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Biomedical subjects

C Préfaut

Publications and source records attributed to C Préfaut.

At least 127 records · Page 7Linked to original sources
PubMed1988

A one year double blind follow-up of blood gas tensions and haemodynamics in almitrine bismesylate therapy.

Almitrine bismesylate, a chemoreceptor agonist, improves blood gases in chronic obstructive lung disease (COLD). Some authors have observed an increase in pulmonary artery pressure (Ppa) after single doses of almitrine bismesylate (A). This led to the present one year double blind placebo (P) controlled study to assess haemodynamic effects of long-term oral treatment in COLD (1.5 mg/kg/day for one year), together with clinical benefit and blood gas improvement. Twenty moderately severe patients entered the study, fifteen of whom completed it (eight in group (A), seven in group (P]. Blood gas values, minute ventilation (VE), mean pulmonary artery pressure (Ppa) and cardiac output (Qc) were periodically measured. Ppa and Qc remained unchanged in both groups throughout the study. We observed relevant clinical improvement without side effects and no significant increase in VE in group (A). Arterial oxygen tension (PaO2) showed a 1.2 kPa (9 mmHg) mean increase in group (A) and remained unchanged in group (P). These data and those from the literature seem to indicate that almitrine induces a vascular effect, especially after a single dose. However, as long as PaO2 improves simultaneously no long-term haemodynamic consequence is apparent. The discrepancy between immediate and long-term vascular effects of almitrine might be explained by the improvement in gas exchange which could reduce and/or counter-balance the vasoactive response. In conclusion, after one year of therapy almitrine bismesylate results in considerable clinical and blood gas improvements without significant haemodynamic change.

Aged↗
PubMed1988

[Pregnancy and the respiratory function].

The respiratory function of pregnant women is changed for more than one reason. There is a mechanical effect due to the increase in the uterine volume and the elevation of the diaphragm. However, there are only modest functional consequences, because the pulmonary volumes are only little changed, with the exception of a reduction in the functional residual capacity. Bronchial permeability is unaltered due to the balancing of constrictors (mechanical, hypocapnia) and dilators (hormonal influences). As regards pulmonary haemodynamics, the hypovolaemia of the pregnant woman has no repercussions on pulmonary vascular pressure. Gas exchange and alveolar-capillary diffusion are normal or even improved as a consequence of chronic hyperventilation. The latter is the most important functional change, sometimes expressed as a sensation of dyspnoea. The origin of this hyperventilation relates to the diminution of the threshold of sensibility in the respiratory centres to CO2 due to the effect of raised progesterone levels.

Female↗
PubMed1986

Breathing pattern and occlusion pressure during exercise in pre- and peripubertal swimmers.

In two groups of young swimmers (prepubertal stage: group A; peripubertal stage: group B), the ventilatory response to graded exercise work with a cycle ergometer was studied. Ventilatory variables (ventilation, VE, tidal volume, VT, respiratory frequency,f, ratio between inspiratory period and total breath duration, TI/TTOT, and mean inspiratory flow, VT/TI) as well as mouth occlusion pressure measured at 100 msec (P0.1), effective impedance of the respiratory system (P0.1/VT/TI), inspiratory power for breathing (W) and O2 uptake (VO2) were measured during the third minute of each work load. At the same level of exercise both groups showed identical values of VT/TI, but VE was higher in group A individuals. This resulted from higher values of respiratory frequency with higher TI/TTOT ratios. P0.1, P0.1(VT/TI) and W were also much higher during work load in group A than in peripubertal subjects. When the above results were related to the same percentage of VO2 max, P0.1, W, respiratory frequency and duty cycle did not differ within both groups. However, VE, VT and VT/TI were lower in group A subjects with a higher P0.1/(VT/TI) ratio. Further corrections of VT, VT/TI and P0.1/(VT/TI) ratios by body weight cancelled all these differences. In conclusion, our results strongly suggest that biometric factors only determined interindividual differences in ventilatory response to exercise in prepubertal and peripubertal swimmers.

Adolescent↗
PubMed1986

[Pulmonary and systemic vascular effects of ATP in man].

ATP induced-vasodilation was studied using Striadyne, on pulmonary and systemic arterial bed on 10 patients with stable chronic obstructive pulmonary disease. Such significant effects varied according to the dose: pulmonary vasodilation reached maximal level during low rate infusion (2 mumoles/kg/20 min) and systemic vasodilation was related to the dose. The latter became dominant at maximal dose (5 mumoles/kg/20 min). Simultaneously, on four patients, circulating blood level of ATP was assessed. It increased in proportion with the infusion rate and reached respectively 167% and 149 of baseline level on arterial and mixed venous blood.

