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Biomedical subjects

R Pariente

Publications and source records attributed to R Pariente.

At least 55 records · Page 3Linked to original sources
PubMed1986

Effect of halothane on diaphragmatic muscle function in pentobarbital-anesthetized dogs.

The mechanism underlying the decrease in minute ventilation (VE) observed under halothane anesthesia was investigated in nine spontaneously breathing dogs. Anesthesia was induced with pentobarbital sodium and was maintained with halothane. Inspired fraction of halothane (FIhal) was increased every 30 min, from 0.005 to 0.02. VE decreased from 8.1 +/- 0.9 to 4.8 +/- 0.4 l . min-1 (P less than 0.001), as FIhal increased from 0 to 0.02. This resulted from a decrease in both mean inspiratory flow (VT/TI) and the duty ratio (TI/TTOT). Transdiaphragmatic pressure (Pdi) and the integrated electrical activity of both hemidiaphragms (Edi) were measured during normal breathing, and during breathing against closed airways (P0di, E0di), in order to obtain an index of the inspiratory neuromuscular output of the diaphragm. With increasing FIhal, there was a significant decrease in Pdi, P0di, Edi, and E0di. The authors measured Pdi and Edi generated during supramaximal stimulation of the two phrenic nerves (PSdi, Esdi) at frequencies of 10, 20, 50, and 100 Hz, in order to eliminate in this decrease the role played by a decrease in the neural drive to breathing. PSdi and ESdi decreased significantly with increasing FIhal, and had not returned to the control values 30 min after discontinuation of halothane administration. The authors conclude that, in pentobarbital-anesthetized dogs, halothane is responsible for a diaphragmatic dysfunction, which may be located either at the neuromuscular junction, on the contractile processes of the muscle, or on both, and for a decrease in the activation time of the inspiratory muscles. Both of these effects contribute to the decrease in VE observed under halothane anesthesia.

Anesthesia↗
PubMed1986

Effects of digoxin on diaphragmatic strength generation.

Contrary to hindlimb muscle, extracellular calcium plays an important role in diaphragmatic strength generation (J. Appl. Physiol. 58: 2054-61, 1985). Since the inotropic effect of digitalis appears to be related to cell membrane transport of calcium, we studied the effect of digoxin on diaphragmatic contractility in 20 anesthetized dogs. The diaphragm was electrically stimulated with intramuscular electrodes. The transdiaphragmatic pressure (Pdi) during supramaximal (50 V) 2-s stimulations applied over a frequency range of 10-100 Hz was measured with balloon catheters at functional residual capacity. Cardiac output was measured with a Swan-Ganz catheter and diaphragmatic blood flow (Qdi) by timed volume collections of left inferior venous effluent. The force generated by the sartorius muscle during electrical stimulations was studied concomitantly to Pdi. In 10 dogs (group A) 0.04 mg/kg of digoxin was infused in 10 min. In 10 other dogs (group B) 0.2 mg/kg was administered. All measurements were performed during control and 30, 60, 90, and 120 min after digoxin administration. In group A, digoxin plasmatic level at 60 min reached a therapeutic range in all dogs (1.8 +/- 0.3 ng/ml), whereas in group B, digoxin plasmatic level was higher (8 +/- 1.3 ng/ml). No significant change in cardiac output and Qdi was noted after administration of digoxin, either in the dogs of group A or those of group B.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Effects of theophylline on isolated diaphragmatic fibers. A model for pharmacologic studies on diaphragmatic contractility.

An in vitro model of isolated diaphragmatic muscle fibers was developed to study the effects of theophylline on diaphragmatic contractility. The effects of theophylline on this model were compared for each dose with the effects of the drugs on a "classic" hemidiaphragmatic muscle preparation. Diaphragmatic strips obtained from 20 rats were placed into an open topped channel of a plexiglass tissue chamber and perfused with continuously flowing Krebs solution heated to 37 degrees and bubbled with a 95% O2 and 5% CO2 gas mixture so as to maintain pH, PO2, PCO2 constant (7.4, 100, and 35 mmHg, respectively). Isometric force generated in response to 1 Hz supramaximal electrical stimulation was measured with a highly sensitive photoelectric transducer. Graded doses of aminophylline (15 to 75 mg/L) were administered and their effect assessed on diaphragmatic peak twitch tension. On the single diaphragmatic muscle fibers preparation, theophylline produced a dose dependent increase in peak twitch tension, which, at a concentration of theophylline of 15 mg/L, a therapeutic dose, amounted to 111 +/- 1.5% of control (p less than 0.05). At a concentration of 60 mg/L the increase in peak twitch tension averaged 35 +/- 2.5% of control, (p less than 0.001). On the other hand, theophylline had no effect on the hemidiaphragm preparation until a dose of 250 mg/L. These findings suggest that the effects of theophylline on diaphragmatic contractility are due to a direct action of the drug on the contractile properties of the diaphragmatic fibers and also validate the presented in vitro model as a promising one for future pharmacologic studies on diaphragmatic contractility.

