PubMed Health⌕ Search

Biomedical subjects

J P Derenne

Publications and source records attributed to J P Derenne.

At least 19 recordsLinked to original sources
PubMed1979

The interaction between the diaphragm, intercostal/accessory muscles of inspiration and the rib cage.

During Mueller maneuvers (MM), the volume change of rib cage, delta Vrc, and abdomen, delta Vab, are equal and opposite. Thus delta Vrc = -delta Vab. Substituting delta Prc.Crc for delta Vrc and delta Pab.Cab for delta Vab yields: delta Prc = - delta Pab.Cab/Crc, where delta Prc, delta Pab, Crc and Cab are applied pressures and compliances of rib cage and abdomen respectively. MM performed solely with the diaphragm permits calculations of Prc in terms of observed changes in Pab and pleural pressure, Ppl. Three trained subjects performed MM with no evidence of inspiratory intercostal or abdominal muscle contraction. During the diaphragmatic MM delta Pab was positive and delta Prc negative. The magnitude of delta Prc/delta Pab was 2-6 times greater than that of delta Ppl/delta Pab. We conclude that neither Pab nor Ppl by themselves displace the relaxed rib cage during Mueller maneuvers. A model in which the diaphragm acts both in parallel and in series with the rib cage, and in which Prc is the sum of Pab and a pressure lying between Pab and Ppl explains these results as well as the hypothesis that Pab displaces the relaxed rib cage during quiet breathing.

Diaphragm↗
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↗
PubMed1978

[Pan-lobular emphysema: relationship with serum alpha-1-antitrypsin levels, Pi phenotype and the HLA system (author's transl)].

Pi phenotypes have been studied in a group of 433 patients. Patients with panacinar emphysema and/or bullae were identified from careful analysis of their clinical, physiological, radiological and anatomical characteristics. Twenty-five p.cent of the emphysematous patients were MZ; there was no significant difference in the alpha-1-antitrypsin plasmatic levels between the groups. The HLA antigens were studied in order to try to identify the possible cofactors in the development of emphysema. The role of occupational pollutants and/or of tobacco is discussed. The frequency of the MZ phenotype in our series differs from previous publications. This discrepancy is discussed on the basis of the criterious used to identify the emphysematous patients.

Blister↗
PubMed1977

Bronchial lymphoepithelial nodules in the rat: morphologic features and uptake and transport of exogenous proteins.

Using morphologic and ultrastructural criteria, the present study in the rat was undertaken to distinguish lymphoepithelial modules from lymphoid aggregates and lymph modes, and to demonstrate the uptake and transport of ferritin and latex particles, instilled in the trachea, by the lymphoepithelium. Unlike lymph nodes or lymphoid aggregates, lymphoepithelial nodules can be distinguished by the following characteristics of the lymphoepithelium: it is flattened and devoid of goblet cells; it contains intracellular and "intercellular" vacuoles; occasional macrophage-like cells infiltrates and surrounding lymphocytes clusters can be observed. At any time, no latex particle was found inside or under the lymphoepithelium, but until 1 hour after local instillation, ferritin particles were localized close to the cilia, at the luminal surface of the epithelium, within vesicles at the surface of some cells, and in the intercellular space. Moreover, ferritin particles were consistently present on both sides of the basement membrane after 1 hour. These results suggest that lymphoepithelial nodules may be considered as original structures capable of uptake and transport across the basement membrane of certain foreign materials.

Animals↗
PubMed1976

Occlusion pressures in men rebreathing CO2 under methoxyflurane anesthesia.

