Chest Radiographic Changes Research Articles

Patterns in follow up of chronic airway obstruction

Over 5 years from 2000 to 2004 a consecutive series of 420 cases of obstructive airway disease were studied with full history, spirometry, chest radiograph, and other relevant investigations. Several were followed and reassessed: 58.1 % were males - of these 42.1 % were smokers. Sixty percent (252) belonged to age above 40 years; 200 cases revealed clinical history of upto 5 years: 9.3% had a family history of asthma. 55.5% showed some changes in chest radiograph 52.6% had a daily chest symptoms Chronic cough was seen in 59.5% and paroxysmal dyspnoea in 38.9% Clinically asthma was labelled in 43.8% and COPD in 56.2% On follow up 45.6% showed an improvement while 34.1 % deteriorated. Mainly management was oral theophyllin (93.1 %), beta stimulant inhalers (81.2%). During exacerbations 94.1 % were given antibiotics and 24-29 % had steroids. A history of hospitalization was seen in 51.9%: 4 died, 4 had IPPR and 8 had malignancies mainly in Lung. 50.2% had hypertension, 26.1% ischemia and 10.8% a prior lung tuberculosis 11.2% Showed diabetes. FVC, FEV 1 , AND VE50 could assess the degree of functinol disability: asthmatics showed a larger bronchoreversibility. In many, distinction from asthma to COPD was not easy and mainly clinical.

Adverse effects of asbestos exposure and smoking on lung function

Exposure to asbestos is a well-recognized cause of both malignant and nonmalignant diseases of lung parenchyma and pleura. This study was conducted to determine the adverse effects of exposure to asbestos and smoking on pulmonary function. Four hundred and sixty-eight workers who were occupationally exposed to asbestos for an average of 13 years were selected from an asbestos-product factory in China. Of them, 85 workers were diagnosed with asbestosis. Additionally, 282 workers who had no experience of exposure to industrial dust were included as a control group. A questionnaire was administered during a face-to-face interview and spirometric maneuvers and single-breath CO diffusing capacity (DL(CO)) were performed. Multivariate regression analysis showed that exposure to asbestos was more strongly associated with decreased forced vital capacity (FVC) and DL(CO), and asbestosis more strongly associated with decreased FVC, while smoking was a major contributing factor to reduced FEV1/FVC. The results were confirmed by a further analysis where the subjects were grouped exclusively by smoking, asbestos exposure, and chest radiographic changes. No interaction or joint effect was observed between asbestos exposure and smoking. This analysis suggested that asbestos and smoking might play independent roles, in which asbestos caused mainly a restrictive impairment, and smoking was a major causal factor for airway obstruction in the workers who were intensively exposed to asbestos.

Postoperative chest radiographic changes after on- and off-pump coronary surgery

A variety of chest radiograph abnormalities are recognized after coronary artery bypass grafting (CABG). This study analyzes the appearance of preoperative and postoperative chest radiographs in two groups of patients undergoing myocardial revascularization with or without the use of cardiopulmonary bypass (CPB). Chest radiographs (preoperative and at 1 day, 6 days and 6 to 8 weeks post operatively) were analyzed according to a detailed protocol in cases of conventional CABG on CPB (n=60) or off-pump coronary artery bypass (OPCAB) (n=60) surgery. On each film 17 different major potential postoperative abnormalities were analyzed. Clinical findings were similar in the two groups. Patients undergoing OPCAB surgery had decreased blood loss, decreased red cell and platelet transfusion, significantly lower intubation time and required less postoperative inotropic support compared with patients undergoing CPB. The CPB group had a significantly higher incidence of left band atelectasis than the OPCAB group (37.6% vs 17.5%, p=0.01) at 6 days postoperatively. There was no other statistically significant difference in any of the 16 remaining major chest radiograph findings between the two groups. Although OPCAB surgery is associated with improved clinical outcome compared with conventional CABG surgery, the analysis of postoperative chest radiographs demonstrated only a minor benefit as shown by a reduced degree of left band atelectasis in the OPCAB group.

