Archie was in the E.R. with asthma symptoms for the third time this year. Archie, a 25-year-old artist, had no health insurance and although he'd gotten a prescription for a corticosteroid-based inhaler, the medication cost several hundred dollars each month; so instead, he'd been relying on over-the-counter Primatene Mist epinephrine inhalers.
He'd been at a party at a house owned by some people who had a cat. Archie is allergic to cats. He thought he'd be fine if he just stayed for an hour or so, but he ended up meeting an interesting woman and got distracted from his plans. When his asthma symptoms started, he left the party, but by the time he got home, he was struggling to stay conscious, and his inhaler wasn't really helping, so he had his roommate drive him to the emergency room again.
Archie was given a breathing treatment, which calmed his symptoms, but the E.R. doctor wouldn't let him go until he'd had a stern talking-to. "Your hematocrit levels are elevated, which means that your body isn't getting enough oxygen on a regular basis. You need to take your asthma medicine every day and not just use the inhaler when you're having an attack! You can die from this! And stay away from cats, too!"
Archie felt embarrassed, and knew that the doctor was right.
Use the information from this sheet and any other reliable resources available to you to answer the following questions.
Questions
1. What is asthma? Why is it sometimes linked to allergies? Asthma is a chronic inflammatory disease which inflames and narrows the airways. The bands of muscle that surround airways tighten; this causes them to narrow causing a broncho spasm. The cells in the airways produce a thicker than normal mucus. Symptoms include periods of wheezing, tightness in the chest, shortness of breath and coughing. Inflammation is amplified by local responses of the epithelium, smooth muscle, and fibroblasts through the production of chemokines, cytokines, and proteases (Cohn et al. 2004). Because the airways of an asthma suffer may be inflamed they are more sensitive to allergens. The hypersensitivity can cause asthma suffers to also be allergy suffers.
2. How might inhaled epinephrine improve asthma symptoms? Explain in terms of receptors. What might be the side effects of an epinephrine inhaler? Relaxation and contraction of smooth muscles is controlled by epinephrine receptors. Calmodulin is binded to calcium ions when the concentration is ten times higher than normal cells. The Calcium-Calmodulin complex activates the mysosin light chain kinacse (MLCK) .This phosphorylates the LC2 causing contraction. The binding of epinephrine to the epinephrine receptors produces cyclic AMP. Cyclic AMP acitivates protein kinase phosphorylating the MLCK. The MLCK now has a low affinity for the Calcium- Calmodulin complex and is inactived. This inactivation relaxes smooth muscle. When the smooth muscle is relaxed the airways are no longer constricted. (University of Delaware, Epinephrine) Complications of this medication include myocardial irritability, dysrythmias,fast heartbeat, headache, loss of appetite and nervousness. Absorption of epinephrine from the respiratory tract following large doses by oral inhalation may result in adverse effects such as bronchial irritation and edema. Some patients experienced severe asthma attacks. As the effects of epinephrine end rebound bronchospasm may occur . Arterial oxygen tension is already reduced during asthmatic attacks and may be further reduced following oral inhalation of epinephrine. American Society of Health System Pharmacists; AHFS Drug Information 2009. Bethesda, MD. (2009), p. 1392]
3. Why does elevated hematocrit indicate chronic low oxygen levels? A hematocrit level is a way of measuring what percentage of blood cells in your blood stream are red blood cells. Red blood cells are the cells that carry oxygen you're your lungs to the rest of your body. They are often known as sacs of hemoglobin which is what actually gives your red blood cells the ability to carry oxygen. High hematocrit means higher concentration of hemoglobin in the blood. When your body is low on oxygen it over produces red blood cells to meet the oxygen demands of your body.
4. If Archie goes to high altitude, list three physiological changes that can occur.
5. What happens to the oxygen hemoglobin curve if Archie exercises?