PubMed Health⌕ Search

Biomedical subjects

M Ramonatxo

Publications and source records attributed to M Ramonatxo.

At least 55 records · Page 3Linked to original sources
PubMed1989

Ventilatory control during exercise in children with mild or moderate asthma.

The aim of this study was to specify whether during exercise the neural response to increased resistive load in asthmatic children corresponds to a modification of the neuromuscular inspiratory drive, to a modification of the breathing pattern, or to both. Thus, nine children with mild or moderate asthma (aged 10-15 yr) and nine normal children (aged 11-16 yr) were studied during an incremental load exercise with a cyclic ergometer, the load of which was increased by steps of 30 W.3 min-1. During the 3rd min of each workload, we measured the following parameters: O2 consumption (VO2), CO2 production (VCO2), ventilation (VE), tidal volume (VT), respiratory frequency (f), ratio of inspiratory to total time of respiratory cycle (T1/TTOT), mean inspiratory flow (VT/T1) as well as mouth occlusion pressure measured at 100 ms (P0.1), and inspiratory power for breathing (W). At maximum level, the two groups showed identical values for heart rate, ventilation divided by weight (VEBW), T1/TTOT), VT/T1, P0.1, and W. However, asthmatic children had lower maximal power (P less than 0.02), higher tidal volume divided by weight (VTBW) (P less than 0.05), and lower f (P less than 0.01). At a same level of exercise (60, 90, or 120 W), in both groups, we found identical values for P0.1, VEBW, VO2, T1/TTOT, and VTBW/T1. However, asthmatic patients exhibited higher VTBW and lower f(limit of significance). This resulted from higher inspiratory and total time durations. Furthermore, they showed a higher inspiratory power for breathing. It was the same for f and VTBW if the results were expressed in relation to the VO2 in ml.kg-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
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

Breathing pattern and load compensatory responses in young scoliotic patients.

The breathing pattern and mouth occlusion pressure developed in 0.1 seconds (P0.1) were measured at rest in sixteen young scoliotic patients in whom the blood gases were within the normal limits. The patients exhibited rapid and shallow breathing. P0.1 was increased above normal, indicating a compensatory increase of neuromuscular inspiratory drive in the face of a stiffer respiratory system. P0.1 (% predicted) correlated positively with the angle of scoliosis. Both duration of inspiration and inspiratory duty cycle correlated negatively with angle of scoliosis and P0.1 (% predicted). On theoretical grounds we show that these changes in breathing pattern are beneficial, both in terms of reducing the energy cost of breathing and preventing the development of inspiratory muscle fatigue.

Adolescent↗
PubMed1987

Effect of aerobic training quantity on the VO2 max of circumpubertal swimmers.

Maximal oxygen uptake (VO2 max) was measured in 38 swimmers aged 10-14 years. Thirty of 38 boys participated in this study for at least 2 consecutive years. Group 1 consisted of 23 subjects (48 measures) who trained for 7 h/week while group 2 consisted of 15 subjects (27 measures) who trained for 14 h/week. In group 2, VO2 max normalized to body weight was significantly higher at 14 years of age than at 10, whereas the increase was nonsignificant during this period in group 1. The subjects of group 2 showed a large increase of VO2 max/kg body weight from the age of 13, which corresponded in this study to the age of peak height growth velocity. The differences between the two groups were statistically significant at both 13 (P less than 0.02) and 14 years of age (P less than 0.05). At 13 and 14, the most trained subjects also showed significantly higher (P less than 0.05) values of maximal oxygen pulse/kg body weight (VO2 max/kg/HR max). Maximal heart rate (HR max) was similar in the two groups between 10 and 14 years of age. Therefore, we conclude that an increase in a training program of the aerobic type induces a large increase in VO2 max from the age of peak height growth velocity. This is likely due to an increase in the stroke volume.

Adolescent↗
PubMed1987

Is ventilatory anaerobic threshold a good index of endurance capacity?

This study was undertaken to assess whether ventilatory anaerobic threshold (T vent) reflected endurance capacity (EC) in sports medical control. Fifteen subjects performed two cycle ergometer tests. The first was a maximal exercise test, which consisted of increasing the load 20 W/min until exhaustion. During this test, the gas exchange anaerobic threshold was determined and VO2 max was measured. The second was an endurance exercise test, which consisted of asking the subject to work, as long as possible, a load representing 80% of his maximal aerobic power. During this test, we measured endurance time (ET). The statistical analysis showed the lack of relationship between VO2 max and ET and the linear correlations between VO2 T vent ml/min/kg and ET min (r = 0.521, P less than 0.05), VO2 T vent l/min and ET min (r = 0.524, P less than 0.05), and T vent % VO2 max and ET (r = 0.738, P less than 0.01). These results establish that ventilatory anaerobic threshold actually reflects endurance capacity. This relation can be explained referring to the muscle energetic metabolism during exercise. Therefore, T vent should be determined systematically in addition to VO2 max during maximal exercise tests to better evaluate physical fitness.

