American Thoracic Society Journal news tips for August 2005 (first issue)


Lower Lung Function Test Scores Prior To Transplantation Signal Respiratory Failure and Death for Stem Cell Recipients

Researchers found that a less than normal score on a common lung function test taken prior to stem cell transplantation constituted a significant risk factor for the patient to develop early respiratory failure followed by death.

Investigators conducted a retrospective analysis of pretransplant lung function test scores of 2,852 patients who received their stem cell transplants between 1990 and 2001. (All transplants were allogeneic, meaning that the stem cells came from another person with a matching tissue type.)

According to the medical scientists, over 80 percent of the patients had normal lung function tests prior to transplantation. However, they found that a pretransplant forced expiratory volume in one-second (FEV1) of less than 70 percent of a predicted age-adjusted value was significantly associated with early respiratory failure. Such responses occurred in 396 (14 percent) of the 2,852 patients. (The risk for respiratory failure among those who had a moderate to severe decreased lung function score was about 28 percent.)

A total of 359 patients or about 91 percent of those with early respiratory failure died after receiving mechanical ventilator support.

All stem cell recipients had cancers for which they had been treated. They received either total body irradiation or non-total body irradiation and/or chemotherapy.

With a high dose of radiation and/or chemotherapy, damage can be done to the patient's bone marrow and other tissue. Bone marrow is rich in blood-forming stem cells, which develop into oxygen-bearing red blood cells, infection fighting white blood cells, and clot-forming platelets.

One way to offset the effects of cancer treatment is through stem cell transplantation, which helps to strengthen the body's blood forming system that has been weakened either by aggressive cancer treatment or by the disease itself.

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

An Alternative Therapy for Mild Sleep-Disordered Breathing in Children

Research investigators have shown that there is an alternative therapy to the removal of tonsils and adenoids for the relief of mild sleep-disordered breathing in children.

In a 16-week study involving 24 young people, researchers employed montelukast, an anti-inflammatory agent used in asthma and allergic rhinitis. They found that the oral therapy resulted in significant reductions in the children's adenoid size as well as decreases in respiratory sleep disturbances.

The researches said that the chief concept emanating from this study supports the existence of a chronic inflammatory process in children with sleep-disordered breathing.

The 24 children recruited for the study, as well as the 16 controls, were older than age 2, but younger than 10. Each child was a habitual snorer who had been found to have a sleep apnea index of more than 1 but less than 5 events per hour during an overnight polysomnography evaluation at the sleep center.

In obstructive sleep apnea, the sleeping person temporarily stops breathing long enough to decrease the amount of oxygen in the blood and to build up carbon dioxide. After a breathing pause of 10 seconds or more, the person awakens and resumes breathing.

Obstructive sleep apnea affects 2 to 3 percent of children. It is usually associated with a blockage in the throat or upper airway. An apnea-hypopnea index of from 1 to 4 breathing pauses (called "events") an hour constitute mild sleep-disordered breathing. Removal of tonsils and adenoids is usually reserved for children whose respiratory index (AHI) during sleep exceeds 5 events per hour of sleep.

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

'State of the Art' in Occupational Asthma

In a "State of the Art" article on occupational asthma, the authors report that the illness has become one of the most common forms of occupational lung disease in industrialized countries, constituting 9 to 15 percent of all adult asthma.

According to the article, the most cost-effective way to lower the rate of this type of asthma is to reduce the employee's exposure to the offending agent as early as possible to prevent sensitization. (Sensitization occurs when repeated exposure to a noxious substance in the workplace causes the person's airway to become inflamed and narrow.)

Occupational asthma is characterized by variable airflow limitation and/or airway hyperresponsiveness due to causes and conditions directly attributable to a particular occupational environment.

Work-aggrevated asthma varies from occupational asthma because the outcome, medical management, and preventive measures differ substantially. Work-aggrevated asthma involves preexisting or concurrent asthma that is exacerbated by workplace exposure.

According to the article, the most common form of occupational asthma, which accounts for 90 percent of the cases, is immunologic in nature, induced by the immunoglobulin E mechanism or other immune responses to particular workplace agents. Such materials include dust from various woods, epoxy compounds in spray paint; animal, plant, insect, and fungal allergens; cleaning agents; flour dust; or food and animal proteins.

(Immunoglobulin E (IgE) is one of the five classes of antibodies produced by lymph tissue in response to the invasion of foreign substances. It is present primarily in skin and mucus membranes and plays a role in allergic reactions.)

The less common type of occupational asthma, irritant-induced asthma, accounts for about 7 percent of all cases. Industries in which workers are exposed to irritant-induced asthma include metal refining, fertilizer manufacturing (with ammonia), and mining.

Although the level of exposure is a critical factor for the development of occupational asthma, when given the same level of exposure, only a small proportion of workers will develop sensitization and/or occupational asthma, which suggests host susceptibility is a factor, according to the authors.

The article appears in the first issue for August 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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