Race and ethnicity have significant influence on fractional exhaled nitric oxide.

BACKGROUND: Race and ethnicity have been shown to influence fractional exhaled nitric oxide (FeNO). There is a need to investigate cutoff points for different races and ethnicities to improve clinical application. OBJECTIVE: To investigate cutoff points for different races and ethnicities by analyzing the FeNO data collected by the National Health and Nutrition Examination Survey from 2007 to 2012. METHODS: This study included 23,433 participants. After excluding participants with confounding factors, 11,084 participants were eligible for data analysis. Based on age and the probability of having allergic airway inflammation, participants were divided into 4 groups. The geometric mean and 5th, 50th, and 95th percentiles of FeNO in Hispanic, white, black, and other races were analyzed in all groups. RESULTS: Compared with white participants, the geometric mean for FeNO in black participants was 36% to 41% higher in children and 5% to 8% higher in adults. Hispanic children had significantly higher FeNO values (14% to 19%) compared with non-Hispanic white children; however, those differences were not significant in adults. Other races had significantly higher FeNO values in children (24-54%) and adults (9-29%) compared with white participants. Further, for normal healthy black children, the 95th percentile was 40.2 parts per billion (ppb), which is significantly higher than the cutoff point recommended by current guidelines. CONCLUSION: Although there are significant differences in FeNO values among races and ethnicities, the current cutoff point at 50 ppb is sufficient to separate healthy from asthmatic populations in adults. However, for black children, we suggest increasing the cutoff point from 35 to 40 ppb to avoid unnecessary diagnosis and treatment.

Hyperventilation-induced syncope: no need to panic.

Accurately diagnosing and treating adult patients presenting with recurrent syncope can be extremely problematic. We present the case of a patient who presented with recurrent syncope. We propose that many cases currently classified as idiopathic may in fact be due to orthostatic hypotension secondary to hyperventilation, or simply hyperventilation-induced syncope. The presence of undiagnosed psychiatric disorders should be considered in these patients.