Flashcards in Small Group 4 Ventilation Control/ Sleep Deck (10):
Why do the lower, lateral costal margins show inward motion during inspiration in a COPD patient?
costal margins are pulled inwards by a flattened diaphragm
Why would leaning forward assist in breathing for a patient with severe COPD?
increased abdominal pressure at the end of exhalation causes the diaphragm to start from a more mechanically advantageous position
Does tobacco use effect sleep apnea?
How do levels of chemical stimuli (PaCO2 and PaO2) fluctuate during periodic breathing?
during apnea PaCO2 increases and PaO2 decreases upon microarousal, PaCO2 decreases and PaO2 increases
an increased gain in ventilatory response in this situation causes the PaCO2 to fall below the apnea threshold
Neuromuscular disease would be expected to present with what changes in normal lung volumes?
low TLC, normal FRC, high RV, low ERV
additionally, patients with bilateral diaphragmatic paralysis typically describe supine dyspnea (no gravity to aid the diaphragm descent)
Why is paradoxical inward abdominal motion observed in cases of neuromuscular weakness?
diaphragm is pulled into the chest by negative intrathroacic pressure, when upright, gravity tends to counteract this process
How is definitive diagnosis of bilateral diaphragmatic paralysis made?
measurements of trans-diphragmatic pressure
Why is central apnea more common in patients with muscular dystrophy?
REM sleep normally inhibits the activity of skeletal muscles (except the diaphragm) which are particularly important in cases of bilateral diaphragmatic paralysis, to continue adequate ventilation
How would you differentiate a high PaCO2 caused by inspiratory drive v. muscle weakness?
inspiratory drive is measured by mouth occlusion pressure and mean inspiratory flow, if these are normal, muscle weakness should be considered for possible decrease in TV