American journal of respiratory and critical care medicine
-
Am. J. Respir. Crit. Care Med. · Jan 1996
Comparative StudyAirways responsiveness, wheeze onset, and recurrent asthma episodes in young adolescents. The East Boston Childhood Respiratory Disease Cohort.
To describe the role of airways responsiveness in predicting incidence of wheeze in early adolescence and to examine the association between airways responsiveness and active asthma symptoms, children who had been tested for airways hyperresponsiveness were assessed prospectively. Of 770 children in the East Boston Childhood Respiratory Disease Cohort who were between 5 and 9 yr of age at time of entry into the study, 281 children received airways challenges during voluntary follow-up conducted between 1980 and 1986. Each subject presented a sequence of wheeze or asthma diagnosis reports along with a sequence of time-varying covariates, including airways challenge results and symptom and exposure information. ⋯ In the analysis of recurrent asthma episodes, airways responsiveness at a given visit was associated with a greater tendency to have an asthma diagnosis reported at the subsequent visit (OR = 4.2, 95% CI = 1.92, 9.23). For subjects presenting multiple airways responsiveness challenge studies, two successive positive airways responsiveness results were independently associated with a higher likelihood of recurrent asthma episodes. These results confirm the predictive importance of airways responsiveness in the natural history of the development and persistence of asthmatic symptoms.
-
Am. J. Respir. Crit. Care Med. · Jan 1996
Comparative StudyEffects of overnight supplemental oxygen in obstructive sleep apnea in children.
Supplemental oxygen during sleep may be useful as a temporary palliative treatment in children with obstructive sleep apnea syndrome (OSAS) associated with significant hypoxemia. However, supplemental O2 may also blunt hypoxic ventilatory drive and worsen ventilation. To assess the safety of the use of supplemental O2 in children with OSAS, we studied 16 children ages 2-8 (mean: 4.28 +/- 2.88 yr) with OSAS secondary to adenotonsillar hypertrophy. ⋯ The density and average duration of central apneas remained unchanged. In addition, supplemental O2 increased the percentage of REM sleep time and decreased the number of microarousals. We conclude that supplemental O2 might be a safe and beneficial temporary treatment in children with OSAS.
-
Am. J. Respir. Crit. Care Med. · Jan 1996
Comparative Study Clinical Trial Controlled Clinical TrialSkeletal muscle microvascular blood flow and oxygen transport in patients with severe sepsis.
To compare skeletal muscle microvascular blood flow at rest and during reactive hyperemia in septic patients, a prospective, controlled trial was conducted on 16 patients with severe sepsis and a control group of 10 patients free of infection in the intensive care unit of a university hospital. Systemic hemodynamics, whole-body oxygen transport, and skeletal muscle microvascular blood flow at rest and during reactive hyperemia were measured. Reactive hyperemia was produced by arrest of leg blood flow with a pneumatic cuff; on completion of the 3 min ischemic phase the occluding cuff was rapidly deflated to 0. ⋯ Cyclic variation in blood flow (vasomotion) was observed in control subjects but not in septic patients. Skeletal muscle microvascular perfusion is altered in patients with severe sepsis despite normal or elevated whole-body oxygen delivery. These microvascular abnormalities may further compromise tissue nutrient flow and may contribute to the development of organ failure in septic patients.
-
Am. J. Respir. Crit. Care Med. · Jan 1996
Review Comparative StudyHealth effects of outdoor air pollution. Committee of the Environmental and Occupational Health Assembly of the American Thoracic Society.
Particles, SOx, and acid aerosols are a complex group of distinct pollutants that have common sources and usually covary in concentration. During the past two decades, the chemical characteristics and the geographic distribution of sulfur oxide and particulate pollution have been altered by control strategies, specifically taller stacks for power plants, put in place in response to air pollution regulations adopted in the early 1970s. While the increasing stack heights have lowered local ambient levels, the residence time of SOx and particles in the air have been increased, thereby promoting transformation to various particulate sulfate compounds, including acidic sulfates. ⋯ This review suggests that the epidemiologic studies of adverse morbidity measures are coherent with the mortality studies showing quantitatively similar adverse effects of acute exposures to particulate pollution. Despite these epidemiologic findings for acute and chronic adverse health effects from air pollution associated with relatively low levels of inhalable particles, there are no complementary data from toxicologic studies or from acute human exposures to similar levels of respirable particles. Thus, controlled human exposures to various particles, including H2SO4, at relevant levels (< 150 micrograms/m3) have not identified significant alterations in respiratory function in healthy individuals.(ABSTRACT TRUNCATED)
-
Am. J. Respir. Crit. Care Med. · Jan 1996
Comparative StudyResource use implications of do not resuscitate orders for intensive care unit patients.
This study describes the use of do not resuscitate (DNR) orders for ICU patients in four northeastern U. S. teaching hospitals and investigates the relationship between DNR orders and length of stay. The use of detailed data from the mortality probability model (MPM II) study on 6,290 consecutive ICU admissions to general adult medical and surgical ICUs during 1989 through 1991 allows us to control for severity of illness and the time during the ICU stay at which the DNR order was entered. ⋯ Nonsurvivors with early (first 24 h) DNR had shorter mean and median ICU and hospital stays than the comparison group of non-DNR patients. The percentage of patients with very long ICU (> 30 d) and hospital (> 60 d) stays was smaller among DNR patients. The use of DNR orders, particularly early in the ICU stay, may be associated with significant resource use reduction for an identifiable group of patients.