Animals↗
PubMed1986

[Experimental allergic asthma].

This paper is concerned with the induction of experimental allergic asthma by active sensitization of the airways "vis-à-vis" heterologous protein. Thus in the rodent it is possible to sensitize the airways by direct intra-tracheal injection of the allergen without producing an allergic alveolitis; the concomitant injection of an adjuvant is however indispensable. Confirmation of the sensitized state can be made by in vitro measurements of isometric contraction of tracheal smooth muscle in the presence of the allergen. This active sensitization is accompanied by histocytological changes which are detected by immunomorphological techniques: the rise in the number of plasma cells sensitized to IgE in the mediastinal modes: the appearance (or increase in number) of intra-cytoplasmic IgE in the sub-epithelial tracheal mast cells and in certain non ciliated intra-epithelial cells, probably basophils, morphologically close to the mast cells.

Allergens↗
PubMed1986

[Evaluation of the efficacy of the surgical treatment of panlobular emphysema].

26 patients presenting with panlobular emphysema between 1978 and 1984 were submitted to a thoracotomy for surgical resection of their bullae. Pre-operative and post-operative evaluations of the following were made: The level of dyspnoea in 5 grades. The FEV1 (VEMS) the forced vital capacity (CVF) the functional residual capacity (CRF) measured plethysmographically, the residual volume (VR), the total lung capacity (CPT). Arterial blood gases. The presence of radiological signs of compression on pulmonary angiography and on plain chest radiographs: an index of compression rated 0 to 6 was defined at the outset. The subjects were split into 3 groups based on their post-operative respiratory function: Group 1: no improvement (n = 7). Group 2: moderate improvement of dyspnoea (n = 11). Group 3: a big improvement in dyspnoea (n = 7). These three groups were homogenous as regards their preoperative respiratory function. On the other hand, the compression caused by the bullae based on the pre-operative radiological data was much greater (p 0.01) in the group of patients who improved. In addition when the index of compression was equal or superior to 3 (n = 14) all the patients were improved (n = 6). The comparison of pre- and post-operative values shows the following results: The change in blood gases was very limited in all groups; the ventilatory parameters were unchanged in group 1; on the other hand in group 2 and 3 one notes an overall improvement in pulmonary function. The size of the improvement however, was very variable from one individual to another.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Effect of hypophosphatemia on diaphragmatic contractility in patients with acute respiratory failure.

We studied the effects of hypophosphatemia on diaphragmatic function in eight patients with acute respiratory failure who were artificially ventilated. Their mean serum phosphorus level was 0.55 +/- 0.18 mmol per liter (normal value, 1.20 +/- 0.10). The contractile properties of the diaphragm were assessed by measuring the transdiaphragmatic pressure generated at functional residual capacity during bilateral supramaximal electrical stimulation of the phrenic nerves. Diaphragmatic function was evaluated in each patient before and after correction of hypophosphatemia, which was achieved by administration of 10 mmol of phosphorus (as KH2PO4) as a continuous infusion for four hours. After phosphate infusion, the mean serum phosphorus level increased significantly (1.33 +/- 0.21 mmol per liter, P less than 0.0001). The increase in serum phosphorus was accompanied by a marked increase in the transdiaphragmatic pressure after phrenic stimulation (17.25 +/- 6.5 cm H2O as compared with 9.75 +/- 3.8 before phosphate infusion, P less than 0.001). Changes in the serum phosphorus level and transdiaphragmatic pressure were well correlated (r = 0.73). These results strongly suggest that hypophosphatemia impairs the contractile properties of the diaphragm during acute respiratory failure, and they emphasize the importance of maintaining normal serum inorganic phosphate levels in such patients.

Acute Disease↗
PubMed1985

[Function of the respiratory muscles in acute cardiac decompensation].

