American Association for Respiratory Care
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AARC Diagnostics Section

June 2013

Nominate a Peer for Specialty Practitioner of the Year

The deadline for nominating a fellow section member for our 2013 Specialty Practitioner of the Year Award is July 31, so start brainstorming worthy candidates and then nominate them using the nomination form on our SECTION WEBSITE.

Race and Gender Bias in COPD Diagnosis

Is there race and gender bias in the diagnosis of COPD? According to Temple University researchers presenting at the ATS 2013 International Conference, the answer is yes. They looked at nearly 9000 non-Hispanic white and African-American patients enrolled in the COPDGene study. All were 45 years of age or older with a history of at least ten pack years of cigarette smoking. Baseline assessment included spirometry and determination of prior COPD diagnosis. Compared with whites, African-American subjects at all GOLD stages of airflow obstruction had significantly higher odds of not having had a prior COPD diagnosis. Compared with men, women at all GOLD stages had significantly higher odds of having had a prior COPD diagnosis. “The under-diagnosis and potential under-treatment of COPD among African Americans that we detected in our study is cause for concern,” study author Albert Mamary, MD, was quoted as saying. READ PRESS RELEASE

Ethnic Differences in South Asian Lung Function May be Genetic

Noting that age- and height-adjusted spirometric lung function is lower in South Asian children when compared to white children, Swiss researchers studied 1088 white children and 275 South Asian children born in the U.K. to assess for factors influencing the ethnic differences. Children in the study were aged 9 to 14. Using five different models to adjust for cultural factors, socioeconomic status, intrauterine growth, environmental exposures, and personal and family history of wheeze, the investigators found height- and gender-adjusted FVC and FEV1 were lower in South Asian children, FEV1/FVC was higher, and PEF and FEF50 were similar. “This suggests that differences in lung function may be mainly genetic in origin,” write the authors. The study was published ahead of print by Pediatrics on May 27. READ ABSTRACT

Salbutamol’s Effect on DLCO

A new study out of New Zealand finds salbutamol may significant reduce DLCO in some patients with airway obstruction reversibility. However, it has no effect on the mean DLCO, mean alveolar volume (VA), or DLCO/VA (KCO) in patients without reversibility or those with normal spirometry. The study was conducted among 20 subjects in each of the three groups who were measured for spirometry, plethysmographic lung volumes, DLCO, pulse rate, and arterial blood gases at baseline and then again after administration of a placebo inhaler and 400 μg salbutamol. In most patients with airway reversibility the reduction in DLCO was not significant, but in four subjects there was a significant reduction, thought to be the result of a minor increase in VA and substantial decrease in KCO. The study was published ahead of print in Respirology on May 23. READ ABSTRACT

Reference Equations for IOS

Spirometry can be difficult to perform in elderly patients with physical or mental limitations. German researchers suggest impulse oscillometry (IOS) could be a good alternative and provide reference equations for Caucasians, including those of advanced age, in a new study published in the May edition of PLoS One. The research was conducted among a population based sample of 1990 subjects aged 45-91. IOS was performed in all of these individuals; from that group 397 never-smoking, lung healthy subjects with normal spirometry were identified and sex-specific quantile regression models with age, height, and body weight as predictors for respiratory system impedance, resistance, reactance, and other parameters of IOS were applied. Among the results:

  • Women (n = 243) showed higher resistance values than men (n = 154), while reactance at low frequencies (up to 20 Hz) was lower (p<0.05).
  • A significant age dependency was observed for the difference between resistance values at 5 Hz and 20 Hz (R5-R20), the integrated area of low-frequency reactance (AX), and resonant frequency (Fres) in both sexes whereas reactance at 5 Hz (X5) was age dependent only in females.
  • In the healthy subjects (n = 397), mean differences between observed values and predictions for resistance (5 Hz and 20 Hz) and reactance (5 Hz) ranged between -1% and 5% when using the present model.
  • In contrast, differences based on the currently applied equations (Vogel & Smidt 1994) ranged between -34% and 76%.
  • Regarding the equations the indices were beyond the limits of normal in 8.1% to 18.6% of the entire cohort (n = 1990), and in 0.7% to 9.4% with the currently applied equations.

“Our study provides up-to-date reference equations for IOS in Caucasians aged 45 to 85 years,” write the authors. “We suggest the use of the present equations particularly in advanced age in order to detect airway dysfunction.” READ ABSTRACT

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