Medical imaging in nephropathia epidemica and their clinical correlations

Background This study was designed to evaluate radiological findings in chest and sinus radiographs and renal ultrasound (US) in patients with nephropathia epidemica (NE) and to determine whether changes in these medical images are related to each other or to the clinical course of NE. Methods Radiological findings and clinical course were studied in 380 hospital-treated NE patients during the years 1982–1998. Results In 35% of the patients there were clear changes in chest radiographs. Pleural effusion, atelectasis, and interstitial infiltration were the most common X-ray findings. Forty-seven percent had changes in renal US, with increased cortical echoicity and cortical swelling being the most common findings. Thirty-three percent of the patients with clinical symptoms of sinusitis had changes in sinus radiographs. Abnormal findings on chest radiographs were clearly associated with fluid volume overload, high blood pressure level, leukocytosis, degree of clinical renal insufficiency, and thrombocytopenia. Abnormal findings in renal US were associated to some extent with fluid volume overload and degree of clinical renal insufficiency. Conclusions Some 35% of patients had clear changes in chest radiographs and 47% showed changes in renal US. Abnormal findings in chest radiographs were clearly associated, and abnormal findings in renal US were associated to some extent, with the severity of the clinical course of NE.

Coronavirus as a possible cause of severe acute respiratory syndrome

SummaryBackgroundAn outbreak of severe acute respiratory syndrome (SARS) has been reported in Hong Kong. We investigated the viral cause and clinical presentation among 50 patients.MethodsWe analysed case notes and microbiological findings for 50 patients with SARS, representing more than five separate epidemiologically linked transmission clusters. We defined the clinical presentation and risk factors associated with severe disease and investigated the causal agents by chest radiography and laboratory testing of nasopharyngeal aspirates and sera samples. We compared the laboratory findings with those submitted for microbiological investigation of other diseases from patients whose identity was masked.FindingsPatients' age ranged from 23 to 74 years. Fever, chills, myalgia, and cough were the most frequent complaints. When compared with chest radiographic changes, respiratory symptoms and auscultatory findings were disproportionally mild. Patients who were household contacts of other infected people and had older age, lymphopenia, and liver dysfunction were associated with severe disease. A virus belonging to the family Coronaviridae was isolated from two patients. By use of serological and reverse-transcriptase PCR specific for this virus, 45 of 50 patients with SARS, but no controls, had evidence of infection with this virus.InterpretationA coronavirus was isolated from patients with SARS that might be the primary agent associated with this disease. Serological and molecular tests specific for the virus permitted a definitive laboratory diagnosis to be made and allowed further investigation to define whether other cofactors play a part in disease progression.

Longitudinal analyses of chest radiographs from the European Carbon Black Respiratory Morbidity Study.

High levels of exposure to carbon black have been linked with an increased prevalence of chest radiograph abnormalities. However, it is unclear to what extent current levels of exposure in the carbon black manufacturing industry are associated with new cases of and progression in small opacities. Longitudinal analyses were carried out on data from workers in the European carbon black manufacturing industry who provided three full-size chest radiographs sequentially between 1987-1995. All chest radiographs were independently read by three experienced readers according to the International Labour Organisation (ILO) classification. After exclusion of participants with previous lung diseases or injuries, females, unreadable chest radiographs and from factories with a low participation rate, data from 675 workers were available for the longitudinal analyses. An association was observed between cumulative carbon black exposure and new cases of chest radiograph abnormalities (ILO category > or = 1/0) and progression in small opacities. These associations were mainly related to changes in chest radiographs from workers at one factory. A large percentage of workers with chest radiograph abnormalities reversed to normal chest films; however, after adjusting for other factors, this was not associated with levels of exposure to carbon black dust. In conclusion, the results show that exposure to carbon black is associated with increased risk of chest radiographic abnormalities, which may be reversible after reduction or cessation of exposure.

