Ms. MC is a 59 yo woman with long history of smoking 1 – 1.5 packs/day (20+ years) but is no longer smoking. She notices that she fatigues quickly, is often short of breath, coughs frequently and has ankle swelling. She has trouble sleeping but noted some improvement with extra pillows. You note an increase in anteroposterior chest diameter, prolonged expiratory phase with wheezing. She also has cyanosis of nailbeds with moderate pitting edema bilaterally. Lab tests reveal Hgb is high normal, PaO2 is low at 48 mmHg, O2 saturation is at 80%, PCO2 is significantly elevated (70 mmHg) and HCO3- is also elevated above normal (35 mEq/L). Your diagnosis is a combination of chronic bronchitis and emphysema (COPD). Pulmonary function tests revealed a decrease in Vital Capacity and Expiratory Flow Rate combined with an increase in both Residual Capacity and Functional Residual Capacity. These types of tests could also reveal other conditions, such as asthma, as well as guide treatment to prevent significant attacks.
1 What changes occurred in her airways that led to obstruction and increased airway resistance? (Hint: View it in two parts: 1) the airway changes and 2) the alveolar tissue changes relating to elasticity and compliance). (Pulmonary System MO2,3,5,7,8,23,26)
2 How does acidosis, such as caused by ketones or CO2 retention, alter the delivery of oxygen to the tissues? (Pulmonary System MO2,5,9,11,12,16)
3 What is a V/Q ratio and how does it affect oxygenation of blood in health and disease? In late stages of COPD, such as seen above, how is V/Q altered (Hint, see fig. 27-17) (Pulmonary System MO5,6,9,10)
4 Why does she have ankle edema? What role does the lung play in hydrostatic pressure changes seen here? What is the effect pulmonary artery pressure and resultant changes to the right side of the heart? (Pulmonary System MO9,13,14,18,25,30)
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