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Effect of increased closing volume on lung mechanics
BTTA
increase with age. Important complications are muscular dysfunction (e.g. poliomyelitis) and chronic non-specific lung diseases (CNSLD), obstructive airway disease with or without bacterial bronchial infection. In a few selected patients with severe kyphoscoliosis tracheostomy or mechanical ventilation may be of therapeutic value. The results of treatment of patients with kyphoscoliosis with cuirass respirators were reported. Some additional information about tailor-made cuirass shells was given. Effect of Increased Closing Volume on Lung Mechanics
L. c. LUM (Cambridge) Attention has recently been focused on the raised closing volume which occurs in old age, and the early stages of chronic bronchitis, etc. Articles have tended to concentrate on the diagnostic aspects of this rather than on the effect on lung mechanics. We have been studying the latter by pressure volume loops. Airway closure implies :(a) that the pressure outside the airway will be above the intra-luminal pressure, and (b) that an ‘opening pressure’ will have to be generated before re-inflation can begin in the affected lung unit. This can be readily observed by pressure volume techniques, plotting oesophageal pressures against tidal volumes. When airway closure occurs at volumes above residual volume a typical deformation of the lower end of a pressure volume loop is observed. At closing volume the intrathoracic pressure swings sharply in a positive direction; at the beginning of inspiration there is a sharp swing to negative (opening pressure) before inflation commences. We have observed no qualitative difference between curves obtained in early bronchitis, asthma in remission, and pulmonary congestion of cardiac origin. The opening pressure phenomenon highlights the similarity of the mechanism of dyspnoea in these conditions. It throws additional light on the mechanics of cardiac dyspnoea for which the traditional explanation of increased lung stiffness is recognised to be inadequate.
The Airflometer: A Simple Device for Asses&g
Respiratory Function
and MAX FRIEDMAN(London) The frequent assessment of airways obstruction is useful in the clinical management of asthmatic patients, and the Wright peak flow meter has become the standard instrument with which patients monitor their own lung function daily at home. Although this device is compact and easy to use, its cost is probably one of the factors that limits its use. The peak flow gauge has been introduced recently as an alternative to the meter but this also has disadvantages. The airflometer, which is a new, inexpensive instrument for measuring respiratory function, is simple to operate, light and portable. A number of production models of the airllometer have now been compared with Wright peak flow meters and peak flow gauges to determine the reproducibility of results and the variation between instruments. Also a total of 421 normal and asthmatic adults and children have been studied and measurements of forced expiratory volume in 1 second (FEV,), peak expiratory flow rate (PEFR) and airflometer readings (AFM) have been made over a wide range of lung function, Age, sex and height were recorded, and the order in which the measurements were made was randomised. This study has confirmed the findings obtained using a prototype, and shows that the airflometer provides measurements of ventilatory function which correlate well with FEV,. Thus the instrument should prove a useful alternative to the Wright peak flow meter and peak flow gauge. STUART WALKER
increase with age. Important complications are muscular dysfunction (e.g. poliomyelitis) and chronic non-specific lung diseases (CNSLD), obstructive airway disease with or without bacterial bronchial infection. In a few selected patients with severe kyphoscoliosis tracheostomy or mechanical ventilation may be of therapeutic value. The results of treatment of patients with kyphoscoliosis with cuirass respirators were reported. Some additional information about tailor-made cuirass shells was given. Effect of Increased Closing Volume on Lung Mechanics
L. c. LUM (Cambridge) Attention has recently been focused on the raised closing volume which occurs in old age, and the early stages of chronic bronchitis, etc. Articles have tended to concentrate on the diagnostic aspects of this rather than on the effect on lung mechanics. We have been studying the latter by pressure volume loops. Airway closure implies :(a) that the pressure outside the airway will be above the intra-luminal pressure, and (b) that an ‘opening pressure’ will have to be generated before re-inflation can begin in the affected lung unit. This can be readily observed by pressure volume techniques, plotting oesophageal pressures against tidal volumes. When airway closure occurs at volumes above residual volume a typical deformation of the lower end of a pressure volume loop is observed. At closing volume the intrathoracic pressure swings sharply in a positive direction; at the beginning of inspiration there is a sharp swing to negative (opening pressure) before inflation commences. We have observed no qualitative difference between curves obtained in early bronchitis, asthma in remission, and pulmonary congestion of cardiac origin. The opening pressure phenomenon highlights the similarity of the mechanism of dyspnoea in these conditions. It throws additional light on the mechanics of cardiac dyspnoea for which the traditional explanation of increased lung stiffness is recognised to be inadequate.
The Airflometer: A Simple Device for Asses&g
Respiratory Function
and MAX FRIEDMAN(London) The frequent assessment of airways obstruction is useful in the clinical management of asthmatic patients, and the Wright peak flow meter has become the standard instrument with which patients monitor their own lung function daily at home. Although this device is compact and easy to use, its cost is probably one of the factors that limits its use. The peak flow gauge has been introduced recently as an alternative to the meter but this also has disadvantages. The airflometer, which is a new, inexpensive instrument for measuring respiratory function, is simple to operate, light and portable. A number of production models of the airllometer have now been compared with Wright peak flow meters and peak flow gauges to determine the reproducibility of results and the variation between instruments. Also a total of 421 normal and asthmatic adults and children have been studied and measurements of forced expiratory volume in 1 second (FEV,), peak expiratory flow rate (PEFR) and airflometer readings (AFM) have been made over a wide range of lung function, Age, sex and height were recorded, and the order in which the measurements were made was randomised. This study has confirmed the findings obtained using a prototype, and shows that the airflometer provides measurements of ventilatory function which correlate well with FEV,. Thus the instrument should prove a useful alternative to the Wright peak flow meter and peak flow gauge. STUART WALKER