A Longitudinal Study of Chest Radiographic Changes of Workers in the Refractory Ceramic Fiber Industry

This industry-wide longitudinal study examines chest radiographic changes of workers manufacturing refractory ceramic fibers (RCF). Chest radiographs were obtained every 3 years and were interpreted using the 1980 International Labour Organization classification for pneumoconiosis. Three exposure metrics were calculated: duration and latency in a production job, and cumulative exposure (fiber-months per cubic centimeter). The radiographic survey included 625 current workers at five manufacturing sites and 383 former workers at two of the five sites. Pleural changes were seen in 27 workers (2.7%). Of workers with > 20 years of latency from initial production job or 20 years of duration in a production job, 16 workers (8.0%) and 5 workers (8.1%) demonstrated pleural changes, respectively. Results from the cumulative exposure analysis (> 135 fiber-months per cubic centimeter) demonstrated a significant elevated odds ratio (OR) of 6.0 (95% confidence interval [CI], 1.4 to 31.0). The incidence of irregular opacities at profusion categories > or = 1/0 was similar to other nonspecified dust-exposed worker populations at 1.0%, and showed a nonsignificant elevated OR in regard to cumulative fiber exposure of 4.7 (95% CI, 0.97 to 23.5). RCF are significantly associated with pleural changes that were predominantly pleural plaques, but have not resulted in a statistically significant increase in interstitial changes.

Early Treatment of Stage II Sarcoidosis Improves 5-Year Pulmonary Function

To evaluate the 5-year prognosis of patients with stage I and stage II newly detected (< 3 months) pulmonary sarcoidosis treated immediately after diagnosis with prednisolone for 3 months followed by inhaled budesonide for 15 months. Randomized, double-blind, placebo-controlled, parallel-group study for 18 months. Thereafter, open follow-up without treatment. Twenty pulmonary medicine departments in Finland. One hundred eighty-nine adult patients, most of them with normal lung function, were randomized to treatment. One hundred forty-nine patients were followed up for 5 years: 79 patients with initial stage I disease and 70 patients with stage II disease. Oral prednisolone for 3 months followed by inhaled budesonide for 15 months (800 microg bid), or placebo tablets followed by placebo inhaler therapy. Thereafter, treatment only on an individual basis in the case of clinical deterioration. Yearly follow-up visits with chest radiographs, lung function tests (FEV(1), FVC), diffusion capacity of the lung for carbon monoxide (DLCO), serum angiotensin-converting enzyme (SACE), and serum and urinary calcium measurements. No initial differences were observed in chest radiographic findings between the active-treatment and placebo-treatment groups, either in patients with initial stage I or stage II(-III) disease. However, after the 5-year follow-up, 18 steroid-treated patients (26%) and 30 placebo-treated patients (38%) still had remaining chest radiographic changes. Placebo-treated patients more frequently required treatment with corticosteroids during the 5-year follow-up (p < 0.05). Steroid-treated patients with initial stage II(-III) disease improved more in FVC and DLCO (p < 0.05). No differences in reported adverse events or in SACE, serum calcium, or urinary calcium values were seen. Immediate treatment of pulmonary stage II(-III) sarcoidosis-but not stage I disease-improved the 5-year prognosis with regard to lung function variables.

Pulmonary tuberculosis in children in a developing country.

We evaluated the clinical and epidemiologic characteristics of Peruvian children presenting with pulmonary tuberculosis (PTB) to determine whether features predictive of confirmed PTB could be identified. This was a cross-sectional study of 135 children (mean age: 6.8 years) presenting to the Hospital del Niño in Lima, Peru, with presumptive diagnosis of PTB. Clinical, epidemiologic, and laboratory findings were compared between 3 groups of pediatric patients with a presumptive diagnosis of PTB: those with positive Mycobacterium tuberculosis (MTB) cultures, those likely to have PTB based on clinical criteria but with negative cultures, and those who did not meet clinical diagnostic criteria or have positive cultures. A total of 50 (37%) patients were diagnosed with definitive PTB based on positive sputum culture. Another 55 (47%) patients were classified as having probable PTB based on meeting at least 2 of the following criteria: cough lasting for at least 2 weeks, typical chest radiograph changes, purified protein derivative (PPD) >/=10 mm, or history of tuberculosis family contact. Patients with definitive or probable PTB were significantly older than patients without clinical PTB, and those with symptomatic disease were significantly older than those with asymptomatic disease. Patients with PTB diagnosed by culture were significantly more likely than those diagnosed using clinical criteria to have cough lasting >/=2 weeks, fever, and a PPD >/=10 mm. The typical presentation of PTB in Peruvian children includes symptoms of active pulmonary disease similar to those seen in adults. This presentation differs significantly from that reported in developed countries, where many children have minimal or no symptoms at the time of presentation. The diagnostic criteria for pediatric PTB must be modified in hyperendemic developing country environments where features may differ from those described in the United States. The triad of cough lasting >/=2 weeks, fever, and a PPD >/=10 mm was highly predictive for culture-positive PTB among children in this low-income Peruvian population.

