diabetes mellitus and hypertension.
  4. Patients with active tuberculosis
  5. Patients receiving steroids and other anti-inflammatory medications oral or inhaled.


Patients who fit into these criteria were selected and informed about the study.

Study procedure

One hundred and five patients who fulfilled the inclusion criteria were enrolled into the study. Informed written consent was taken from all patients included in the study. Detailed relevant demographic and clinical history was obtained. Detailed physical examination and respiratory system examination was done, and findings were noted. Spirometry was performed as per the ATS guidelines in all the patients. FENO was measured in all the patients. FENO value above 35 ppb was considered significantly high as per the Medisoft FENO software that was used to measure the FENO. The data collected were tabulated and analyzed to attain the study objectives.


  Results and Observations Top


Our study group had a total of 105 patients, 28 were female and 77 were male. Among them, 51 were COPD and 54 had bronchial asthma. The age and gender wise distribution of the diseases is as per [Table 1].
Table 1: Age and gender wise distribution of chronic obstructive pulmonary disease and bronchial asthma

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Males were more than females in both COPD and bronchial asthma. COPD was more common in the age group of 41–60 years. Bronchial asthma was more common in the age group of 18–40 years [Table 1].

Among bronchial asthma patients 85% had high FENO values, whereas 15% had normal values. Among patients with high FENO maximum (24 patients) had FENO in the range between 51 and 150, 15 patients had their FENO between 35 and 50. This was followed by 9 patients who had FENO above 150 ppb. Mean FENO of bronchial asthma patients was 74.64 ppb.

The severity of obstruction was assessed in all 54 patients of bronchial asthma by forced expiratory volume in 1 s (FEV1). Most of the patients (32) had moderate obstruction, followed by severe obstruction in 16 patients. Five patients had very severe obstruction while only one patient had mild obstruction. Mean FEV1 of bronchial asthma patients was 54.57 L/s.

Patients were stratified into mild, moderate, severe, and very severe obstruction based on the FEV1 values. Among bronchial asthmatics, patients with very severe obstruction (5) had the highest FENO values indicating increased inflammation, with the mean FENO being 86 ppb. This was followed by patients with moderate obstruction (32) had mean FENO of 74.31 ppb. Asthmatics with severe obstruction (16) had a mean FENO of 73.6 ppb, while patients with mild obstruction (1) had the least FENO values, with the mean being 47 ppb [Table 2].
Table 2: Mean fractional exhaled nitric oxide with respect to severity of obstruction in bronchial asthma

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To assess the correlation between FEV1 and FENO among bronchial asthma patients, single tailed unpaired t-test was applied to FEV1 and FENO values of all bronchial asthma patients. It was found to be 0.005848. P value was calculated using t-value in online calculator and it was 0.498 (>0.01). There was no statistically significant correlation between FEV1 and FENO.

Among COPD patients, most patients had normal values (<35 ppb), indicating low eosinophilic inflammation in the airways. Eighty-six percent of the COPD patients (44) had FENO values below 35 ppb. FENO was high in only 14% of the patients. Mean FENO in COPD patients was found to be 27.33 ppb.

Majority (25) of the COPD patients had moderate obstruction, followed by 20 patients who had severe obstruction. Four patients had very severe obstruction, whereas only two patients had mild obstruction. Mean FEV1 was 53.03 L/s.

COPD patients with mild obstruction were found to have slightly higher FENO values indicating eosinophilic inflammation in their airways. Mean FENO of the mild COPD patients was 48.5 ppb. This was followed by patients with severe obstruction with mean FENO of 33.7 ppb. COPD patients with moderate obstruction had mean FENO of 21.24 ppb, whereas patients with very severe obstruction had least mean FENO of 2.25 ppb indicating negligible eosinophilic inflammation [Table 3].
Table 3: Mean fractional exhaled nitric oxide with respect to severity of obstruction in chronic obstructive pulmonary disease

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To assess the correlation between FEV1 and FENO among COPD patients, single-tailed unpaired ”t” test was applied to FEV1 and FENO values of all COPD patients. It was found to be 1.31003. P value was calculated using t-value in online calculator and it was 0.207 (>0.01), showing no significant correlation between FEV1 and FENO. There was no statistically significant correlation between FEV1 and FENO in COPD patients also.

To find correlation between FENO in COPD and bronchial asthma patients, Student's t-test was calculated by using the mean values. t-test between FENO in COPD and bronchial asthma is 5.52 and P = 0.114 (>0.01). Although the t-test was not significant, the mean FENO in bronchial asthma was much higher than that in COPD.


  Discussion Top


One hundred and five newly diagnosed bronchial asthma and COPD patients who meet the clinical criteria were included in the study. The diagnosis was based on the clinical symptoms, clinical examination, and spirometry. All patients included in the study underwent FENO. In our study, both bronchial asthma and COPD were more common among males. COPD was the highest in the older age group, whereas bronchial asthma was common in the young patients.

Akhila et al.[4] from Telangana conducted a study to observe demographic pattern in bronchial asthma and COPD. They found that bronchial asthma is more among the individuals of young age 10–25 years, whereas COPD was more between the age group of 60–70 years. Only few patients had asthma above the age of 61 years. Among COPD patients, higher number were in the age group of 61–70 years, followed by 51–60 years, then 40–50 years. Only few patients were in the age group of 35–40 years and above 81 years. Our study has similar findings.

