March 2007

Section-Only Webcast Coming Up May 9
The AARC is hosting a special webcast just for members of the Diagnostics Section on May 9, and everyone will be able to earn one FREE CRCE for viewing the live or archived session. So head over to the SECTION WEB SITE now to register for PFTs in Infants, which will be presented by Tim Myers and promises to bring us all up-to-date on this important area of care.

A Simpler Pulmonary Function Test?
British researchers have developed a new measure of the transformation of inspiratory effort into airflow they believe may be beneficial in testing patients who are unable to cooperate with the clinician during pulmonary function testing, such as those with cognitive impairments or a reduced level of consciousness, or young children. Referred to as inspiratory transductance, the test produces an index that is predicted to rise when airflow resistance falls, such as when an asthma attack responds to bronchodilator drugs, and maintain directional integrity even when inspiratory muscles become fatigued. They write, “Measuring the index would require little co-operation from a conscious patient and none from an unconscious patient.” The report appeared in the February 3 Epub edition of Medical Hypotheses. READ ABSTRACT

FEV1 Rate of Decline Predicts Mortality
Researchers from the Centers for Disease Control and Prevention’s National Institute for Occupational Safety and Health have determined the risk of death associated with cutoff points for the rate of decline in FEV1. Based on a 12 year study involving 1,730 miners, the authors find:

  • Compared to a rate of decline below 30 mL/yr the risk ratios were 1.39 in the 60 to less than 90 mL/yr category and 1.90 in the 90 mL/yr and above category.
  • Rates of decline above 90 mL/yr were consistently related to excess mortality.
  • In nonsmokers and those with neither restrictive nor obstructive patterns at the first survey, a rate of decline above 60 mL/yr was significantly associated with increased mortality.

 

The authors conclude, “Risk of death increases in individuals with rates of decline above about 60 mL/yr and is statistically significant in declines 90 mL/yr or more. These results should be useful to health care providers in the assessment of lung function declines observed in individuals.” The researchers published their findings in the March 1 Epub edition of Occupational and Environmental Medicine. READ ABSTRACT

O2 Washout Device Performs Well in Study
A new study out of Germany finds good results for a new device used to estimate functional residual capacity (FRC) via the O2 washout technique. The device uses a sidestream O2-analyzer to calculate FRC from end-inspired and end-expired O2 concentrations during fast changes of Fio2. The study involved 23 healthy, spontaneously breathing volunteers in the sitting position who were measured for FRC using helium dilution (FRC-He), body plethysmography (FRC-bp), and oxygen washout (FRC-O2). Results showed both the bias and precision of FRC-O2 were clinically acceptable when compared with FRC-He and FRC-bp. The authors believe these results suggest the device may be useful for bedside measures of FRC. The study appears in this month’s Anesthesia and Analgesia. READ ABSTRACT

Allergic Rhinitis Patients Have Lower deltaFVC than Mild Asthmatics
The provocation concentration of inhaled methacholine or histamine that causes a decrease in FEV1 of 20 percent (PC20) is typically used to measure airway sensitivity. Can the percentage decrease in forced vital capacity at the PC20 (deltaFVC) serve as a surrogate marker for this measure? Korean researchers set out to answer that question in a study involving 72 children with allergic rhinitis and airway hypersensitivity, and 72 with mild asthma who were matched for the PC20. The mean deltaFVC was significantly lower in the rhinitis group than in the asthma group, which the authors believe suggests “the level of maximal airway response in patients with allergic rhinitis is lower than that in mild asthmatic patients with a similar degree of airway hypersensitivity.” The study was published in the February issue of the Annals of Allergy, Asthma & Immunology. READ ABSTRACT

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