Respiratory diseases in the first year of life in children born to HIV-1-infected women.

Our objective was to describe the respiratory complications, clinical findings, and chest radiographic changes in the first year of life in infected and uninfected children born to HIV-1-infected women. We prospectively followed a cohort of 600 infants born to HIV-1-infected women from birth to 12 months in a multicenter study. Of these, 93 infants (15.5%) were HIV-1-infected, 463 were uninfected, and 44 were of unknown status prior to death or loss to follow-up. The cumulative incidence ( +/- SE) of an initial pneumonia episode at 12 months was 24.1 +/- 4.7% in HIV-1-infected children compared to 1.4 +/- 0.6% in HIV-1-uninfected children (P < 0.001). The rate of Pneumocystis carinii pneumonia (PCP) was 9.5 per 100 child-years. The HIV-1 RNA load was not higher in the group that developed pneumonia in the first year vs. those who did not. Children who developed lower respiratory tract infections or PCP had increased rates of decline of CD4 cell counts during the first 6 months of life. Lower maternal CD4 cell counts were associated with higher rates of pneumonia, and upper and lower respiratory tract infections. The rates of upper respiratory tract infection and bronchiolitis/reactive airway disease in infected children were not significantly different than in uninfected children. At 12 months, significantly more HIV-1-infected than uninfected children had tachypnea and chest radiographs with nodular and reticular densities. There was no relationship between cytomegalovirus infection in the first year of life and radiographic changes or occurrences of pneumonia. In conclusion, despite a low incidence of PCP, rates of pneumonia remain high in HIV-infected children in the first year of life. The incidence of pneumonia in uninfected infants born to HIV-1-infected mothers is low. Chest X-ray abnormalities and tachypnea suggest that subacute disease is present in infected infants. Further follow-up is warranted to determine its nature.

Computer‐aided diagnosis for detection of changes in sequential chest radiographs (in Japanese)

The subtraction image of digital chest radiographs taken at different times improved the diagnostic accuracy of radiologists viewing screening chest radiographs. The accurate registration of two chest images using “lung markings” instead of “rib edges” enables us to detect subtle changes in the “difference image.” The “lung markings” are the shadows of blood vessels traversing lung substance. Most of the morbid changes grow in lung substance not in the rib cage. Twenty‐nine pairs of posteroanterior chest radiographs with and without temporal morbid changes were selected from approximately 200 sequential cases. The images were 1760×1760 matrix and 1024 gray scale with a computed radiography system (Fuji Medical System, Tokyo). Image registration employed the matching of “lung markings” in the two radiographs. Observer performance tests with and without the use of the “difference image” were carried out by eight radiologists. Six of the eight observers diagnosed with higher sensitivity. The mean for eight observers increased from 43.9% to 55.3% with a statistical significance of The mean area under the AFROC (Alternative Free‐Response Receiver Operating Characteristics) curve improved from 0.596 to 0.647 with a statistical significance of The false positive response was comparable with and without the use of the subtraction image. We conclude that the use of the subtraction image with the new registration technique improves the diagnostic accuracy for detection of subtle changes between radiographs, such as nodule, infiltrate, and cardiomegaly of radiographic findings.

Experience with prolonged induced hypothermia in severe head injury.

