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Biomedical subjects

M Lopata

Publications and source records attributed to M Lopata.

63 records · Page 4Linked to original sources
PubMed1976

Phrenic nerve activity and occlusion pressure changes during CO2 rebreathing in cats.

Changes in phrenic nerve activity, quantified as a moving time average, PNG(t), were characterized during complete airway occlusion at functional residual capacity (FRC) and compared to simultaneously occurring changes in intratracheal pressure. In anesthetized cats breathing room air and during CO2 breathing, PNG(t) during occlusion was the same as that found during unobstructed breathing until it reached a value approximately corresponding to that at peak inspiration in the preceding unoccluded breath, the rate of change of PNG(t) usually remained the same but in a few cases (2 out of 11) increased. When intratracheal occlusion pressure was plotted as a function of PNG(t), both while breathing room air and during CO2 rebreathing, an approximately linear relationship was obtained. Thus, changes in intratracheas occlusion pressure obtained at FRC parallel changes in phrenic motor nerve activity. Quantification of electrical activity of respiratory nerves as a moving time average provides a means of characterizing changes in the average level of electrical activity during an inspiratory effort.

Airway Obstruction↗
PubMed1976

Disseminated pulmonary blastomycosis in an immunosuppressed patient. Diagnosis by fiberoptic bronchoscopy.

A 73-year-old man with malignant lymphoma who was undergoing treatment with systemic chemotherapy presented with an acute, febrile illness associated with cough and sputum production. The patient developed bilateral, diffuse, pulmonary interstitial infiltrates with rapidly progressive respiratory insufficiency. The diagnosis was made by demonstrating Blastomyces dermatitidis in bronchial brush and transbronchial lung biopsy specimens obtained through fiberoptic bronchoscopy.

Aged↗
PubMed1976

Effect of elastic loading on mouth occlusion pressure during CO2 rebreathing in man.

In 7 normal subjects, mouth occlusion pressure was evaluated as an index of neural drive to the respiratory muscles during CO2 rebreathing, with and without the addition of 2 degrees of elastic loads. During control and loaded rebreathing, changes in both mouth occlusion pressure and ventilation were linearly related to changes in end-tidal PCO2. With elastic loading, the slope of occlusion pressure versus end-tidal PCO2 response consistently increased from control values in all subjects and was greater with the higher load in 6 of 7 subjects. The ventilatory response to elastic loading was variable and inconsistent owing to the variable increase in frequency of breathing, the tidal volume always being diminished. In normal subjects, both mouth occlusion pressure and ventilation appeared to assess neural drive to the respiratory muscles in response to CO2 rebreathing; with elastic loading, only occlusion pressure continued to reflect neuromuscular output. This increased pressure response could have been mediated by neural reflex and/or intrinsic muscle mechanisms. The data suggest that mouth occlusion pressure may be a useful parameter for evaluating neuromuscular control mechanisms under conditions of increased lung elastance.

Adult↗
PubMedDate not supplied

Comparison of magnetometer and inductance plethysmography derived Konno-Mead diagrams during CO2 rebreathing.

Magnetometers measure changes in antero-posterior diameters of the rib cage and abdomen while respiratory inductance plethysmography (RIP) measures changes in chest wall cross-sectional area. We compared Konno-Mead diagrams derived from isovolume calibrated magnetometers and RIP in the DC-mode during room air and CO2 rebreathing in the sitting and supine positions. Chest wall configurations obtained during quiet tidal breathing were similar in both sitting and supine positions. During CO2 stimulated breathing, however, derived chest wall configurations were at times dissimilar. The RIP per cent rib cage contribution to tidal volume was greater than that of magnetometers during room air and CO2 rebreathing in both sitting and supine positions. Changes in end expiratory levels measured by magnetometers and RIP during CO2 rebreathing are in general proportionate to each other; however, the magnetometers usually depicted quantitatively greater decreases in abdominal end expiratory levels during rebreathing. We conclude that the qualitative and quantitative assessment of chest wall configurations and volume displacement vary depending on the method used. RIP by including lateral wall motion may more accurately reflect compartmental displacements, while magnetometers by solely measuring antero-posterior diameter may better reflect changes in abdominal volume and thus diaphragm configuration.

Adult↗