The effect of general anesthesia on control of breathing was studied by CO2 rebreathing and occlusion pressure measurements in six normal human subjects under methoxyflurane anesthesia. CO2 was found to increase the amplitude of the occlusion pressure wave without changing its shape, so that CO2 responses in terms of the occlusion pressure developed 100 ms after the onset of inspiration (Po/0.1) gave results equivalent to the responses in terms of Po/1.o or any other parameter of the pressure wave. Methoxyflurane depressed the ventilatory response to CO2 but not the occlusion pressure response, implying that the most important action of the anesthetic was to increase the effective elastance of the respiratory system rather than to depress the respiratory centers. The elastance was further increased by CO2, and this mechanical change had the effect of shifting the "apneic threshold" extrapolated from the ventilatory response curve to a lower PAco2. Frequency of breathing, inspiratory and expiratory times were not altered by CO2 in anesthetized subjects.

Adult↗
PubMed1976

Adaptation of anesthetized men to breathing through an inspiratory resistor.

Normal men anesthetized with methoxyflurane rebreathed carbon dioxide under two conditions. In one case they breathed most of the time through a low-resistance circuit and an inspiratory resistor of 40.4 cmH2O/1-s-1 was applied at intervals. In another case they breathed most of the time through the resistor and were allowed occasional free breaths. There were no differences between the two types of runs in tidal volume, respiratory frequency, duration of inspiration of loaded or unloaded breaths, or in amplitude or shape of occlusion pressure waves. It is concluded that the reaction of conscious men to an inspiratory resistive load, consisting of a compensatory augmentation of neural drive to respiratory muscles that does not depend on a chemical stimulus, is absent in anesthetized men.

Adult↗
PubMed1975

Occlusion pressure as a measure of respiratory center output in conscious man.

The output of the "respiratory centers" has been estimated by measuring ventilation, inspiratory muscle power, EMG of the diaphragm, and by various other means, each of which has serious disadvantages. The static pressure generated by the inspiratory muscles at FRC against an obstructed airway is here suggested as a useful alternative. Ten conscious, normal, sitting human subjects were subjected to CO2 rebreathing (Read, 1967) and their airways were occluded at end-expiration at intervals without the subjects being aware in advance. The inspiratory pressure waves so generated were found to be distorted by conscious or unconscious responses to the occlusion which had a minimum latency of 0.15 sec. The pressure generated at 0.1 sec after the onset of inspiration (P0.1) was nevertheless easy to measure and was reproducible in each subject. The CO2 response obtained by plotting P0.1 against PCO2, was curvilinear, the P0.1 increasing more rapidly at high PCO2. The P0.1 is independent of pulmonary mechanics. Since it measures the rate of rise of inspiratory activity and not the peak activity it is also independent of mechanisms that alter the respiratory pattern by affecting inspiratory duration, in particular the vagal volume-related inspiratory-inhibitory reflex. It is concluded that measurements of P0.1 represent a useful index of the output of the respiratory centers.

Airway Obstruction↗
PubMed1975

Control of depth and frequency of breathing during baroreceptor stimulation in cats.

In 10 tracheotomized anesthetized cats during steady-state inhalation of various concentrations of CO2 and O2, the acute respiratory response to baroreceptor stimulation produced by transient inflation of a balloon placed in the descending aorta was studied. The latter induced a sudden rise in mean arterial pressure, ranging from 62 to 95 mmHg. At all PACO2 levels above 30 mmHg, elevation in arterial pressure was accompanied by an immediate drop in tidal volume (VT) and prolongation of the durations of inspiration (Ti) and total breath (Ttot). Breaths obtained during baroreceptor stimulation fell along the same VT vs. Ti and VT vs. Ttot relationships obtained in the normotensive state, suggesting that the lung volume-related vagal control of Ti and Ttot is unaffected by changes in arterial pressure. Since, for a given change in arterial pressure, a constant reduction in VT was obtained at all PACO2 levels above 30 mmHg, it can be concluded that the interaction between PACO2 and arterial pressure is additive. In three cats, at PACO2 levels below 30 mmHg, aortic obstruction resulted in brief periods of apnea. Following apnea, the control of Ti and Ttot was transiently offset, describing hysteresis pathways on the VT vs. Ti and VT vs. Ttot relationships.

Abdominal Muscles↗