BACKGROUND: Recent prospective controlled trials of induced moderate hypothermia (32-34 degrees C) for relatively short periods (24-48 h) in patients with severe head injury have suggested improvement in intracranial pressure control and outcome. It is possible that increased benefit might be achieved if hypothermia was maintained for more periods longer than 48 h, but there is little in the literature on the effects of prolonged moderate hypothermia in adults with severe head injury. We used moderate induced hypothermia (30-33 degrees C) in 43 patients with severe head injury for prolonged periods (mean 8 days, range 2-19 days). RESULTS: Although nosocomial pneumonia (defined in this study as both new chest radiograph changes and culture of a respiratory pathogen from tracheal aspirate) was quite common (45%), death from sepsis was rare (5%). Other findings included hypokalaemia on induction of hypothermia and a decreasing total white cell and platelet count over 10 days. There were no major cardiac arrhythmias. There was a satisfactory neurological outcome in 20 out of 43 patients (47%). CONCLUSION: Moderate hypothermia may be induced for more prolonged periods, and is a relatively safe and feasible therapeutic option in the treatment of selected patients with severe traumatic brain injury. Thus, further prospective controlled trials using induced hypothermia for longer periods than 48 h are warranted.

Utility of Thoracic Impedance to Evaluate Admission Chest Radiograph Changes in Acute Heart Failure Patients

Society of Critical Care Medicine; 28th Educational and Scientific Symposium; San Francisco, California, USA; January 23-27, 1999: Poster Presentations: Poster Hall

The utility of thoracic impedance to evaluate chest radiograph changes from acute heart failure patients in the emergency department

The utility of thoracic impedance to evaluate chest radiograph changes from acute heart failure patients in the emergency department

Aetiology and outcome of severe community-acquired pneumonia in Singapore.

The aim of this study was to determine the aetiology and outcome of severe community-acquired pneumonia, and to assess whether the existing guidelines for initial antimicrobial therapy are being applied. The records of 57 consecutive nonimmunocompromised patients admitted to the medical intensive care unit (ICU) between January 1989 and May 1993 with this diagnosis were reviewed. The microbiological data, chest radiographic changes and outcome were analysed. Nine (16%) of the 57 patients had pulmonary tuberculosis. When these patients were excluded from further analysis, a microbiological diagnosis was made in 41 (72%) cases. The most commonest pathogens were Burkholderia pseudomallei (n=10), Klebsiella spp. (n=5) and Staphylococcus aureus (n=5), Mycoplasma pneumoniae (n=4) and Streptococcus pneumoniae (n=2) were less common. This microbiological spectrum was quite different from that in the West, where the incidence of S. pneumoniae was higher. Also, when pulmonary tuberculosis was excluded, the mortality (67%) was much higher than that in other series. This was attributed to the high incidence of unrecognized B. pseudomallei infection, which is associated with a very high mortality in the region under study. In addition to applying published guidelines on severe community-acquired pneumonia, the endemicity of certain organisms such as Mycobacterium tuberculosis and Burkholderia pseudomallei in different geographical regions needs to be considered when choosing initial empirical antimicrobial therapy.

Radiological Pulmonary Changes During Gram Negative Bacillary Nosocomial Bloodstream Infection (BSI) In Premature Infants. † 1143

We designed a retrospective study to characterize changes in chest radiographs that occur at the time of Gram negative bacilli (GNB) nosocomial BSI and to determine the radiological findings of neonatal nosocomial pneumonia. Forty-one infants who had BSI (study group) and 50 GNB airway colonized infants who had sepsis workup with negative blood cultures (control group) were studied. We correlated clinical data, 95 blood and 305 tracheal aspirate (TA) cultures, with radiographic findings from the day before, the day of, and the day after blood cultures were taken. Two radiologists independently graded 258 films using a modified score (AJDC, 1984;138:581) for bronchopulmonary dysplasia (BPD) and a semi-quantitative system (probable, possible or unlikely) for pneumonia. Of the study population, 54% were male, 21% black, 89% received surfactant, 79% dexamethasone and 88% survived. Mean birth weight was 1057g and 1044g for the study and control groups, respectively. Average age at the time of blood cultures was 23 days for both groups. Most common isolates from blood and TA were Klebsiella pneumoniae, Enterobacter cloacae, Escherichia coli and Pseudomonas aeruginosa. BSI infants (mainly P.aeruginosa and K.pneumonia) died twice as often as controls. Radiological findings: BPD scores did not change in relation to the day of the blood culture and were similar between study and control groups. Twenty-one BSI patients presented with newly positive TA at the time, or within 24 hours of blood culture. Probable or possible pneumonia was diagnosed in 18 of them. Their BPD scores were higher than those of the remaining BSI patients, of whom 7 were already airway colonized, 9 had negative TA's, and 4 were not intubated. Only one of these 20 patients had a possible pneumonia score. CONCLUSION: Radiographic signs of pneumonia in infants with BPD are of significance only when associated with positive blood culture with a respiratory pathogen. Thus, the CDC definition of nosocomial pneumonia is correct and is further supported by the recovery of the same GNB from the airway of an infant with previously negative tracheal aspirate cultures.

