Acute exacerbations of COPD

Acute exacerbations of COPD (AECOPD) are a common cause of morbidity and mortality. There is a need for a standardised definition of an exacerbation of COPD. The common aetiological factors are bacterial, viral infection and air pollutants. Exacerbations of COPD may adversely affect the natural history of COPD. Several strategies are available now to prevent or reduce exacerbations of COPD including immunisation against influenza and inhaled corticosteroids in patients with moderate/severe disease. The mainstay of treatment involves increasing bronchodilator therapy, systemic glucocorticoids which have now been shown to have a beneficial effect. The circumstances for the use of antibiotic therapy is now established in patients with increased breathlessness, increased sputum production and/or sputum purulence. In those with respiratory failure, noninvasive ventilation has been shown to reduce intubation rates, shorten lengths of hospitalisation, and improve mortality. Early or immediate supported discharge for selected patients has been shown to be effective in the management of patients with COPD.     

Management of acute exacerbations in chronic obstructive pulmonary disease

An acute exacerbation of chronic obstructive pulmonary disease (COPD) is characterized by an acute worsening of symptoms accompanied by lung infection. In severe cases, an acute exacerbation may cause respiratory failure and death. Successful management of acute exacerbation of COPD in either the inpatient or outpatient setting requires attention to a number of key issues. In this review, issues regarding the management of acute exacerbations of COPD are discussed. An inhaled beta-2 agonist along with the inhaled anticholinergic bronchodilator are recommended. Antibiotic therapy has been demonstrated to improve clinical recovery and physical outcomes. It should be directed against the most commonly occurring pathogens and, in more severe cases, coverage against Gram-negative bacteria is considered. Short course of systemic steroids does provide benefit in hospitalized patients. Supplemental oxygen is appropriate for all patients with hypoxemia. Ventilatory support treatment may be necessary, noninvasive ventilatory assistance being preferable early in the course of the acute episode. In a high number of cases, endotracheal intubation may be avoided. Promoting smoking cessation and the use of influenzae and pneumococcal vaccination may help decrease frequency of episodes of these exacerbations.     

Pseudomonal infections in patients with COPD: epidemiology and management

COPD is a common disease with increasing prevalence. The chronic course of the disease is characterized by acute exacerbations that cause significant worsening of symptoms. Bacterial infections play a dominant role in approximately half of the episodes of acute exacerbations of COPD. The importance of pseudomonal infection in patients with acute exacerbations of COPD stems from its relatively high prevalence in specific subgroups of these patients, and particularly its unique therapeutic ramifications. The colonization rate of Pseudomonas aeruginosa in patients with COPD in a stable condition is low.A review of a large number of clinical series of unselected outpatients with acute exacerbations of COPD revealed that P. aeruginosa was isolated from the patients' sputum at an average rate of 4%. This rate increased significantly in COPD patients with advanced airflow obstruction, in whom the rate of sputum isolates of P. aeruginosa reached 8-13% of all episodes of acute exacerbations of COPD. However, the great majority of bacteria isolated in these patients were not P. aeruginosa, but the three classic bacteria Streptococcus pneumoniae, Hemophilus influenzae, and Moraxella catarrhalis. The subgroup of patients, with acute exacerbations of COPD, with the highest rate of P. aeruginosa infection, which approaches 18% of the episodes, is mechanically ventilated patients. However, even in this subgroup the great majority of bacteria isolated are the above-mentioned three classic pathogens. In light of these epidemiologic data and other important considerations, and in order to achieve optimal antibacterial coverage for the common infectious etiologies, empiric antibacterial therapy should be instituted as follows. Patients with acute exacerbations of COPD with advanced airflow obstruction (FEV(1) <50% of predicted under stable conditions) should receive once daily oral therapy with one of the newer fluoroquinolones, i.e. levofloxacin, moxifloxacin, gatifloxacin, or gemifloxacin for 5-10 days. Patients with severe acute exacerbations of COPD who are receiving mechanical ventilation should receive amikacin in addition to one of the intravenous preparations of the newer fluoroquinolones or monotherapy with cefepime, a carbapenem or piperacillin/tazobactam. In both subgroups it is recommended that sputum cultures be performed before initiation of therapy so that the results can guide further therapy.     

