Key Points
➤ Asthma endotypes have replaced the single entity model of asthma.
One of the major endotypes is "T2" asthma.
➤ Nitric oxide (NO) is produced by airway cells, particularly the airway
epithelium, and is a marker of inflammation of the airways: in general,
a higher level of exhaled NO (FeNO) is associated with the T2 endotype.
➤ T2 high endotype is eosinophilic asthma; T2 low is non-eosinophilic.
➤ In the appropriate setting, elevated levels of FeNO reflect airway
inflammation and hyperresponsiveness of the airways. This finding may
indicate the need to intensify therapy for asthma.
➤ This focused CPG addresses a single important question that is
complementary to other broad guidelines, and provides Evidence to
Decision (EtD) knowledge-based recommendations* regarding whether
patients with asthma in whom treatment is contemplated should
undergo FeNO testing. This CPG does not provide specific cut-off values
for the interpretation of the test.
➤ The recommendations are designed for treatment decisions in
ambulatory settings for the ongoing management asthma, and the use
of FeNO testing should be placed in the individualized context of asthma
treatment (Figure 1).
* See the "For clinicians" section of Table 1.
