American Thoracic Society journal news tips for October 2005 (first issue)

09/21/05

TREATING SEVERE ASTHMA IN CHILDREN BASED ON EXHALED NITRIC OXIDE LEVELS

Physicians can better determine the most effective inhaled corticosteroid dose for children with moderate to severe allergic asthma by measuring the nitric oxide levels in the patient's breath, rather than by observing symptoms, according to a study published in the first issue for October 2005 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.

In the study, doctors based their inhaled corticosteroid treatment on exhaled nitric oxide levels, while considering symptoms, in 39 asthmatic children who were, on average, age 12. In 46 children of approximately the same age, inhaled corticosteroid levels were based on symptoms alone. All the children had atopic asthma, an allergic illness to which they have an inherited tendency.

According to the researchers, at the end of the study year, the exhaled nitric oxide-based group did not increase their steroid dose, yet they did reduce their inflammation level, as compared with the symptom group.

When explaining the new approach, the investigators noted that airways produce nitric oxide and that its fractional concentration in exhaled air is elevated in patients with atopic asthma that has not been treated with steroids. They called the nitric oxide test an "inflammometer" for the disease.

In asthma, airways narrow because of hyperreactivity to certain stimuli that produce inflammation. This narrowing can be triggered by many stimuli, including pollens, mold, animal dander, and dust mites.

During the study, exhaled nitric oxide levels were measured in one test group at each of five visits to a center over one year, while airway hyperresponsiveness and lung function were determined in both groups at the start and end of the one-year study.

Over the course of the study, the nitric oxide group had 8 severe exacerbations, as compared with 18 in the symptom group.

The researchers said that most often physicians look at symptoms to guide inhaled corticosteroid dosing in asthma. However, symptoms are nonspecific and not closely related to the presence and severity of airway inflammation. They note that symptom-based treatment could lead to excessive inhaled corticosteroid doses, while fear of side effects could lead to underdosing, especially in children.

The study appears in the first issue for October 2005 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.

INCREASE IN STEM CELL SUBTYPE INDICATES BETTER SURVIVAL RATE IN ACUTE LUNG INJURY

Researchers found that an increase in the number of a certain type of stem cell in patient's blood was associated with a much improved survival rate for those hit by a devastating cause of respiratory failure, acute lung injury (ALI).

According to the authors, the improved survival rate among 45 patients with ALI correlated with higher colony counts of a stem cell subtype called endothelial progenitor cells (EPCs). Patients with ALI, which constitutes a very serious illness, usually require ventilator support, and face a high death rate.

The researchers noted that repair of damaged endothelium--the layer of flat cells that lines the heart, blood and lymph vessels, as well as some body cavities--is important in recovering from acute lung injury. In animal models, bone marrow-derived EPCs differentiate into mature endothelium and assist in repairing a damaged vascular system.

The researchers said that patients with ALI who had a colony count for EPCs of 35 or more had a mortality rate of 30 percent as compared with 61 percent in those with colony counts of less than 35.

Of the 45 patients with ALI, 26 survived. Among all ALI patients, 27 had colony-forming units exceeding 35, and 18 had colony-forming units numbering less than 35.

Acute lung injury and acute respiratory distress syndrome represent twin deadly types of lung failure that can result from different disorders. In this study, 33 of the 45 patients had lung injury primarily associated with pneumonia.

Stem cells derived from bone marrow can change into a variety of tissue-specific human cell types. In this research, EPCs represent the specific subtype of stem cell involved, and were isolated from the peripheral blood of the patients.

The authors believe that the measurement of EPC colony-forming units is promising as a novel prognostic marker for survival in patients with ALI.

The research appears in the first issue for October 2005 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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