Emmanuel and his mother live in an urban community housing complex. The building is worn down and dirty from the urban dust, cockroaches, and mold. Emmanuel is 5 years of age and has suffered from asthma for the last 2 years. One evening, his mother poured him some milk and put him to bed. Shortly afterward, Emmanuel woke up wheezing and coughing. As he gasped for air, he became more and more anxious. His mother ran for his inhaler, but he was too upset and restless to use it. Emmanuel’s skin became moist with sweat, and as he began to tire, his wheezing became quieter. His mother called 911 and waited anxiously for the ambulance to arrive.
1. Emmanuel uses a corticosteroid inhaler for the management of his asthma. What is the mechanism of action of this drug? How is its action different from the β2-agonist inhalants?
2. Why does someone with severe asthma become physically fatigued during a prolonged attack? What are the physiologic events that occur during an attack?
3. One of the complications of respiratory fatigue is the development of hypercapnia. How does the body compensate for an increase in CO2? What are the effects of hypercapnia on the central nervous system
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Introduction:
Emmanuel is a 5-year old child who suffers from asthma and lives in an urban community housing complex. One evening, he had an asthma attack, which caused him to wheeze and cough uncontrollably. His mother tried to give him his inhaler; however, he was too anxious and restless to use it. Eventually, she called 911 and waited anxiously for the ambulance to arrive. As a medical professor, it is important to understand the mechanism of action of corticosteroid inhalers, the physiologic events that occur during prolonged asthma attacks, and the effects of hypercapnia on the central nervous system.
1. What is the mechanism of action of corticosteroid inhalers? How is its action different from the β2-agonist inhalants?
Corticosteroid inhalers work by reducing inflammation in the airways. They contain a corticosteroid medication which is inhaled into the lungs. Once inhaled, the medication travels to the airways and reduces inflammation. This reduces the swelling and mucus production in the airways, which helps to prevent and control asthma symptoms.
In contrast, β2-agonist inhalants work by relaxing the muscles in the airways. They bind to β2 receptors in the lungs, which stimulates the muscles to relax. This opens up the airways and makes breathing easier.
While both corticosteroid inhalers and β2-agonist inhalants are used to treat asthma, they have different mechanisms of action. Corticosteroid inhalers focus on reducing inflammation, while β2-agonist inhalants focus on relaxing the muscles in the airways.
2. Why does someone with severe asthma become physically fatigued during a prolonged attack? What are the physiologic events that occur during an attack?
During an asthma attack, the airways become inflamed and swollen. This causes the muscles around the airways to contract, making it difficult to breathe. The body’s response to this decreased oxygen supply is to try to compensate by increasing the effort of breathing. This requires a lot of energy and can cause physical fatigue.
In addition to physical fatigue, prolonged asthma attacks can lead to hypoxemia, or low oxygen in the blood. This can cause drowsiness, confusion, and even loss of consciousness.
3. How does the body compensate for an increase in CO2? What are the effects of hypercapnia on the central nervous system?
When there is an increase in CO2 levels in the blood, the body compensates by increasing the respiratory rate. This increases the amount of air that is breathed in, which helps to remove the excess CO2 from the body. The body’s pH is also regulated by the kidneys, which help to remove excess CO2 as bicarbonate.
Hypercapnia, or high levels of CO2 in the blood, can have several effects on the central nervous system. Initially, it can cause headache, confusion, and drowsiness. If left untreated, it can progress to a more severe form of acidosis, which can cause seizures, coma, and even death. Therefore it is important to monitor and maintain proper CO2 levels in the body.
