Lower airway

Handling and Toxicity. Tungsten hexafluoride is irritating and corrosive to the upper and lower airways, eyes, and skin. It is extremely corrosive to the skin, producing bums typical of hydrofluoric acid. The OSHA permissible exposure limits is set as a time-weighted average of 2.5 mg/kg or 0.2 ppm (22). 

Lower airways The portion of the human conducting airways distal to the... 

The aerodynamic particle diameter determines the fate of particles in the respiratory system. Coarse particles are deposited in the nose and nasopharynx. Smaller particles that pass the upper airway can be deposited in the bronchial region and lower airway. A size-selective deposition model and sampling of particles has been standardized both in Europe and internationally. The... 

The particle size is the most important factor that contributes to the clearance of particles. For particles deposited in the anterior parts of the nose, wiping and blowing are important mechanisms whereas particles on the other areas of the nose are removed with mucus. The cilia move the mucus toward the glottis where the mucus and the particles are swallowed. In the tracheobronchial area, the mucus covering the tracheobronchial tree is moved upward by the cilia beating under the mucus. This mucociliary escalator transports deposited particles and particle-filled macrophages to the pharynx, where they are also swallowed. Mucociliary clearance is rapid in healthy adults and is complete within one to two days for particles in the lower airways. Infection and inflammation due to irritation or allergic reaction can markedly impair this form of clearance. 

Asthma is a reversible obstructive disease of the lower airway. With asthma there is increasing airway obstruction caused by bronchospasm and bronchoconstriction, inflammation and edema of the lining of the bronchioles, and the production of thick mucus that can plug the airway (see Pig. 37-1). There are three types of asthma ... 

Lower airway obstruction Congestive heart failure... 

During absorption of this particular F-PHEA (Mw = 8.6 kD, Mn = 5.3 kD), through the rat lung, transfer occurred at an apparently constant rate of 110 43 ig/h or 3.5 1% of the administered dose per hour. Because mucociliary clearance from the lower airways occurs very slowly (7) these absorption rates convert to substantial bioavailabilities when the absorption process is extrapolated over a 12 h period [(3.5% x 12) or, around 42% may be feasible]. 

Beta-2-adrenergic receptor Beta-2-adrenergic receptor Beta-2-adrenergic receptor polymorphisms affect Susceptibility to lower airway reactivity... 

Dermal (skin) contact with sulfur mustard agents causes erythema and lesions (blistering), while contact with vapor may result in first and second degree burns contact with liquid typically produces second and third degree chemical burns. Any burn area covering 25 percent or more of the body surface area may be fatal. Respiratory contact is a dose-related factor in the sense that inflammatory reactions in the upper and lower airway begin to develop several hours after exposure and progress over several days. 

Bullens DM Measuring T-cell cytokines in allergic upper and lower airway inflammation can we move to the clinic Inflamm Allergy Drug Targets 2007 6 81-90. 

Kagawa and Toyama in Tokyo followed 20 normal 11-yr-old school children once a week from June to December 1972 with a battery of pulmonary-function tests. Environmental factors studied included oxidant, ozone, hydrocarbon, nitric oxide, nitrogen dioxide, sulfur dioxide, particles, temperature, and relative humidity. Temperature was found to be the most important environmental factor affecting respiratory tests. The observers noted that pulmonary-function tests of the upper airway were more susceptible to increased temperature than those of the lower airway. Although the effect of temperature was the most marked, ozone concentration was significantly associated with airway resistance and specific airway conductance. Increased ozone concentrations usually occur at the same time as increased temperature, so their relative contributions could not be determined. 

The respiratory tract may be divided into three major regions the nasopharyngeal (upper airways), the tracheobronchial tree (lower airways), and the pulmonary (alveoli). 

Koren HS, Devlin RB, Graham DE, et al Ozone-induced inflammation in the lower airways of human subjects. Am Rev Respir Dis 139 407-115, 1989... 

Ipratropium is virtually devoid of the CNS side effects associated with atropine. The most prevalent peripheral side effects are dry mouth, headache, nervousness, dizziness, nausea, and cough. Unlike atropine, ipratropium does not inhibit mucociliary clearance and thus does not promote the accumulation of secretions in the lower airways. 

Fig. 3 Aquaporin deletion reduces osmotic water permeability in lung, but does not impair active fluid absorption, a AQP expression in epithelia and endothelia in nasopharyngeal cavity, upper and lower airways, and alveoli, b Osmotically driven water transport across the airspace/capillary barrier in perfused lungs from wildtype and indicated AQP null mice. Note the remarkable slowing of osmotic equilibration in mice lacking AQPl or AQP5. c Alveolar fluid clearance measured from the increased concentration of a volume marker 15 min after instillation of isosmolar fluid at 37°C. Where indicated, fluid absorption was inhibited by amiloride or stimulated by isoproterenol. From Bat et al. (1999) and Ma et al. (2000a)...

Increased lower airway mucous secretion Relaxation vascular smooth muscle Positive inotropy Slows AV conduction... 

The major difference in management of exacerbations is in the routine use of antibiotics, because exacerbations in COPD far more often involve bacterial infection of the lower airways than occurs in asthma. 

Irritant gases (eg, chlorine, ammonia, sulfur dioxide, nitrogen Corrosive effect on upper and lower airways Cough, stridor, wheezing, pneumonia... 

Morphometry of the upper and lower airways (degree of obstruction)... 

Rhinitis, lower airway irritation and corneal oedema have been reported in workers exposed to morpholine (IARC, 1989). 

The Hi Receptor and its Ligands. The H receptor mediates effects, through an increase in cyclic adenosine monophosphate (cAMP). such as gastric acid secretion relaxation of airway smooth muscle and of pulmonary vessels increased lower airway mucus secretion esophageal contraclion inhibition of basophil, but not mas cell histamine release inhibition of neutrophil activation and induction or suppressor T cells. There is no evidence that the H- receptor causes significant modulation of lung function in the healthy human subject or in the asthmatic. 

It is recommended to propose a strategy combining the treatment of both the upper and lower airway disease in terms of efficacy and safety. 

In conclusion, the ARIA WHO workgroup emphasized the link between rhinitis and asthma and declared rhinitis a major chronic respiratory disease and a risk factor for the development of lower airway disease. It is therefore critical to treat both airway manifestations in a combined strategy, and immunotherapy has been proven to be a suitable treatment when patients are selected carefully. 

Chakir J, Laviolette M, Boutet M, Laliberte R, Dube J, Boulet LP Lower airways remodeling in nonasthmatic subjects with allergic rhinitis. Lab Invest 1996 75 735-744. 

Anticholinergic Agents in the Upper and Lower Airways, edited by S. L. Spector... 

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