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At least 415 records · Page 23Linked to original sources
PubMed1997

Analysis of perfluorochemical elimination from the respiratory system.

We describe a simple apparatus for analysis of perfluorochemicals (PFC) in expired gas and thus a means for determining PFC vapor and liquid elimination from the respiratory system. The apparatus and data analysis are based on thermal conduction and mass transfer principles of gases. In vitro studies were conducted with the PFC vapor analyzer to determine calibration curves for output voltage as a function of individual respiratory gases, respiratory gases saturated with PFC vapor, and volume percent standards for percent PFC saturation (%PFC-Sat) in air. Voltage-concentration data for %PFC-Sat of the vapor from the in vitro tests were accurate to within 2.0% from 0 to 100% PFC-Sat, linear (r = 0.99, P < 0.001), and highly reproducible. Calculated volume loss of PFC liquid over time correlated well with actual loss by weight (r = 0.99, P < 0. 001). In vivo studies with neonatal lambs demonstrated that PFC volume loss and evaporation rates decreased nonlinearly as a function of time. These relationships were modulated by changes in PFC physical properties, minute ventilation, and postural repositioning. The results of this study demonstrate the sensitivity and accuracy of an on-line method for PFC analysis of expired gas and describe how it may be useful in liquid-assisted ventilation procedures for determining PFC volume loss, evaporation rate, and optimum dosing and ventilation strategy.

Animals↗
PubMed1998

[Tuberculosis in respiratory system--tracheo-bronchial tuberculosis, pulmonary tuberculosis, tuberculous pleurisy and thoracic empyema].

Tuberculosis in respiratory system is most common in mycobacterial infections. Eighty percent of the patients with pulmonary tuberculosis visit hospital because of the respiratory symptoms, and only 10% of them were discovered by chest X-ray mass screening. In order to confirm respiratory tuberculosis, various methods to obtain specimens for mycobacterial examination have been carried out; hypertonic saline nebulizing for sputum expectoration, trans-bronchoscopic biopsy, percutaneous needle aspiration, and so on. The recent development of imaging modalities including CT, MRI, and ultrasonogram have been much contributed to the improvement of diagnosis of pleural tuberculosis. Basically, the main treatment for respiratory tuberculosis is chemotherapy except chronic tuberculous thoracic empyema. The initial chemotherapy regimen should be chosen among the three arms; [INH + RFP + PZA + EB (or SM)] x 2-->[INH + RFP] x 6, [INH + RFP + EB (or SM)] x 6-->[INH + RFP] x 3-6, and [INH + RFP] x 6-9. The sputum positive patient is recommended to have the chemotherapy regimen including PZA. In the patients with tracheo-bronchial tuberculosis an attention should be paid for the airway narrowing or obstruction during and after the scheduled chemotherapy. For a part of patients with tuberculous pleurisy and thoracic empyema, a surgical treatment must be indicated.

Empyema, Tuberculous↗
PubMed1990

[Passive compliance of the total respiratory system in newborn infants born by cesarean section].

The compliance of the total respiratory system (CRS) was measured by the occlusion technique: a) at H1-H2, H6-H7 and D3-D4 in 8 full-term newborns after cesarean section; b) at H1-H2 and H6-H7 in 6 full-term newborns delivered vaginally and at D3-D4 in 10 full-term newborns delivered vaginally. At H1-H2 respiratory frequency measured by inductive plethysmography was not significantly different between newborns after cesarean section (60 +/- 6 c/min) and newborns delivered vaginally (53 +/- 16 c/min). CRS normalized for body weight was not significantly different between newborns after cesarean section and those delivered vaginally at H1-H2 (0.6 +/- 0.1 vs 0.7 +/- 0.1 ml/cmH2O/kg) and at H6-H7 (0.7 +/- 0.1 vs 0.8 +/- 0.3 ml/cmH2O/kg). At D3-D4, CRS was significantly greater than at H6-H7 in newborns after cesarean section (1.1 +/- 0.2 ml/cmH2O/kg, p less than 0.001) and in newborns delivered vaginally (1 +/- 0.1 ml/cmH2O/kg, p less than 0.02). We conclude that in newborns after cesarean section without tachypnea, the evolution in CRS is similar to that in newborns delivered vaginally.

