Reference no: EM132902886

BIOL122 Human Biological Science - Australian Catholic University

Twenty-one-year-old Lisa long has been suffering from asthma and is now experiencing an asthma attack while taking an afternoon walk with her sister. It is a cold, windy, early spring weekend. She complains of acute shortness of breath and has audible wheezing, episodic cough, and chest tightness with itchy red watery eyes and a stuffy, runny, itchy nose. These symptoms become worse within 5 minutes. Her sister called 000 and paramedics promptly attended to Lisa, who was fully conscious, appeared wide-eyed and frightened, and unable to breathe effectively. She was

immediately transferred to the nearest hospital for full respiratory function assessment and treatment of acute asthma.

A physical exam reveals a HR of 120/min, RR of 38/min, with signs of accessory muscle use. Chest auscultation reveals decreased breath sounds bilaterally, with inspiratory and expiratory wheezes. Lisa is coughing up small amounts of thin, clear sputum and has an arterial oxygen saturation of 90%.

Nebulised salbutamol, oxygen by facial mask, and systemic corticosteroid were administered. A second small-volume nebuliser treatment was ordered 20 minutes later. Chest auscultation revealed diminished wheezes; RR was 24 at this time and HR was 102. Over the next 24 hours Lisa showed steady improvement and was discharged for follow-up with her local GP to review her asthma action plan and change any medications as needed to help prevent future exacerbations.

Question 1. List two factors that could have triggered Lisa's acute asthma attack and explain the link between the named factors and her asthma.

Question 2. Explain the pathophysiological steps leading to acute asthma attack. In your answer, you are expected to link type 1 hypersensitivity reaction to the role of histamine in acute asthma.

Question 3. Briefly explain the mechanisms of action of (i) salbutamol and (ii) corticosteroids in the treatment of acute asthma and describe their benefits in Lisa's condition.

Question 4. Explain the mechanism of action of anticholinergic/anti-parasympathetic medications and their potential benefit(s) in asthma treatment.

Lisa's grandmother, Maria, is a 67-year-old retired, obese woman, who lives with her husband Max. She enjoys sitting down to a movie every night with a bottle of Shiraz and a large packet of salt and vinegar chips or tub of cookies and cream ice cream. She has always loved a glass or two of wine with dinner but now figures she can have a few more since she no longer has to get up for work.

Maria doesn't like to exercise; her only form of exercise is walking around Coles on Friday whilst doing her weekly shopping. Her sister has asked her to join her walking group on numerous occasions, but Maria would rather stay home and bake. Maria's mother moved in with her many years ago when her father passed away from a heart attack at the age of 60. Her mother isn't in the best of health, she has type II diabetes and hypertension, which she controls with medication.

One day Maria decides to visit her neighbour, taking with her a batch of freshly baked cookies. Whilst walking to her neighbour's house, she notices that she is short of breath and is feeling a slight pain in her chest, but when she sits down, she feels fine, so she dismisses it once again, putting it down to her poor fitness. However, on her way home she begins to feel light-headed and weak and feels like she is going to be sick. She notices that she has been feeling like this quite a lot lately, even when resting in the evening, so she decides to make an appointment with her GP for later in the week.

At the medical clinic, the GP takes Maria's blood pressure reading. It has been elevated on a number of occasions, and today is no different-the reading shows 140/95 mmHg. The GP prescribes an ACE inhibitor and tells Maria she really needs to make some lifestyle changes. He writes a referral for her to see a cardiovascular specialist for an ECG and a coronary angiogram to determine why Maria has been short of breath and unwell.

One day, whilst waiting for her results, Maria starts to feel more nauseous and dizzier than usual. She starts to feel clammy and sweaty, and her face seems gray in colour. The chest pain returns but now feels like a crushing pain, and she can't breathe. Her husband, Max, dials 000, and she is rushed to hospital. An ECG shows that Maria has an ST elevation, and a blood test indicates that she has high levels of troponin in her blood. Maria is given heparin intravenously as well as an anti-platelet and a fibrinolytic drug. She is taken into surgery, where a coronary angioplasty is performed.

Question 5. Explain what Maria's blood pressure readings suggest and discuss two risk factors that might have contributed to Maria's present condition.

Question 6. Explain the expected benefits of ACE inhibitors in the above case study by referring to their pharmacodynamics and pharmacological effects.

Question 7. Name the condition Maria was suffering from when she was rushed to hospital and discuss two clinical findings that support your claim.

As part of her therapy, Maria takes a new, hypothetical medication (called MedX), which has narrow therapeutic index, therefore you (as a health care professional) need to exercise special care when it comes to the determination of her required dosage.
MedX is taken orally and has the following features:
• In healthy adults, the absorbed MedX is subject to first pass liver metabolism, which decreases its bioavailability to 10%.
• The active ingredient that enters the systemic circulation is water-soluble and shows very high protein binding: 98% of the drug molecules present in the plasma are bound to albumin and, to a smaller extent, α1 globulin.
• Most of the drug is excreted by the kidneys, where it is both freely filtered and actively secreted in the proximal tubule.

Question 8. Based on the above properties of the drug, explain why you would recommend dose reduction in Maria's case. In your answer, explain four age-related changes in the pharmacokinetics of MedX to justify why dose reduction is necessary in the present scenario. For each of those age-related changes described, you will need to consider how the free plasma concentration of the drug is expected to change in Maria's case compared to that of a young or middle-aged individual.