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J Halík

Publications and source records attributed to J Halík.

10 recordsLinked to original sources
PubMed1988

Determining the basic characteristics of aerosols suitable for studies of deposition in the respiratory tract.

Studies of aerosol particle deposition in the respiratory tract requires experimental inhalation of artificial model aerosols. The paper formulates some of the most important requirements for the properties of such aerosols. Several suitable fractions were prepared as part of a research project dealing with the use of microporous polymers for diagnostic purposes. 5 fractions of the polymer designated G-gel 60 with the particle size as stated by the manufacturer, ranging from 3 to 7 micron were evaluated using a 16-channel particle dispersity analyzer HIAC/ROYCO MT 3210 with the sensor 1200 and operated by a microprocessor, the equipment being coupled to an APPLE IIe computer. G-gel 60 particles introduced into the aerosol were characterized by the parameters CMAD, MMAD and sg both numerically and graphically. The measurement procedure was found to be very sensitive with respect to all fractions in evaluating the subtile differences between different lot numbers of the aerosol. G-gel 60 fractions characterized both numerically and graphically were compared with the known aerosols from paraffin oil and atmospheric air. The equipment MT 3210 enables prompt determination of the percentages of aerosol particles distribution by size class. The authors conclude that the procedure, both in its numerical and graphical versions, is particularly suitable for the diagnosis of aerosol particles deposition in the respiratory tract, offering a new application for HIAC/ROYCO in the field of medicine. In evaluating atmospheric aerosol in exhaled air, the number of particles was found to be below that in inhaled air, the difference being dependent on the choice of investigation methods. Percentual distribution of deposited particles following one minute ventilation proved to be at its maximum, as regards atmospheric aerosol, in the 0.30-0.50 micron range. The deposition curve was similar to already published curves, being characterized by an S-shaped pattern with maximum deposition in the greater size classes. An analysis of inhaled, exhaled and deposited aerosol suggested that deposited aerosol is more polydisperse and has particles of greater sizes than inhaled aerosol. Investigation of the effect of apnoe on deposition indicated that deposition increased as a function of apnoeic pause.

Aerosols↗
PubMed1984

Aerosol particle deposition in human lungs.

The pneumoconiosis developing after inhalation of air-borne dusts in the work place depends on the relation between the value of particle deposition in the respiratory tract and the rate of particle clearance from sites of their deposition. For testing the deposition in humans an aerosol of paraffin oil was given to a cohort of healthy persons. The characteristic parameters of the aerosol had been defined. The concentration of particles in 5 channels were measured in both the inhaled and exhaled air samples using the particle counter ROYCO 225. The deposition fraction was calculated from the relation of particle amount in expired air to the amount in inhaled air in each distribution class. In this preliminary report the results comparable with the prediction mathematical curve are discussed.

Aerosols↗
PubMed1980

Aerosol deposition in the respiratory tract of the rat. Experimental results and mathematical modelling.

The deposition fraction in the respiratory tract of rats were determined experimentally using aerosol 85Srl2 in saline. The dimensions of the particles [MMD 1.63 /+- /+- 0.47 micron, Sg = 1.29] were measured by two independent methods. Rats weighing 200 g were exposed for a period of 60 min [t] in the inhalation apparatus PIANO 3 with a generator according to Lauterbach. From the volume activity [A] of 3 - 11 Bq/litre air a depot of 35-129 kBq was formed in the animals. Spirometric values measured with a modified Jäger ergospirometer were: V = 178.8 /+- 42.9 ml, VT = = 1.18 /+- 0.24 ml. f = 163.1 /+- 28.1 cycles/min. The total amount inhaled [Q] was calculated [Q = V.A.t], the deposited amount [D] was measured by a whole body counter. THe mean deposition fraction was 0.570 /+- 0.052 and was not related either to exposure time or to aerosol activity. In view of the broad validity of the conclusions for aerosols of round-shaped particles, the mean deposition fraction was determined with the help of a mathematical model according to Landahl. The theoretical values amounted to 0.609 [from 0.522 to 0.686]. The good agreement between the mean deposition fractions estimated by two independent methods indicates that on the basis of the probability theory and dimensional analysis, the mathematical model can also be used in humans for simulation deposition as one of the basis foundations for a quantitative evaluation of inhalation risk from any kind of aerosol.

Aerosols↗