1. Respiratory Deposition and Different Modeling Approaches Hussain Majid Ph.D Scholar

6. Head airway (HA) Air and aerosol enter from HA Use to remove dust and other particles from entering the respiratory Humidify the air before entering the lung Separate out food to digestive system Tracheaobronchial (TB) Trachea direct air into the lung Bronchial tree is the first part of the lung. This part directs air in the lung Each branch in the tree split into 2 part Lung Regions Mouth Pharynx Larynx Nose Bronchial Tree Trachea Parent Branch Major daughter Minor daughter Bifurcation

7. Alveolar or Pulmonary (AV) Alveoli are located at the end of the bronchial tree Gas exchange occur at the Alveoli If particle deposit in this region it can directly enter the blood stream alveoli Alveolar duct Alveolar entrance rings 100µm Alveoli

9. Deposition Mechanisms Involved Major: Minor: Diffusion Sedimentation Impaction Interception Electrostatic Naso-pharyngeal: impaction, sedimentation, electrostatic (particles > 1 μm) Tracheo-bronchial: impaction, sedimentation, diffusion (particles < 1 μm) Pulmonary: sedimentation, diffusion (particles < 0.1 μm)

10. Diffusion Cause by Brownian motion Diffusion is the deposition mechanism for small particles. Diffusion depends increases with decreasing particle size and flow rate. More deposition occurs in the alveoli region because longer residence time and smaller airway.

12. Impaction Particle cannot follow the trajectory due to its inertia and hit the wall called impaction. Impaction increases with particle size and flow rate. This type of deposition occur through out the lung. This is important, especially in the head airway where most of the large particles are screened out Impaction occurs mostly in the upper generation airways due to high velocity

18. Raabe Lung Model Made in 1976 by the Lovelace foundation The lung’s airways are asymmetric making the model more realistic but difficult to model Lung is divided into 5 area: Right Upper Right Middle Right Lower Left Upper Left Lower Structure of the lung was taken from replica of human lung casts.

21. Deposition Experiment

23. Human Experiment (contd.) Deposition Fraction Dosage Rate A – Activity V min – 1 Minute Ventilation C – Concentration This experimental method is very common in pulmonary drug studies To see how much drug would be deposit when administrated. Unless the aerosol particle emits radiation, this method does not give any information about where particles are deposited. The radioactive aerosol can be scanned for regional deposition location using PET* scan Ultrafine Particle Deposition in Subjects with Asthma

24. Lung Deposition Modeling

27. Inhalation Fraction Original aerosol Aerosol inhale Inhaling Inhalation fraction is the ratio on aerosol inhaled to the total aerosol in the airflow. This is affected by the entry point, the orientation of the flow to the entry point, the flow rate and particle size. IF is usually presented as orientation average IF =

28. ICRP Model Empirically fitting the 3 deposition equations will give:

29. ICRP Prediction

33. Air flow governing equations: Continuity equation Momentum equation Turbulence kinetic energy equation CFPD Pseudo-vorticity equation Particle transport equations: Slip collection factor Reynolds number Particle trajectory equation

34. CFPD The equations are solved using commercially available program CFX4.4 is used by Zhang et. al Need to set up algorithm and other parameters before the program can be run Outputs: Time, position, velocity of each particles at the end of each iteration Run simulation Time it take to run will depend on processing power and the simulation parameter Air Flow Equations Particle Equations Lung Model

35. CFPD Micro-particle transport and deposition in a human oral airway model

39. Inspiratory spatial deposition patterns of 1 nm particles, representing unattached radon progeny in a symmetric idealized bronchial airway bifurcation (generations 3-4) for 10 3 randomly selected particle trajectories. The inspiratory flow rate of 4 L/min corresponds to a respiratory minute volume of 30 L/min.

40. Bronchial deposition fraction under resting breathing conditions (V T = 1000 mL, t = 4s) as a function of particle diameter using different scaling procedures

41. Deposition patterns of 10 nm particles under sedentary breathing conditions (V T = 500 mL, t = 4s) for five sets of diffusion deposition equations. Deposition is normalized to the number of particles entering the trachea.