Question

A/. A lung with pulmonary fibrosis would exhibit which of the following characteristics?

a. Decreased airway resistance
b. Decreased lung compliance
c. Decreased PVR
d. Decreased surface tension

B. Which of the following indicate a patient is severe decrease in respiratory muscle inspiratory strength?

a. MIP less than -50 cm H20
b. MIP less than -60 cm H20
c. MIP greater than -20 cm H20
d. MIP lower than -20 mm Hg

C.  What is the term for alveolar ventilation without pulmonary capillary perfusion?

a.   alveolar deadspace   c.   minute alveolar ventilation
b.   physiologic deadspace   d.   anatomic deadspace

Answer 1

A. Answer : b. Decreased lung compliance

Pulmonary fibrosis is a condition in which the lung tissues becomes damaged and scarred. The scarring and thickening of the tissues reduces the functioning of the lung which reduces oxygen intake. The main causes of pulmonary fibrosis are viral and bacterial infections; autoimmune diseases such as rheumatoid arthritis, lupus, vasculitis etc ; environmental factors such as exposure to asbestos fibers, radiation; medications such as chemotherapy. When the cause of fibrosis is unknown its termed as idiopathic pulmonary fibrosis. Lung compliance is the elasticity of the lung tissues. In patients with pulmonary fibrosis, the lung tissues are scarred too much making it less elastic.

B. Answer : d. MIP lower than 20mm Hg

Maximum inspiratory pressure is also known as negative inspiratory force. It is the maximum pressure that can be generated against an occluded airway beginning at functional residual capacity. It is used as a method to estimate the respiratory muscle function and strength. The normal value is 80 cm H2O. The acceptable value is 20 cm H2O. Value less than 20 cm H2O is considered is unacceptable. 20cm H2O is equal to 14.7112 mm Hg.

C. Answer: a. Alveolar deadspace.

Alveolar deadspace refers to amount of air that does not take part in gas exchange though the alveoli are well ventilated. That is ventilation is present without perfusion.

Dead space in general refers tp to the amount of air that does not take part in gas exchange. It is of two types : anatomic and physiologic.

Anatomic dead space is the region from the nasal or oral cavity to the terminal branches of the bronchi. Physiologic dead space includes the alveolar deadspace with the anatomic deadspace.