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Obstructive lung .docx

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University of Calgary
NURS 203

Obstructive lung A. Deals with compliance/elasticity concept In obstructive lung dz, no prob getting air in, but have a problem in getting the air out. Why don’t you have a problem getting it in? B/c the elastic tissue support is destroyed, so it is very ez to fill up the lungs. However, b/c the elastic tissue support is destroyed, it is very difficult hard to get it out b/c it collapses on expiration, so you can get air in, but cannot get air out. In a pt with obstructive air dz, they breathe in with no problem, but have trouble getting it out. So, something is left over in the lung – cannot get all the air out, therefore the residual volume is increased (whenever something is left over, it is called the ‘residual’). So, if you cannot get air out, then the residual volume increases, which means that the TLC will increase, which means that the diaphragm will go down b/c as the lungs are over inflated, and the AP diameter will go out. So, with obstructive lung dz, you have increased AP diameter and diaphragms go down (depressed). There is only a certain amount of expansion your chest can go. Eventually, the chest starts to compress other volumes (as you trap air and residual volumes go up). So, tidal volume starts decreasing, vital capacity goes down b/c the residual vol is increasing and you are compressing other volumes. So, TLC and RV increases, everything else decreases. On spirometer, FEV1 is very low (usually 1 – normally it is 4). In other words, you have a better FEV1 with restrictive lung dz b/c you can get air in. The FVC (total amt they can get out) is 3 liters (vs. 5 liters). When you do a ratio of FEV1/FVC, the ratio has decreased, hence distinguishing restrictive from obstructive dz’s. Classic COPD x-ray: hard to see the heart, with depressed diaphragms (at level of umbilicus), increased AP diameter – dx? Classic obstructive dz x-ray – prob getting air out, therefore the diaphragm is down and AP diameter is increased. Example: 3 month old can have this same finding due to RSV Example: Newborn with Chlamydia trachomatis pneumonia b/c he is trapping air. B. There are 4 type of obstructive lung dz’s: chronic bronchitis, bronchiectasis, emphysema, asthma. The ones associated with smoking are bronchitis and emphysema. 1. Chronic Bronchitis Purely a clinical dx = Pt has productive cough for 3 months out of the year for 2 consecutive years. Where is the dz? Terminal bronchioles (you have main stem bronchus, segmental bronchi, terminal bronchioles, resp bronchioles, alveolar ducts, alveoli). As soon as you hit the terminal bronchioles, these are small airway; it is all turbulent air up to terminal bronchioles. After that, it is parallel branching of the airways. The turbulent air hits the terminal bronchioles and then hits a massive cross sectional airway where you can go diff path’s b/c parallel branching of the small airways. So, the airflow changes from turbulent to laminar airflow. By the time you hit the resp unit, it is not moving the air. Most small airway dz’s are inflammation of the terminal bronchioles, leads to wheeze. Terminal bronchioles are the site of chronic bronchitis. This is the same area as asthma and bronchiolitis. More prox to the terminal bronchioles, in bronchitis, you will get a mucus gland hyperplasia, and a lot of crap is coming up (that’s the productive part). The actual area of obstruction is the terminal bronchiole. Have goblet cell metaplasia and mucous plugs. Think about having one terminal bronchiole and one mucous plug – this is affecting a major cross sectional area of lung b/c all the parallel branches that derive from here will not have CO2 in them, and they are trying to get air past the mucous plug, but cannot. So, there is a HUGE vent-perfusion mismatch. This is why they are called blue boaters – they are cyanotic. They have mucous plugs in the terminal bronchioles and cannot rid CO2. 2. Emphysema Not in the terminal bronchioles. It is in the resp unit (resp unit is where gas exchange occurs – cannot exchange gas in the terminal bronchioles – aka nonresp bronchiole); it is the primary place for expiratory wheeze and small airway dz, however. Gas exchange occurs in the resp bronchiole, resp alveolar duct and alveoli. Only need to know 2 emphysemas: centrolobular and panacinar. Emphysema affects gas exchange and where it affects the airway is more distal, compared to chronic bronchitis (proximal). So, when you have emphysema with all the inflammation associated with it, not only destroy the resp unit, but also the vasculature associated with it. Therefore, there is an even loss of ventilation and
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