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Biomedical subjects

C Fromageot

Publications and source records attributed to C Fromageot.

8 recordsLinked to original sources
PubMed2001

Supine fall in lung volumes in the assessment of diaphragmatic weakness in neuromuscular disorders.

OBJECTIVE: To determine whether diaphragmatic function can be determined by noninvasive respiratory indices in neuromuscular disease. DESIGN: Vital capacity (VC) and mouth pressure generated during a maximal static inspiratory effort (Pi max) were measured with patients in both sitting and supine positions. SETTING: Rehabilitation hospital. PATIENTS: Twenty-four patients with generalized neuromuscular disease. MAIN OUTCOME MEASURES: Changes in indices from sitting to supine position were compared with invasive diaphragmatic function indices consisting of transdiaphragmatic pressures during maximal sniff (Pdi sniff) and the ratio of gastric pressure (Pga) increases over transdiaphragmatic pressure (DeltaPga/DeltaPdi) during quiet breathing. RESULTS: The fall in VC in the supine position was greater in the 15 patients who had spontaneous paradoxical diaphragmatic motion (DeltaPga/DeltaPdi < 0) than in the 9 patients who did not. Specificity and sensitivity of a greater than 25% supine fall in VC for the diagnosis of diaphragmatic weakness (DeltaPga/DeltaPdi < 0 and/or Pdi sniff < 30cmH2O) were 90% and 79%, respectively. Stepwise multiple regression analysis of Pdi sniff showed that both the supine fall in VC and Pi max were associated with diaphragmatic weakness (R(2) =.66; p <.0001). These factors contributed 52% and 14% of the Pdi sniff variance, respectively. CONCLUSIONS: Simple VC measurement in the sitting and supine positions may be helpful in detecting severe or predominant diaphragmatic weakness.

Adult↗
PubMed2000

Postural breathing pattern changes in patients with myotonic dystrophy.

We recorded by pneumotachography the breathing in nine patients with myotonic dystrophy (MD), both seated and supine and with eyes open in both positions. Irregular breathing (coefficient of variation >20% for VT and TTOT) was observed in six of the patients, two of whom showed irregularity in both positions whilst the remaining four had irregular breathing only when supine. In addition, in this latter group, irregularities first appeared in VT and only after a few minutes in TTOT. Whereas in the group exhibiting irregular breathing in both seated and supine positions, irregularities were observed throughout the recording. However, no significant difference in any ventilatory variable was observed as between the two postures. Rib cage (RC) and abdomen (AB) motions were recorded by uncalibrated respiratory inductance plethysmography. Although for MD patients the mean values of the RC/AB ratio lay within the normal range the relative decrease in value as between seated (0.78+/-0.52) and supine (0.31+/-0.13) position was less than in healthy subjects. These observations suggest that MD may cause deficiencies in several mechanisms. Analyses of the respiratory pattern in each patient may provide information leading to the identification of the impaired respiratory mechanisms.

Adult↗
PubMed1999

Mechanisms underlying effects of nocturnal ventilation on daytime blood gases in neuromuscular diseases.

The hypothesis that, in neuromuscular and chest wall diseases, improvement in central respiratory drive explains the effects of night-time ventilation on diurnal gas exchanges was tested. The effects at 6 months, 1, 2 and 3 yrs of intermittent positive pressure ventilation (IPPV) on arterial blood gas tension, pulmonary function, muscle strength, sleep parameters, respiratory parameters during sleep and ventilatory response to CO2 were evaluated in 16 consecutive patients with neuromuscular or chest wall disorders. As compared with baseline, after IPPV daytime arterial oxygen tension (Pa,O2) increased (+2.3 kPa at peak effect) and arterial carbon dioxide tension (Pa,CO2) and total bicarbonate decreased (-1.8 kPa and -5 mmol x L(-1), respectively) significantly; vital capacity, total lung capacity, maximal inspiratory and expiratory pressures and alveolar-arterial oxygen gradient did not change; the apnoea-hypo-opnoea index and the time spent with an arterial oxygen saturation (Sa,O2) value <90% decreased (-24 and -101 min, respectively), sleep efficiency and mean Sa,O2 increased (+16% and +5%, respectively); and ventilatory response to CO2 increased (+4.56 L x min(-1) x kPa(-1)) significantly. The reduction in Pa,CO2 observed after IPPV correlated solely with the increase in the slope of ventilatory response to the CO2 curve (r=-0.68, p=0.008). In neuromuscular or chest wall diseases, improvement of daytime hypoventilation with nocturnal intermittent positive pressure ventilation may represent an adaptation of the central chemoreceptors to the reduction of profound hypercapnia during sleep or reflect change in the quality of sleep.