In anesthetized dogs the performance of the respiratory muscles during cardiogenic shock and their influence on its outcome was studied. Shock was induced by cardiac tamponade. Cardiac output during shock amounted to 25-35% of control and was kept constant. Minute ventilation (VE) initially increased and then progressively decreased until respiratory arrest. The latter was due to impairment of respiratory muscle contractility, the pressure generated by the diaphragm (Pdi) decreasing despite a marked increase in the diaphragmatic electromyogram and of the phrenogram. Mechanical ventilation during shock prolonged survival for the same decrease in cardiac output, and also decreased substantially the severity of lactic acidosis. Furthermore, blood flow to the respiratory muscles during shock was different in the animals breathing spontaneously (SB) from that in mechanically ventilated animals (MV). The fraction of cardiac output distributed to the respiratory muscles during control amounted to 1.85% in MV and 2.79% in SB. With shock this decreased to 1.55% in MV while in SB it decreased by 21%, which suggests that mechanical ventilation during shock preserves a large portion of cardiac output used by the respiratory muscles during spontaneous breathing, thus making it available to other organs.

Animals↗
PubMed1985

Bilateral phrenic stimulation: a simple technique to assess diaphragmatic fatigue in humans.

Transdiaphragmatic pressure (Pdi) and the rate of relaxation of the diaphragm (tau) were measured at functional residual capacity (FRC) in six normal seated subjects during single-twitch stimulation of both phrenic nerves. The latter were stimulated supramaximally with needle electrodes with square-wave impulses of 0.1-ms duration at 1 Hz before and after diaphragmatic fatigue produced by resistive loaded breathing. Constancy of chest wall configuration was achieved by monitoring the diameter of the abdomen and the rib cage with a respiratory inductive plethysmograph system. During control the peak Pdi generated during the phrenic stimulation amounted to 34.4 +/- 4.2 (SE) cmH2O and represented in each subject a fixed fraction (17%) of its maximal transdiaphragmatic pressure. After diaphragmatic fatigue the peak Pdi decreased by an average of 45%, amounting to 18.1 +/- 2.7 cmH2O 5 min after the fatigue run, and tau increased from 55.2 +/- 9 ms during control to 77 +/- 8 ms 5 min after the fatigue run. The decrease in peak Pdi and the increase in tau observed after the fatigue run persisted throughout the 30 min of the recovery period studied, the peak Pdi amounting to 18.4 +/- 2.8 and 18.9 +/- 3.3 cmH2O and tau to 81.3 +/- 5.7 and 88.7 +/- 10 ms at 15 and 30 min after the end of the fatigue run, respectively. It is concluded that diaphragmatic fatigue can be detected in man by bilateral phrenic stimulation with needle electrodes without any discomfort for the subject and that the decrease in diaphragmatic strength after fatigue is long lasting.

Action Potentials↗
PubMed1985

Effects of hypocalcemia on diaphragmatic strength generation.

We studied the effects of hypocalcemia on diaphragmatic force and diaphragm blood flow (Qdi) in 12 anesthetized dogs. The diaphragm was electrically stimulated with intramuscular electrodes surgically implanted in the ventral surface of each hemidiaphragm. The transdiaphragmatic pressure (Pdi) during supramaximal (50 V) 2-s stimulations applied over a frequency range of 10-100 Hz was measured with balloon catheters during tracheal occlusion at functional residual capacity. A catheter was placed via the femoral vein into the left inferior phrenic vein, and Qdi was measured by timed volume collections of left inferior venous effluent. A catheter was introduced in a femoral artery to monitor blood pressure (BP). In five additional dogs, the force generated by the sartorius muscle during electrical stimulation was also studied concomitantly to diaphragmatic force. The animals were mechanically ventilated throughout the experiment, and the arterial blood gases and pH were maintained constant. Hypocalcemia was induced by a continuous infusion of EGTA (70 mg X kg-1 X h-1), which led to a progressive decrease (P less than 0.0001) of ionized calcium plasmatic level from 2.21 +/- 0.4 meq/1 during control to 1.69 +/- 0.06, 1.25 +/- 0.5, and 1.07 +/- 0.5 meq/1 after 30, 60, and 120 min, respectively. Hypocalcemia decreased progressively Pdi, which amounted to 84 +/- 3 (P less than 0.001) and 98 +/- 2% of control values for the low frequencies (10 and 20 Hz) and the high frequencies (50 and 100 Hz), respectively, after 30 min of EGTA infusion and to 74 +/- 5 and 79 +/- 6% for the low and high frequencies, respectively, after 120 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Work of breathing in patients with chronic obstructive pulmonary disease in acute respiratory failure.