Adolescent↗
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

[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↗
PubMed1984

[Pulmonary hemodynamic monitoring in chronic respiratory insufficiency treated with almitrine bismesilate for 4 months in a double-blind study].

Six subjects suffering from chronic airflow obstruction and respiratory failure were treated with oral almitrine bismesylate (3 mg/kg/day). Studies were made before and after 2 and 4 months treatment on: total ventilation, arterial blood gases, pulmonary artery pressure by a micro-catheter and cardiac out-put by rebreathing CO2. The results were compared with those of a placebo group of 3 subjects. While in the almitrine group a significant improvement in blood gases was observed, no change was seen in the two populations in either the haemodynamic or ventilatory variables. The medium term haemodynamic stability observed is contrasting with single dose effects of almitrine. This discrepancy could be due, at least in part, to a balance between the possible vasoconstrictor effect of almitrine bismesylate and vasodilator consequences of blood gases improvement.

Adult↗
PubMed1982

Prostaglandin biosynthesis by the rat uterus during the oestrus cycle, temporal correlation with plasma oestradiol and progesterone concentrations, identification of 6 keto PGF1 alpha as the major metabolite.

Prostaglandin biosynthesis was studied in the rat uterus during the oestrous cycle. Uterine homogenates were incubated for 20 minutes inthe presence of exogenous substrate (2.10(-5)M). PGF2 alpha and PGE2 were measured by R.I.A.. A sharp peak of PGF2 alpha and a smaller peak of PGE2 were observed at prooestrus, 20 h. Another small PGE2 peak occurred at dioestrus II, 15 h. The lowest values of both PGs were found on dioestrus, 15 h. Plasma oestradiol concentrations were highest at proestrus, 15 h and 20 h. A sharp progesterone peak occurred at prooestrus, 20 h. The PGF2 alpha peak is next to the oestradiol peak and is superimposable or lags slightly beyond the progesterone peak. Incubation with 14C arachidonic acid and subsequent analysis of extracts by TLC and scanning showed that the major metabolite is PGI2, identified as 6 keto PGF1 alpha. The conversion rate of arachidonic acid into 6 keto PGF1 alpha is 5 times higher than into PGF2 alpha. 6 Keto PGF1 alpha was further identified by GC/MS. No significant difference was observed between 6 keto PGF1 alpha production during oestrus and dioestrus.

6-Ketoprostaglandin F1 alpha↗
PubMed1982

Effect of oestradiol 17 beta on prostaglandin biosynthesis by the uterus of ovariectomized rat and guinea pig.

In vitro prostaglandin biosynthesis by uteri of ovariectomized rats and guinea pigs treated or untreated with oestradiol 17 beta, administered subcutaneously, was measured by R.I.A. of PGF2 alpha and PGE2. Incubations with [1-14C] arachidonic acid were also performed and labelled metabolites were analyzed by TLC. The main metabolite in rats was 6 keto PGF1 alpha and in decreasing order of magnitude, PGF2 alpha and PGE2. In guinea pig PGF2 alpha was the main product. Ovariectomy in rats completely changed the pattern of synthetized prostanoids : PGI2 production was doubled when compared to cycling rats and PGE2 increased 10 fold. PGF2 alpha values were similar to the mean value measured during the cycle. OE2 treatment almost completely inhibited PGI2 synthesis and reduced PGE2 by half. Total PG synthesis in OE2 treated animals was decreased by 5 fold when compared to spayed rats. Endogenous PGF2 alpha synthesis was slightly stimulated. In the guinea pig OE2 treatment of ovariectomized animals increased the total synthesis from 50 per cent. PGF2 alpha was always the main metabolite. In conclusion OE2 regulation of uterine PG synthesis is depending on the animal species and cannot be explained by a unique effect on the cyclooxygenase, but rather by an interplay on the various enzymes of the arachidonic acid cascade.

Animals↗
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↗
PubMed1980

[Mechanical effects of obesity on lung function (author's transl)].

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.

Adolescent↗
PubMed1978

Human gas exchange during water immersion.

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.

Adult↗
PubMed1978

[Comparative study of a vagolytic and a beta 2 sympathomimetic drug on the respiratory function of the asthmatic patient].

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.

Adolescent↗
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↗
PubMed1976

[Effect of low lung volume ventilation on the relative proportions of carbon monoxide partial ductances (author's transl)].

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.

Adult↗