[The contribution of effort tests in the evaluation of factors related to dyspnea in pneumonology]. / Apport de l'épreuve d'effort dans l'appréciation des facteurs de la dyspnée en pneumologie.

Forty nine patients suffering from respiratory disorders underwent an exercise test carried out on a bicycle ergometer (n = 45) or by walking rapidly on flat or inclined ground (n = 4). The respiratory restrictions on effort were correlated with a degree of dyspnoea (stages 1 to 4) established by a questionnaire. The analysis of the effort test had consequences of practical importance: in effect, in this study, nearly half the patients benefited from advice orientated in particular towards the level of activity which would be suitable for them, and to reduction in their weight.

Influence of the previous deep inspiration on the spirometric measurement of provoked bronchoconstriction in asthma.

The measurement of the forced expiratory volume in one second (FEV1) after a maximal inspiration is often used to assess the effect of inhaled bronchoconstrictor agents. In persons with asthma, a deep inspiration transiently alters the bronchial tone in a variable way. This may result in a variable decrease of FEV1 despite a similar degree of pharmacologically induced bronchospasm. In 71 patients with asthma we induced a comparable increase (approximating 200%) in airway resistance (Raw) with aerosolized carbachol. We then measured the change in Raw induced by one deep inspiration; when Raw had returned to the value observed before deep inspiration, the FEV1 was measured. A significant correlation (r = 0.74; p less than 0.001) was found between the transient changes in Raw induced by a deep inspiration (ranging individually from a 33% increase to a 70% decrease) and the decrease in FEV1 (from 0 to 70%). The decrease in FEV1 was greatest in patients in whom a deep inspiration increased Raw and least in those in whom Raw decreased. The initial and post-carbachol Raw values of the 17 patients exhibiting a less than 20% decrease in FEV1 were similar to those of the 54 patients with a decrease in FEV1 of more than 20%. Because a prior deep inspiration prevents changes in FEV1 in some patients with asthma, the use of the FEV1 for bronchial provocation tests can be misleading.

[133 Xe radiospirometry: prediction of VC and FEV1 (author's transl)]. / Valeur de l'estimation par le 133 Xe des volumes pulmonaires après exérèse.

In patients with impaired lung function who are scheduled for lung surgery, a means of estimating the ventilatory consequences of parenchymal resection is needed. We have tested the ability of lung scanning with aerosolized and intravenous 133Xe to fulfil this purpose in 100 pneumonectomized or lobectomized patients. Postsurgery VC and FEV1 values were evaluated as follows: each lung was horizontally divided into two areas and lower and upper VC values were calculated as percentages of the total radioactivity count. Using the regional percentages and the absolute values of VC measured spirometrically, the VC expected postsurgery values were calculated according to the type of resection planned (e.g. if the left lung was to be removed and if it accounted for 50% of the radioactivity on the scan, the postsurgery VC would be halved). Postsurgery FEV1 values were estimated by using the VC value and the FEV1/VC ratio measured before surgery. A significant correlation (p less than 0.001) was found between the values estimated in such way and the actual FEV1 and VC values obtained shortly after surgery (between 6 and 15 days). From these results, we conclude that the xenon scan is a valuable technique for estimating the consequences of lung removal on ventilation.

[Correlations between the changes in the affinity of hemoglobin of oxygen and the anaerobic metabolism during muscular exercise in 20 silicotic patients (author's transl)]. / Corrélation entre modifications de l'affinité de l'hémoglobine pour l'oxygène et métabolisme anaérobie au cours de l'exercice musculaire chez 20 silicotiques.

This study investigated the changes in hemoglobin affinity for oxygen -- P50 standard [P50 (7.40)]; P50 in vivo (P50 IV), and 2,3-diphosphoglycerate concentration (2,3-DPG) -- and the anaerobic metabolism during a short muscular exercise in 20 silicotic patients. P50 (7.40) and 2,3-DPG remained unchanged at the end of the exercise but P50 IV increased significantly. A negative correlation was found between the increase in the arterial lactates and the increase in P50 IV. Such a shift to the right of the oxyhemoglobin dissociation curve probably improves the tissular oxygenation and can be regarded as a compensatory mechanism in patients with pulmonary impairment during exercise.

[Periodic oscillating respiration outside of comatous stages]. / Respiration périodique oscillante en dehors d'états comateux

A periodic oscillating breathing was observed in 11 subjects during study of their pulmonary function. All these patients were male and more than 50 years old. A cardiovascular disease was clinically evident in eight of them. Arterial hypoxemia was found in five subjects and a light hypocapnia in three. Analysis of oscillating rhythms first, revealed unexistence of ventilatory pauses between periods of deep breaths in some subjects and secondly, showed existence of permanent or discontinuous periodic rhythms. Breath by breath changes in ventilation were essentially induced by oscillations in tidal volume. Discontinuous oscillating breathing appeared after forced maximal inspiration and this periodic rhythm was frequently associated with sights. This periodic breathing began or persisted under progressive hypoxia but disappeared under normobaric hyperoxia. These data are discussed in terms of changes in the ventilatory control system and in central regulation of breathing patterns.