The role of atypical respiratory pathogens in exacerbations of chronic obstructive pulmonary disease.

The aetiology of acute exacerbations of chronic obstructive pulmonary disease (COPD) is heterogeneous and still under discussion. Serological studies have suggested that Mycoplasma pneumoniae, Chlamydia pneumoniae and Legionella pneumophila may play a role in acute exacerbations of COPD. The presence of these atypical pathogens in sputum samples was investigated in patients with stable COPD and with acute exacerbations of COPD using real-time PCR. The present study was part of a randomised, double-blind, single-centre study and a total of 248 sputum samples from 104 COPD patients were included. In total, 122 samples obtained during stable disease (stable-state sputa) and 126 samples obtained during acute exacerbations of COPD (exacerbation sputa) were tested. Of the 122 stable-state sputa, all samples were negative for M. pneumoniae and C. pneumoniae DNA, whereas one sample was positive for Legionella non-pneumophila DNA. Of the 126 exacerbation sputa, all samples were negative for M. pneumoniae and C. pneumoniae DNA, whereas one sample was positive for Legionella non-pneumophila DNA. The possible relationship between the presence of atypical pathogens and the aetiology of acute exacerbations in chronic obstructive pulmonary disease was investigated in patients with stable disease and in those with acute exacerbations using real-time PCR. No indication was found of a role for Legionella spp., Chlamydia pneumoniae or Mycoplasma pneumoniae in stable, moderately severe chronic obstructive pulmonary disease and in its exacerbations.     

Yield of sputum microbiological examination in patients hospitalized for exacerbations of chronic obstructive pulmonary disease with purulent sputum

BACKGROUND: Whether sputum microbiological examination should be performed systematically in hospitalized patients with chronic obstructive pulmonary disease (COPD) exacerbations remains unclear. OBJECTIVES: To assess the yield of sputum microbiological examination in COPD patients hospitalized in a medical ward for an acute exacerbation with purulent sputum. METHODS: Two hundred consecutive exacerbations in 118 patients were studied. Patients underwent sputum microbiological examination on admission and baseline lung function tests and CT scans were recorded. Factors associated with positive culture were analyzed. RESULTS: Sputum culture was positive (>or=10(7) CFU/ml) in 59% of samples, Haemophilus influenzae and Streptococcus pneumoniae being the most frequent pathogens. Factors associated with positive culture were bronchiectasis, long-term oxygen therapy and low FEV1. Pseudomonas spp. were found in 8.5% of all patients, who all had a FEV1<50% of predicted and were older. Only 25% of sputum samples satisfied all quality criteria. Sputum culture was positive in a high proportion of these samples (80.5%), but also in one half of samples with >25 leukocytes but >10 epithelial cells per field. Microbiological results induced a change in antibiotic therapy in 43.9% of cases with both quality criteria but also in 25.2% of cases with only one quality criterion. Finally, a predominant aspect after Gram stain was found in all positive samples. CONCLUSIONS: These data suggest that sputum microbiological examination with direct examination and leukocyte count should be performed routinely in patients hospitalized for COPD exacerbations with purulent sputum, especially when FEV1 is less than 50% predicted and in patients with bronchiectasis.     

COPD-Exazerbation und Intensivtherapie

Chronic obstructive pulmonary disease (COPD) is regarding prevalence, morbidity and mortality one of the most important disorders in medicine. Severe COPD exacerbation may cause admission to the intensive care unit (ICU). COPD exacerbation is defined as an increase of symptoms that goes beyond usual day-to-day variation and that necessitates a change in drug therapy. The in-hospital mortality of COPD patients with severe exacerbations lies between 3–10%. By admission to an ICU, mortality rises to 40% and above. Besides inhalation with bronchodilators, systemic steroids play a major role in COPD exacerbation therapy. Therapy with systemic steroids should not exceed 10–14 days. Antibiotics have a role if bacterial infection is probable. Macrolides should be used with caution, because up to 40% of Streptococcus pneumoniae spp. show resistance. Beside drug therapy, physiotherapy may have an impact on COPD exacerbation outcome, although prospective and randomized trials are missing. Patients with severe exacerbations may need temporary non-invasive or invasive ventilation. There is a clear priority for non-invasive ventilation. This article focuses on diagnosis and therapy of exacerbated COPD patients including ventilatory support.     

