[en] Inhalation is the first step towards respiratory tract intake of chemical and radioactive toxics. Particle deposition in human airways has been described by several authors as showing large individual variations. This study intends to contribute to assess this variability limits especially with reference to age. The method used is basically a measurement of retention, by difference between inhaled and exhaled air concentrations, of inert monodispersed aerosols, during controlled breathing. Particles of 1, 2, 3 μm MMAD (polystyrene latex) are measured in size and concentration by laser velocimetry. A Fleish pneumotachograph is used for controlling respiratory parameters. Healthy subjects, male and female, undergo the test at various tidal volumes, frequencies and flow rates, simulated resting and exercising ventilation; their respiratory function is also explored in a very complete way. 20 adults between 23 and 54 years have been tested in order to assess the laboratory reference values. 25 children, 8 under the age of 8 years, and 17 between 8 and 15 years, have been tested in a similar way. Compared to adults, children, especially under 8 years, have different total deposition mean values, higher for spontaneous and quiet controlled breathing, lower for exercising controlled breathing. Total deposition is dependent on particle size, higher for 2 than for 1 μm MMAD, but also, on lung volume, V.C., T.L.C., F.R.C., to which it is inversely proportional

[en] In order to recommend reference values to assess lung dosimetry models, recently published data of ventilation rates and respiratory physiological parameters have been reviewed. The resulting values concern adults and children of various population groups. Mean values and standard deviations of height and weight, vital capacity (VC), functional residual capacity (FRC), total lung capacity (TLC) and dead space (V_D) are tabulated for American and European Caucasians, Afro-Americans, Indians, Japanese, Chinese and Native Americans. Values of VC and FRC are also plotted against body size within populations. Resting tidal volume and respiratory frequency do not show clear differences between ethnic groups. On the contrary, lung volumes are consistently higher in Caucasians than in the other groups, by up to 20% for VC and 10% for FRC. (author)

[en] Dosimetry of inhaled radionuclides requires information upon airway dimensions and air volumes breathed every day by people under exposure to gases and aerosols. Using recent data of economic surveys, and of respiratory physiology, modern standards have been tabulated for specific categories of a population: adult worker men and women, housewives, children 3 months and 1, 5, 10 and 15 years old. These parameters can be adapted to various population groups in the world. (author)

[en] Probabilities for deposition of aerosols in the human respiratory tract can be predicted by calculation models widely based upon ventilatory airflows, lung dimensions and anatomical features. A study of the impact of impaired lung function on airway deposition was performed on three groups of subjects: 18 healthy non-smokers, 15 patients with moderately restrictive lung function, and 15 patients with moderately obstructive lung function. Total deposition of an aerosol inhaled through the mouth at identical ventilation rates for all subjects and containing three sizes of monodisperse inert particles (1.2, 2.3 and 3.3 μm aerodynamic diameter) was measured by comparing inhaled and exhaled concentrations by laser velocimetry. Results were significantly higher in all the patients than in the healthy non-smokers. In restricted patients, Total Lung Capacity (TLC), Functional Residual Capacity (FRC), and Forced Expiratory Volume in one second (FEV1) presented significant inverse correlation coefficients with deposition. In obstructive patients, inverse correlation was observed only with FEV1. (Author)

[en] An experimental device was designed to measure partitioning of airflow between nose and mouth in response to incrementally graded exercise on an ergometer bicycle. Oral and nasal flow rates were recorded separately by two Fleisch pneumotachographs; cardiac frequency and arterial blood pressure were also recorded. Posterior rhinomanometry and flow rates during maximal vital capacity manoeuvre were simultaneously measured. Airflow fractions by mouth breathing were dependent upon the total ventilation required: at the maximal work load completed by ten subjects, they ranged from 30 to 67%. In six of them, breathing became abruptly oronasal at ventilation levels from 38 to 65 1. min^-1. In the other four, oral breathing was already considerable at rest; and it increased regularly towards maximal ventilation. In these subjects, the oral to nasal airflow ratios, measured by the flow-volume curve method, were higher than in the other six. (author)

[en] Inhalation is the first step towards respiratory tract intake of chemical and radioactive toxics. Particle deposition in human airways has been described by several authors as showing large individual variations. This study intends to contribute to assess this variability limits especially with reference to age. The method used is basically a measurement of retention, by difference between inhaled and exhaled air concentrations, of inert monodispersed aerosols, during controlled breathing. Particles of 1, 2, 3 μm MMAD (polystyrene latex) are measured in size and concentration by laser velocimetry. A Fleish pneumotachograph is used for controlling respiratory parameters. Healthy subjects, male and female, undergo the test at various tidal volumes, frequencies and flow rates, simulated resting and exercising ventilation; their respiratory function is also explored in a very complete way. 20 adults between 23 and 54 years have been tested in order to assess the laboratory reference values. 25 children, 8 under the age of 8 years, and 17 between 8 and 15 years, have been tested in a similar way. Compared to adults, children, especially under 8 years, have different total deposition mean values, higher for spontaneous and quiet controlled breathing, lower for exercising controlled breathing. Total deposition is dependent on particle size, higher for 2 than for 1 μm MMAD, but also, on lung volume, V.C., T.L.C., F.R.C., to which it is inversely proportional. 19 refs.; 4 tabs

[en] To compare experimental data with age-dependent model calculations, total airway deposition of polystyrene aerosols (1, 2.05 and 2.8 μm aerodynamic diameter) was measured in ten adults, twenty children aged 12 to 15 years, ten children aged 8 to 12, and eleven under 8 years old. Ventilation was controlled, and breathing patterns were appropriate for each age, either at rest or at light exercise. Individually, deposition percentages increased with particle size and also from rest to exercise, except in children under 12 years, in whom they decreased from 20-21.5 to 14-14.5 for 1 μm particles and from 36.8-36.9 to 32.2-33.1 for 2.05 μm particles. Comparisons with the age-dependent model showed that, at rest, the observed data concerning children agreed with those predicted and were close to the adults' values, when the latter were higher than predicted. At exercise, child data were lower than predicted and lower than adult experimental data, when the latter agreed fairly well with the model. (author)

[en] We studied the performance of a new nebuliser (Pentasave) by comparison both in vitro and in vivo with a standard nebuliser (Respirgard II). In vitro, deposition of pentamidine labelled with technetium-99m human serum albumin was measured indirectly by capturing inhaled particles on an absolute filter and measuring radioactivity with a gamma camera. The nebulisers were initially assessed with a pentamidine dose of 100 mg in 5 ml al 44 psi and an air flow of 10 l/min for Respirgard II and 16 l/min for Pentasave. Nebuliser output, expressed as the percentage of the initial nebuliser radioactivity captured by the inhalation filter, was 15%±2% (mean±SD) for Respirgard II, and significantly increased to 23%±3% for an initial version and to 33%±2% for the final version of Pentasave. Measurements with a gamma camera in a group of ten patients with human immuno-deficiency virus infection were made in vivo. The results revealed that pulmonary drug distributions are good using both Respirgard II and Pentasave. We measured pulmonary pentamidine deposition of 20.22±4.31 mg using Respirgard II (with 300 mg in 5 ml) and of 16.00±7.18 mg using Pentasave (with 150 mg in 6 ml). These findings show that the therepeutic dose of pentamidine (9 mg) was widely exceeded with both nebulisers. (orig./MG)