Irreversible airflow obstruction. Evolution in asthma

To determine whether asthma can cause irreversible airflow obstruction (IAO) 89 subjects with uncomplicated asthma received intensive treatment for four weeks. FEV1 was measured at 0, two and four weeks; pulmonary elasticity and flow resistance was measured in 46 of the subjects at four weeks. Severity of asthma and cigarette consumption were ascertained by a questionnaire. The mean difference between the predicted and highest FEV1 during treatment was 0.29 L (P less than 0.001). The highest FEV1% predicted correlated (P less than 0.001) with the duration and severity of asthma in the entire group, in the 51 nonsmokers, and in the 47 subjects with the adult onset of asthma. Pulmonary resistance, but not elastic recoil, correlated with the duration and severity of asthma (P less than 0.01). The results show that chronic asthma can cause narrowed airways and IAO, and suggest that this may be prevented by improved control of asthma.     

Spirometric indices of early airflow obstruction.

Thirty cigarette smokers and 25 non-smoking controls, all men were evaluated by history, physical examination and simple spirometry. The history and physical examination were not of much use in predicting airflow obstruction. Forced mid-expiratory flow (FEF 25-75%) was abnormally low in 23 of the 30 subjects, while forced expiratory volume in 1 second (FEV1) and FEV1/FVC (forced vital capacity) were less sensitive. Thus simple spirometry is a useful screening tool to detect early airflow obstruction even when it is clinically undetectable.     

Respiratory therapy. Current practice in ambulatory patients with chronic airflow obstruction.

The role of respiratory therapy in treating ambulatory patients with chronic obstructive pulmonary disease is becoming more clearly defined. Oxygen therapy on a continuous basis is needed for patients with arterial PO2 values below 45 mm Hg and should be considered for patients with arterial PO2 values between 45 and 55 mm Hg who have chronic cor pulmonale, erythrocytosis with hematocrit value greater than 55%, and disturbances of cognition and sleep. Concentrated bronchodilator and corticosteroid aerosols have established roles in therapy; the place of bland aerosols is less clear They may increase ease of expectoration and should be given by simple compressed-air nebulizer systems; their administration by brief periods of intermittent positive-pressure breathing is rarely justified. Three-positional, postural drainage with chest percussion and vibration may be helpful in mobilizing secretions in patients with severe disease.     

The effects of supplementary nicotine in regular cigarette smokers

Blood nicotine levels were measured in eight subjects over a 5-week period, while smoking normally, while smoking and chewing gum containing 2 mg nicotine, and while smoking and chewing placebo gum. Despite a small but significant rise in blood nicotine levels during the period of the nicotine gum chewing (mean 35.3 ng/ml) compared with placebo (mean 28.9 ng/ml) and control (mean 26.3 ng/ml), cigarette consumption butt lengths, filter nicotine and blood carboxyhaemoglobin levels did not change indicating that there had been no significant changes in smoking patterns. The reasons for this failure to demonstrate an effect are discussed. It is concluded that the dose of nicotine used was probably not adequate to produce an effect.     

Psychiatric morbidity in patients with chronic airflow obstruction

Fifty consecutive patients with chronic airflow obstruction who were admitted to a respiratory unit were assessed medically and psychiatrically. A high rate of psychiatric morbidity (58%) was detected with panic and other anxiety disorders (34%) being particularly prevalent. Various physiological and psychological reasons for the high rate of anxiety disorders are discussed.     

Patterns of recovery of airflow obstruction in severe acute asthma

The speed and patterns of recovery of airflow obstruction were analysed in 209 patients receiving a standard therapeutic regime for severe acute asthma. Initial rates of recovery were rapid. Three-quarters of the patients had achieved 50% of their total improvement in peak expiratory flow rate (PEFR) within 24 hr. The time taken to reach eventual maximum PEFR was very much longer, 50% of the patients taking one week or more. Diurnal variation of moderate or severe degree was seen in 78% of patients. Length of history of asthma, time of deterioration and other measures of the severity of attack on admission did not differ in faster and slower responders. The rise of PEFR within 4 hr of starting treatment was highly significantly correlated with a higher PEFR at 24 hr and a shorter time to full recovery. Although the mean arterial PCO₂ was higher (P<0·01) in the slower responding group and they were slightly older (P<0·05) and had lower mean FEV₁ (P<0·02) and FVC (P<0·05) these differences were less helpful in predicting which patients responded fastest.     