Adenosine Triphosphate↗
PubMed1986

[Optimization of the method of progressive hypercapnia by determination of the sensitivity threshold].

Ventilatory response to CO2 rebreathing is a method which allows to evaluate the reactivity of chemoreceptors. However this method doesn't study the sensibility threshold, i.e. the Pe.t.CO2 value for which the ventilatory response appears clearly. This sensibility threshold was measured in 10 healthy subjects by rebreathing a gas mixture: 7% CO2 and 50% O2 to avoid hypoxy. It was defined as the value of Pe.t.CO2 for which the ventilation was above the tidal ventilation + 2 standard deviations. The sensibility threshold (51 +/- 4.35 mm Hg) was independent of the reactivity slope represented by the slope of the linear relation between minute ventilation (VE) and Pe.t.CO2 (1.34 +/- 0.60 l/min/mm Hg/m2) and consequently appears as an interesting parameter in order to evaluate the ventilatory response to CO2 by rebreathing.

Adult↗
PubMed1982

[Carbon monoxide tests in a steady state. Uptake and transfer capacity, normal values and lower limits].

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.

Adolescent↗
PubMed1981

[Small airways disease (author's transl)].

The authors define small airways disease and then describe its anatomical characteristics. In the early stage bronchial inflammation is found along with arterial lesions. As the disease develops, there are multiple bronchial and vascular alterations, often accompanied by emphysema. The few existing studies of the morphology/lung function test correlation show a relationship between small airways disease and abnormal respiratory function tests. One of the aims was to find the most sensitive and specific tests using the smoker as a model. However, as only 25% of smokers develop clinical abnormalities, the main problem is probably not early screening, but finding the parameter with the highest prognostic value. This should be the FEVI, measured at about age 40. At a younger age, the information is still too incomplete. More studies are needed to justify early screening. Finally, the authors discuss the procedure to be followed when abnormalities are detected, and its possible consequences on lung function and behaviour.

Forced Expiratory Volume↗
PubMed1980

[Effects of almitrine on the pulmonary circulation].

Almitrine was injected intravenously at a dose of 1 mg.kg-1 over a period of sixty minutes in eight men aged from 49 to 69 years suffering from chronic bronchitis and obstructive airway disease, with signs of chronic cor pulmonale. During the study, patients on artificial respirator were in stable ventilation. Measurements gave the following results: arterial pO2 rose at all the times of study (P < 0.02). Arterial pCO2 decreased, the difference being significant 20 minutes after the end of the infusion. Q tended to increase accompanied by a slowing in heart rate, an increase in cardiac index and in systolic ejection work (P < 0.01 at T60). Pw increased (with P < 0.05 at the 20th minute) and subsequently varied in the same direction in parallel with pulmonary resistance. The authors concluded that almitrine, apart from its well known effects on ventilatory mechanics, results in blood gas changes with are not directly correlated with variations in VE by direct action on pulmonary vascular flow with any notable improvement in the upper zones of the lung.

Aged↗
PubMed1980

[Almitrine per os in the therapy of chronic obstructive bronchopneumopathies].

A double-blind study was conducted to evaluate the effects of almitrine, administered orally as 3.5 mg/kg/day for one month, when compared with placebo in 20 patients with chronic obstructive pneumopathies from smoking, currently in the stage of chronic hypercapnic respiratory insufficiency. Clinical improvement was obtained, with a reduction in dyspnea and a more comfortable respiration. Objective signs of improvement where enhanced adaptation to assisted ventilation (3 cases out of 5), and less secondary infection in the almitrine group (0/10) than the placebo group (4/10). A statistically significant improvement (p less than 0.01) was recorded in blood oxygen and bicarbonates levels, and to a lesser degree, in blood CO2 levels (p less than 0.05) and without any increase in overall ventilation. As tolerance was good (8/10), almitrine appears to occupy a place of choice in the field of respiratory analeptic therapy. Its efficacy and convenience in use for daily practice require confirmation in long-term studies (more than 6 months).

Administration, Oral↗
PubMed1977

[Influence of body position on human gas exchanges. Role of age (author's transl)].

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.

Adult↗
PubMed1977

[Respiratory physiology during water immersion (author's transl)].

In this review, the author recalls the essential modifications induced by water immersion up to the neck. The ventilatory mechanics show an important decrease of end expiratory level being able to bring a ventilation in closing volume. We notice an increase of cardiac output, of pulmonary artery pressure and central blood volume. After the age of 25, we notice an hypoxia likely due to ventilation at closing volume level.

Airway Resistance↗