Adult↗
PubMed1996

Thermoregulation in homeotherms: central temperature results from optimization of energy transfers.

In contrast to the classical homeostatic concept of the constancy of the central temperature, this study proposes an original model of thermoregulation based on the optimization of energy transfers. Exchange of the energy consumed or produced by the cell between the cell and the external medium has an associated energy cost. The different variables of the internal medium-flows, pressures, concentrations and also temperatures, since heat is but a particular form of energy--are continuously set at optimal values such that this cost is always minimal for the prevailing constraints with which the organism is faced. The proposed thermoregulatory model accounts for the physiological spatial and temporal variability of the body's temperatures. The predictive curves suggest a new approach to experimental studies concerned with thermal regulation and throw new light on their results.

Animals↗
PubMed1992

Breathing disorders during sleep in myasthenia gravis.

Twenty consecutive patients (16 women and 4 men), with a mean age of 40 years, who were diagnosed and treated for myasthenia gravis were enrolled in a prospective investigation aimed at determining the amount of respiratory disturbance occurring during sleep while they received treatment. Patients were clinically evaluated to determine body mass index, presence of upper airway anatomical abnormalities, level of functional capacity and activity scored from 1 to 5, and presence of sleep-related complaints. They underwent daytime pulmonary function tests, determination of maximal static inspiratory pressure, measurement of transdiaphragmatic pressure, and measurement of arterial blood gas levels. Polygraphic monitoring during sleep, evaluating respiration and oxygen saturation, was also performed. Results indicated that in the studied population, all subjects had evidence of daytime diaphragmatic weakness as demonstrated by transdiaphragmatic pressure measurements, independent of the degree of autonomy and functional capacity and activity level reached. Older patients with moderately increased body mass index, abnormal total lung capacity, and abnormal daytime blood gas concentrations were the primary candidates for development of diaphragmatic sleep apneas and hypopneas, and oxygen desaturation of less than 90% during sleep. However, these clear indicators were not found in all subjects with sleep-related disordered breathing. Rapid-eye-movement sleep was the time of highest breathing vulnerability during sleep. Sleep-related complaints may also help identify subjects at risk for abnormal breathing during sleep, even when daytime functional activity is judged normal.

Adult↗
PubMed1988

Adult maltase acid deficiency myopathy: treatment with long-term home mechanical ventilation.

We report a study of an adult with a maltase acid deficiency myopathy. A restrictive respiratory syndrome due to respiratory muscle weakness is associated with paralysis of other muscular groups. In 1982 the patient presented with an alveolar hypoventilation, and mechanical ventilation was required after acute respiratory failure. The patient has received nocturnal mechanical ventilation by tracheostomy at home for 5 years. His clinical status gradually improved in parallel to amelioration of his respiratory condition. Functional respiratory tests improved: initial hypoxia-hypercapnia disappeared, vital capacity increased. The possible mechanisms underlying the improvement are discussed. Increase in pulmonary compliance is an argument to explain the functional improvement observed. Ventilatory response to carbon dioxide was abnormal whereas the ventilatory response to exercise and maxima minute ventilation test were normal. Results are consistent with a respiratory control impairment. The role of mechanical ventilation is difficult to assess in the improvement we observed.

Adult↗
PubMed1981

[Hemodynamic control by optimization of the cardiac pump].

Transport of energy appears as the ultimate finality of the force convection cardiovascular system. Blood pressure cardiac output and vascular resistances are the three major components of the circulatory system. Among them, blood pressure is regarded as the regulated parameter whose control value is the best adapted parameter, to each kind of activity, neurogenic mechanisms. The authors, considering the physiological variations of blood pressure during increasing energetic loads imposed on the organism, propose a new control function: optimization of cardiac mechanical power necessary to assure convection of the energy needed by the organism. Blood pressure is no more regarded as a constant. Simultaneous changes in cardiac output and blood pressure are both significant, adjusted to realize energetic minimisation of the cardiac pump. This cardiovascular regulation is described by a system of equations whose resolution leads to results in good accordance with physiological data.

Adaptation, Physiological↗