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PubMed2000

[Evolution of Spanish scientific production in international respiratory system journals from 1987 to 1998].

BACKGROUND: A relevant increase in the clinical relevance of respiratory system area has occurred in the last few years. The aims of this study were: to analyze the evolution of production and impact of Spanish scientific activity in the respiratory system area between 1987 to 1998; and to assess the participation of the different Spanish autonomic communities in this activity. METHODS: Papers published in 38 international journals of respiratory system during this period of time were selected by the MedLine system, delimiting Spanish production. Geographical and institutional distribution of the production, specialist of authors, main publication journals and type of publication were recorded. Production and impact bibliometric indicators were estimated. RESULTS: The number of Spanish documents from 1987 to 1998 multiplied by eight, reaching the 1.49% of the total published documents in 1998. However, the growth model of scientific production during this period was lineal. The increase in the scientific production was associated with a increase over time in the expected impact factor. In 1998, expected impact factor was 2. 206. Forty-two percent of the papers were signed by pneumologists. The highest contributor were hospitals. The most productive autonomous communities were Catalonia, Cantabria and Madrid. The communities with the highest expected impact factor were Balears and Catalonia. CONCLUSIONS: A relevant increase has occurred in the scientific production and impact of Spanish biomedical activity in respiratory system area.

Publishing↗
PubMed1997

Evaluation of the equine respiratory system using physical examination and endoscopy.

Defining respiratory disease is not always easy in the horse because auscultation with accurate interpretation of lung sounds can be difficult. However, performing a thorough physical examination, including rebreathing auscultation and percussion of the thorax and sinuses, is very useful in elucidating the problem. Endoscopic examination of the upper respiratory system is also critical for definitively diagnosing certain conditions.

Ambulatory Care↗
PubMed1995

Paralysis has no effect on chest wall and respiratory system mechanics of mechanically ventilated, sedated patients.

OBJECTIVE: To evaluate the separate effects of sedation and paralysis on chest wall and respiratory system mechanics of mechanically ventilated, critically ill patients. SETTING: ICU of the University "La Sapienza" Hospital, Rome. PATIENTS AND PARTICIPANTS: 13 critically ill patients were enrolled in this study. All were affected by disease involving both lungs and chest wall mechanics (ARDS in 4 patients, closed chest trauma without flail chest in 4 patients, cardiogenic pulmonary oedema with fluidic overload in 5 patients). MEASUREMENTS AND RESULTS: Respiratory system and chest wall mechanics were evaluated during constant flow controlled mechanical ventilation in basal conditions (i.e. with the patients under apnoic sedation) and after paralysis with pancuronium bromide. In details, we simultaneously recorded airflow, tracheal pressure, esophageal pressure and tidal volume; with the end-inspiratory and end-expiratory airway occlusion technique we could evaluate respiratory system and chest wall elastance and resistances. Lung mechanics was evaluated by subtracting chest wall from respiratory system data. All data obtained in basal conditions (with the patients sedated with thiopental or propofol) and after muscle paralysis were compared using the Student's t test for paired data. The administration of pancuronium bromide to sedated patients induced a complete muscle paralysis without producing significant modification both to the viscoelastic and to the resistive parameters of chest wall and respiratory system. CONCLUSIONS: This study demonstrates the lack of additive effects of muscle paralysis in mechanically ventilated, sedated patients. Also in view of the possible side effects of muscle paralysis, our results question the usefulness of generalized administration of neuromuscular blocking drugs in mechanically ventilated patients.

Adult↗
PubMedDate not supplied

[Effects of organic aerosols on the respiratory system in occupational exposure].

The effects of organic dusts on the respiratory system of workers employed in food processing, in textile workers, as well as in agricultural and livestock farmers are reported. Deposition and elimination of particles from the lung as well as the possible mechanisms of the organic dust effects on respiratory system are described. Separately are presented results of our investigations on the prevalence of respiratory symptoms and diseases as well as lung function tests as indicators of the condition of the respiratory system. Data on the experimental studies with aqueous extracts of organic dusts on smooth muscle of isolated guinea pig trachea suggest that the bronchoconstrictive effects in humans can be reproduced in nonsensitized guinea pigs. The preventive measures in the development of respiratory impairments in subjects occupationally exposed to organic dusts are described.