Analysis of Variance↗
PubMed1995

Elevated static compliance of the total respiratory system: early predictor of weaning unsuccess in severed COPD patients mechanically ventilated.

OBJECTIVE: To assess in a group of COPD patients mechanically ventilated for an episode of acute respiratory failure the respiratory mechanics with a simple and non invasive method at the bedside in order to evaluate if these parameters may be predictive of weaning failure or success. DESIGN: A prospective study. SETTING: Intensive care and intermediate intensive care units. PATIENTS: 23 COPD patients ventilated for acute respiratory failure and studied within 24 hours from intubation. METHODS: Using end-expiratory and end-inspiratory airway occlusion technique, we measured PEEPi, static compliance of the respiratory system (Crs, st) maximum respiratory resistance (Rrsmax) and minimum respiratory resistance (Rrsmin). MEASUREMENTS AND RESULTS: The weaned group (A) and the not weaned group (B) were not different regarding to static PEEPi (group A 8.5 +/- 4.0 vs group B 8.9 +/- 2.6 cmH2O), TO Rrsmax (22.4 +/- 5.3 versus 22.2 +/- 9.0 cmH2O/1/s) and to Rrsmin (17.6 +/- 5.5 versus 17.9 +/- 8.0 cmH2O/1/s), while a significant difference (p < 0.001) has been found in Cst, rs (62.7 +/- 17.% versus 111.6 +/- 18.0 ml/cm H2O). The threshold value of 88.5 ml/cmH2O was identified by discriminant analysis and provided the best separation between the two groups, with a sensitivity of 0.85 and a specificity of 0.87. CONCLUSION: Cst, rs measured non invasively in the first 24 h from intubation, provided a good separation between the patients who were successfully weaned and those who failed.

Acute Disease↗
PubMed1978

The anatomy and physiology of the bovine respiratory system relating to pulmonary disease.

Bovine respiratory anatomy and physiology were reviewed and considered in relationship to the pathogenesis of pulmonary disease. Factors which may predispose cattle to respiratory disease included a small physiological gaseous exchange capacity, greater basal ventilatory activity, and greater anatomical compartmentalization of the lung as compared with other mammals, a low level and atypical bioactivity of bovine lysozyme, and low numbers of macrophages within the alveolar lumen.

Animal Feed↗
PubMed1997

[Theoretical basis for the antibiotic therapy of the upper part of the respiratory system].

The paper presents the views on the etiology of infections in the respiratory system. Beside the so called "old pathogens" such as Streptococcus pneumoniae, Haenophilus influenzae, Moraxella catarrhalis, "atypic" microorganisms are becoming more and more important, i.e. Mycoplasma pneumoniae, Legionella pneumophila, Chlamydia pneumoniae. Mixed flora with aerobic and anaerobic bacteria is observed in chronic infections. Viral infections facilitate bacterial infections. Antibiotic used first should be active against the "old" and "new" pathogens. Future prospects are set on macrolides such as clarythromycin.

Anti-Bacterial Agents↗
PubMed1998

Biochemical and histopathological changes in respiratory system of rats following exposure to diesel exhaust.