In 11 spontaneously breathing patients with chronic obstructive pulmonary disease (COPD) in acute ventilatory failure, we measured the total inspiratory (WItot) and total resistive (WI + Eres) work rate of breathing, together with lung mechanics (dynamic pulmonary elastance and inspiratory and expiratory pulmonary flow resistance). All variables were markedly increased compared with those in normal subjects. No significant correlation was found between WItot and WI + Eres with lung mechanics data. However, when WItot and WI + Eres were expressed per liter of ventilation, a significant positive correlation was found with all lung mechanics data. These results indicate that although in patients acutely ill with COPD, work rate and work per liter of ventilation are increased, only the latter is related to the severity of pulmonary mechanical impairment, and it could be used as one of the criteria for extubation. In addition, our results indicate that at end-expiration the alveolar pressure was positive (range, 6 to 13 cm H2O) in all patients (intrinsic PEEP), a fact that must necessarily affect hemodynamics; furthermore, it imposes an extra burden on the inspiratory muscles.

Acute Disease↗
PubMed1985

[Effect of glucocorticoids in chronic dyspneic asthma: histological and immunohistochemical study of the bronchial mucosa].

This prospective study was done in 8 patients with chronic asthma, hospitalised for an exacerbation of their illness without any evidence of airway infection. The intention was to measure both qualitatively and quantitatively the impact of high dosage glucocorticoids on the inflammatory changes of the bronchial mucus in such patients. Biopsies of the proximal bronchi by fibreoscopy were taken before and after 6 to 9 days of Prednisolone (0.5-0.75 mg/kg per day), this treatment led to a relative rise in the FEV1 (VEMS) of at least 15%. These biopsies were fixed in Bouin and Paraffin, and the sections simultaneously processed for qualitative identification (histochemical and immuno-peroxidasic) of cells infiltrating the bronchial mucosa and for a count of these cells in a pre-determined sub-epithelial zone. It was noted: In all patients at the entry to the study: an essentially lympho-monocytic cellular infiltrate of the bronchial mucosa, a virtual absence of neutrophils, and various abnormalities of the surface epithelium. After 6 to 9 days of steroids there was a persistence of epithelial lesions and in 6 out of 8 patients a statistically significant fall in the density of the inflammatory infiltrate. In 75% patients suffering from exacerbations of chronic asthma, the improvement in the ventilatory function with dosage corticotherapy was accompanied by a fall in the level of inflammatory infiltrate in the proximal bronchi.

Adult↗
PubMed1979

[Extensive bronchial dystrophy. Physiopathology and treatment of suppurative complications (author's transl)].

Extensive bronchial dystrophy differs by its histopathology, course and treatment from chronic obstructive bronchitis. This dystrophy leads to cavities which are virtually constantly infected. The extension of infection to adjacent alveoli may be dramatic, contrasting with underlying slight chronic respiratory failure. The existence of these cavities explains the preponderant role in therapy of drainage and the fact that antibiotic therapy would appear to be indicated only in the case of extension of infection to the alveoli and the peribronchial tissues.

Anti-Bacterial Agents↗
PubMed1979

[Therapy of asthma].

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Adrenal Cortex Hormones↗
PubMed1979

[Abnormalities in bronchial permeability after induction of a chronic SO2 bronchopathy in rat (author's transl)].

Our aim was to study the effects of a chronic exposure to SO2 on the permeability of bronchial epithelium in the rat, in vivo and in vitro, in relation with a marker (ferritin). The anatomical lesions observed in light and electron microscopy considerably increased the passage of ferritin both in vivo and in vitro through the epithelium of trachea and primary bronchi. This increase was still found although more discrete three months after the end of exposure while the histological appearance returned to normal. Those results showed that SO2 induces in upper airways functional abnormalities persisting beyond the necessary lapse of time for the repairing of histological lesions which could therefore intervene in the pathogeny of chronic bronchopathies.

Animals↗
PubMed1979

[Interest of helium-oxygen flow volume and isoflow volume curves in chronic obstructive lung disease (author's transl)].

We have compared changes in maximal flows induced by breathing gases of different density in 54 patients suffering from emphysema and chronic bronchitis. We considered as positive responders those subjects displaying an increase by at least 20% of maximal expiratory flows while breathing gases of lower density. Such a response was demonstrated in 21 cases, the remainder (33 cases) being non-responders. Hence, in such patients, airways obstruction may primarily be localised in central or peripheral airways. There was no correlation between the nature of this response and the clinical diagnosis, but non-responders, in general, were those in whom respiratory insufficiency was more severe. There seemed to be no additional information gained by measuring isoflow-volume (iso V vol.) in comparison with measuring differences in maximal flows at 50% of vital capacity.

Bronchitis↗