Changes in sputum T-lymphocyte subpopulations at the onset of severe exacerbations of chronic obstructive pulmonary disease

CD8+ve T-cell responses play a primary role in chronic obstructive pulmonary disease (COPD), but there is little information regarding COPD exacerbations. Sputum induction is a relatively non-invasive and safe method to study airway inflammation. The aim of the study was to investigate changes in airway T-lymphocyte subpopulations at the onset of severe COPD exacerbations via analysis of sputum. Induced sputum samples were collected from 12 COPD patients aged (mean+/-sd) 69+/-7 years, ex-smokers (68+/-23 pack-years), mean FEV1 (%predicted) 40+/-14 at the onset of an acute severe exacerbation requiring hospital admission and 16 weeks after remission of the exacerbation. Inflammatory cells and T-lymphocyte subpopulations (CD4, CD8, Tc1, Tc2) were measured using chemical and double immunocytochemical methods. Increased percentages of sputum neutrophils (P=0.002) and decreased CD4/CD8 and CD8-IFNgamma/CD8-IL4+ve (Tc1/Tc2) cell ratios (P=0.03, P=0.02, respectively) were found at the onset of exacerbation compared to stable state. We conclude that a CD8+ve type-2-mediated immune response is induced at the onset of severe COPD exacerbation.     

Pseudomonal Infections in Patients with COPD

COPD is a common disease with increasing prevalence. The chronic course of the disease is characterized by acute exacerbations that cause significant worsening of symptoms. Bacterial infections play a dominant role in approximately half of the episodes of acute exacerbations of COPD. The importance of pseudomonal infection in patients with acute exacerbations of COPD stems from its relatively high prevalence in specific subgroups of these patients, and particularly its unique therapeutic ramifications. The colonization rate of Pseudomonas aeruginosa in patients with COPD in a stable condition is low.A review of a large number of clinical series of unselected outpatients with acute exacerbations of COPD revealed that P. aeruginosa was isolated from the patients’ sputum at an average rate of 4%. This rate increased significantly in COPD patients with advanced airflow obstruction, in whom the rate of sputum isolates of P. aeruginosa reached 8–13% of all episodes of acute exacerbations of COPD. However, the great majority of bacteria isolated in these patients were not P. aeruginosa, but the three classic bacteria Streptococcus pneumoniae, Hemophilus influenzae, and Moraxella catarrhalis. The subgroup of patients, with acute exacerbations of COPD, with the highest rate of P. aeruginosa infection, which approaches 18% of the episodes, is mechanically ventilated patients. However, even in this subgroup the great majority of bacteria isolated are the above-mentioned three classic pathogens.In light of these epidemiologic data and other important considerations, and in order to achieve optimal antibacterial coverage for the common infectious etiologies, empiric antibacterial therapy should be instituted as follows. Patients with acute exacerbations of COPD with advanced airflow obstruction (FEV₁ <50% of predicted under stable conditions) should receive once daily oral therapy with one of the newer fluoroquinolones, i.e. levofloxacin, moxifloxacin, gatifloxacin, or gemifloxacin for 5–10 days. Patients with severe acute exacerbations of COPD who are receiving mechanical ventilation should receive amikacin in addition to one of the intravenous preparations of the newer fluoroquinolones or monotherapy with cefepime, a carbapenem or piperacillin/tazobactam. In both subgroups it is recommended that sputum cultures be performed before initiation of therapy so that the results can guide further therapy.     