Assessment of pulmonary function in the early phase of ARDS in pediatric patients.

Scant data are available on lung function in acute respiratory distress syndrome (ARDS) in pediatric patients. We measured respiratory mechanics by single-breath occlusion and maximum expiratory flow-volume curves by forced deflation in ten critically ill infants with clinical ARDS. Ten mechanically ventilated infants without lung disease served as the control group. To assess the severity of the lung injury in the infants with ARDS, we modified an adult scoring system that calculates a score (from 0 to 4; > 2.5 indicates severe lung injury) based on the extent of chest radiographic changes, degree of hypoxemia, amount of positive end-expiratory pressure (PEEP), and total respiratory system compliance. The lung injury scores of our patients were in the range of 2.75 to 3.75. The lung injury scores of the control group were zero. The predominant alteration in lung function was restrictive, as characterized by a significant decrease in total respiratory system compliance (0.41 +/- 0.13 ml/cmH2O/kg versus 1.12 +/- 0.16 ml/cmH2O/kg of controls; P < 0.001) and forced vital capacity (21.5 +/- 6.5 ml/kg versus 59.2 +/- 6.3 ml/kg of controls; P < 0.001). Maximum expiratory flow rates at 10% forced vital capacity were significantly increased (23.6 +/- 20.1 ml/kg/sec versus 8.4 +/- 2.5 ml/kg/sec of controls; P < 0.05), confirming the absence of any significant obstructive abnormalities. The passive expiratory flow-volume curves were curvilinear and convex in shape, indicating inhomogeneous lung pathology. The inhomogeneous distribution of lung injury in ARDS restricts the validity of respiratory mechanics measurements that rely on a single-compartment model. However, the forced deflation technique allows accurate spirometric assessments of the severity of restrictive (and obstructive) lung function changes in intubated infants with severe ARDS. Such measurements can be incorporated into lung injury scoring systems to classify the severity of the disease process for the purpose of outcome evaluation and to evaluate the effect of therapeutic interventions.

Refractory ceramic fiber exposure and pleural plaques.

Refractory ceramic fibers (RCF) are manmade vitreous fibers (MMVF) manufactured for high-temperature applications. Between 1987 and 1992, a retrospective cohort and nested case-control study evaluated chest radiographs from 652 workers involved in the manufacture of these fibers for plausibility of a causal relationship between exposure to RCF and chest-radiographic changes. The exposure-response relationship was modeled with three variables: years since first fiber production job, years in fiber production, and cumulative fiber exposure to date of study X-ray. The case-control study used a comprehensive characterization of possible asbestos exposure to investigate asbestos as the potential causative agent of chest-radiographic changes. Chest radiographs of 20 workers (3.1%) demonstrated 19 pleural plaques and one diffuse pleural thickening. Nine of 72 workers (12.5%) with more than 20 yr since their first fiber-production job had plaques (odds ratio [OR] = 9.5; 95% confidence interval [CI] = 1.9 to 48.2). Five of 19 workers with more than 20 yr in fiber-production work (26.3%) had plaques (OR = 22.3; 95% CI = 3.6 to 137.0). Similarly, adjusted ORs demonstrated a progressive relationship between cumulative fiber-months per milliliter (fiber-mo/ml) exposure and plaques. The case-control study confirmed that asbestos exposure did not account for the observed association between fiber exposure and plaques. A validity review of historical films demonstrated biologic plausibility for the association, since sufficient latency existed from the time of first RCF exposure to the development of plaques. There was no significant increase in parenchymal changes consistent with interstitial fibrosis.