A study conducted by Singh et al.[5] at Jaipur included 151 cases of bronchial asthma patients. Maximum were males and most cases were in the age group of 16–30 years followed 31–45 years. Our study has similar age and gender distribution to this study.

Akhila et al.[4] also showed the significant occurrence of bronchial asthma and COPD in female population. The percentage of female population is higher when compared to males with frequencies of 64 and 46, respectively. Unlike this study, our study had more males than females.

In our study, mean FENO of bronchial asthma patients was found to be 74.64 ppb and that of COPD was 27.33 ppb. Majority of the bronchial asthma patients with very severe airway obstruction had high FENO values, although there was no statistically significant correlation between FEV1 and FENO.

A study conducted by Salviano et al.[6] showed that the median levels of FENO in bronchial asthma patients were 35.5 ppb.

A study conducted by Li Z, Qin W, Li L, Wu Q, Wang Y[7] from China assessed FENO in COPD and bronchial asthma. Among them, 500 had bronchial asthma and 132 had COPD. The FENO value in patients with bronchial asthma was 45 ppb, which was significantly higher than that in the COPD group (18 ppb), which was similar to our study.

The following [Table 4] shows the studies that shows correlation between FEV1 and FENO in bronchial asthma patients.
Table 4: Various studies showing association between FEV1 and FENO

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The findings of our study were similar to all of the above studies except one.

In our study, most of the COPD patients had normal FENO values. Slightly higher FENO levels were found in patients with mild airway obstruction, and there was no significant correlation between FEV1 and FENO.

Rawy and Mansour[8] studied correlation between FENO and pulmonary function test (PFT) in patients of COPD and bronchial asthma. The study included 60 COPD patients and FENO was positively correlated with PFT. Unlike this, our study has no correlation between FENO and FEV1.

A study conducted by Dilka et al.[11] to assess correlation between FENO and FEV1 in COPD, included 112 COPD patients, 98 males and 14 females. The mean FENO was 11.9 ± 7.6 ppb and found no significant correlation between the mean FENO to the degree of bronchial obstruction. These findings were similar to our study.


  Conclusions Top


In our study, predominantly, males had both COPD and bronchial asthma, bronchial asthma was more prevalent in young people whereas COPD in older population.

FENO values were higher among bronchial asthmatics compared to COPD patients. Among bronchial asthma, FENO values were higher in patients with very severe airway obstruction. FENO values were normal among most COPD patients. It was slightly higher in patients with mild airway obstruction, suggesting eosinophilic airway inflammation and good reversibility in them.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Gao J, Wu F. Association between fractional exhaled nitric oxide, sputum induction and peripheral blood eosinophil in uncontrolled asthma. Allergy Asthma Clin Immunol 2018;14:21.  Back to cited text no. 1
    
2.
Högman M, Thornadtsson A, Bröms K, Janson C, Lisspers K, Ställberg B, et al. Different relationships between FENO and COPD characteristics in smokers and ex-smokers. COPD 2019;16:3-4.  Back to cited text no. 2
    
3.
Agustí AG, Villaverde JM, Togores B, Bosch M. Serial measurements of exhaled nitric oxide during exacerbations of chronic obstructive pulmonary disease. Eur Respir J 1999;14:523-8.  Back to cited text no. 3
    
4.
Akhila J, SreeKeerthi MV, Mahender V. A retrospective study on epidemiology of asthma and chronic obstructive pulmonary disease. J Pulm Respir Med 2017;7:418.  Back to cited text no. 4
    
5.
Singh AK, Jain VK, Mishra M. Clinical profile of Bronchial Asthma patients reporting at respiratory medicine outpatient department of teaching hospital. Indian J Allergy Asthma Immunol 2015;29:3-6.  Back to cited text no. 5
  [Full text]  
6.
Salviano LD, Taglia-Ferre KD, Lisboa S, Costa AC, Campos HD, March MF. Association between FENO, spirometry and clinical control of asthma in children and adolescents. Rev Paul Pediatr 2018;36:8.  Back to cited text no. 6
    
7.
Li Z, Qin W, Li L, Wu Q, Wang Y. Diagnostic accuracy of exhaled nitric oxide in asthma: A meta-analysis of 4,691 participants. Int J Clin Exp Med 2015;8:8516-24.  Back to cited text no. 7
    
8.
Rawy AM, Mansour AI. Fraction of exhaled nitric oxide measurement as a biomarker in asthma and COPD compared with local and systemic inflammatory markers. Egypt J Chest Dis Tuberc 2015;64:13-20.  Back to cited text no. 8
    
9.
Gemicioglu B, Musellim B, Dogan I, Guven K. Fractional exhaled nitric oxide (FeNo) in different asthma phenotypes. Allergy Rhinol (Providence) 2014;5:157-61.  Back to cited text no. 9
    
10.
Nguyen VN, Chavannes NH. Correlation between fractional exhaled nitric oxide and Asthma Control Test score and spirometry parameters in on-treatment-asthmatics in Ho Chi Minh City. J Thorac Dis 2020;12:2197-209.  Back to cited text no. 10
    
11.
Dilka E, Tashi E, Nushi E, Todri D, Teferici A, Kore R, et al. The use of FENO in COPD: The relationship to pulmonary function tests and its importance in differential diagnosis. Eur Respir J 2017;50 Suppl 61:PA1099.  Back to cited text no. 11
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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