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At least 253 records · Page 14Linked to original sources
PubMed1991

Acoustic transmission of the respiratory system using speech stimulation.

Two methods for the analysis of the acoustic transmission of the respiratory system are presented. Continuous speech utterance is used as acoustic stimulation. The transmitted acoustic signal is recorded from various sites over the chest wall. The AR method analyzes the power spectral density function of the transmitted sound, which heavily depends on the microphone assembly and the utterance. The method was applied to a screening problem and was tested on a small database that consisted of 19 normal and five abnormal patients. Using the first five AR coefficients and the prediction error of an AR(10) model, as discriminating features, the system screened all abnormals. An ARMA method is suggested, which eliminates the dependence on microphone and utterance. In this method, the generalized least squares identification algorithm is used to estimate the ARMA transfer function of the respiratory system. The normal transfer function demonstrates a peak at the range of 130-250 Hz and sharp decrease in gain for higher frequencies. A pulmonary fibrotic patient demonstrated a peak at the same frequency range, a much higher gain in the high frequency range with an additional peak at about 700 Hz.

Adult↗
PubMed1986

Intermittent positive pressure breathing in patients with respiratory muscle weakness. Alterations in total respiratory system compliance.

Intermittent positive pressure ventilation (IPPB) is reported to improve lung compliance and decrease the work of breathing in subjects with kyphoscoliosis. These results suggest that IPPB may improve chest wall and lung compliance in patients with neuromuscular disease. We studied the short-term effects of IPPB on total respiratory system compliance in 14 subjects with neuromuscular disease. Seven were quadriplegics, and seven had muscular dystrophy. Vital capacity was reduced to 38 +/- 14 percent of the predicted normal values. Baseline measurements of total respiratory system compliance were 57 +/- 18 percent when compared to normal control values. After a 20 minute treatment of IPPB delivered with inspiratory pressures of 20 to 25 cm H2O that more than tripled resting tidal volume, there was no significant change in total respiratory system compliance in either group of patients. These findings indicate that patients with quadriplegia or muscular dystrophy do not derive immediate improvement in ventilatory mechanics from IPPB treatments.

Adolescent↗
PubMed1998

Effects of inhaled nitric oxide on respiratory system mechanics, hemodynamics, and gas exchange after cardiac surgery.

OBJECTIVE: To evaluate the hemodynamic and respiratory effects of inhaled nitric oxide (NO) in postoperative cardiac patients. DESIGN: A prospective evaluation. SETTING: A university hospital intensive care unit. PARTICIPANTS: Fourteen adults with pulmonary hypertension, studied postoperatively. INTERVENTIONS: 60 minutes of NO inhalation (20 ppm). MEASUREMENTS AND MAIN RESULTS: Respiratory mechanics were analyzed by inflating the relaxed respiratory system with constant flow, followed by rapid airway occlusion at end-inflation, which was maintained until a plateau in tracheal pressure was obtained. Gas exchange and hemodynamics were evaluated by conventional means. The data were studied using the analysis of variance for repeated measures. Minimum airway resistance (Rmin) increased significantly from 8.87+/-3.24 cm H2O/L x s to 9.69 +/-3.22 cm H2O/L x s at the end of NO inhalation and remained elevated after NO was discontinued. A selective vasodilator effect on pulmonary vasculature was observed in the pulmonary-systemic vascular resistance ratio, which decreased from 0.18+/-0.11 to 0.13+/-0.08 at the end of inhalation and returned to baseline values after gas suspension. No significant alterations in oxygenation were observed. CONCLUSION: The effects of NO as a powerful and useful vasodilator agent were confirmed. However, it is important to be aware that the effects observed on respiratory mechanics may interfere with the final response of the respiratory system to NO.

Administration, Inhalation↗
PubMed1992

Ancillary testing for the ruminant respiratory system.