Effect of exposure to diesel exhaust (DE) for different durations was evaluated using histopathological and biochemical parameters in respiratory system of the rats. Animals were exposed to 1 part DE diluted with 5 parts of clean air in a simulation chamber for 15 min/day for 1, 7, 14 and 21 days. After completion of various exposures, biochemical parameters including elastase inhibitory capacity (EIC) and protein content of the bronchial airway lavage (BAL) and histopathological changes along with lung/body weight ratio were assessed. The elastase inhibitory capacity (an index of the protection against destruction of elastin, a lung connective tissue) was maximum at 1 week indicating thereby that the body renders protection against injury by increasing EIC levels in the initial phase. However, protein content in the BALF increased after 1 week and reached maximum at 2 weeks. Histopathological changes followed similar time course of pattern with accumulation of macrophages and protein exudation. Prolonged exposure up to 3 weeks, however was accompanied by chronic inflammatory changes and thickening of alveolar septa and blood vessels. Changes in lung/body weight ratio and suspended particulate matter (SPM) deposited on filters (simulation chamber) correlated well with EIC, protein content in BALF and histopathological changes. The biochemical findings accompanied with chronic structural changes in the lungs of rats following exposure to DE could be relevant to the clinical observation of increased incidence of chronic lung diseases after continued DE exposure.

Air Pollutants↗
PubMed1989

[Function of the respiratory system in miners with chronic regional hypobaric hypoxia and hypothermia].

The role of meteotropic factors (low atmospheric pressure and cold climate) in the development of functional disorders of respiratory system was studied for miners of the North-East region of the USSR. Regularities in forming external respiration dysfunctions during adaptation of migrating population and development of dust pathology are demonstrated. It was found that general adaptation syndrome in miners exposed to chronic hypobaric hypoxia and hypothermia is characterized by development of hyperventilation syndrome, leading to increase in dust load and moderate mobilization of respiratory tissue. Early failure of compensatory processes and forming of marked hyperventilation syndromes, an increase in pulmonary elastic draught and mobilization of respiratory tissue are observed in dust pathology in the analyzed conditions.

Adaptation, Physiological↗
PubMed1996

Differentiation of Pasteurella multocida subspecies multocida isolates from the respiratory system of pigs by using polymerase chain reaction fingerprinting technique.

PCR fingerprinting technique was applied to subtype 44 Pasteurella multocida subspecies multocida (P.m.sp.m.) isolates from the respiratory system of pigs. Two single primers were tested for their abilities to generate individual fingerprints by using PCR. Primer 1 (core sequence of the M13 phage) grouped the 44 P.m.sp.m. strains into five distinct fingerprinting profiles, while primer 2 ((GACA)4) grouped them into seven profiles. The results suggest that PCR fingerprinting is an efficient technique to detect DNA polymorphism in the species P.m.sp.m. This technique could be used to differentiate P.m.sp.m. strains of the same capsular serotype.

Animals↗
PubMed1978

How aging affects the structure and function of the respiratory system.

Age-associated changes in the lung resemble emphysema. Progressive loss of the aging lung's static recoil forces produces airway closure at lung volumes in the tidal volume range,which leads to decreased arterial Po2. Under conditions that decrease oxygen content of arterial blood, the increase in both ventilation and cardiac output is smaller in elderly persons than in younger subjects. Therefore, less oxygen may be delivered to the tissues. Muscular strength of the respiratory apparatus consistently declines and the chest wall stiffens with advancing age. Thus, the elderly have weaker muscles to act on a chest wall that becomes progressively harder to move. Both maximal inspiratory and expiratory pressures are significantly decreased. Loss of the functional reserve of the respiratory system with age increases the risk of respiratory failure and leaves elderly subjects with decreased compensatory mechanisms for dealing with even moderate stress. The physician must be aware of these problems and provide early and vigorous respiratory care for elderly patients.

Adult↗
PubMed1989

Passive total respiratory system compliance and gas exchange in newborns with hyaline membrane disease.