Effects of acute rejection and antirejection therapy on arteries and veins from canine single lung allografts

Experiments were designed to compare the function of the endothelium and smooth muscle in intralobar pulmonary arteries and veins of transplanted lungs during acute rejection and after treatment of rejection. Single lung allografts were performed in dogs. Dogs were monitored for 5 days to allow good recovery from the operation and resolution of early chest radiographic changes. In group I, immunosuppression (cyclosporine A, azathioprine, and methylprednisone) was withdrawn to allow rejection, which typically occurred after 3 days. In group II, immunosuppression was reinstituted at this time during acute rejection until the chest roentgenograms again cleared (approximately after 6 days). The blood vessels were studied at this time. Rings were cut from intralobar pulmonary arteries and veins of the allotransplanted lungs and suspended for the measurement of isometric force in organ chambers. Contractions of arteries and veins to phenylephrine but not endothelin-1 were significantly reduced during acute rejection. In arteries and veins, endothelium-dependent relaxations to bradykinin but not the calcium ionophore A23187 were reduced with rejection. Relaxations of the smooth muscle to histamine increased with rejection in both blood vessels. Relaxations to nitric oxide were reduced with rejection in veins but not arteries. Treatment of rejection reversed all responses toward those observed in arteries and veins in lungs from dogs not undergoing transplantation. These results suggest that responses of the endothelium and smooth muscle of pulmonary arteries and veins of transplanted lungs are altered similarly during rejection. Further, treatment of rejection restores function of the pulmonary blood vessels of lung allografts toward that observed in unoperated lungs. (J T HORAC C ARDIOVASC S URG 1996;111:1219-29)

Community-acquired pneumonia: epidemiologic and clinical consideration

An incidence of between 2 and 44 per 1000 population has been reported for community-acquired pneumonia. Epidemiologic studies describe a wide range of causative organisms, including Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Legionella spp., Moraxella catarrhalis, Chlamydia pneumoniae and viruses such as influenza A and B. However, the frequency with which they are reported varies widely. On analysis of these studies, the variation can be explained by a number of factors. The results depend on the definition of pneumonia and the criteria for assigning a causative role to any particular organism. Older studies have not included diagnostic methods for newly described organisms such as C. pneumoniae and Legionella spp. The improved diagnostic methods for these organisms and for Mycoplasma pneumoniae are reflected in more recent studies. Further variation depends on the population studied. As many patients with mild pneumonia are successfully treated in the community, those studies that are hospital-based include patients with more severe pneumonia often in the elderly or in patients with underlying diseases such as chronic obstructive pulmonary disease. The prior use of antibiotics not only contributes to the high percentage of cases for which no etiologic agent is found, but also ensures that treatment failures are selected for hospitalization. This further changes the result, depending on the antibiotic agents used most commonly in the community. The inclusion of nursing home patients or groups where alcoholism is more common will also favor particular organisms. Finally, the timing of the study may be such that an epidemic is included. This has relevance mostly for Mycoplasma pneumoniae, C. pneumoniae, Legionella spp. and influenza. In the assessment of the patient with community-acquired pneumonia, any one of the above organisms can be considered to be responsible. As initial treatment is empirical, other information can be used to ensure that an antibiotic with an adequate spectrum is chosen. Factors of importance are age, underlying illness, severity of disease and any locally recognized epidemics or endemic organisms. Differences in clinical presentation are not sufficiently distinct to allow for accurate prediction of the causative agent. Similarly, chest radiograph changes are not sufficiently specific to discriminate reliably between diverse organisms such as S. pneumoniae, Mycoplasma pneumoniae and Legionella spp. Current recommendations for choice of an empirical antibiotic agent are therefore based, not on the assumption of a single etiologic agent indicated by clinical presentation or radiographic appearances, but on age of the patient, severity of illness, the presence of underlying conditions and the range of possible organisms in that patient group.