Question

Group 3: Topic 6 – 17-year-old girl case study

1. A 17-year-old student has experienced reversible, periodic attacks of chest tightness with coughing, wheezing, and hyperpnea. She states that expiration is more difficult than inspiration. She is most comfortable sitting forward with arms leaning on some support. X-rays revealed mild overinflation of the chest. Results from laboratory and pulmonary function tests are as follows:

Frequency	20 breaths/min
Forced Vital capacity (FVC)	2.9 L
FEV1.0	1.4 L
FEV1.0/FVC
Functional residual capacity (FRC)	3.89 L
Total lung capacity (TLC)	6.82 L
PaO2	70 mm Hg
PaCO2	26 mm Hg
Pulse	108 b/min
BP	120/76 mm Hg

Intermittent use of a bronchial smooth muscle dilator (1:1000 epinephrine by nebulizer) for several days caused marked improvement, resulting in the following laboratory and pulmonary function tests:

FVC	4.15 L
FEV1.0	3.1 L
FEV1.0/FVC
FRC	3.7 L
TLC	5.96L
PaO2	89 mm Hg
PaCO2	38 mm Hg
Pulse	129 b/min
BP	122/78 mm Hg

1. What is the likely disorder of this 17-year-old student? What is her FEV₁ / FVC ratio before treatment? What is her residual volume before treatment? Do these values point to restrictive or obstructive lung disease? Why is expiration more difficult than inspiration in this person?

2. Determine the FEV₁ / FVC ratio and residual volume (RV) after the use of the bronchodilator. How does this compare to pre bronchodilator therapy? What does the change in pulmonary function after the bronchodilator therapy indicate? Why does the bronchodilator exaggerate the tachycardia?
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3. How would you explain the signs and symptoms noted above (wheezing, coughing, hyperpnea, etc.) to the pathophysiology of asthma?
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4. What causes the hypoxemia and the hypocapnemia in this person? Explain why she is hypocapnic rather than hypercapnic. Predict the effect on PCO2 and pH if she were having a prolonged and severe acute asthma attack.
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5. The physician ordered a β-adrenergic agonist and an inhaled corticosteroid for this student. How are both medications important in the treatment of asthma? Which one is a quick-relief medicine, and which one of these is a long-term control medication?
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Answer 1

A. The 17 year old boy is suffering from asthmatic attack.

The FEV1 /FVC ratio also termed as tiffineau - pinelli index , refers to the amount of air a person can forcefully exhale from lungs . Normal FEV1/ FVC ration is 70%. According to the question, FEV1/ FVC before treatment is 48% ( 1.4/ 2.9)

Residual volume is the volume of air remaining in the lungs after maximal exhalation, according to the question , RV before treatment;

RV = FRC- ERV , FRC =3.89 L, ERV is not mentioned in the question.

The patient with asthma attack has a longer expiration than inspiration due to mild airway obstruction, so its hard to breath out during asthma attack and more air gets trapped inside the lung so the stridor sound is heard on auscultation.

B.FEV1/ FVC after use of bronchodilator =3.1/4.15= 74% ; which points to an improvement in patient than the normal value for 4 %.

After the use of a bronchodilator, it relaxes the muscle bands around the airway, which help to rapidly open the airway letting free movement of air in and out of the lungs.and it helps in expelling the excess mucus present in the lungs.so the pulmonary function before and after bronchodilator therapy shows an improvement in patient.

Bronchodilators has a direct stimulation of cardiac beta 2 adrenoreceptor and atimulation of sympathetic rexeptors in heart which cause arrhythmia , vasodilation and consequentreflex vagal withdrawl.

C. TRIGGER FACTOR ---> AIRWAY INFLAMMATION ----> hypersecreation of mucus/ airway muscle constriction/ swelling of bronchial membrane------> NARROW BREATHING PASSAGE----> COUGH, WHEEZING, CHEST TIGHTNESS, SOB

D. HYPOXEMIA and Hypocapnemia due to hyperventilation.The predicted outcome is RESPIRATORY ACIDOSIS.,as  PH decreases and Co2 increase in the body during severe acute asthma attack.

E. Beta adrenergic agonist help in dilation of the blood vessel and bronchioles and corticosteroides help to reduce the inflammation and excess mucus secreation in the respiratory tract.The combined effect of both this medication help by free air movement , by reduction of inflammation and removal of mucus from the tract. Beta adrenergic agonist example salbutamol is used as a long term control medication for asthma attack patient.