How does emphysema affect breathing and gas exchange in the lungs?
Along with the previous answer, it also destroys the integrity of the airways, causing them to lose the elasticity that keeps them open. Once the lungs inflate air becomes trapped by these soft airways collapsing and the sufferer must work to expel each breath, which happens simply by relaxing in healthy lungs.
Does low oxygen (decreased lung expansion) decreases cardiac output?
During inspiration, expansion of the lungs and pulmonary tissues causes pulmonary blood volume to increase, which transiently decreases the flow of blood from the lungs to the left atrium,putting these patients at greater risk for hypoxia.Therefore, left ventricular filling actually decreases during inspiration. In contrast, during expiration, lung deflation causes flow to increase from the lungs to the left atrium, which increases left ventricular filling. The net effect of increased rate and depth of respiration, however, is an increase in left ventricular stroke volume and cardiac output. By the process of diffusion the exchange of oxygen and carbon dioxide occurs in the alveolar-capillary membrane area. The relationship between ventilation (airflow) and perfusion (blood flow) affects the efficiency of the gas exchange. Normally there is a balance between ventilation and perfusion. However, certain conditions can offset this balance, resulting in impaired gas exchange. Altered blood flow from a pulmonary embolus or decreased cardiac output or shock can cause ventilation without perfusion. Conditions that cause changes or collapse of the alveoli impair ventilation, such as atelectasis, pneumonia, pulmonary edema, and adult respiratory distress syndrome (ARDS). Other factors affecting gas exchange include high altitudes, hypoventilation, and altered oxygen carrying capacity of the blood from reduced hemoglobin. Elderly patients have a decrease in pulmonary blood flow and diffusion as well as reduced ventilation in the dependent regions of the lung where perfusion is greatest. Chronic conditions such as chronic obstructive pulmonary disease (COPD) put these patients at greater risk for hypoxia. Other patients at risk for impaired gas exchange include those with a history of smoking or pulmonary problems, obesity, prolonged periods of immobility, and chest or upper abdominal incisions.
What effect does increased CO2 levels in the blood have on patients suffering from COPD?
Carbon Dioxide (CO2) retention is something that can occur in people with moderate to severe COPD. Normal arterial CO2 range is from 35-45 mmHg. CO2 becomes an acid in the blood, and can cause the bloods pH to change when the levels of CO2 change. As we know, COPD is usually a slowly progressing lung disease. When lung function declines over time, this normal range of CO2 may rise. When it happens slowly, the kidneys retain bicarbonate to keep the pH of the blood from becoming too acidic. All organs in the body will suffer if the blood pH is out of range. Some people with COPD can have a CO2 level of 60mmHg or higher, but as long as this rise occures over time, the kidneys are able to compensate, and make sure the pH of the blood does not drop (become more acidic). Even though the carbon dioxide level is higher than normal, the kidneys have compensated, keeping the blood pH in normal range. On the other hand, if the carbon dioxide level rises quickly, the kidneys do not have time to compensate, and the pH of the blood will drop (acute respiratory failure). This can be serious, and even life-threatening. There is some concern about using higher levels of oxygen in people who are CO2 retainers. There are some that feel that when oxygen levels in the blood are too high, the stimulus to breathe may be affected in people who already have higher levels of CO2. Other experts dispute this claim. The bottom line for me is that oxygen should be treated just like any other drug, using only the lowest level that will get the desired results. On occasion, people with COPD will need higher levels (usually closely monitored in the hospital), but the need should be re-assessed on a regular basis.
What is the difference between COPD and pulmonary fibrosis?
