Alterations in Ventilation-perfusion Relationships in the Lung after Breathing Inert Dust or Bronchoconstrictor Aerosols and after Short Periods of Voluntary Hyperventilation.
نویسندگان
چکیده
The increase in airway resistance that follows the breathing of fine inert dust was first demonstrated by DuBois and Dautrebande (1), who also showed that an aerosol of carbachol had the same effect. The compliance of the lungs was reduced, which led these authors to conclude that the increased airway resistance was unevenly distributed. Constantine and associates (2) confirmed the increased airway resistance in similar experiments and also noted an increase in intrathoracic gas volume, which they attributed to trapping of gas. McDermott (3) found a significant increase in airway resistance after breathing similar dusts at concentrations almost certainly less than those used by the previous workers and more comparable to the concentrations encountered under certain industrial conditions. She also commented on the considerable individual variation in response. The first part of the present study had two main objectives, the first of which was to determine the extent to which these inhaled materials altered the distribution of alveolar ventilation and to observe the effects this had upon respiratory gas exchange in the lungs. Of at least equal importance was the possibility that the experiments might reveal something of how the distribution of alveolar perfu-sion responds to an acute alteration in the distribution of alveolar ventilation, and this has influenced the design of the experiments. During these experiments the possibility arose that the observed effects might result from the associated moderate hyperventilation. A preliminary observation lent support to the idea that hy-perventilation was followed by an increase in * physiological dead space, and this led to the second series of experiments. The results, which have already been reported briefly (4), showed a prolonged increase in physiological dead space after hyperventilation in the sitting position. This was prevented by substituting a mixture containing carbon dioxide for air during the period of hyperventilation and was much less evident when the subjects were supine. Methods Respiratory gas exchange was investigated by the measurement of the alveolar-arterial difference in oxygen tension (A-aD) and physiological dead space. Expired gas was collected in a Tissot spirometer for 2 minutes and was analyzed by the Scholander method. During this time three samples of blood for estimation of Po2 and two samples for Pco2 were obtained from a needle in the brachial artery, sampling extending over the whole of the 2-minute period. The Po2 of arterial blood was measured within 10 minutes of sampling by a polythene-covered combined electrode …
منابع مشابه
What is the best definition of the term "hyperventilation"?
TO THE EDITOR: In the context of a discussion about a patient with chronic obstructive pulmonary disease (COPD), a secondyear medical student recently asked: What is the definition of hyperventilation? My initial response was that, when the CO2 production rate is constant, an individual who is hypocapnic (i.e., has a lower than normal CO2 tension in arterial blood) must have hyperventilated. Th...
متن کاملGestation Increases the Energetic Cost of Breathing in the Lizard, Tiliqua Rugosa 3 4
16 17 High gestational loads result in fetuses that occupy a large proportion of the body 18 cavity and may compress maternal organs. Compression of the lungs results in 19 alterations in breathing patterns during gestation which may affect the energetic 20 cost of breathing. In this study, the energetic cost of breathing during gestation was 21 determined in the viviparous skink, Tiliqua rugos...
متن کاملComparison of the effects of inhaled ipratropium bromide and salbutamol on the bronchoconstrictor
A double blind, placebo controlled compa-rison was made of the effects of nebulised ipratropium bromide (0O05 and 0-5 mg) and salbutamol (0-25 and 2-5 mg) on lung function and the airway response to hyperventilation in eight normal subjects. Both agents at both doses caused similar baseline bronchodilatation, confirming the presence of resting bronchomotor tone. The overall mean increases as pe...
متن کاملThe effect of intermittent positive pressure breathing and voluntary hyperventilation upon the distribution of ventilation and pulmonary blood flow to the lung in chronic obstructive lung disease.
متن کامل
Pulmonary gas-exchange analysis by using simultaneous deposition of aerosolized and injected microspheres.
Numerical methods for determining end-capillary gas contents for ventilation-to-perfusion ratios were first developed in the late 1960s. In the 1970s these methods were applied to validate distributions of ventilation-to-perfusion ratios measured by the multiple inert-gas-elimination technique. We combined numerical gas analysis and fluorescent-microsphere measurements of ventilation and perfus...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- The Journal of clinical investigation
دوره 43 شماره
صفحات -
تاریخ انتشار 1964