Bacteria in exacerbations of chronic obstructive pulmonary disease: phenomenon or epiphenomenon?

Our understanding of the pathogenesis and consequences of acute exacerbations of chronic obstructive pulmonary disease (COPD) has increased considerably in the past decade. Several new lines of evidence support bacterial causation of approximately half of the exacerbations in COPD. Acquisition of new strains of bacterial pathogens in patients with COPD is associated with a substantial increase in risk of exacerbation. Bacterial pathogens are isolated in significant concentrations from bronchoscopic samples obtained during acute exacerbation. Neutrophilic airway inflammation is associated with isolation of bacterial pathogens from sputum. A specific immune response to the infecting strains of bacterial pathogens isolated from sputum during exacerbations has been demonstrated. Future work should strive to understand better the host-pathogen interaction that leads to an exacerbation and to develop novel therapeutic and preventive measures.     

Granulocyte inflammatory markers and airway infection during acute exacerbation of chronic obstructive pulmonary disease

There is increasing evidence that chronic obstructive pulmonary disease (COPD) is associated with chronic inflammation in the airways and lung parenchyma; however, little is known about the inflammatory response during acute COPD exacerbation. The objectives of this study were (1) to determine if inflammatory markers associated with neutrophilic inflammation and activation increase at times of acute COPD exacerbation relative to the clinically stable state, and (2) to determine whether the presence of acute bacterial or viral infection at the time of COPD exacerbation could be correlated with increases in sputum markers of inflammation. Induced sputum was collected from patients with COPD when they were clinically stable, during the time of an acute exacerbation, and 1 mo later. Sputum was analyzed at each time point for soluble markers associated with neutrophilic inflammation; myeloperoxidase (MPO), tumor necrosis factor-alpha (TNF-alpha), and interleukin-8 (IL-8). Serologic assays on acute and convalescent sera were performed for respiratory viruses, and induced sputum was also subject to quantitative bacterial cultures, viral cultures, and polymerase chain reaction (PCR) for detection of respiratory viruses. Fourteen of the 50 patients enrolled in the study met predetermined criteria for an acute COPD exacerbation over the 15-mo study period. TNF-alpha and IL-8 were significantly elevated in the sputum of patients during acute COPD exacerbation compared with when they were clinically stable (p = 0.01 and p = 0.05, respectively). Concentrations of these cytokines declined significantly 1 mo after the exacerbation. Three of 14 patients (21%) had confirmed bacterial or viral respiratory tract infections. Patients with documented infection did not demonstrate greater increases in sputum levels of inflammatory cytokines during exacerbations compared with patients without demonstrable infection. We conclude that markers of airway neutrophilic inflammation increase at the time of acute COPD exacerbation and then decline 1 mo later, and that this acute inflammatory response appears to occur independently of a demonstrable viral or bacterial airway infection.     

In-hospital mortality following acute exacerbations of chronic obstructive pulmonary disease

BACKGROUND: Acute exacerbations of chronic obstructive pulmonary disease (COPD) are a frequent cause of hospitalization in the United States. Previous studies of selected populations of patients with COPD have estimated in-hospital mortality to range from 4% to 30%. Our objective was to obtain a generalizable estimate of in-hospital mortality from acute exacerbation of COPD in the United States and to identify predictors of in-hospital mortality using administrative data. METHODS: We performed a cross-sectional study utilizing the 1996 Nationwide Inpatient Sample, a data set of all hospitalizations from a 20% sample of nonfederal US hospitals. The study population included 71 130 patients aged 40 years or older with an acute exacerbation of COPD at hospital discharge. The primary outcome assessed was in-hospital mortality. RESULTS: In-hospital mortality for patients with an acute exacerbation of COPD was 2.5%. Multivariable analyses identified older age, male sex, higher income, nonroutine admission sources, and more comorbid conditions as independent risk factors for in-hospital mortality. CONCLUSIONS: Mortality during hospitalization in this nationwide sample of patients with acute exacerbations of COPD was lower than that of previous studies of select populations. This estimate should provide optimism to both clinicians and patients regarding prognoses from COPD exacerbations requiring hospitalization. Our results indicate that the use of administrative data can help to identify subsets of patients with acute exacerbations of COPD that are at higher risk of in-hospital mortality.     

