RESUMEN

The aim of this study was to establish data which would best demonstrate the variations of different tests using Carbon Monoxide as a tracer gas (total and partial functional uptake coefficient and transfer capacity) to establish mean values and lower limits of normal of these tests. Multivariate statistical analysis was used; in the first stage a connection was sought between the fractional uptake coefficient (partial and total) to other parameters, comparing subjects and data. In the second stage the comparison was refined by eliminating the least useful data, trying, despite a small loss of material, to reveal the most important connections, linear or otherwise. The fractional uptake coefficients varied according to sex, also the variation of the partial alveolar-expired fractional uptake equivalent (DuACO) was largely a function of respiratory rate and tidal volume. The alveolar-arterial partial fractional uptake equivalent (DuaCO) depended more on respiratory frequency and age. Finally the total fractional uptake coefficient (DuCO) and the transfer capacity corrected per liter of ventilation (TLCO/V) were functions of these parameters. The last stage of this work, after taking account of the statistical observations consistent with the facts of these physiological hypotheses led to a search for a better way of approaching the laws linking the collected data to the fractional uptake coefficient. The lower limits of normal were arbitrarily defined, separating those 5% of subjects deviating most strongly from the mean. As a result, the relationship between the lower limit of normal and the theoretical mean value was 90% for the partial and total fractional uptake coefficient and 70% for the transfer capacity corrected per liter of ventilation.

Asunto(s)

RESUMEN

Spirometry, blood gases, steady state diffusing lung capacity for carbon monoxyde, ductance for carbon monoxyde were determined in 27 obeses. In 13 of them we also measured closing volume. In 80 per cent of these patients we observed a decrease in expiratory reserve volume certainly due to a shift on the right of the chest wall volume-pressure curve. In 50% of the obeses we found an arterial hypoxia, usually observed when the expiratory level was lower than closing volume. Finally in 20% of the subjects we observed a decrease in diffusing lung capacity and/or ductances probably due to an important fall in and expiratory level at the closing volume level with impairment of the distribution of ventilation.

Asunto(s)

Asunto(s)

RESUMEN

We have studied the maximal expiratory flow volume curves with air and with an 80% helium-oxygen mixture, using 12 normal and 33 asthmatic children chosen according to clinical, functional and immunological criteria. In the normal children, the average delta Vmax (difference between the maximal flow in HeO2 and in air at corresponding lung volumes) was 49% and was similar from 60% to 20% of vital capacity. The iso flow volume (lung volume level at which the HeO2 and air flow volume curves intersect) was 3% of vital capacity. Eleven of the asthmatics were non-responders to the helium mixture (no significant differences in flow between HeO2 and air curves), five at 50% and 25% VC and six at only 25% VC. The other 22 asthmatics were responders, but nine of them showed a rise of the iso flow volume. Eight subjects showed no obstruction according to the flow volume curves in air; three of these had an abnormal response to the helium mixture. All the non-responders at 50% VC and half of the non-responders at 25% VC had a clinical history of recurrent infections. These results suggest, firstly, that when there is no history of recurrent infections, the site of obstruction in asthmatic children is mainly central. This does not exclude a coexisting peripheral obstruction which could persist after recovery of the central component. Secondly, by studying the HeO2 response at 25% VC, we can get more information than by measuring only the delta Vmax50 or iso flow volumes.

Asunto(s)

Asunto(s)

Asunto(s)

RESUMEN

We measured lung volumes, closing volume (CV), alveolo-arterial oxygen difference (P(A-a)O2) and steady-state diffusing lung capacity per liter ventilation (DLCO/V) in 18 men immersed up to the neck in water. The subjects were divided into 3 groups, according to relative changes in P(A-a)O2 and DLCO/V. In group 1 (n = 6), P(A-a)O2 decreased and DLCO/V increased, probably because of the hemodynamic changes induced by immersion. Their end expiratory level was above closing volume in water. In group 3 (n = 6), P(A-a)O2 increased and DLCO/V decreased, probably as a result of a decrease in ventilation in the dependent parts of the lung, considering that breathing range (ERV + VT) was less than closing volume. In group 2 (n = 6), P(A-a)O2 increased significantly and DLCO/V, only slightly. Tidal volume was only partially included in closing volume. The increase in exchange surface area was probably unable to compensate for the arterial hypoxia brought on by the decrease in ventilation in the dependent parts of the lung. The relationship between end expiratory level and closing volume, which seemed to explain the results observed during immersion, was itself a consequence of the subjects' age and body build.