Passive total respiratory system compliance (CRS) and gas exchange measurements were performed in nine newborns during the course of hyaline membrane disease. None of the subjects presented bronchopulmonary dysplasia at follow-up investigations. Gestational age ranged from 29 to 37 weeks. CRS was measured by the multiple occlusion technique. Gas exchange parameters were the fraction of inspired oxygen concentration (FIO2) and the arterial/alveolar ratio for oxygen (a/AO2 ratio). In each subject four tests were performed: test 1 during the first day of life; test 2 during the second day of life; test 3 between the fourth and the seventh days of life; test 4 after extubation. CRS/BW (CRS normalized for body weight) was not statistically different at tests 1-3, but it significantly increased (P less than 0.001) between tests 3 and 4. FIO2 and a/AO2 ratio presented no statistical difference at tests 1-2 but several significant differences were noted thereafter: FIO2 decreased significantly (P less than 0.001) when results from tests 2 and 3 were tabulated. The a/AO2 ratio increased significantly between tests 2 and 3 (P less than 0.001), and a further significant increase (P less than 0.01) was also noted when results obtained during tests 3 and 4 were compared. A significant relationship existed during the evolution of the disease between CRS/BW and gas exchange parameters (FIO2 and a/AO2 ratio) (P less than 0.01), but gas exchange improved earlier than lung mechanics.

Bronchopulmonary Dysplasia↗
PubMed1993

Changes in the cardiovascular and respiratory systems during laparoscopic cholecystectomy.

The effects of peritoneal insufflation on the cardiovascular and respiratory systems were investigated in eight patients who underwent laparoscopic cholecystectomy. During the operation, intraabdominal pressure was maintained at a constant 12 mm Hg with carbon dioxide. The cardiac index had increased significantly at 20 and 40 min after the start of insufflation (3.6 +/- 0.6, 3.9 +/- 0.8 mL/min, respectively) and after evacuation (4.2 +/- 0.6 mL/min) compared with the control value (3.2 +/- 0.6 mL/min). Mean arterial pressure was significantly increased at 20 min after the start of insufflation (94.6 +/- 11.2 mm Hg) relative to the control value (79.9 +/- 11.1 mm Hg) and remained high after evacuation (101.5 +/- 11.9 mm Hg). Central and femoral venous pressure rose significantly during the operation from baseline values (12 +/- 6 and 4 +/- 4 mm Hg, respectively) to 18 +/- 10 and 11 +/- 6 mm Hg, respectively, at 20 min, and to 18 +/- 10 and 19 +/- 8 mm Hg, respectively, at 40 min after the start of insufflation. These parameters returned to control levels immediately after evacuation. Dynamic lung compliance decreased by 25% as a result of the elevated intraabdominal pressure. These findings demonstrate that some cardiopulmonary changes occur even at an intraabdominal pressure of 12 mm Hg, which up to now has been considered a safe level.

Carbon Dioxide↗
PubMed1987

Modeling of respiratory system impedances in dogs.

Mechanical impedances between 4 and 64 Hz of the respiratory system in dogs have been reported (A.C. Jackson et al. J. Appl. Physiol. 57: 34-39, 1984) previously by this laboratory. It was observed that resistance (the real part of impedance) decreased slightly with frequency between 4 and 22 Hz then increased considerably with frequency above 22 Hz. In the current study, these impedance data were analyzed using nonlinear regression analysis incorporating several different lumped linear element models. The five-element model of Eyles and Pimmel (IEEE Trans. Biomed. Eng. 28: 313-317, 1981) could only fit data where resistance decreased with frequency. However, when the model was applied to these data the returned parameter estimates were not physiologically realistic. Over the entire frequency range, a significantly improved fit was obtained with the six-element model of DuBois et al. (J. Appl. Physiol. 8: 587-594, 1956), since it could follow the predominate frequency-dependent characteristic that was the increase in resistance. The resulting parameter estimates suggested that the shunt compliance represents alveolar gas compressibility, the central branch represents airways, and the peripheral branch represents lung and chest wall tissues. This six-element model could not fit, with the same set of parameter values, both the frequency-dependent decrease in Rrs and the frequency-dependent increase in resistance. A nine-element model recently proposed by Peslin et al. (J. Appl. Physiol. 39: 523-534, 1975) was capable of fitting both the frequency-dependent decrease and the frequency-dependent increase in resistance. However, the data only between 4 and 64 Hz was not sufficient to consistently determine unique values for all nine parameters.

Airway Resistance↗
PubMed1984

[Effect of furfural on the respiratory system].