With greater use of a wide variety of diagnostic tools, such as transtracheal washing, respiratory endoscopy, chest radiography, thoracic ultrasonography, blood gas analysis, and lung biopsy, veterinarians are gaining tremendous insight into pathogenic mechanisms of the ruminant respiratory system. We have available many diagnostic aids; some fairly simple and inexpensive, others highly sophisticated and presently at far greater cost than justifiable on most individual food animals. Some methods recently developed, such as same-day viral particle detection in BAL samples,6 have tremendous potential for rapid and accurate diagnosis in ruminant pulmonary medicine. Undoubtedly, future research in this area will provide an ever widening array of powerful and rapid diagnostic aids to deal with respiratory disease of ruminants.

Animals↗
PubMed1999

Respiratory system mechanics in patients receiving aerosolized ribavirin during mechanical ventilation for suspected respiratory syncytial viral infection.

Respiratory syncytial virus (RSV) is an important respiratory pathogen for infants. Aerosolized ribavirin (AR) has been used in mechanically ventilated (MV) patients with RSV bronchiolitis. The purpose of this study was to measure respiratory system mechanics (RSM) in pediatric patients requiring MV and receiving AR for suspected RSV. Patients were prospectively randomized to receive AR, either at a regular dose (RD) (6 g/300 mL over 18 hr/day) or a high dose (HD) (6 g/100 mL over 2 hr, three times a day). To measure changes in RSM, a passive exhalation technique was used before and after each dose of AR; time constant (tc) in s, resistance (Rrs) in cmH(2)O/mL/kg/s, and quasistatic compliance (Crs) in mL/cmH(2)O/kg were measured. Airway pressure and flow signals were obtained and analyzed using a pneumotachograph, a differential pressure transducer, and a computer interface. Statistical analysis was done by Mann-Whitney and Wilcoxon rank tests. Thirteen patients were enrolled: 5 patients in the HD group (mean age of 52 months), and 8 patients in the RD group (mean age of 10 months). Four and 5 patients were positive for RSV by ELISA in the HD and RD groups, respectively. The RSM in the HD group were: tc, 0.58 +/- 0.15 s and 0.55 +/- 0.20 s before and after AR, respectively; Rrs, 0.03 +/- 0. 03 cmH(2)0/mL/kg/s and 0.02 +/- 0.02 cmH(2)0/mL/kg/s, respectively; and Crs, 0.63 +/- 0.21 mL/cmH(2)O/kg and 0.70 +/- 0.13 mL/cmH(2)O/kg, respectively. In the RD group, the RSM were: tc, 0.37 +/- 0.12 s and 0.31 +/- 0.10 s before and after AR, respectively; Rrs, 0.03 +/- 0.02 cmH(2)0/mL/kg/s and 0.02 +/- 0.01 cmH(2)0/mL/kg/s, respectively (P < 0.05); and Crs, 0.46 +/- 0.20 mL/cmH(2)O/kg and 0.46 +/- 0.19 mL/cmH(2)O/kg, respectively. We conclude that the use of AR for bronchiolitis in infants and young children during mechanical ventilation does not worsen RSM.

Administration, Inhalation↗
PubMed1995

[Exercise test in respiratory system].

A ramp exercise test was thought to be adequate especially for evaluation of patients with respiratory system diseases. First, we told about the significances, the methods and apparatus, the arrangements for workload and the matters that demand special attentions of this exercise test. Next, various indices which were obtained during ramp exercise and the estimations of them were explained. Furthermore, we referred to the exercise-limiting factors for patients with COPD and pulmonary fibrosis as symmetrical respiratory system diseases.

Anaerobic Threshold↗
PubMed1984

[Review of the organogenesis of the respiratory system (excluding the pulmonary parenchyma)].

A simplified panorama of the different formation phases of the upper respiratory system (larynx, trachea, main bronchi) is presented. Chronologic evolution of organogenesis in embryologic phase and fetal phase is emphasized. Post-natal growing is also described. A classification of malformations of the upper respiratory system is done, based on topographic data. The mechanism of genesis of the malformations remains of hypothetical value.

Bronchi↗
PubMed1997

A model study of periodic breathing, stability of the neonatal respiratory system, and causes of sudden infant death syndrome.