Agricultural Workers' Diseases↗
PubMed1985

Analysis of the behavior of the respiratory system with constant inspiratory flow.

For a respiratory system with constant compliance and resistance a constant flow can occur during part or all of inspiration in two situations: when the flow is constrained to be constant throughout inspiration, such as is the case with some mechanical ventilators, and when the applied pressure is a ramp (i.e., increasing constantly with time), which may occur during mechanical ventilation and spontaneous breathing. After initial transients in pressure and flow, respectively, have decayed away both situations result in linear volume-time and pressure-time relationships. The slope of the corresponding pressure-volume line then yields an estimate of the total compliance of the respiratory system, and the intercept, divided by the constant flow, provides the total resistance. We have shown theoretically that, for a model composed of two compartments in parallel, the total compliance is the same as the static compliance and equals the sum of the compliances of the two compartments. Furthermore, this compliance is independent of the breathing frequency. However, the total resistance is, in general, a function of both the resistances and the compliances. When the time constants of the two compartments are equal the total resistance assumes its minimum value and becomes independent of the compliances. This minimum value of resistance can be obtained, regardless of the time constants, by dividing the immediate drop in airway opening pressure, obtained after occluding during steady state inspiration, by the inspiratory flow.

Airway Resistance↗
PubMed1992

Effect of tidal volume on respiratory system elastance and resistance during anesthesia and paralysis.

Recent studies have shown that the mechanical properties of the respiratory system at normal breathing frequency in awake humans depend on tidal volume. Few measurements of respiratory system properties during anesthesia have accounted for this dependence. From measurements of airway pressure, flow and esophageal pressure, we calculated elastances and resistances of the total respiratory system (Ers and Rrs), chest wall (Ecw and Rcw), and lungs (El and Rl) in supine human volunteers during quasisinusoidal volume forcing in a normal range of breathing (250 to 800 ml) at normal breathing frequency (0.2 Hz). Measurements were made (1) with subjects awake and voluntarily relaxed; (2) after isoflurane-N2O anesthesia (end-tidal isoflurane concentration 0.3 to 0.5%); and (3) after complete muscle paralysis with vecuronium. In all conditions, Ers, Ecw, El, Rrs, and Rcw decreased at 800 ml tidal volume compared with 250 ml; Rl showed a similar decrease in awake measurements only. Compared with awake measurements, each elastance tended to increase after anesthesia, but only the increase in Ers was significant. Compared with anesthesia, there was no effect of paralysis on any measurement. We conclude that (1) tidal volume dependence of respiratory system properties in the normal range of breathing occurs in the absence of muscle activity; (2) anesthesia increases Ers and (3) respiratory muscle activity appears to be inhibited by isoflurane-N2O anesthesia at end-tidal isoflurane concentration of 0.3 to 0.5% during normocapnia.

Adult↗
PubMed1984

Airway pressures in an asymmetrically branched airway model of the dog respiratory system.

A computer model of the mechanical properties of the dog respiratory system based on the asymmetrically branching airway model of Horsfield et al. (11) is described. The peripheral ends of this airway model were terminated by a lumped-parameter impedance representing gas compression in the alveoli, and lung and chest wall tissue properties were derived from measurements made in this laboratory. Using this model we predicted the respiratory system impedance and the distribution of pressures along the airways in the dog lung. Predicted total respiratory system impedances for frequencies between 4 and 64 Hz at three lung volumes were found to compare quite closely to measured impedances in dogs. Serial pressure distributions were found to be frequency-dependent and to result in higher pressures in the lung periphery than at the airway opening at some frequencies. The implications of this finding for high-frequency ventilation are discussed.

Airway Resistance↗
PubMed1955

Increased mortality from cancer of the respiratory system.

