1. NO Oh, mama mia, mama mia, mama mia, let me go Freddy Mercury, 1975

2. Analysis of Exhaled Nitric Oxide for Patients with Asthma Paul Enright, MD The University of Arizona LungGuy@AOL.com

3. Outline Background Indications Methods Interpretation Summary References

4. Background 1991 – eNO first measured by Gustafsson 1993 – eNO found elevated in asthmatics Kjell Alving – Karolinska Institute Guidelines 1997 ERS 1999 ATS 2005 ATS+ERS >1200 eNO publications

5. eNO is an index of eosinophilic airway inflammation. eNO is not increased with bronchospasm. eNO = F E NO * * The abbreviation for ivory tower physiologists Fraction of exhaled nitric oxide at a flow of 50mL/sec 0.05

6. Indications Confirm asthma Differentiate asthma from COPD Guide inhaled corticosteroid therapy Predict ICS response (& non-response) Monitor ICS compliance Titrate ICS daily dose (step-up, step-down)

7. A high eNO confirms asthma in children with recurrent wheeze Normal range 5-30 ppb Saito J, JACI 2005

8. Asthma vs. COPD A few COPD patients also have eosinophilic inflammation. A few asthma patients have no eosinophilic inflammation. Fabbri, AJRCCM 2003

9. eNO remains normal during COPD exacerbations Normal range 5-30 ppb Maziak, AJRCCM 1998

10. eNO >50ppb predicts ICS response much better than does spirometry Hi ROC curve from Smith, AJRCCM 2005 Optimal eNO cut-point FEV1 BD Response

11. ICSs suppress airway inflammation, so eNO falls rapidly with ICS therapy. 100 µg/day 400 µg/day placebo Kharitonov, ERJ 2000 7 days on ICS7 days off ICS Good asthma control Green zone Poor asthma control Yellow-orange zone

12. ICS dose : eNO response Silkoff, Chest 2001 Beclomethasone QVAR DPI low – med – high daily ICS dose ICS naive

13. A reduction in eNO suggests good compliance with ICS therapy eNO fell in half Beck-Ripp, ERJ 2002 Good % Poor ICS Compliance

14. eNO to titrate ICS dose while maintaining good asthma control Smith, NEJM 2005 A high daily ICS dose whilst following NAEP guidelines

15. Future Indications Guide prednisone tapers Determine Singulair efficacy ? Determine chronic cough cause Epidemiological surveys Occupational asthma surveillance

16. Singulair pills lower eNO in some patients with asthma Sandrini, Chest 2003 one week

17. Singulair vs. ICS responses Szefler AJRCCM 2005. CARE, a multi-center, NIH-funded study 55% no response 17% respond to both 23% respond only to ICS (predicted by higher eNO) 5% respond only to Singulair 126 children with mild to moderate asthma, crossover, 8 wk study

18. Correlates Bronchial responsiveness Methacholine PC-20 Eosinophils (count and %) Induced Sputum Blood BAL and lung biopsy Lung function (FEV1)

19. eNO correlates with airway biopsy indices of inflammation Van den Toorn AJRCCM 2001 Symptomatic no symptoms MBP = major basic protein ppb 21 ICS-naive adolescents with asthma

20. Good correlations with blood IgE Saito J, JACI 2005 An epi study of 278 Japanese school children

21. Poor correlation with FEV1 Saito J, JACI 2005

22. Advantages of eNO Immediate results A painless and easy maneuver Effort independent Entirely safe No sample processing Predicts and measures ICS response

23. Disadvantages Expensive instrument No reimbursement (yet) Doesn’t measure bronchospasm

24. Methods On-line Single, slow exhalations Multiple exhalations with 5 different flows (MEFT) central versus peripheral 5 minute tidal breathing Off-line Nasal NO (+ humming for sinusitis)

25. Online eNO sampling assembly mouthpiece Ambient air inspired Exhalation resistor Sample to NO analyzer to pressure gauge for feedback Filter removes Ambient NO

26. eNO signals during testing 5-20cmH 2 O 50 mL/sec Ignore the peak Report the plateau value

27. Offline eNO sampling Tedlar or Mylar bacteria-free balloon It’s okay to include dead space exhalate Measure samples within 12 hours.