A mathematical model of the neonatal respiratory system has been modified and used to examine the system under various physiological conditions at different stages of maturity. The respiratory responses in hypoxia, periodic breathing and following a sign have been analyzed. The effects of different respiratory parameters on the stability of the system for normal and premature infants have been investigated. The causes of periodic breathing, apnea spells and sudden infant death syndrome for full-term and premature infants have been studied, and the results compared with the available experimental findings. The response of the infant respiratory system has been found to be highly sensitive to several parameters of the system, as indicated by the results of this study. These significant parameters are sensitivity factor of central receptors to carbon dioxide, sensitivity factor of arterial receptors to carbon dioxide, sensitivity factor of arterial receptors to oxygen, functional residual capacity of the lungs, the alveolar-arterial oxygen difference and the lungs shunt ratio. It has been shown that different parts of the respiratory controller have antagonistic effects on hypoxic periodic breathing and apnea of infancy.

Computer Simulation↗
PubMed1984

Total resistance of the respiratory system in preterm infants with and without an endotracheal tube.

The passive compliance and resistance of the respiratory system were measured in 12 spontaneously breathing newborn infants before and after endotracheal extubation. End-inspiratory airway occlusions were used to relax the respiratory muscles, allowing occlusion pressure to be measured and respiratory system compliance and resistance to be calculated from the flow volume relationship of the subsequent passive expiration. Airway pressure was measured from an endotracheal tube or a face mask, expiratory flow from a pneumotachograph, and expiratory volume from the integrated flow signal. In six of the infants, diaphragmatic electromyography was also performed before and after extubation. Resistance and EMG findings were both decreased by extubation (mean decrease 43.9%, P less than 0.001 and 27.3%, P less than 0.05, respectively), but compliance was unchanged. Thus, by substantially increasing resistance, an endotracheal tube causes the diaphragm to increase its activity to maintain ventilation.

Airway Resistance↗
PubMed2005

The effects of environmental pollution on the respiratory system of children in western Macedonia, Greece.

The indoor and outdoor environmental pollution effects on the respiratory system of 3,559 children aged 9-12 were studied. It was a cross-sectional and interlocal (geographical differentiation) study. The research was conducted during the period between 2000-2001 in five cities of Western Macedonia and more particularly: 1046 children from Ptolemaida, 1249 children from Kozani, 466 from Florina, 419 from Kastoria and 379 from Grevena. The study was performed by means of a questionnaire for the detection of respiratory diseases during childhood, plus spirometry and rhinomanometry measurements. The diachronic quantitative analysis of environmental pollutants was conducted by The Laboratory of Physics of the Atmosphere of the Aristotle University of Thessaloniki. The environmental pollution was found to have a detrimental effect on the respiratory system of children, mainly attributable to the occurrence of rhinitis and infectious bronchitis. The highest prevalence of rhinitis (40.3%) and infectious bronchitis (12.1%) was observed in Ptolemaida, which is a highly polluted region, whereas the lowest (21.2% and 6.7%, respectively) was seen in Grevena, a non-polluted area. As for the indoor pollution, maternal smoking was found to increase the prevalence of respiratory problems in children. Finally, the father's educational level and a past history of nursery school attendance increase the prevalence of respiratory diseases during childhood.

Child↗
PubMed1980

[Respiratory system diseases among the rural population].

The author analyzes the level and structure of morbidity of respiratory system diseases among the rural population, according to age--sex groups on the base of the data from routine statistics (1970-1978) and typological studies of general morbidity carried out in Sliven district (1977). The complex methodics applied allowed to study the morbidity according to repeated visits (registered) and that, established at the prophylactic screening (latent) of a representative sample of the population under observation. The results from that study revealed that the actual morbidity (registered according to visits and established with the complex medical screening) of the respiratory system diseases, among rural population is 625,7%. Morbidity among males is higher (664,2%) than that of females (570,3%). Highest is the morbidity among subjects over the age of 60 and among children (0-14 years).

Adolescent↗