The author reviews statistics of mortality from cancer of the respiratory system over the years 1949-52 in sixteen countries, first considering the general trend and then analysing the figures country by country. It is noted that the levels of recorded mortality from malignant tumours of the respiratory system differ considerably between countries, and that the death-rate from these causes has considerably risen, mainly in males, in all those countries in the course of the four years under study. The rise in recorded mortality in men has mainly been due to an increased number of tumours of the trachea, bronchus, and lungs. But the situation regarding mortality from these causes in women is not so clearly apparent. How much of the recorded increase is attributable to improved diagnosis and case-finding it is not yet possible to say.It is clear that cancer of the lung is becoming an important medical problem to which close attention must be paid.

Female↗
PubMed1991

Respiratory system mechanical behavior in the chicken.

We evaluated whether the avian respiratory system displays the same fundamental mechanical behavior during external forcing as found in mammals. We measured airway flow and pressures in the trachea, air sacs and thoracoabdominal cavity in 4 anesthetized-paralyzed roosters during sinusoidal volume oscillations at the trachea in the normal range of euthermic breathing frequency, f(0.2 to 1.0 Hz), and tidal volume, VT (10-50 ml). From the pressure and flow waveforms, we calculated resistance (R) and elastance (E) of the total respiratory system and its major compartments (lungs, air sacs and chest wall). E of the chest wall was minimum (147 cmH2O.L-1 +/- 7 SE) at 0.2 Hz-50 ml and was consistently, slightly lower than E of the total respiratory system over the entire range studied. Both elastances showed the same dependence on f and VT, increasing slightly with increasing f and decreasing with increasing VT. R of the chest wall was maximum (35.6 cmH2O.L- 1.sec-1 +/- 2.2 SE) at 0.2 Hz-10 ml and decreased with increasing f and VT, although the VT effect diminished at the higher f. E and R of the air sacs were much smaller than those of the chest wall, but showed similar f and VT dependencies. R of the lungs, due to resistance of the airways, was minimum (6.8 cmH2O.L-1.sec-1 +/- 1.5 SE) at 0.2 Hz-10 ml and increased with both f and VT. Total respiratory R reflected R of the air sacs and chest wall at low f and R of the lungs at high f. The f and VT dependencies of E and R in the chicken were strikingly similar to those measured in various types of mammalian respiratory tissues (Stamenović et al. (1990) J. Appl. Physiol. 69: 973-988. We conclude that, despite important anatomical differences between species, avian and mammalian respiratory tissues exhibit fundamentally similar mechanical behavior.

Airway Resistance↗
PubMed1993

Effects of fentanyl administration on respiratory system compliance in infants.

OBJECTIVE: To determine if the analgesic doses of fentanyl used in a pediatric intensive care unit (ICU) setting adversely affect dynamic total respiratory system compliance in awake, intubated infants. DESIGN: Prospective case-control study. SETTING: Pediatric and pediatric cardiac ICUs of a tertiary university hospital. PATIENTS: Thirteen awake and mechanically ventilated children < 6 months of age. INTERVENTIONS: Measurements of dynamic total respiratory system compliance were obtained during steady-state conditions for 6 mins and continued for 10 mins after the rapid, intravenous administration of 4 micrograms/kg of fentanyl. No patient had received a narcotic, benzodiazepine, or muscle relaxant within the previous 4 hrs. MEASUREMENTS AND MAIN RESULTS: After fentanyl administration, dynamic total respiratory system compliance was unchanged in three patients, improved in nine patients, and deteriorated in one patient. The mean value for the entire group increased from 0.76 mL/cm H2O/kg before infusion to 0.82 mL/cm H2O/kg after infusion (p < .02), representing a 9.6% increase. None of the patients showed oxygen desaturation as assessed by continuous pulse oximeter, or episodes of chest wall rigidity. CONCLUSIONS: This work corroborates our clinical impression that rapid infusions of fentanyl at the dose tested in small infants do not adversely affect dynamic total respiratory system compliance. To the contrary, the sedating and analgesic effects may improve synchronous breathing and decrease voluntary muscle tone, resulting in improved dynamic total respiratory system compliance.