Patterns of drug taking in patients with chronic airflow obstruction

A questionnaire on the pattern of drug taking was completed by 185 patients with chronic airflow obstruction. Of these, 49% admitted to taking their prescribed therapy regularly and 33% could be regarded as being fully compliant. The use of increasing numbers of drugs was not accompanied by a fall in compliance. Regular drug taking was better in patients (particularly females) with asthma than in patients with chronic bronchitis and emphysema. During acute exacerbations of airflow obstruction, excessive use of bronchodilators beyond the recommended increase in medication was rare; indeed, underuse of therapy in this situation was commoner. These conclusions must be regarded as tentative since the questionnaire was not validated by repeat interviewing or measurement of drug usage.     

Response of pulmonary circulation to oral pirbuterol in chronic airflow obstruction

The effects of the oral beta agonist pirbuterol on pulmonary haemodynamics and gas exchange were studied in nine patients with severe irreversible airflow obstruction and moderate arterial hypoxaemia. After administration of 15 mg pirbuterol pulmonary vascular resistance fell by 19% but cardiac output rose by 24%, so that pulmonary arterial pressure showed no significant change. Systemic arterial oxygen pressure fell by 7%, limiting the rise in oxygen delivery to 21%. All changes were significant at the 2% level. These results show that pirbuterol dilates the pulmonary bed at the cost of a slight worsening of gas exchange, which is compensated by an independent rise in blood flow.     

Perceived risks of heart disease and cancer among cigarette smokers

Context  Cigarette smoking causes more preventable deaths from cardiovascular disease and cancer than any other modifiable risk factor, but smokers may discount the increased personal risk they face from continued smoking. Objective  To assess smokers' perceptions of their risks of heart disease and cancer. Design and Setting  Telephone and self-administered survey in 1995 of a probability sample of US households with telephones. Participants  A total of 3031 adults aged 25 to 74 years, including 737 current smokers (24.3%). Main Outcome Measures  Respondents with no history of myocardial infarction (MI) (96.2%) or cancer (92.9%) assessed their risk of these conditions relative to other people of the same age and sex. Among current smokers, perceived risks were analyzed by demographic and clinical factors using logistic regression. Results  Only 29% and 40% of current smokers believed they have a higher-than-average risk of MI or cancer, respectively, and only 39% and 49% of heavy smokers (40 cigarettes per day) acknowledged these risks. Even among smokers with hypertension, angina, or a family history of MI, 48%, 49%, and 39%, respectively, perceived their risk of MI as higher than average. In multivariate analyses, older (65 years), less educated (< high school graduate), and light smokers (1-19 cigarettes per day) were less likely than younger, more educated, and heavy smokers to perceive an increased personal risk of MI or cancer. Conclusions  Most smokers do not view themselves at increased risk of heart disease or cancer. As part of multifaceted approaches to smoking cessation, physicians and public health professionals should identify and educate smokers who are not aware of smoking-related health risks.      

无症状吸烟者的肺功能改变

[目的]探讨吸烟对人体肺功能的影响,提高尽早戒烟的意识。[方法]采用MedGraphics 1085D肺功能仪（美国）对大连医科大学附属第二医院健康体检中151名健康成年人进行肺功能检测,分析吸烟对肺功能的影响。[结果]在肺功能检测指标中,吸烟组（81例）与不吸烟组（70例）相比,吸烟组肺活量（VC）、1秒率（FEV1/FVC）、最大分钟通气量（MVV）、FEF50%、FEF75%、MMEF均较非吸烟组明显降低（P均〈0.05）;吸烟组与非吸烟组FVC、FEV1、FEV1/VC差异无显著性意义。[结论]无临床症状吸烟者与非吸烟者相比,肺活量、通气功能、小气道功能明显降低;肺功能检查对无临床症状吸烟者具有重要意义。