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At least 559 records · Page 31Linked to original sources
PubMed1991

[Determination of respiratory system compliance from resonance frequency--animal experiment].

10 anaesthetized and tracheotomized rabbits were used to test the possibility for calculation of total respiratory system compliance from resonance frequency (CR). Reference values were obtained by inflation method compliance (CI). A new servocontrolled infant ventilator was used with an integrated negative ventilator resistance mode for resistive unloading of combined resistances of lung, endotracheal tube and ventilator. This evoked oscillation at resonant frequency. By analogy with electrical circuit theory compliance was calculated as follows: CR = 1/(4 pi 2 x square root I.RF2). Pairs of CI and CR values were obtained from each animal during spontaneous breathing, after pancuronium relaxation and after surfactant depletion by lavage. There was found a significant linear correlation between CR and CI values (CR = 1.1 x CI-0.74; r = 0.97).

Animals↗
PubMed1975

[Functional conditions of the respiratory system and work site pollution. II. Prevalence of respiratory function changes in workers employed in bichromate and chromic acid production (author's transl)].

The authors report the prevalence of respiratory function changes in two groups of workers employed in bichromate and chromic acid production. In the first group (82 subjects) examined at the Institute of Occupational Medicine, the following tests were performed: filling out of a questionnaire for cronic bronchitis; chest x-ray; spirometry; pulmonary diffusing capacity (DLco) measurement; blood gas analysis on arteriolized capillary; He and CO2 rapid expiratory curves determination. No environmental pollution data were available. In the second group (180 subjects) examined at the working site, the following tests were performed: filling out of a questionnaire -or chronic bronchitis; spirometric determination. Environmental pollution data were available. A causal connection is hypothesized by the authors between either roentgenologic or respiratory functional changes and chromium exposure, and an increased proportion between lung function changes and exposure length is stressed.

Adult↗
PubMed1987

Physiological, anatomic and behavioural changes in the respiratory system of Salmo gairdneri Rich. On acute and chronic exposure to chlorothalonil.

1. Various changes in anatomical, physiological and behavioural aspects of the respiratory system of Salmo gairdneri on exposure to chlorothalonil (TCIN) were examined, along with the relationship between LC50 response and oxygen concentration. 2. The TCIN LC50 was significantly lower at 5 mg/l oxygen concentration than at 8 mg/l. 3. Haematocrit was depressed on exposure to TCIN, whereas exposure to pentachlorophenol and lindane raised the haematocrit. Muscle lactate was not elevated in acutely exposed fish. 4. Ventilatory frequency was raised above 30 micrograms/l TCIN. 5. Gills of fish exposed to 2.0 micrograms/l TCIN for 24 days had reduced lamellar diffusive capacity, primarily caused by an increase in blood barrier thickness.

Animals↗
PubMed1994

Changes of respiratory system mechanics in ventilated lungs of preterm infants with two different schedules of surfactant treatment.

We investigated the time course of changes in the static respiratory system compliance and resistance in relationship to surfactant administration by means of single-breath and multiple-occlusion techniques. The study comprised 12 infants receiving a high-dose schedule (200 mg/kg, maximum 600 mg/kg) and 13 infants receiving a low-dose schedule (100 mg/kg, maximum 300 mg/kg) of porcine surfactant. Eight healthy preterm infants served as a comparison group. Respiratory mechanics were studied before and at 1.5, 8, and 72 h after surfactant administration. Results were related to changes in gas transfer, including an estimate of venous admixture. Static compliance improved after surfactant instillation, and changes were similar in the two treatment groups during the first eight h (0.8 In.(hour + 1) mL.kPa-1). The compliance values remained below the values of the healthy comparison group during the whole study period, but resistance remained at the same level. There was a considerable delay in changes of respiratory mechanics in relationship to the rapid fall of the venous admixture, from 27 to 19%, and the rapid increase of the transcutaneous oxygen pressure/fraction of inspired oxygen ratio from 13 to 27 kPa within the hour. There were no clues that short-term changes in compliance were masked by breathing at a higher and flatter portion of the pressure-volume curve. Both treatment schedules resulted in a similar improvement of compliance within 72 h and the two groups benefited similarly in terms of venous admixture.

Airway Resistance↗