Fentanyl↗
PubMedDate not supplied

Congenital defects of respiratory system among the children hospitalized in the clinic in years 1983-1989.

Congenital defects of respiratory system in children constitute a small percentage of all innate defects. In 1983-1989 in the Clinic Pulmonology and Allergology Medical School in Warsaw hospitalized 2522 children. Authors recognized the congenital defects of respiratory system in 29 cases. The opinions of authors only a complex diagnostic examinations makes it possible in most of the cases to rapidly correct diagnosis and choose proper treatment.

Child, Preschool↗
PubMed2002

The impact of morbid obesity, pneumoperitoneum, and posture on respiratory system mechanics and oxygenation during laparoscopy.

UNLABELLED: We studied the effect of morbid obesity, 20 mm Hg pneumoperitoneum, and body posture (30 degrees head down and 30 degrees head up) on respiratory system mechanics, oxygenation, and ventilation during laparoscopy. We hypothesized that insufflation of the abdomen with CO(2) during laparoscopy would produce more impairment of respiratory system mechanics and gas exchange in the morbidly obese than in patients of normal weight. The static respiratory system compliance and inspiratory resistance were computed by using a Servo Screen pulmonary monitor. A continuous blood gas monitor was used to monitor real-time PaCO(2) and PaO(2), and the ETCO(2) was recorded by mass spectrometry. Static compliance was 30% lower and inspiratory resistance 68% higher in morbidly obese supine anesthetized patients compared with normal-weight patients. Whereas body posture (head down and head up) did not induce additional large alterations in respiratory mechanics, pneumoperitoneum caused a significant decrease in static respiratory system compliance and an increase in inspiratory resistance. These changes in the mechanics of breathing were not associated with changes in the alveolar-to-arterial oxygen tension difference, which was larger in morbidly obese patients. Before pneumoperitoneum, morbidly obese patients had a larger ventilatory requirement than the normal-weight patients to maintain normocapnia (6.3 +/- 1.4 L/min versus 5.4 +/- 1.9 L/min, respectively; P = 0.02). During pneumoperitoneum, morbidly obese, supine, anesthetized patients had less efficient ventilation: a 100-mL increase of tidal volume reduced PaCO(2) on average by 5.3 mm Hg in normal-weight patients and by 3.6 mm Hg in morbidly obese patients (P = 0.02). In conclusion, respiratory mechanics during laparoscopy are affected by obesity and pneumoperitoneum but vary little with body position. The PaO(2) was adversely affected only by increased body weight. IMPLICATIONS: Morbid obesity significantly decreases respiratory system compliance and increases inspiratory resistance. Increased body weight, and not altered mechanics of breathing, was associated with worse PaO(2) during laparoscopy.

Adult↗
PubMed1993

Mathematical study of periodic breathing as an instability of the respiratory system.

A theoretical study of respiratory stability, based on a simple CO2 model of the respiratory system, investigates each component of respiration: the plant system and the central and peripheral controller systems. Analysis of the dynamic properties of the plant leads to a simplified respiratory model for the study of the influence of the central and peripheral controller components on stability. It is shown that the central component is not involved in respiratory instability phenomena such as periodic breathing whereas the peripheral component plays a major role. The explicit analytical index of stability obtained allows definition of the conditions of occurrence of periodic breathing in terms of the fundamental respiratory parameters. Moreover, this index can be used to evaluate the influence of various respiratory parameters on the stability of respiration.

Carbon Dioxide↗
PubMedDate not supplied

[The effect of the NMDA-receptor blocker MK-801 on sensitivity of the respiratory system to carbon dioxide].

Changes in the sensitivity of the respiratory system to carbon dioxide was studied after administration of NMDA receptor antagonist MK-801 by comparison of the response of the respiratory system with arterial blood pressure in anaesthetized non-inbred albino rats during 5 min hypercapnic (5-6% CO2 in the air) gas mixture inhalation before and 30 min after systemic MK-801 administration. It was established that after NMDA receptors blocking in rats the respiratory response was the same as it was in the control animals. Thus, NMDA receptors blocking is not followed by a significant change in respiratory chemosensitivity to carbon dioxide.