Reduced spontaneous apoptosis in peripheral blood neutrophils during exacerbation of COPD.

A major feature of acute exacerbation of chronic obstructive pulmonary disease (COPD) is the accumulation of activated neutrophils in the bronchial tree. This phenomenon can be explained by an increased migration and/or by a prolonged survival due to an inhibition of spontaneous apoptosis. The aim of this study was to assess the apoptotic behaviour of peripheral blood neutrophils in COPD patients during an acute exacerbation. Thirty-six hospitalised COPD patients with an acute exacerbation and 10 healthy volunteers were included. Blood samples were obtained at admission, after 3-5 days and at discharge. Spontaneous apoptosis of isolated neutrophils was measured based on Annexin V-PE binding and nuclear morphology after culturing for 18 h. At admission, significantly lower rates of spontaneous apoptosis were noted in COPD patients compared with healthy volunteers (mean +/- SD 31 +/- 13% versus 44 +/- 18%). The mean percentages of apoptotic neutrophils were 31 +/- 13% at admission, 39 +/- 15% after 3-5 days and 47 +/- 18% at discharge. There was a statistically significant difference between the rates of spontaneous apoptosis on the first day and at discharge. Neither forced expiratory volume in one second < 35% predicted, smoking habit, corticosteroid therapy nor evidence of bacterial infection showed any influence on the spontaneous apoptosis in this study. In conclusion, during acute exacerbations of chronic obstructive pulmonary disease, neutrophil granulocytes show a reduced spontaneous apoptosis that increases progressively after treatment and clinical remission. This raises the question of the importance of neutrophil apoptosis in the development and resolution of exacerbations of chronic obstructive pulmonary disease.     

动态监测诱导痰Tc1/Tc2比值在COPD患者中的临床价值

目的 探讨动态监测诱导痰Tc1/Tc2比值在COPD患者中的临床价值.方法 选取90例研究对象,分为不吸烟组为A组、戒烟组为B组、吸烟组为C组,每组30人,D组10例正常对照.入组后动态监测入院时、出院时、出院6月及12月诱导痰中相关指标并进行统计学分析.结果 A、B、C三组在各时间点CD8+T细胞％、Tc1/Tc2比...     

Predicting early mortality in acute exacerbation of chronic obstructive pulmonary disease using the CURB65 score

Background and Objective: Hospitalization for exacerbation of COPD is associated with a high risk of mortality. A risk‐prediction model using information easily obtained on admission could help to identify high‐risk individuals. The CURB65 score was developed to predict mortality risk in community acquired pneumonia. A retrospective study found that this score was also associated with mortality in COPD exacerbations. We conducted a prospective study to assess the utility of the CURB65 score in acute COPD exacerbations. Methods: Consecutive patients with physician diagnosed COPD exacerbations admitted to a public hospital during a 1‐year period were studied prospectively. The CURB65 scores were calculated from information obtained at initial hospital presentation. CURB65 = one point each for Confusion, Urea > 7 mmol/L, Respiratory rate ≥ 30/min, low Blood pressure, age ≥ 65 years. Results: 30‐day mortality data were available for 249 of 252 patients. CURB65 scores on admission significantly predicted risk of death during the hospital admission and at 30 days. The 30‐day mortality by score groups were: low risk (scores 0–1) 2.0% (2/98), moderate risk (score 2) 6.7% (6/90) and high risk (scores 3–5) 21.3% (13/61). CURB65 scores were not predictive of 1‐year mortality. Conclusions: A simple 6‐point score based on confusion, blood urea, respiratory rate, blood pressure and age can be used to stratify patients with COPD exacerbation into different management groups. The CURB65 score was as effective in predicting early mortality in our cohort of acute COPD exacerbations as it was in previous cohorts with community acquired pneumonia. Our findings suggest that CURB65 scores can help clinicians to assess patients with exacerbation of COPD.     

