The inhalation and deposition of charged particles within the human lung

Abstract

When particles are inhaled they deposit within the respiratory system depending on particle size, shape and charge together with breathing conditions such as inhalation flow rate, breath-holding pause and exhalation flow rate. In addition further control of particle deposition may be achieved by pulsing the aerosol particles into the lung during only part of the inhalation phase. We have developed a mathematical model of the human lung which is implemented on a personal computer. It is of value for studies of airborne pollutant particle hazards, the administration of drugs and for the diagnosis of lung disease. When small particles of about 1 μm are considered the importance of electrical charge on particle deposition is demonstrated. Increases in deposition occur above a threshold charge level as charge is increased. The model may be used to demonstrate how particle deposition within a diseased lung may be controlled by means of aerosol pulses. It is possible by means of adjusting pulse volume and pulse delay time to target particular regions within the respiratory system. Clinical studies using radio labelled, monodisperse aerosols and also polydisperse aerosols from nebulizers are under way. These studies are with both healthy human volunteers and mildly asthmatic subjects. Clinical data is in the form of images obtained by means of a Gamma camera. Much of the present work is directed at transforming the observed experimental data which is in spatial form to the airway branching structure. Success has been achieved with the correlation of clinical and predicted data.