American Thoracic Society Journal news tips for March 2004

03/12/04

Second Issue

Maternal smoking significantly affects respiratory and arousal patterns in preterm infants

Based on multichannel sleep studies in the first few weeks after birth, pediatric investigators found that preterm infants who were exposed to cigarette smoke in the womb showed a significant increase in the number of obstructive apneas (breathing pauses), along with a specific decrease in their respiratory arousal index. The researchers studied 16 infants who had been exposed prenatally to cigarette smoke, and compared them with 14 control babies who had not been exposed. Maternal smoking was associated with a significant increase in the apneic index in these infants who had 28 events (breathing pauses per hour), as compared with slightly over 13 in the control babies. Apnea was defined as cessation of airflow for at least 2 respiratory cycles. The mothers in the study group smoked from 10 to 40 cigarettes per day during pregnancy. None of the mothers in the control group smoked. The children in the study were 34 weeks gestational age, were not on respiratory stimulants, and did not have any listed cardiorespiratory events for at least 1 week before the sleep study. They were in the Natal Intensive Care Unit about 8 weeks before sleep testing. No significant differences existed in gestational and current ages, sex, or birth weight between subject and control babies at the start of the study. The authors also found that a significant decrease in the total arousal index was observed in preterm babies born to the smoking mothers. The study appears in the second issue for March 2004 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.

Reducing airway inflammation in cystic fibrosis

According to the authors, this study is the first to demonstrate that recombinant human deoxyribonuclease (rhDNase) is not only an effective method of reducing sputum secretion viscosity in patients with cystic fibrosis (CF), it also prevents the increase in airway inflammation seen in untreated patients. The investigators examined 105 CF patients, aged 5 to 37 years (with the mean age about 12), using the bronchoaveolar lavage (BAL) test. (In BAL, doctors wedge a bronchoscope into a small airway of the lung, instill water through the instrument, and then suction it out to examine the fluid.) Through the use of BAL, prior studies had shown that neutrophil-dominated airway inflammation can be present very early in the course of CF. (An increase in the number of neutrophils (a form of white blood cell), occurs in infections and inflammations.) Of the 105 who received the BAL test, 46 were randomized to rhDNase treatment, 39 to no treatment, and 20 were not randomized due to the low percentage of neutrophils in the BAL fluid. (CF is a common inherited disease, occurring in 1 in every 2,500 white babies. A missing gene that regulates chloride and sodium transport across cell membranes causes problems, leading to dehydration and the production of very sticky secretions. In CF, the mucus-producing glands of the lung produce thick, abnormal secretions that clog the airways, damage the lungs, and form an environment in which bacteria can grow.) In this study, the researchers were able to show that rhDNase over 3 years had no proinflammatory effect but rather prevented the increase in airway inflammation that was observed in untreated patients. The study appears in the second issue for March 2004 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.

Access to diagnosis and treatment for suspected sleep apnea

Based on an individualized, informal survey of the diagnostic and treatment capabilities for sleep-disordered breathing in 5 different industrialized nations, authors of a "Pulmonary Perspective" point out that the major problem faced by patients with suspected sleep apnea is access to resources to allow them to be appropriately diagnosed and treated in a timely manner. The article offers information on population size, the annual number of sleep studies performed, the range of wait time experienced, and the problem of the mismatch between demand and capacity. (In sleep apnea, an individual repeatedly stops breathing long enough to decrease the amount of oxygen in the blood and brain and to increase the level of carbon dioxide. It can cause a host of difficulties, including hypertension, falling asleep at the wheel of a car, etc. The problem can be treated effectively with continuous positive airway pressure (CPAP)). In the United Kingdom, the overall wait for referral to CPAP treatment is 14 months. About two-thirds of the "sleep study" tests in the U.K. involved oximetry alone. That procedure only monitors oxygen concentrations in the blood by placing an electrode on the finger or earlobe. In Belgium, there are 50 sleep laboratories for the 10 million residents. A non-urgent case there waits 1 to 3 months from referral to the start of therapy. In Australia, with its 19 million citizens, patient wait time runs from 3 to 16 months from referral to the start of the treatment process. In the U.S., with its 280 million population, there are almost 1,300 sleep laboratories. The wait time from referral to treatment runs from 2 to 10 months. Wait times are generally longer in laboratories located in university, state, and government facilities. In Canada, with its 31 million population, the wait time to utilize one of the 100 sleep laboratories in the county varies from 4 to 36 months. The average time for completion of studies in eastern and western Canada is 24 months. However, the wait times in Ontario province are much shorter for consultation and polysomnography, averaging a little over 2 months. The article appears in the second issue for March 2004 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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