Читать книгу Respiratory Medicine - Stephen J. Bourke - Страница 39

1 1.1 The principal muscle(s) involved in inspiration is (are):the diaphragmrectus abdoministhe scalene musclessternocleidomastoidsthe intercostals

2 1.2 Lung compliance:is reduced as lung volume increasesis reduced in emphysemais increased in lung fibrosisis the change in pleural pressure per unit change in lung volumeis the principal factor determining forced expiratory flow

3 1.3 In relation to airway resistance:overall airway resistance increases as lung volume increasesin health, at high lung volume, the greater part of airway resistance is situated in the central airwaysairway resistance is reduced in emphysema due to diminished retractile force on the airwayairway resistance is proportional to the cubed power of the radius of the airway (r3)forced expiratory flow is unrelated to effort

4 1.4 In relation to ventilation (V) and perfusion (Q): the upper zones of the lungs are ventilated more than the lower zonesthe upper zones of the lungs receive more perfusion than the lower zonesV/Q is greater in the lower zonesVQ matching is essential to gas exchangereduced overall ventilation leads to a fall in PCO2

5 1.5 In a patient breathing room air at sea level, the arterial blood gases were: pH 7.36, PCO 2 3.2 kPa, PO 2 12 kPa, aHCO 3 – 19, base excess –5. The alveolar–arterial gradient is:2.5 kPa5.0 kPa5.5 kPa6.5 kPa10.0 kPa

6 1.6 During expiration, the diaphragm: risesremains unchangedshortensstiffenscauses a fall in intrathoracic pressure

7 1.7 A reduction in ventilation leads to: a rise in PaCO2 and PaO2a fall in PaCO2 and PaO2a rise in PaCO2 and a fall in PaO2a fall in PaCO2 and a rise in PaO2a rise in PaCO2 and no change in PaO2

8 1.8 VQ mismatching leads to: a rise in PaCO2 and no change in PaO2a fall in PaCO2 and PaO2a rise in PaCO2 and a fall in PaO2a fall in PaCO2 and a rise in PaO2no change in PaCO2 and a fall in PaO2

9 1.9 In relation to the control of breathing: hypoxia is irrelevanta rise of 0.2 kPa in pCO2 is required before ventilation is driven to increasea metabolic acidosis can increase ventilation and therefore PaO2a fall in blood pH will tend to reduce ventilationa fall in pH implies there has been a reduction in ventilation

10 1.10 In relation to airway resistance: resistance is unrelated to lung volumethe site of principal resistance moves to the smaller airways as lung volume is reducedmaximum forced expiratory flow can be achieved at mid lung volumeFEF25–75 provides accurate information on the calibre of the large airwaysFEF25–75 provides accurate information on the calibre of the small airways