28. Pre-test preparations Avoid ETS exposure for 2 hours Avoid meals, drinks, smoking, exercise for 1 hr No spirometry or BD in prior 30 min Determine smoking status Any cigarettes in last week? Consider exhaled CO confirmation Determine asthma controller use Ask about recent viral URIs Ask ICS, Singulair, & prednisone last 2 weeks ATS+ERS 2005

29. Step-by-step testing sequence 1. Don’t use nose-clips 2. Deep inhalation of NO-free air 3. Don’t pause at TLC 4. Slow exhalation for >6 seconds * 5. Discard dead space 6. Wait >30sec, repeat 2 or 3 times * 3 sec okay for preschool kids

30. Quality Assurance Verify analyzer accuracy daily 100-400ppb calibration gas Exclude nasal and sinus NO Maintain back-pressure of 5-20cmH 2 O Display target pressure (display or gauge) Dynamic resistor preferred Discard dead space gas if on-line Report mean value during flat plateau

31. Quality Assurance (continued) Maintain target exhalation rate Standard: 50 mL/sec Repeat maneuvers until eNOs match Goal: 3ppb or 5% match Report the mean eNO and flow Rates of acceptable results 70% children ages 4-8 90% adults ATS+ERS 2005

32. Effect of exhalation flow eNO will be underestimated if the subject exhales too fast. standard target ATS+ERS 2005

33. Effect of recent smoking eNO will be underestimated if the subject was smoking recently Robbins, Chest 1995

34. 3ppb short-term repeatability Kharitonov, ERJ 2003 No learning effect No diurnal variation

35. Repeatability: children vs adults The eNO coefficient of variability (CV%) is about 5% in healthy adults and about 10% in children. Your name here

36. Instruments Chemiluminescence Sievers (now GE Analytical, USA) Aerocrine NIOX (Sweden) * Eco Medics (Switzerland) Logan Research (UK) Electrochemical (very new) Hand-held, no vacuum pump Can’t measure multiple rates Enright’s conflict of interest statement: Aerocrine bought dinner for me 3 times NIOX

37. Instrument Specifications Sensitivity: 1 ppb Accuracy: better than 1 ppb Repeatability: better than 1 ppb Range: 1-500 ppb Signal to noise: better than 3:1 ATS+ERS guidelines 2005

38. Instrument differences Muller KC, Respir Med 2005 “Differences due to calibration procedures” L, M, & H were 3 German biologic control subjects, tested once per day after a re- calibration EcoMedics CLD88

39. Reimbursement Aerocrine obtained FDA 510k pre-marketing approval for its NIOX model in 2003. An AMA-CPT code for the test was awarded Dec 2005, with reimbursement expected 2007. Meanwhile, you can charge patients directly for the test.

40. Interpretation Consider the pre-test probability Consider the major confounders Cigarette smoking Asthma controller medication use Nitrate-rich diet High or low values may be abnormal >30ppb indicates out-of-control asthma <5ppb (very low) may indicate PCD Normal values increase with age in children

41. eNO in healthy children Upper limit of the normal range Mean values Buchvald 2003

42. Response rates to ICS therapy eNO begins to fall within 3-5 days FEV1 Methacholine Saito J, JACI 2004

43. Summary eNO measures allergic airway inflammation eNO is a fast, safe, & easy test eNO is standardized and highly repeatable eNO determines ICS need and response In asthma, eNO is complementary to FEV1

44. Nasal NO during humming detects sinus blockage Maniscalso, ERJ 2003 Very high nasal NO from sinuses during humming Low nasal NO with blocked sinus drainage

45. Recommended Reading ATS+ERS guidelines, AJRCCM 2005; 171:912 Kharitonov SA, Swiss Med Wkly 2004; 134: 175 Smith AD, Curr Opin Allergy Clin Imm 2005; 5:49 Malmberg LP, J Asthma 2004; 41:511 Smith AD, NEJM 2005; 352(21):2163 Aerocrine, “Scientific Backgrounder” booklet, 2005