Fifty-one workers of Butadien Plant, exposed to furfurol , had their respiratory system examined. Questionnaire studies demonstrated chronic bronchitis in 23.5% of subjects. Spirometric tests do not show subjective complaints. This seems to be related to hypercortisolemia, as experiments on animals indicate that furfurol inhalations increase corticosteroids concentrations in blood serum.

Adolescent↗
PubMedDate not supplied

[Early morphological changes of the respiratory system after blunt multiple trauma].

Pronounced changes with a specific development sequence were detected on the basis of microscopy and morphometry examinations of peculiarities of structural changes in the respiratory system in death soon after mechanical trauma concomitant with head injuries. It was demonstrated the way the severity of histomorphologic changes occurring in the lungs influence the survival time of victims after trauma (time prescription).

Erythrocyte Aggregation↗
PubMed1986

Forced oscillatory impedance of the respiratory system at low frequencies.

Respiratory mechanical impedances were determined during voluntary apnea in five healthy subjects, by means of 0.25- to 5-Hz pseudo/random oscillations applied at the mouth. The total respiratory impedance was partitioned into pulmonary (ZL) and chest wall components with the esophageal balloon technique; corrections were made for the upper airway shunt impedance and the compressibility of alveolar gas. Neglect of these shunt effects did not qualitatively alter the frequency dependence of impedances but led to underestimations in impedance, especially in the chest wall resistance (Rw), which decreased by 20-30% at higher frequencies. The total resistance (Rrs) was markedly frequency dependent, falling from 0.47 +/- 0.06 (SD) at 0.25 Hz to 0.17 +/- 0.01 at 1 Hz and 0.15 +/- 0.01 kPa X l-1 X s at 5 Hz. The changes in Rrs were caused by the frequency dependence of Rw almost exclusively between 0.25 and 2 Hz and in most part between 2 and 5 Hz. The effective total respiratory (Crs,e) and pulmonary compliance were computed with corrections for pulmonary inertance derived from three- and five-parameter model fittings of ZL. Crs,e decreased from the static value (1.03 +/- 0.18 l X kPa-1) to a level of approximately 0.35 l X kPa-1 at 2-3 Hz; this change was primarily caused by the frequency-dependent behavior of chest wall compliance.

Abdominal Muscles↗
PubMed1996

Lung volumes and pressure-volume relations of the respiratory system in small ventilated neonates with severe respiratory distress syndrome.

Total lung capacity (TLC), inspiratory capacity (IC), functional residual capacity (FRC), and deflation pressure-volume (P-V) curves were studied in 16 intubated neonates (540-3300 g), 10 with severe respiratory distress syndrome (RDS) and 6 air-ventilated with normal chest radiograms. FRC was measured using washout of a tracer gas (sulfur hexafluoride), and TLC and IC were calculated after inflating the lungs to 30 cm H2O. P-V curves were obtained during expiration from TLC using an interrupter technique, and the steepest slope of the curve, i.e. the maximum compliance (Crs-max), was calculated. In addition, an index of ventilation inhomogeneity (pulmonary clearance delay, PCD) was computed from the shape of the SF6 washout curve. TLC/body weight was less in the RDS group than in the air-ventilated group (median 19 and range 16-43 mL/kg versus 48 and 43-52 mL/kg, respectively; p < 0.01), mainly because of a marked reduction in IC (median 11 and range 8-24 mL/kg versus 29 and 28-40 mL/kg; p < 0.01). The flatter P-V curve in the RDS group was reflected also in a lower Crs-max (median 0.7 and range 0.4-1.7 cm H2O-1 kg-1) than in the air-ventilated group (2.3 and 2.0-3.1 mL cm H2O-1 kg-1, respectively; p < 0.01). Thus, there was no overlap in IC or Crs-max between the groups, suggesting that reductions in these measures may be main characteristics of RDS. On the other hand, no difference in PCD was found, indicating that, in infants with RDS, the tidal volume is distributed fairly homogeneously to the ventilated parts of the lungs.

Functional Residual Capacity↗