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Exhaled Nitric Oxide Does Not Correlate with Pulmonary Hypertension

O. Humbarger

Tonya Zeiger


M. G. Heckman

Charles Burger


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Conference: 2010 International PHA Conference and Scientific Sessions

Release Date: 06.24.2010

Presentation Type: Abstracts

Humbarger O, Zeiger T, Heckman M, Burger C. 
Mayo Clinic, Florida, Jacksonville, FL, USA

BACKGROUNDNitric Oxide (NO), a vasodilator, is known to play a role in the pathophysiology of pulmonary arterial hypertension (PAH). Levels of fractional concentration of exhaled NO (FeNO) have been shown in preliminary studies to correlate with disease activity. We hypothesized that FeNO levels would correlate with the type and severity of PH.

METHODSWe analyzed the age, gender, type and severity of PH, WHO functional class and diagnostic group, and clinical status and treatment for 55 consecutive patients seen in the PH Clinic at Mayo Clinic Florida who had been tested for exhaled NO levels. Values were compared to 32 healthy, non-asthmatic volunteers. The data was examined using a Wilcoxon rank sum test (binary category variables), a Kruskal-Wallis rank sum test (nominal categorical variables), or Kendall’s correlation tau (numerical variables or ordered categorical variables). P-values ≤ 0.05 were statistically significant.

RESULTSThe control patients were younger (45 vs 67 years) and did not have PH. As seen in Figure 1, there is no evidence of a difference in exhaled NO levels between PH patients and controls (Median: 21 ppb vs 21 ppb, P=0.64). Similarly, in PH patients, exhaled NO was not noticeably affected by WHO class (P=0.77) or diagnostic group (P=0.37), BNP (P=0.31), six minute walk distance (P=0.77), SPAP (P=0.29), or MPAP (P=0.31).

CONCLUSIONSThere was no difference in exhaled NO levels in PH patients compared to controls. Due to the relatively small sample size, there is low power to detect associations with exhaled NO. Larger studies are needed to exclude potentially meaningful differences.

Exhaled Nitric Oxide Does Not Correlate with Pulmonary Hypertension

Figure 1: Exhaled nitric oxide in PH patients and volunteers. The sample median for each group is shown with a solid horizontal line.