Other Sites : www.indianchestsociety.in
www.getwellhospitals.com
www.aecrt.com
Dr. Rajesh Swarnakar
Director
Getwell Hospital and Research Institute
Contact Info:
9271276116
DrRajeshSwarnakar@gmail.com
   
FENO

Improving Diagnosis and Management

Asthma Management
Made Easy

The measurement of fractional exhaled nitric oxide (FeNo) has been validated as a way of measuring the airway inflammation that underlies asthma.

Feno measurement is:

þ  Accurate
þ  Reproducible
þ  Immediate
þ  As informative as biopsy
FeNo

Measurement offers:

þ Correct asthma diagnosis
þ Rapid identification of non­compliance
þ Insights into steroid   effectiveness
þ Prediction of steroid response
þ Steroid dose-titration that reduces cost and improves patient outcome
þ Notification of loss of control
þ Prediction of asthma relapse

Feno Measures the Inflammation
- Not Just the Symptoms

Asthma is, by definition, a chronic inflammatory process - which leads to air­flow limitation and increased responsiveness to asthma triggers. Standard methods for diagnosing and monitoring asthma traditionally focus on symptoms and airway contraction. Until now, routine assessment of the underlying level of inflammation has not been possible.
FeNo measurement is:

þ Accurate              þ Reproducible
þ Immediate              þ As informative as biopsy

FeNo measurement is accurate and reproducible when measured with standardized, approved devices. Results are available immediately, allowing the clini­cian to measure the underlying inflammation while the patient is in the clinic.FeNo measurement has been shown to be as informative as biopsy12 and bronchoalveolar lavage-techniques78 which are the traditional "gold standards" in determining ongoing airway inflammation.
FeNo measurement is comparable to sputum analysis in determin­ing the level of inflammation9.
Exhaled NO values increase even before the onset of symp­toms or loss of control. This makes FeNo measurement a helpful tool both in predicting loss of control10 and assessing compliance with inhaled steroids11.

Change was observed in exhaled NO levels in a group of patients with atopic asthma who were placed in an Alpine home away from their allergens. NO levels fell during the 3 months in the Alpine home and remained stable even when gluco­corticoids were withdrawn. Three weeks after returning to their homes, the patients' exhaled NO levels in­creased. In comparison, spirometry results continued to improve after the patients returned home'2.

FeNo also responds more rapidly than spirometry to changes in inflammation following aller­gen exposure, making it a more sensitive marker of the disease12, ,3. Spirometry and FeNo are inde­pendent measures of different aspects of the disease. So, there is little correlation between Feno levels and pulmonary function tests in asthma patients.
                          

How Can FeNo Measurement
Help Improve Clinical Decision Making?

FeNo measurement has been shown to be SUPERIOR TO THE MAJORITY OF CONVENTIONAL TESTS recommended in international guidelines for diagnosing asthma in symptomatic patients.
FeNo measurement offers:
þ Correct asthma diagnosis

It has been demonstrated that while exhaled air from normal adult subjects typically contains between 5 and 25 parts per bil­lion (ppb) nitric oxide (5 to 20 ppb in children), the exhaled air of asthmatic subjects shows between double and four times the normal nitric oxide level.
This means that used in con­junction with well-established techniques such as spirometry, Feno measurement can be used by clinicians to help in the differ­ential diagnosis of eosinophilic bronchial asthma, thereby, mini­mizing inappropriate or ineffec­tive therapy.
Text Box:
FENo measurement offers the clinician:

Correct asthma diagnosis in over 80% of patients 8-75 years using a cut off of 20ppb.

Correct asthma diagnosis in nearly 80% of children 4-8 years using a cut off of 10ppb.
Exhaled NO (solid line) offers a higher degree of diagnostic accuracy for asthma (sensitivity 88% at a cut-off of 20ppb) than tests based on lung function (dotted line). The diagnosis of asthma was ascertained by a positive response to broncho-dilator and/or positive bronchial hyperresponsiveness in accordance with ATS guidelines.

