December 2007

Section Welcomes New Chair-Elect, Honors Specialty Practitioner of the Year
The Diagnostics Section congratulates Melynn K. Wakeman, BS, RRT, RPFT, RPSGT, for her election to our chair-elect position. Melynn won the seat in a close race with Christopher S. Kling, RRT, RPFT, who we also want to thank for running for the position.

We want to congratulate our 2007 Specialty Practitioner of the Year as well. Russell L. Harris, CRT, RPFT, received the honor at the recent AARC Congress in Orlando, FL.

FeNO in African Americans
A recent study out of Duke University Medical Center sheds new light on factors that may influence fraction of exhaled nitric oxide (FeNO) levels in African Americans. Researchers measured FeNO levels in 895 healthy African American adults between the ages of 18 and 40, repeating the measurements in 84 of the subjects. Factors potentially associated with FeNO were measured as well, including blood pressure, height, weight, serum total IgE, eosinophil cationic protein, C-reactive protein, and nitrate levels. Researchers also collected data on respiratory symptoms. Results showed FeNO levels were stable during repeated measurements. Sex, serum total IgE levels, and current upper respiratory infection symptoms contributed significantly to FeNO variability but together accounted for less than 50% of the variation, leading the authors to conclude, “The high correlation between repeated measurements of FeNO and the low correlation coefficients of known factors associated with FeNO suggest that other factors might contribute substantially to variability of FeNO levels in African Americans.” The study appeared in the November 23 Epub edition of the Journal of Allergy and Clinical Immunology. READ ABSTRACT

Reference Values for DLNO
St. Louis researchers who set out to create reference values for single-breath DLNO using a short breath-hold time find:

• When normalizing for height and age, women have 650ml lower forced vital capacity, 660ml lower VA, and a 6 and 32ml/min/mmHg lower DLCO and DLNO, respectively, compared to men.
• Normalizing for lung volume and age, women have, on average, a 3.2 and 18ml/min/mmHg lower DLCO and DLNO, respectively, compared to men.

The study was conducted among 130 healthy, non-smoking men and women between the ages of 18 and 85 with varying heights and weights. The report appeared in the October 22 Epub edition of Nitric Oxide. READ ABSTRACT

What Really Causes Increased Responsiveness to Methacholine Challenge?
A new study out of Canada suggests the increased responsiveness to methacholine challenge may be due less to an intrinsic change in smooth muscle than to other changes in the lung manifesting as an increase in respiratory resistance. They arrived at that finding after studying induced airway hyperresponsiveness in mice using the lung slice technique. Mice were sensitized and then subjected to either brief exposure involving 2 challenges with intranasal chicken egg ovalbumin (IN OVA) or chronic exposure involving 6 H two-day periods of IN OVA challenges, each separated by 12 days. Control mice received intranasal saline challenges. Lung slice and other analysis showed neither brief nor chronic allergen exposure resulted in greater airway narrowing and increased velocity as compared to saline controls, but structural changes such as goblet cell hyperplasia, subepithelial fibrosis, and increased contractile tissue were detected in the airways of mice chronically challenged with allergen. The study was published in the November 21 Epub edition of the European Respiratory Journal. READ ABSTRACT

New Test for Preschoolers?
Analysis of recorded oscillations of the mouth pressure after measurement of the interrupter resistance may have a role to play in testing the lung function of preschool children, report researchers from Estonia publishing in Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society. They calculated four different amplitude parameters in 44 preschool children who completed methacholine challenge. All correlated strongly with each other and changed significantly after methacholine challenge, with the most sensitive indices to describe the change in airway mechanics being the maximum instantaneous amplitude and the difference between the first pressure maximum and minimum. READ ABSTRACT