AEROSOL THERAPY DEVICES DEEMED EQUALLY EFFECTIVE

Aerosol therapy devices used for the delivery of bronchodilators and steroids can be equally efficacious when used properly, according to evidence-based guidelines published in the January Chest. The guidelines were developed by the American College of Chest Physicians and the American College of Allergy, Asthma, and Immunology, and are based on a systematic review of 59 randomized, controlled clinical trials. They provide recommendations on device selection in general, as well as in common clinical settings.

According to the authors of the guidelines, “None of the pooled meta-analyses showed a significant difference between devices in any efficacy outcome.” Therefore, the guidelines state that health care providers should not base device selection exclusively on efficacy but rather on other factors such as device availability, clinical setting, patient age, ability to use the selected device correctly, cost, drug administration time, convenience, and physician and patient preference.

“Health care providers should choose a device based on the individual characteristics of each patient. If asthma control is not achieved using one delivery device, it may be beneficial for patients to switch to another device after consulting with his or her provider,” said Myrna B. Dolovich, PEng, an author of the guidelines and Associate Clinical Professor at McMaster University in Hamilton, Ontario.

The guidelines also provide recommendations for device selection in certain clinical settings. In the inpatient setting, nebulizers and metered-dose inhalers with spacer/holding chambers should be used. In the emergency department setting, nebulizers and metered-dose inhalers with spacer/holding chambers should be used for delivery of β2-agonists. Furthermore, when administering medication to mechanically ventilated patients, health care providers should be aware of the proper technique for using a nebulizer or metered-dose inhaler in such a setting, since technical factors can have important effects on the efficiency of aerosol delivery.

The authors of the guidelines also recommended that “physicians, respiratory therapists, and nurses caring for patients with respiratory diseases should be familiar with issues related to performance and correct use of aerosol delivery devices in order to instruct their patients on proper usage.” They added, “Regardless of what delivery system is chosen, patient education is essential to [ensure] optimal outcomes.”

Dolovich MB, Ahrens RC, Hess DR, et al. Device selection and outcomes of aerosol therapy: evidence-based guidelines. Chest. 2005;127:335-371.

ARSENIC INGESTION AND CIGARETTE SMOKE ARE ASSOCIATED WITH AN INCREASED RISK OF LUNG CANCER

Residents of Taiwan who consumed well water with high levels of arsenic have a higher risk of lung cancer, and cigarette smokers in this group have an even higher risk, according to the December 22/29 JAMA. Chi-Ling Chen, PhD, of the National Taiwan University in Taipei, and colleagues studied 10,591 residents of the southwestern and northeastern coasts of Taiwan—two arsenic-endemic areas—for an average period of eight years and found a significant dose-response relationship between ingested arsenic and lung cancer risk.

The researchers estimated the joint effect of arsenic ingestion and cigarette smoking by both etiologic fraction and synergy index. Information on arsenic exposure, cigarette smoking, and other risk factors was collected at enrollment through interviews conducted by public health nurses. Arsenic exposure was determined using information on arsenic concentration in water, residential history, and duration of well-water consumption. “Measurements of cigarette smoking included smoking status (never, current, or past), numbers of cigarettes smoked per day, total years of cigarettes smoked, and cumulative exposure of cigarette smoking (pack-years),” said the researchers.

According to Dr. Chen and his colleagues, arsenic concentration ranged from 350 to 1,140 µg/L in the southwestern area and from less than 0.15 to 3,590 µg/L in the northeastern area. Most southwestern residents consumed an average arsenic level greater than 100 µg/L, while most northeastern residents consumed an average arsenic level less than 100 µg/L.

The researchers found that etiologic fractions ranged from 0.32 to 0.55, indicating that 32% to 55% of lung cancer cases were attributable to the combined damaging effect of cigarette smoking and arsenic ingestion. Furthermore, they reported, “synergy indices ranged from 1.62 to 2.52, which were all above 1, indicating a synergistic effect under an additive scale.”

The risk ratio associated with the highest arsenic level was 3.29. Nonsmokers who were exposed to the highest arsenic level had a twofold risk of lung cancer, compared to those exposed to the lowest level. Residents who had the lowest level of arsenic exposure and the highest level of cigarette smoking exposure had a fourfold risk of lung cancer, compared with nonsmokers. In addition, “those who consumed well water with an arsenic level of 700 µg/L or more and smoked for more than 25 pack-years had a greater than 11-fold risk of developing lung cancer.”

The investigators concluded that “appropriate public health interventions, such as cigarette smoking cessation programs and reduction in arsenic concentration of drinking water, are warranted.”

Chen CL, Hsu LI, Chiou HY, et al. Ingested arsenic, cigarette smoking, and lung cancer risk: a follow-up study in arseniasis-endemic areas in Taiwan. JAMA. 2004;292:2984-2990.

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