Question

Emma Norton, aged 26, is admitted to hospital with an acute exacerbation of her COPD. Using your knowledge of the respiratory system (M2) and the cardiovascular system (M3), please answer the following questions below. Be sure to clearly label the different parts:

PART A / Emma undergoes a pulmonary lung function test. How would her total lung capacity test and her FEV1/FVC values compare to normal physiological values?

PART B / In hospital, Emma is placed on oxygen but develops respiratory depression. Explain why Emma stops breathing when she is administered oxygen.

PART C / Emma's COPD has caused pulmonary hypertension and subsequent failure of the right ventricle. What are the roles of venous pressure and capillary hydrostatic pressure in causing edema?

PART D /  Emma's right ventricular failure has caused a decrease in cardiac output. Explain which hormonal system will be activated and how it compensate for this.

Answer 1

Part A)

in the case of Emma , the total lung capacity(TLC) is the maximum volume of air the lungs can have to be filled up or the Total of all volume of air present in lungs after maximum inspiration. The normal range of TLC is approximately 4-6L .

The FEV1/FVC ratio also termed as Tiffeneau-Pinelli index is the ratio of the forced expiratory volume in the first 1 second to the forced vital capacity of the lungs. This is important for the deduction of the percentge of lung size in first second. Lesser ratio (<70%) implies the obstruction in the airways as in asthma, emphysema and COPD that results in Decreased lung recoil pressure.

Part B)

Emma was admitted in the hospital for her acute exacerbation of COPD , this causes Carbondioxide retention in lungs therefore respiratory depression comes into existence.

Emma stops breathing when she is administered oxygen because when in COPD when oxygen is administered the hypoventilation conditions leads to hypercapnia which could ultimately worsen to apnea and respiratory failure as a complication.

Part C)

Emma's COPD has caused pulmonary hypertension and subsequent failure of the right ventricle. The capillary hydrostatic pressure is pressure exerted by blood on capillary walls. When volume overload , increased venous pressure and heart failure altogether are noticed the capillary hydrostatic pressure leads to accumulation of fluid .

The Decreased plasma oncotic pressure and venous pressure being more than oncotic pressure leads to fluid accumulation and edema later on.

Part D)

Emma's right ventricular failure has caused a decrease in cardiac output for compensation of this Rennin , aldosterone and angiotensin would be secreted for vasoconstriction. This vasoconstriction would lead to sodium and water retention thereby counteracting the reduced cardiac output to prevent heart failure.