慢性阻塞性肺疾病急性加重的研究

慢性阻塞性肺疾病（COPD）具有很高的发病率和死亡率,而慢性阻塞性肺疾病急性加重（AECOPD）则是COPD患者就诊以及住院治疗的主要原因,也是庞大医疗费用的主要来源。本文就近年来对AECOPD的定义、病理生理、病因、治疗以及预防等的研究进展进行综述,其中一些方面已得到循证医学的证实,比如吸烟与AECOPD的关系、糖皮质激素及无创性正压通气在治疗AECOPD的作用等;但仍有一些问题尚存在争议,特别是细菌感染在AECOPD中的作用,以及抗菌治疗在AECOPD治疗中的地位,还需要更多的,设计严密的研究来证实。     

Acute exacerbation of COPD

The literature of acute exacerbation of chronic obstructive pulmonary disease (COPD) is fast expanding. This review focuses on several aspects of acute exacerbation of COPD (AECOPD) including epidemiology, diagnosis and management. COPD poses a major health and economic burden in the Asia‐Pacific region, as it does worldwide. Triggering factors of AECOPD include infectious (bacteria and viruses) and environmental (air pollution and meteorological effect) factors. Disruption in the dynamic balance between the ‘pathogens’ (viral and bacterial) and the normal bacterial communities that constitute the lung microbiome likely contributes to the risk of exacerbations. The diagnostic approach to AECOPD varies based on the clinical setting and severity of the exacerbation. After history and examination, a number of investigations may be useful, including oximetry, sputum culture, chest X‐ray and blood tests for inflammatory markers. Arterial blood gases should be considered in severe exacerbations, to characterize respiratory failure. Depending on the severity, the acute management of AECOPD involves use of bronchodilators, steroids, antibiotics, oxygen and noninvasive ventilation. Hospitalization may be required, for severe exacerbations. Nonpharmacological interventions including disease‐specific self‐management, pulmonary rehabilitation, early medical follow‐up, home visits by respiratory health workers, integrated programmes and telehealth‐assisted hospital at home have been studied during hospitalization and shortly after discharge in patients who have had a recent AECOPD. Pharmacological approaches to reducing risk of future exacerbations include long‐acting bronchodilators, inhaled steroids, mucolytics, vaccinations and long‐term macrolides. Further studies are needed to assess the cost‐effectiveness of these interventions in preventing COPD exacerbations.     

The effect of oral clarithromycin on health status and sputum bacteriology in stable COPD

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is characterised by airway inflammation, poor health status and recurrent infective exacerbations. Macrolide antibiotics have been shown to improve symptoms and exacerbation rate in chronic lung disease, particularly cystic fibrosis (CF) and diffuse pan-bronchiolitis. The effect of long-term oral clarithromycin on health status, sputum bacterial numbers and exacerbation rate in subjects with clinically stable COPD is undetermined. METHODS: Subjects with moderate-to-severe COPD were recruited into a prospective, double-blind, randomised-controlled trial of 3-months oral clarithromycin (Klaricid XL) or placebo once-daily. The effect of clarithromycin on health status (St. George respiratory and Short Form-36 questionnaires), sputum quantitative bacterial numbers and exacerbation rate were investigated. RESULTS: Sixty-seven subjects (46 males) were recruited; 31 and 36 subjects received clarithromycin and placebo, respectively. There were 7(10%) withdrawals. Compared to placebo, clarithromycin did not significantly improve health status, sputum bacterial numbers, or exacerbation rate. CONCLUSIONS: Three months of oral clarithromycin given to subjects with stable COPD does not improve health status, sputum bacterial numbers or exacerbation rate. Treatment of COPD with clarithromycin during the clinical stable state yields no clinical advantages and therefore cannot be recommended as means of eliminating sputum bacteria or preventing infective exacerbations.     

