No abstract

1.In dogs that were supported in the upright position and that were breathing spontaneously acute pulmonary oedema was induced either by extracellular fluid volume expansion (n = 5) or by increasing pulmonary microvascular permeability with alloxan (n = 5).2. Before oedema was induced, the bronchi of the right lung were outlined with tantalum powder.3. During a baseline period, standard chest radiographs were taken at inflation pressures from 0 to 2 kPa and the distributions of perfusion (with radioactive microspheres) and ventilation (with 133Xe) were measured. Arterial and mixed venous blood samples were taken to estimate the degree of venous admixture (physiological shunt) and pulmonary arterial and wedge pressures were measured. 4. After oedema had developed the radiographs and observations were repeated at a time when the pulmonary vascular pressures were insignificantly different from the baseline state.5. With induction of oedema, particularly when due to volume expansion, the lower-lung zones decrease in volume. There were no significant changes in the upper zones.6. Abnormal venous admixture occurred only in dogs with >20% loss of lower-zone volume; volume loss and physiological shunt were significantly correlated.7. The distribution of perfusion changed little with induction of oedema. Volume-expanded dogs showed a slight diversion of perfusion away from the bases and towards the upper zones.8. There was an approximately 30% reduction of ventilation to the lung bases and a corresponding increase to the upper zones. 9. With induction of oedema, bronchi were narrowed when there was a reduction of lung volume. There was a significant linear correlation between volume change and narrowing.

1. A rapid method for the analysis of CO in expired air has been developed, which is suitable for use in studies of smoking. 2. The Bohr equation has been used to calculate the mean alveolar CO partial pressure (PA,CO). 3. The values of PA,CO obtained are highly correlated with direct measurements of venous carboxyhaemoglobin (r = 0-96). 4. The method will distinguish between populations of smokers and non-smokers, and can allow the changes of CO in a smoker throughout a 12 h period to be followed. It provides a measure of the dose of cigarette smoke (vapour phase) that results from smoking a single cigarette.

Measurements of patterns of puffing (cigarette-holder pneumotachograph) and ventilation (plethysmography) were made in ten asymptomatic smokers during the smoking of a cigarette, on four separate occasions. There were marked individual differences and these were consistent over 3-5 weeks. In itself, the pattern of smoking could be responsible for a threefold variation in smoke intake. Puffing but not inhalation became less intense as a cigarette was smoked. It was not possible to predict indices of absorption from smoking patterns. Certain smoking patterns, e.g. small puff volume, low puff frequency, short duration of inhalation and expulsion of volume between puff and inhalation, may be less harmful than others and this may explain why some individuals remain healthy despite a lifetime of smoking.

SUMMARY A questionnaire relating to smoking habits, respiratory symptoms, and health attitudes was administered to schoolchildren aged between 11 and 17 throughout a defined geographical area in both 1975 and 1979, with a valid response from 10 498 and 12 002 young people respectively. Each cohort was almost entirely different. The results suggest that although the prevalence of regular smoking has decreased in boys from 16 to 13 Y. it has increased in girls from 13 to 14 %, and that at all ages more girls smoke than boys. However despite the fall in the prevalence of regular smoking in boys there has been an overall increase in cigarette consumption. Young people who are regular smokers predominantly smoke middle tar cigarettes while among experimental smokers there is a high incidence of low tar smoking, which might suggest that such cigarettes facilitate the taking up of the habit by children. The previously described relationships between smoking and respiratory symptoms was confirmed. During the 4-year study period young people's knowledge of the associated links between smoking and heart disease and stroke has increased appreciably. It is suggested that specific health education during the years 197 5-79 has not been successful, and there is the need for research.During the last 5 years a large amount of antismoking propaganda has continued to appear in the UK and much of it has been directed towards young people and the social aspects of the smoking habit. In addition health education in schools is being given more prominence and some of this will also be devoted to the subject of tobacco smoking. This emphasis on smoking and young people has been the result of increasing awareness of the prevalence of smoking in the younger age groups' together with the importance which this early initiation into the habit has with respect to persistent adult smoking and its associated early morbidity and mortality. The immediate effects of cigarette smoking on the health of young smokers is also being increasingly recognised.