'COPD', or the newer terminology Chronic Airway Limitation (CAL) or Chronic Obstructive Airways Disease (COAD) is a group of disorders of very different aetiology but grouped together because of their common underlying functional manifestation- obstruction to airflow. The primary issue is air-trapping. It includes asthma, emphysema (acquired -smoking, or congenital - alpha anti-trypsin deficiency), bronchiectasis and chronic bronchitis. The clinical symptom is dyspnoea medical shorthand for 'increased work of breathing'.Pulmonary fibrosis is formation of fibrotic tissue within the pulmonary interstitium, the connective tissue in the bronchovascular bundles - the lung 'scaffolding'. This increases the distance gas molecules have to diffuse between the alveoli and the capillaries, reducing the diffusion coefficient. This is more rate-limiting for Oxygen than CO2, meaning hypoxaemia is the problem rather than hypercapnia. It has many causes, including exposure to pro-inflammatory particles (such as asbestos fibres) and connective tissue diseases; basically the end -result of any chronic infectious/inflammatory condition, but most cases are idiopathic (cause indeterminate). The fibrosis decreases lung compliance - again clinically manifesting as dyspnoea. It is irreversible, progressive and fatal.Over time both can lead to elevated pressure in the pulmonary arteries - pulmonary arterial hypertension, which in turn eventually causes right ventricular failure (if caused by lung pathology- ‘Cor pulmonale’). This illustrates the interconnectedness of the respiratory and CVS, really one 'tissue oxygenation system'.
What is pulmonary alveolar proteinosis and lymphangioleiomyomatosis?
Pulmonary alveolar proteinosis is a rare condition and patients with this disease usually present with insidious dyspnoea that has progressed over months, sometimes with mild systemic symptoms such as low grade fever and weight loss.Usually, it has a benign course with eventual resolution. Rarely, rapid progression to respiratory failure is seen. Death occurs due to progressive filling of alveoli or superimposed infection. http://www.histopathology-india.net/PrAlPr.htm In the rare condition of lymphangioleiomyomatosis (LAM) a bizarre proliferation of smooth muscle cells (LAM cells) in the lung involves the smooth muscle of lymphatics, arteries, veins, bronchioles, and alveolar walls. Dyspnea is the usual presenting symptom.The condition is characterized clinically by slowly progressive breathlessness and basal shadowing, and three distinctive complications: multiple pneumothoraces, haemoptyses and chylous effusions.Oophorectomy has produced good results. Treatment is by oestrogen antagonists or progestogens but the response is unpredictable and does not always correlate with the presence of oestrogen receptors. http://www.histopathology-india.net/lymphangioleiomyomatosis.htm
Why does carbon dioxide diffuse more rapidly across the respiratory membrane?
More rapidly than oxygen? Because it's dissolved in the blood, and only has to move down the concentration gradient. Oxygen has to bind to hemoglobin, so it takes longer for your blood to "fill up" with oxygen than it does to "empty" of CO2.
What are the diagnostic differences between asthma and COPD?
People with Chronic Obstructive Pulmonary Disease (COPD) and Asthma are familiar with the common symptoms like coughing, wheezing and shortness of breath. It’s easy to mistake one condition for the other as they have one big thing in common: The inability to get enough air into the lungs. Alternatively, after diagnosing the symptoms, medical history, and results of medical tests, your doctor can further determine the severity of it and both the conditions are different from each other.Symptoms and SignsCOPD is a term used for people who are suffering from chronic bronchitis, emphysema, or a combination of both. People with chronic bronchitis find it hard to breathe because of swollen and mucus filled airways. A daily morning cough that produces phlegm is particularly characteristic of chronic bronchitis.Similar changes occur in asthmatic people, but they happen because of triggers like cigarette fumes, pet dander, dust etc. Episodes of wheezing and chest tightness (especially at night) are more common with asthma. People with COPD tend to have fewer symptoms without triggers, but exposing them to triggers can worsen their symptoms.COPD is nearly always linked with a long history of smoking, while asthma occurs in both non-smokers as well as smokers. Smoking also worsens asthma and smokers are more likely to suffer from a combination of both asthma and COPD.COPD patients first develop a chronic cough and dyspnea. However as disease severity progresses, cough and dyspnea result in decreased tolerance of exercise and increased disability.Patients with asthma usually develop wheezing, shortness of breath and cough. Asthma’s symptoms are irregular and cover a spectrum from mild-to-severe disease and are also characterized by reversible airway obstruction.People who have asthma are typically diagnosed as children, while COPD symptoms usually show up only in adults over the age of 40 who are current or former smokers.Environmental FactorsEnvironmental factors that increase the risk of COPD include occupational dusts, long term exposures to cigarette fumes, chemicals and indoor/outdoor pollution. A childhood history of respiratory infection can lead to reduced lung function in adulthood.