A pilot study of inspiratory capacity and resting dyspnea correlations in exacerbations of COPD and asthma

Measurement of inspiratory capacity (IC) as a marker of dynamic lung hyperinflation has been shown to correlate with dyspnea and exercise performance in stable COPD, and is therefore of potential utility in the management of this condition. We have examined whether similar relationships exist during acute exacerbations of COPD and asthma in order to determine whether there is a role for IC monitoring in acute management of these conditions. Eight patients with COPD and ten with asthma requiring hospital admission for acute exacerbations were studied with spirometry (including IC) at admission and at discharge and had concurrent self-perceived resting dyspnea ratings recorded. Over the admission there were significant improvements in resting dyspnea for the COPD group only, and improvements in spirometric indices in the asthma group only. No significant correlations were found between changes in dyspnea and changes in IC, in terms of acute responses to bronchodilator and in response to treatment over the hospital admission. These data suggest that dynamic hyperinflation during acute exacerbations of COPD and asthma is not as sensitive an indicator of resting dyspnea as in stable disease. A role for IC monitoring in the management of acute exacerbations of these diseases has not been identified.     

Mechanical ventilation in children with severe asthma

Hospital admissions for childhood asthma have increased during the past few decades. The aim of this study was to describe the need for mechanical ventilation for severe asthma exacerbation in children in Finland from 1976 to 1995. We reviewed medical records and collected data retrospectively from all 5 university hospitals in Finland, thus covering the entire population of about 5 million. The endpoints selected were the number of admissions and readmissions leading to mechanical ventilation, duration of stay in the hospital, and mortality. Moreover, asthma medications prescribed prior to admission and administered in the intensive care unit (ICU), as well as the etiology of the exacerbation associated with mechanical ventilation were examined. Mechanical ventilation was required in 66 ICU admissions (59 patients). This constituted approximately 10% of all 632 admissions for acute asthma to an ICU. The number of admissions decreased from 1976 to 1995: 41 admissions between 1976 and 1985 vs. 25 admissions during the next 10-year period. The mean age at admission to the ICU was 3.6 years, and 46% of the patients were boys. Prior to the index admission, 70% of the patients had used asthma medication such as oral bronchodilator (50%), inhaled bronchodilator (20%), theophylline (38%), inhaled glucocorticoid (18%), oral glucocorticoid (5%), and cromoglycate (7%). Respiratory infection was by far the most common cause of all the exacerbations (61%), followed by food allergy (8%) and gastroesophageal reflux (3%). In 28% of cases the cause of the severe asthma exacerbation could not be identified. In the mechanically ventilated patients readmissions occurred 38 times between 1976 and 1985 vs. 5 times between 1986 and 1995. Five of the patients who received mechanical ventilation died, and in 3 of these patients asthma was the event causing death. In conclusion, there has been decrease in the number of first and repeat ICU admission for asthma requiring mechanical ventilation between 1970 and 1995. This trend occurred despite a simultaneous 5% yearly increase in hospital admissions for childhood asthma during these 2 decades.     

慢性阻塞性肺疾病患者肺炎衣原体感染的研究

目的 探讨肺炎衣原体感染与慢性阻塞性肺疾病（COPD）的相关性。方法 选择61例COPD急性加重期患者,35例COPD稳定期患者,26名正常对照者,采用微量免疫荧光法测定血清肺炎衣原体特异性抗体IgA,IgM,IgG,套式聚俣酶链反应检测痰中的肺炎衣原体DNA。结果 COPD急性加重期患者的急性肺炎衣原体的感染率为31．1％,明显高于COPD稳定期和且（P＜0．05）。COPD急性加重期组和稳定期组的慢性肺炎衣原体感染率分别为21．3％和31．4％,明显高于对照组（P均＜0．05）,同时IgA的几何平均滴度在COPD急性加重期中最高（20．5）,COPD稳定期组中次之（10．8）,对照组最低（3．6）,三组间差异有显著性（P＜0．05）。结论 急性肺炎衣原体感染为COPD急性加重的一个重要诊因,慢性肺炎衣原体感染可能参与COPD的发病机制。