Tracheobronchial tube

Acetylcholine is released when the vagus nerve is stimulated, causing contraction of the tracheobronchial tube. This is called bronchoconstriction. Epinephrine is released when the sympathetic nervous system is stimulated, causing the bcta2 receptor in the bronchial smooth muscle to relax, resulting in dilation of the tracheobronchial tube. This is called bronchodilation. 

Lower respiratory disorders are conditions that obstruct or restrict tracheobronchial tubes, preventing exchange of gases. These conditions are called chronic obstructive pulmonary disease (COPD), and include bronchitis, chronic bronchitis, bronchiectasis, emphysema, asthma, and chronic asthma. 

Acetylcholine is released when the vagus nerve is stimulated, causing the contraction of the tracheobronchial tube called bronchoconstriction. 

The tracheobronchial tube connects the pharynx to the bronchial tree that extends into the terminal bronchioles in the lungs providing an unobstructed pathway for air to enter the body and carbon dioxide to leave the body. 

The tracheobronchial tube is a fibrous spiral of smooth muscles that become more closely spaced as they near the terminal bronchioles. The size of the airway can be increased or decreased by relaxing or contracting the bronchial smooth muscle. This is controlled by the parasympathetic nervous system— particularly the vagus nerve. 

The vagus nerve releases acetylcholine when it is stimulated, which causes the tracheobronchial tube to contract. This is referred to as bronchoconstriction. The opposite effect is created when the sympathetic nervous system releases epinephrine that stimulates the beta2 receptor in the bronchial smooth muscle. This causes the tracheobronchial tube to dilate. This is called bronchodilation. In a healthy patient the sympathetic and parasympathetic nervous systems counterbalance each other to maintain homeostasis. 

Some conditions obstmct or restrict tracheobronchial tubes and prevent the exchange of gas within the lungs. These conditions are referred to as chronic obstructive pulmonary disease. These include bronchitis, bronchiectasis, emphysema and asthma. 

The vagus nerve releases acetylcholine when stimulated, which causes the tracheobronchial tube to contract. 

The estimated number of tubes in each airway generation depends on the bifurcation model used in describing the tracheobronchial tree. Though bronchial bifurcations are asymmetric, symmetric models, exemplified by Weibel, or asymmetric models, such as one suggested by Horsfield, can... 

Tracheobronchial tree Series of bifurcating tubes originating at the trachea... 

An 8-year-old girl with asthma underwent tonsillectomy and adenoidectomy hemostasis was performed with bismuth-adrenaline paste. A small amount of bismuth was noted in the endotracheal tube before extu-bation, and in the recovery room she developed respiratory difficulty associated with nasal flaring and sternal retraction. A chest X-ray showed aspirated radio-opaque material outlining the tracheobronchial tree and early pulmonary infiltrates. 

When a feeding tube is inserted nasally or orally, there is a risk that the tube may inadvertently enter the tracheobronchial tree. The risk may be higher in patients who have an impaired cough or gag reflex and when a stylet is used for tube insertion. Proper positioning of the tube should always be confirmed by x-ray prior to feeding initiation to avoid inadvertent administration of enteral formula into the lung. 

Z Maintenance of an adequate airway and breathing is necessary if there is obstruction resulting from bronchial secretions and bronclio.spasm. This may require the use of an oral airway (or insertion of an endotracheal tube if medical assistance is available) and assisted ventilation (e.g., mask with manual inflator). Oxygen is valuable because of the potential for hypoxia resulting from airway obstruction secondary to increa.sed tracheobronchial secretions and bronchospasm (Munidasa et al.. 2004). When hospitalized, endotracheal intubation and assisted ventilation may be required (Proudfooi and Vale, 1996),... 

One of the potential advantages of metal stents over the plastic tube stents is the possibility of placement under conscious sedation by flexible endoscopy or fluoroscopy only. However, for a safe and durable access to the tracheobronchial system, the possibility for fine adjustments of the inserted stents, additional therapeutic measures, and permanent control of ventilation, most interventionists prefer to carry out stent implantations under general anesthesia and with the use of a rigid ventilating bronchoscope. Such a setting enables high frequency Venturi jet ventilation. 

The focus of this chapter is primarily on metallic stents. For a detailed overview of the results of placement of plastic tube stents for tracheobronchial obstructions due to malignant tumors, the interested reader is referred to one of the review articles on stenting of the tracheobronchial system written by experienced interventional bronchoscopists (thoracic endoscopist) (Colt and Dumon 1995 Mehta and Dasgupta 1999 Rafanan and Mehta 2000 Wood 2001). 

Rarer complications of plastic tube stents include tracheobronchial ulceration with secondary hemorrhage, perforation of the tracheobronchial wall with secondary mediastinitis and septic shock, tumor overgrowth at the proximal or distal stent margin. 

Interaction of the metalhc stent and the tracheobronchial wall is expected unlike plastic tube stents. This leads to specific problems. Removal of a metalhc stent, which is incorporated into the mucosa several weeks after deployment is extremely difficult and sometimes requires laser destruction of the stent struts in order to remove the stent piece by piece . Similarly, repositioning of an embedded metal stent is more difficult than relocation of a silicone stent. Covered metal stents exert less problems regarding removal and repositioning than uncovered mesh stents, where the open mesh design can lead to complete inoculation of the small stent wires into the mucosa. 

Regarding Y-shaped tubular scaffolds, a limited experimentation has been conducted. Sekine et al. [ 130] implanted a Y-shaped Marlex mesh tube in dogs. The tubes were reinforced with polypropylene spiral and coated with collagen from porcine skin. Six of the 20 dogs have survived after experimentation. The main causes of death were obstmction of the main bronchus, omental necrosis, and air leakage. The same prosthesis was grafted as tracheobronchial bifiircalion replacement after 5 years, the scaffold was completely incorporated. Neitho- stenosis nor dehiscence was observed, and a functional airway was revealed [131]. 

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