Animals↗
PubMed1989

[The role of sensory components in reactions of the human respiratory system to increasing loads].

In 13 healthy male subjects performing an increasing work on veloergometer in conditions of resistive respiratory loads, the moments of sensation of respiratory difficulties and refusal from the work, were recorded. The analysis of the respiratory system functions revealed that the respiratory discomfort occurred with increasing of the alveolar PCO2 up to a certain value and that the refusal occurred on a certain level of inspiratory activity. The subjects believed that the moment of refusal coincided with the complete exhaustion of the respiratory system reserves. Their lung ventilation, however, as well as inspiratory effort were far from reaching the maximal values obtained in special tests. Apparently, the sensory components of responses to the combination of muscular work with an increased resistance against breathing are of a defensive character and directed to the prevention of the exhaustion of the respiratory system functional reserves.

Adult↗
PubMed2005

Aging of the respiratory system: impact on pulmonary function tests and adaptation to exertion.

Normal aging of the respiratory system is associated with a decrease in static elastic recoil of the lung, in respiratory muscle performance, and in compliance of the chest wall and respiratory system, resulting in increased work of breathing compared with younger subjects and a diminished respiratory reserve in cases of acute illness, such as heart failure, infection, or airway obstruction. In spite of these changes, the respiratory system remains capable of maintaining adequate gas exchange at rest and during exertion during the entire lifespan, with only a slight decrease in Pa(O2) and no significant change in Pa(CO2).

Adaptation, Physiological↗
PubMed2001

A bibliometric evaluation of European Union research of the respiratory system from 1987-1998.

This study analyses the evolution of the bibliometric indicators of productivity and repercussion of European Union (EU) research into the respiratory system during the period from 1987-1998, describing the geographical distribution. Using MedLine, a selection was made of those articles by EU authors published between 1987-1998 in 38 respiratory system journals (classification from the Institute for Scientific Information). The journals, country of origin, number of articles and the relation to socioeconomic data, productivity index, visibility index, expected impact factor (EIF) and relative impact factor (RIF) were all analysed. The number of EU publications in respiratory system journals experienced an exponential increase, going from 606 articles (14.3% of world production) in 1987, to 2,325 (33.2%) in 1998. During this same period, the EIF increased from 1,258 to 2,111. The greatest gross productivities were those of the UK, France, Italy and Germany, although when corrected for number of inhabitants, Sweden, the Netherlands, Belgium and Denmark headed the list. The countries with the greatest mean EIF were the Netherlands, the UK, Spain and Belgium. In conclusion, productivity and repercussions of European Union research of the respiratory system experienced an important increase during this period.

Authorship↗
PubMed2005

[Pulmonary hypertension associated with disorders of the respiratory system].

Pulmonary hypertension associated with disorders of the respiratory system is defined by a pulmonary artery mean pressure above 20 mmHg at rest in stable disease. The most frequent form of precapillary pulmonary hypertension is associated with chronic obstructive pulmonary disease, because of its high prevalence. Pulmonary vascular remodeling occurs in the small pulmonary arteries and is due mainly to chronic alveolar hypoxia. Pulmonary hypertension associated with disorders of the respiratory system is usually mild to moderate, with resting pulmonary artery mean pressure ranging between 20 and 35 mm Hg. It may increase markedly during sleep, exercise or exacerbation of respiratory failure, however. Abrupt postload elevation can lead to right heart failure, an indisputable indicator of prognosis. Because the symptoms of pulmonary hypertension are minimal relative to those of the chronic hypoxic lung disease, noninvasive diagnosis is difficult, particularly in patients with chronic obstructive pulmonary disease. Oxygen therapy (at least 16 h/day) is currently the best treatment for this type of pulmonary arterial hypertension.

Disease Susceptibility↗