FeNo measurement offers:

þ Rapid identification of non-compliance
FENO measurement provides an easy to use and non-invasive tool for monitoring adherence to steroid treatment.
In clinical practice, elevated FENO levels in patients taking maintenance doses of inhaled steroids either means the patient is not prescribed enough anti-inflammatory therapy or not ad­hering to the therapy prescribed.
Although anti-inflammatory treatment in asthma usually reduces FENO, some patients continue to have elevated FENO levels, despite steroid treatment. This is most frequently a result of non-compliance, but may also arise from poor inhalation technique, inadequate steroid dosage, chronic exposure to allergen, or non-eosinophilic airway inflammation as the cause of the asthma. Only rarely will an asthma patient be truly steroid resistant.

How Can Feno Measurement Help Improve Clinical Decision Making?

Feno has been shown to decrease rapidly in asthmatic patients when steroid treatment is started. The decrease is a useful indicator of steroid response.

FENO measurement offers:
þ Insights into steroid effectiveness
Text Box: T
FENo responds faster than any other marker to changes in steroid intake. There is a clear dose-dependent relation­ship between the inhaled steroid dose and the fall in FENo level. A reduction in FeNo of at least 20% in unstable patients indicates efficacy of the anti­inflammatory treatment21. The implication for clinical practice is that monitoring a patient's FeNo levels before and during anti-inflammatory therapy is now a simple, quick and patient-friendly way of checking that steroid therapy is having the desired effect on airway inflammation. The response to varied doses of beclomethasone for patients with initial FENO values of > 100 ppb and between 60 to 100 ppb.

Feno measurement offers:
þ Prediction of steroid response
FeNo measurement can be used for immediate and non-invasive identification of steroid respon­siveness. In patients with non­specific symptoms, a FENo value of >47ppb is highly indicative of a subsequent corticosteriod response. FeNo measurement correctly identifies the respon­ded better than spirometry or PEF variability. Exhaled NO as a predictor of response might help to identify individual children who achieve a greater improvement in asthma control days with an inhaled corticosteroid compared with a leukotriene receptor antagonist. Patients with normal FENo levels who do not show any symptom­atic response to anti-inflamma­tory treatment may have little or no underlying inflammation. Other forms of therapy should be considered, and discon­tinuing of anti-inflammatory treatment may also be appro­priate.

 In a group of patients with non­specific respiratory symptoms, FENO measurement was significantly better than FEVI bronchodilator response in correctly identifying those who will respond to inhaled fluticasone.

FENO  measurement offers:

þ Steroid dose-titration that reduces cost and improves patient outcome

Titrating the steroid dose to match the severity of airway in­flammation results in a healthier patient with fewer emergency room visits and significantly fewer exacerbations.
Several studies have now con­firmed that routine monitoring of the Feno level as a marker for inflammation makes it possible to titrate the steroid dose ac­cording to the patient's specific need.
        Use of exhaled NO measure­ments can significantly reduce maintenance doses of inhaled steroids without compromising asthma control. In patients already on steroids, the dose can be gradually reduced just to the point at which the Feno level starts to rise. Then the steroid dose should be raised just enough to keep the FeNOlevel stable.
Compared to conventional treat­ment guidelines, steroid titration based on FeNO and symptoms improved asthma prognosis (measured as improved hyper-responsiveness and less inflam­mation).

There was a significant difference in the distribution of doses of inhaled fluticasone at the end of the study. The mean dose was 370 µg / day in the FENO monitored group and 641 µg/day in the control group. At study end, the control of asthma in the FENO group was non-significantly better.

FENO measurement offers:

þ Notification of loss of control

If a patient's FENO level increases by over 60% from one visit to the next, even in the absence of asthma symptoms, this increase has a positive predictive value of over 80% of an imminent de­terioration in asthma control.

FENO measurement offers:

þ Prediction of asthma relapse

When asymptomatic children in clinical remission stopped taking steroids, a FeNO level of more than 49ppb
2 to 4 weeks later was an effective predictor of asthma relapse.
                                                                                                                                                    

A FENO level higher than 49ppb 4 weeks after steroid removal was highly indicative of asthma relapse.

Diagnosis

Guide to Interpretation of Feno Values in Symptomatic Steroid Naive Patients

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Management

Guide to Interpretation of FENO Values in Anti-Inflammatory Treated Patients

 

 

 

 

 

 

 

 

 

 

 
 
Phone : 9271276116     |     Emergency : 0712 - 6632235   •   6632236     |     Email : DrRajeshSwarnakar@gmail.com
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