Asunto(s)

RESUMEN

The authors compared the effects of a synthetic vagolytic drug, the SCH 1000, and a beta2 sympathicomimetic one (Fenoterol) in two groups of control children (n = 11) and two groups of asthmatic children (n = 23). They studied the following parameters, flow volumes curves, steady state lung diffusing capacity and the blood gases. No difference of efficiency was found between the two types of bronchodilators although the graphic modification of flow volumes curves was different after Fenoterol and after SCH 1000. The modifications consisted in a great improvement in instantaneous flow, a decrease in diffusion capacity and an increase of the Pa O2 significant in the group of asthmatic children after Fenoterol.

Asunto(s)

RESUMEN

In order to localize bronchodilators site of activity we studied the maximal expiratory flow-volume curves breathing air and 80 percent-20 percent helium-oxygen mixture in 11 normal and 23 asthmatic children. We measured delta Vmax. 60 percent TLC. delta Vmax. 45 percent TLC and VisoV. Half of the subjects received 400 gamma of fenoterol (beta2-sympathicomimetic), the other ones 200 gamma of SCH 1000 (synthetic atropine). Whatever the bronchodilator used, we found different types of response: 1 degree No modification in comparison with control period; 2 degree Increase of deltaVmax. with decrease of VisoV; 3 degree decrease of delta Vmax. with rise of VisoV. Thus we were unable to show a specific bronchodilator site of activity. However, in a few subjects, SCH 1000 principally acted on large airways whereas in some others fenoterol essentially acted on small airways.

Asunto(s)

RESUMEN

We measured blood gases, steady state diffusing lung capacity, global and partial lung ductances in 16 subjects aged from 20 to 63 in supine and seated position. We obtained three types of response. In group I, (n = 6) blood gases and TLCO increased probably chiefly due to an increase of perfusion of lung apices and a more even distribution of regional VA/Q (all these subjects are young and thin). In group II, (n = 4) blood gases and TLCO decreased probably due to a ventilation at closing volume level with a decrease of ventilation in the dependent parts of the lung (2 subjects with abdominal obesity and a third who is the oldest one). In group III (n = 7), PaO2 decreased but DLCO increased. Probably ventilation took a slight place in closing volume. The increase of the exchange surface area is likely to be unable to compensate the arterial hypoxemia induced by the low VA/Q in the dependent parts of the lung. Influence of body position seems to be a function of age which increases closing volume.

Asunto(s)

RESUMEN

Twenty patients having previously had a Mendelson's syndrome were subjected to a respiratory functional test. A syndrome of diffuse interstitial pulmonary fibrosis (DIPF) was found only in 3 cases examined shortly after the pneumopathy. In one of these cases, another examination done later showed signs of regressing fibrosis. The authors concluded that if a functional syndrome of DIPF occurred immediately after a Mendelson's pneumopathy, it eventually disappeared in the long term in most cases.

Asunto(s)

RESUMEN

Lacoste has shown the interest of determination of overall ductance of CO and partial expired alveolar ductance and arterio-alveolar partial ductances in the assessment of the efficacy of gaseous exchanges in the lung. DuCO was, by definition, the product : DuACO X DuaCO, the increase in partial ductance may theoretically compensate reduction in the other, the overall ductance then remains normal. This theory was verified studying the effects of low lung volume ventilation. Under these conditions, the dead space series becomes reduced and the DuACO should increase at the same rate, for ventilation occurs at the level of the closing volume. The inspired air is then directed preferentially towards the lung apices. These artificial changes in distribution of ventilation should produce a reduction in DuaCO. The measurements carried out confirmed these theories during low lung volume ventilation ; whereas the differences observed in overall ductance were not significant, those observed on partial ductance were very definitely significant. It appears that isolated measurement of overall ductance is insufficient and may lead to misdiagnosis of a change in the lung exchanges.

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)