Extrathoracic

Note chat turbulent flow (Reynolds number > 3000 is predicted only m the extrathoracic airways at flow races < 30 IVmin. 

Extrathoracic airways The portion of the human conducting airways prox-... 

The ICRP deposition model estimates the fraction of inhaled material initially retained in each compartment (see Figure 3-2). The model was developed with five compartments (1) the anterior nasal passages (ET,) (2) all other extrathoracic airways (ET2) (posterior nasal passages, the naso- and oropharynx, and the larynx) (3) the bronchi (BB) (4) the bronchioles (bb) and (5) the alveolar interstitium (AI). Particles deposited in each of the regions may be removed and redistributed either upward into the respiratory tree or to the lymphatic system and blood by different particle removal mechanisms. 

For extrathoracic deposition of particles, the model uses measured airway diameters and experimental data, where deposition is related to particle size and airflow parameters, and scales deposition for women and children from adult male data. Similar to the extrathoracic region, experimental data served as the basis for lung (bronchi, bronchioles, and alveoli) aerosol transport and deposition. A theoretical model of gas transport and particle deposition was used to interpret data and to predict deposition for compartments and subpopulations other than adult males. Table 3-4 provides reference respiratory values for the general Caucasian population during various intensities of physical exertion. 

Type SR-2 compounds include soluble and reactive gases and vapors which are completely retained in the extrathoracic regions of the respiratory tract. SR-2 compounds include sulfur dioxide (S02) and hydrogen fluoride (HF). 

Leggett (1992) also proposed a respiratory tract model. Deposition of americium particles, depending on their size, are assumed to deposit in three compartments representing extrathoracic, fast-clearing thoracic, and slow-clearing thoracic regions of the respiratory tract (Figure 3-8). 

The more recent thoracic pump theory is based on the belief that blood flow during CPR results from intrathoracic pressure alterations induced by chest compressions. During compression (systole), a pressure gradient develops between the intrathoracic arteries and extrathoracic veins, causing forward blood flow from the lungs into the systemic circulation. After compression ends (diastole), intrathoracic pressure declines and blood flow returns to the lungs. 

Initial staging M-staging. Routine staging workup is based on conventional imaging such as CT and MRI. In the review by Reske et al., [ F]-FDG-PET detected unsuspected extrathoracic metastases in 12% of the cases. The calculated sensitivity and specificity for detection of distant metastases were 94% and 97%, respectively. [ F]-FDG-PET also revealed to be a useful tool in the assessment of adrenal masses and suspected liver metastases. 

The deposition of inhalable uranium dust particles in the various regions of the lungs (extrathoracic, tracheobronchial, and deep pulmonary or alveolar) depends on the size of the particles. Particles larger than 10 pm are likely to be transported out of the tracheobronchial region by mucocilliary action and... 

Sarcoidosis is a primary multisystemic, granulomatous disease of (still) unknown aetiology with enhanced immunity at the site of manifestation. The lungs and the intrathoracic lymph nodes are nearly always affected. In many cases, the extrathoracic organs are involved as well. Sarcoidosis is characterized by the presence of epithelioid cell granulomas, which do not show caseous changes. 

Localization Based on X-ray findings, intrathoracic sarcoidosis can be divided into four stages 0, I-III. The extrathoracic manifestation of sarcoidosis affects the... 

Treatment Intrathoracic sarcoidosis has a high rate of spontaneous remission with possible fibrosis residues. Extrathoracic manifestations may cause considerable symptoms and secondary disorders, depending on the organs affected. This is also true of the liver. Treatment consists of monitored waiting and administration of glucocorticoids (usually as long-term therapy). Liver transplantation is necessary in some cases. 

Average tissue doses to defined respiratory tract regions are calculated, the weighted sum of which provides an equivalent dose to the thoracic or extrathoracic region which is consistent with the ICRP tissue weighted dosimetry system. 

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