摘要:

The theoretical basis for the distribution analysis of inhomogeneities of ventilation, perfusion and O2 diffusing capacity in the human lung is given. The method is based on the continuous recording of the alveolar mixing processes after a sudden concentration change of 3 inspiratory gases. Suitable for this are three gases with different diffusing coefficients, e.g. argon, carbon dioxide, and oxygen. According to a evaluation procedure by Thews and Vogel, the ventilation – perfusion ratio VA/Q and the O2 diffusing capacity perfusion ratio DL/Q in various functional uniform compartments of the lung may be determined. From these data a great number of further informations can be gained. The original calculation procedure rendered a correction in a few points and needed a relatively long time for the evaluation. In the following paper therefore a modification of the evaluation was made, which allows a more correct separation of the functional compartments, without additional assumptions. Furthermore, the constants needed in the evaluation are re-examined. At last a computer program in FORTRAN is given, which reduces the time expense of the entire evaluation to such a degree that a routine application in the lung function diagnostics is possibl

ISSN:0025-7931    

DOI:10.1159/000192815

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

In 12 patients with tight mitral stenosis and in 10 normal subjects the pulmonary diffusing capacity (steady state method) and the distribution of inspired gas (lung clearance index) were studied in sitting position both at rest and during graded exercise. There were no differences between the both groups in the pulmonary diffusing capacity related to oxygen consumption and the 2 groups did not differ in the distribution of inspired gas. The functional residual capacity and the lung clearance index did not change from rest to exercise. The pulmonary diffusing capacity is positively related to the work load, tidal volume and oxygen pulse in both groups of subjects. Patients with mitral stenosis show higher values of ventilation equivalent (VE/Vo2) and higher respiratory frequency. In another session the patients were subjected to right heart catheterization in supine position. In spite of the fact that during exercise the pressures in pulmonary capillaries exceeded the values of oncotic pressure, the patients did not develope clinical signs of pulmonary edema and the PaO2 remained within normal limits. It may be concluded that the pulmonary capillary hypertension in patients with mitral stenosis of short duration of symptoms does not necessarily lead to the impairment of pulmonary gas exchange and does not result in ventilation/perfusion disturbances.

ISSN:0025-7931    

DOI:10.1159/000192842

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

The behaviour of the anatomical dead space cannot be described by passage of a ‘square’ wave front through the conducting airways, with subsequent diffusion of alveolar gas back up the bronchial tree. A computer model based on these assumptions leads to overestimation of the dead space during both rest and exercise. It is suggested that these discrepancies arise from laminar (axial) flow in the smaller airways. A simple description of the anatomical dead space is given by the equation VD = Vf+ (Ve-200)e-kt where VD is the volume of the anatomical dead space, Vf is the volume of the conducting airway to the fifteenth order bronchioles, Ve is the volume from the sixteenth order bronchioles to the second or third order alveolar ducts, 200 is an empirical correction for laminar gas flow, k is a diffusion constant (1.0 for nitrogen, 0.8 for carbon dioxide) and t is the half length of the respiratory cycle, measured in seco

ISSN:0025-7931    

DOI:10.1159/000192816

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

The nature of upper and lower airway obstruction can usually be read from the form of the pressure-flow diagram obtained by body plethysmography during spontaneous breathing. The analysis of the pathological mechanisms of airway obstruction was verified by the clinical picture, anatomical findings and other functional explorations of the lung like chest X-rays, bronchoscopy and ventilation-perfusion studies with radioactive gases. The analysis of the form of the pressure-flow curves obtained with a perfectly on BTPS-condition stabilized rebreathing system in the body plethysmograph is more useful than the drawing of additional resistance lines.

ISSN:0025-7931    

DOI:10.1159/000192817

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

Twelve patients with chronic respiratory failure in obstructive pulmonary emphysema had a significant increase in plasma catecholamines of about three times the normal values. It is suggested that chronic hypercapnia stimulates the sympathetic nervous system thus being partly responsible for several cardiovascular features as tachycardia, arrhythmia and increased cardiac output often observed in patients with chronic respiratory insufficiency.

ISSN:0025-7931    

DOI:10.1159/000192843

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

Changes in O2 concentration in the gas mixture supplied by assistive respirators of the Bird and Bennett type were monitored continuously with a new fast registering O2 analyzer in conjunction with a pneumotachogram. When using 100 % O2 to drive the respirators unfavourably high O2 concentrations were registered even with a single breath, and could be traced as to their origin: The admixture of atmosphere room air via Ventury tube remains rather constant even with high back pressure and low flow adjustment. The air-oxygen flow rate from the Venturi tube to the patient is slowed down or stopped completely by closure of the valve at the end of the tube. Meanwhile the unimpaired flow of the pure oxygen through the nebulizer leads to high inspiratory O2 concentrations. However, eventual toxicity could result only in a case of a low compliance, high inspiratory positive pressure and long term ventilation. In some patients suffering from alveolar hypoventilation the hypoxemic drive of respiration may be retarded even by slight elevation of inspiratory oxygen concentration. In these cases we could confirm previous experience that driving the respirators with compressed air and adding O2 at controlled low flow rates to the atmospheric compartment of the respirators represents a very adequate form of treatment.

ISSN:0025-7931    

DOI:10.1159/000192818

出版商:S. Karger AG    

年代:1971

数据来源: Karger