American journal of respiratory and critical care medicine
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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)
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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.
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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.
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Am. J. Respir. Crit. Care Med. · Jan 1996
Comparative StudyRisk factors for nosocomial pneumonia: comparing adult critical-care populations.
The purpose of the study was to examine risk factors for nosocomial pneumonia in the surgical and medical/respiratory intensive care unit (ICU) populations. In a public teaching hospital, all cases of nosocomial pneumonia in the surgical and medical/respiratory ICUs (n = 20, respectively) were identified by prospective surveillance during a 5-yr period from 1987-1991. Each group of ICU cases was compared with 40 ICU control patients who did not acquire pneumonia, and analyzed for 25 potential risk factors. ⋯ APACHE III score was found to be predictive of nosocomial pneumonia in the surgical ICU population, but not in the medical/respiratory ICU population. We conclude that certain groups deserve special attention for infection control intervention. Surgical ICU patients with high APACHE scores and receiving prolonged mechanical ventilation may be at the greatest risk of acquiring nosocomial pneumonia of all hospitalized patients.
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Am. J. Respir. Crit. Care Med. · Jan 1996
Comparative StudySurfactant alterations in severe pneumonia, acute respiratory distress syndrome, and cardiogenic lung edema.
Bronchoalveolar lavage fluids (BALF) were analyzed for surfactant abnormalities in 153 patients with acute respiratory failure necessitating mechanical ventilation. Diagnoses were acute respiratory distress syndrome (ARDS) in the absence of lung infection (n = 16), severe pneumonia (PNEU; n = 88), ARDS and PNEU (n = 36), and cardiogenic lung edema (CLE; n = 13). The PNEU group was subdivided into groups with alveolar PNEU (n = 35), bronchial PNEU (n = 16), interstitial PNEU (n = 18) and nonclassified PNEU (n = 19). ⋯ Abnormalities in alveolar PNEU surpassed those in bronchial PNEU, and interstitial PNEU presented a distinct pattern with extensive metabolic changes. All surfactant changes were absent in CLE except for a slight inhibition of surface activity by proteins. We conclude that pronounced surfactant abnormalities, comparable to those in ARDS in the absence of lung infection, occur in different entities of severe PNEU, but not in CLE.